Fishes

15 pages, 1806 KiB

Open AccessEditor’s ChoiceArticle

Spawning Potential Ratio Can Provide Reference Points for Fishery Management That Are Robust to Environmental Variability

by Kyle W. Shertzer, Matthew D. Damiano and Erik H. Williams

Fishes 2024, 9(12), 497; https://doi.org/10.3390/fishes9120497 - 3 Dec 2024

Cited by 2 | Viewed by 1218

Abstract

Biological reference points are key quantities provided by stock assessments and used in fishery management for evaluating fishery status and setting future catch levels. For many fisheries worldwide, biological reference points are based on the spawning potential ratio (SPR), which measures per-recruit reproductive [...] Read more.

Biological reference points are key quantities provided by stock assessments and used in fishery management for evaluating fishery status and setting future catch levels. For many fisheries worldwide, biological reference points are based on the spawning potential ratio (SPR), which measures per-recruit reproductive output as a function of the fishing rate relative to that when fishing is absent. SPR depends on the biological characteristics of the stock, which in turn can be influenced by the environment. A fishing rate based on SPR is often used as a proxy for the fishing rate that provides maximum sustainable yield. Here, we evaluate variability in the fishing rate (F₄₀) that provides an SPR of 40%, a commonly used limit reference point, given plausible variability in biological characteristics. Using eight case-study species from marine waters off the southeast United States, we consider both simple random variability and directional variability, both of which might result from climate change. We test the sensitivity of F₄₀ to various life-history traits and compute distributions of F₄₀, given the expected variability in those traits. Based on those distributions, we evaluate the probabilities of overfishing given a target fishing rate (here, 75%F₄₀) that is based on prevailing conditions without considering future variability in F₄₀, consistent with common, current practice. Analyses also considered an SPR of 30% and 50% to evaluate the generality of conclusions. Results support that SPR-reference points are generally robust to plausible levels of variability in life-history traits that might be induced by environmental nonstationarity and that associated target fishing rates can provide meaningful buffers to prevent overfishing. Full article

(This article belongs to the Special Issue Fisheries Stock Assessment and Modeling)

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17 pages, 1652 KiB

Open AccessEditor’s ChoiceArticle

Hepatic Gene Expression Changes of Zebrafish Fed Yeast Prebiotic, Yeast Probiotic, Black Soldier Fly Meal, and Butyrate

by Nancy Gao, Junyu Zhang, Umesh K. Shandilya, John S. Lumsden, Amir Behzad Barzrgar, David Huyben and Niel A. Karrow

Fishes 2024, 9(12), 495; https://doi.org/10.3390/fishes9120495 - 2 Dec 2024

Viewed by 995

Abstract

As global fish consumption rises, improving fish health through immunomodulatory feed ingredients shows promise while also supporting growth performance. This study investigated the effects of yeast prebiotics, probiotics, a postbiotic (butyrate), and black soldier fly larvae (BSFL) meal on fish immune responses. Zebrafish [...] Read more.

As global fish consumption rises, improving fish health through immunomodulatory feed ingredients shows promise while also supporting growth performance. This study investigated the effects of yeast prebiotics, probiotics, a postbiotic (butyrate), and black soldier fly larvae (BSFL) meal on fish immune responses. Zebrafish were fed diets containing these ingredients for 63 days and then exposed to either Pseudomonas aeruginosa lipopolysaccharide (LPS) or live Flavobacterium psychrophilum to assess hepatic candidate gene expression and weight gain. No mortalities were observed post-immune challenges, and weight gains were not significantly different across treatments. Liver samples were collected for mRNA analysis, and real-time qPCR was used to evaluate the expression of immune-related genes such as TNF-α, IL-1β, hepcidin, and NF-κB/p65. NF-κB/p65 was upregulated in response to immune challenges, indicating a reaction to both LPS and pathogen exposure. Fish on the BSFL diet showed decreased NF-κB/p65 expression after the pathogen challenge, while probiotic-fed fish had reduced angiopoietin-like 4 (angptl4) levels following LPS exposure. Butyrate supplementation had the most significant impact, downregulating pro-inflammatory cytokines and other immune-related genes, suggesting a protective effect. These findings support the health benefits of BSFL and sodium butyrate during an immune challenge. Full article

(This article belongs to the Special Issue Effect of Dietary Supplementation on the Growth and Immunity of Fish and Shellfish—2nd Edition)

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14 pages, 1377 KiB

Open AccessEditor’s ChoiceArticle

The Effects of Predominantly Chemoautotrophic Versus Heterotrophic Biofloc Systems on Nitrifying Bacteria, Planktonic Microorganisms, and Growth of Penaeus vannamei, and Oreochromis niloticus in an Integrated Multitrophic Culture

by Raysa Pâmela Oliveira Sena, Dariano Krummenauer, Wilson Wasielesky, Jr., Otávio Augusto Lacerda Ferreira Pimentel, Aline Bezerra, Jorge Renato Tagliaferro dos Santos Junior, Andrezza Carvalho, Elisa Ravagnan, Andrea Bagi and Luis H. S. Poersch

Fishes 2024, 9(12), 478; https://doi.org/10.3390/fishes9120478 - 26 Nov 2024

Viewed by 1042

Abstract

The aim of this study was to evaluate the effect of predominantly chemoautotrophic and heterotrophic biofloc systems on ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and planktonic microorganisms in an integrated Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. Shrimp and tilapia were stocked [...] Read more.

The aim of this study was to evaluate the effect of predominantly chemoautotrophic and heterotrophic biofloc systems on ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and planktonic microorganisms in an integrated Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. Shrimp and tilapia were stocked at a density of 400 shrimp m⁻² and 45 fish m⁻³, respectively. The trial consisted of two biofloc treatments, with three replicates each: chemoautotrophic and heterotrophic. The identification and quantification of the planktonic microorganisms (ciliates, flagellates, microalgae, and total bacteria) and nitrifying bacteria were carried out through direct counting and fluorescence in situ hybridization, respectively. At the end of the trial, heterotrophic treatment had resulted in higher total abundance of bacteria. The relative abundance of AOB and NOB in relation to the total abundance was less than 0.1% for both treatments. The system was dominated by flagellates in both treatment groups. The abundance of microalgae and ciliates was higher with chemoautotrophic treatment. After 43 days, the shrimp weights were higher in the chemoautotrophic group, while the final weights of the tilapia were not significantly different between the two treatments. The type of biofloc system (Chemoautotrophic vs. Heterotrophic) did not significantly alter the establishment of AOB and NOB in a Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. The two treatments proved to be equally efficient for maintaining good water quality, but the chemoautotrophic treatment resulted in better shrimp growth. Thus, our study demonstrated that chemoautotrophic biofloc is a promising approach in integrated multitrophic aquaculture. Full article

(This article belongs to the Special Issue Biofloc Technology in Aquaculture)

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17 pages, 8321 KiB

Open AccessEditor’s ChoiceArticle

Ease and Limitations in Using Environmental DNA to Track the Spread of Invasive Host–Parasite Complexes: A Case Study of the Freshwater Fish Pseudorasbora parva and the Cryptic Fungal Parasite Sphaerothecum destruens

by Théo Deremarque, Rodolphe Elie Gozlan, Ravo Ravaozafindrasoa, Giuliano Mucci, Lucie Delalex, Jean-Michel Foissy, Michaël Cagnant, Mathieu Clair, Justina Givens, Fabienne Justy, Alice Valentini, Delphine Nicolas, Pascal Contournet, Claire Tetrel, Marc Thibault and Marine Combe

Fishes 2024, 9(12), 477; https://doi.org/10.3390/fishes9120477 - 26 Nov 2024

Viewed by 995

Abstract

The spread of non-native species threatens biodiversity and exacerbates societal challenges like food security. To address this, effective conservation programs require detection methods that are easy to implement, accurate, and non-invasive. Over the past 15 years, environmental DNA (eDNA) techniques have gained popularity, [...] Read more.

The spread of non-native species threatens biodiversity and exacerbates societal challenges like food security. To address this, effective conservation programs require detection methods that are easy to implement, accurate, and non-invasive. Over the past 15 years, environmental DNA (eDNA) techniques have gained popularity, surpassing traditional sampling methods. In this context, our study focused on tracking the invasive host–pathogen complex Pseudorasbora parva and Sphaerothecum destruens using eDNA metabarcoding. We collected water samples from freshwater canals over five months in the Camargue region, and once in Corsica Island, both in southern France. Total DNA was extracted from filtered water samples, and PCR-amplicons were sequenced using Illumina or Nanopore technologies. Our results revealed a high detection rate of P. parva in lentic ecosystems, aligning with habitat preferences of this small freshwater fish. Additionally, the detection rate in Camargue increased in May and June, likely due to the peak of the spawning season, which leads to more DNA being released into the environment (i.e., concentration and interaction of individuals). While eDNA successfully detected this invasive fish, we were unable to detect its cryptic fungal parasite, S. destruens, highlighting the challenges of identifying intracellular and cryptic fungal pathogens through eDNA methods. Full article

(This article belongs to the Special Issue Detection and Monitoring of Aquatic Pathogens by Using Environmental DNA (eDNA))

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20 pages, 6057 KiB

Open AccessEditor’s ChoiceArticle

Ultimate Fighting Crab: Agonistic Behaviour, Dominance, and Recognition in the Edible Crab, Cancer pagurus (L.)

by Finlay James Archibald Hamilton, Jonathan David Wilkes and Kevin Scott

Fishes 2024, 9(11), 455; https://doi.org/10.3390/fishes9110455 - 9 Nov 2024

Viewed by 1250

Abstract

Edible crabs (Cancer pagurus) are an economically important species for Scottish inshore fisheries, with an estimated annual landing value of GBP 16 million (2023). Research into the behaviour, particularly agonistic behaviour, of this species is currently lacking. This paper aims to [...] Read more.

Edible crabs (Cancer pagurus) are an economically important species for Scottish inshore fisheries, with an estimated annual landing value of GBP 16 million (2023). Research into the behaviour, particularly agonistic behaviour, of this species is currently lacking. This paper aims to investigate behaviour, social interactions, potential hierarchies, and the impact of claw size on the outcomes of agonistic interactions of male C. pagurus through behavioural trials and retrials. Crabs were semi-randomly assigned to pairs (based on allocated condition index rating) and introduced to one another in trial tanks. Each pair underwent two trials, 24 h apart (the “trial” and “retrial”). Analyses of video records of agonistic bouts revealed that 77% of retrials were won by the initial victors, with a significant decrease in fight time between trials and retrials. Fight time was not correlated with weapon size (claw length, height, and depth). There were no differences in weapon size of winners and losers of bouts. Winners exhibited a significantly higher frequency of aggressive and dominant behaviours (approach, aggressive contact, threat displays, and mounting), and losers exhibited higher frequencies of submissive behaviours (withdrawal, retracting limbs, and remaining motionless). These results suggest that individual behaviour may play more of a role in dominance than size or other morphometric characteristics. Full article

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12 pages, 6995 KiB

Open AccessEditor’s ChoiceArticle

Matings Between Individuals with Similar Major Histocompatibility Complex (MHC) Improve Offspring Survival in the Rainbow Trout (Oncorhynchus mykiss)

by Cinzia Bergamino, Mattia Tomasoni, Silvia Colussi, Vittoria Montemurro, Ilhan Altinok, Marino Prearo, Charalampos Kotzamanidis, Pier Luigi Acutis, Ana Isabel Vela, Simona Sciuto, Giuseppe Esposito, Donatella Volpatti, Elena Bozzetta, Katia Parati, Lucia Aidos, Lucio Fariano and Benedetto Sicuro

Fishes 2024, 9(11), 436; https://doi.org/10.3390/fishes9110436 - 27 Oct 2024

Viewed by 1080

Abstract

The major histocompatibility complex (MHC) consists of genes involved in immune response and molecular discrimination between self and non-self. MHC genes are the most polymorphic in vertebrates. The origin and maintenance of polymorphism in MHC genes in populations is still unresolved. Mechanisms such [...] Read more.

The major histocompatibility complex (MHC) consists of genes involved in immune response and molecular discrimination between self and non-self. MHC genes are the most polymorphic in vertebrates. The origin and maintenance of polymorphism in MHC genes in populations is still unresolved. Mechanisms such as sexual selection and heterozygote advantage have been suggested as explanations for this high variability. In this study, a farmed population of rainbow trout (Oncorhynchus mykiss) characterized by the presence of specific MHC class IIB gene haplotypes at a frequency higher (30%) than that expected from random matings was investigated. Therefore, it was hypothesized that disassortative matings occur with an adaptive advantage for females, resulting in improved reproductive performance when mated with individuals with similar MHC haplotypes. Genetic analyses of the breeders were performed to define the MHC haplotypes and to perform specific matings. The effect of mating was evaluated by analyzing the survival rate of the offspring at various stages of incubation until swim-up. The reproductive performance of the offspring derived from specimens with similar haplotypes showed a better survival trend during the first life stages and reduced malformations. The results obtained are in contrast with the heterozygous advantage theory, therefore it was hypothesized, as for other salmonid species, the presence of a positive selection towards locally adapted MHC genes that promotes reproduction between genetically similar individuals. Full article

(This article belongs to the Special Issue Advances in Rainbow Trout)

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24 pages, 3102 KiB

Open AccessEditor’s ChoiceArticle

Fishes Associated with a Vulnerable Marine Ecosystem Network in the Central Mediterranean Sea

by Angela Carluccio, Francesca Capezzuto, Porzia Maiorano, Letizia Sion and Gianfranco D’Onghia

Fishes 2024, 9(11), 433; https://doi.org/10.3390/fishes9110433 - 26 Oct 2024

Viewed by 819

Abstract

In order to collect information on ichthyofauna of a deep-sea vulnerable marine ecosystem (VME) network along the Apulian margin (central Mediterranean Sea), two low-impact sampling tools were used in three VMEs characterized by cold-water corals (CWC), namely Bari Canyon (BC), off Monopoli (Mn), [...] Read more.

In order to collect information on ichthyofauna of a deep-sea vulnerable marine ecosystem (VME) network along the Apulian margin (central Mediterranean Sea), two low-impact sampling tools were used in three VMEs characterized by cold-water corals (CWC), namely Bari Canyon (BC), off Monopoli (Mn), and off Santa Maria di Leuca (SML). Using an experimental longline, 53 deployments were carried out between a 314 and 650 m depth for a total of 217 fishing hours, whereas when using the baited lander MEMO (Marine Environment MOnitoring system), 31 deployments were carried out between 427 and 792 m, for a total of 223 h of video recordings. A total of 37 taxa were recorded, comprising 13 Chondrichthyes and 24 Osteichthyes. The similarities in species observed among the VMEs confirm the presence of a network of CWC-VMEs along the Apulian margin, whereas some differences detected are due to the different abundance of some species, such as Galeus melastomus, Helicolenus dactylopterus, and Phycis blennoides. The presence of commercial species, vulnerable/endangered cartilaginous fishes, and large and sexually mature individuals of G. melastomus, H. dactylopterus, and Pagellus bogaraveo in all the VMEs confirms that the network of CWC-VMEs along the Apulian margin can act as a network of refuge areas and an essential fish habitat (EFH) for species threatened by fishing activities. Full article

(This article belongs to the Special Issue Biology and Ecology of Coral Reef Fishes)

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11 pages, 273 KiB

Open AccessEditor’s ChoiceArticle

The Impact of Thermal Treatments up to 140 °C on Amino Acid Digestibility of Fish Meal in Rainbow Trout (Oncorhynchus mykiss)

by Pedro Henrique Sessegolo Ferzola, Judith Ringel, Carsten Schulz and Martin Gierus

Fishes 2024, 9(10), 403; https://doi.org/10.3390/fishes9100403 - 6 Oct 2024

Cited by 2 | Viewed by 848

Abstract

Fish meal (FM) is an essential ingredient in fish feeds, but the thermal treatments used during its production might affect its nutrient availability. Therefore, an in vivo digestibility trial was conducted with three different thermal treated FM, at no heat treatment (control), 70, [...] Read more.

Fish meal (FM) is an essential ingredient in fish feeds, but the thermal treatments used during its production might affect its nutrient availability. Therefore, an in vivo digestibility trial was conducted with three different thermal treated FM, at no heat treatment (control), 70, and 140 °C. A total of 216 rainbow trout (230 ± 6.0 g) were randomly assigned to 12 tanks, and feces samples were collected by stripping. FM was produced by lyophilizing mackerel. The lyophilized FM (94% DM) was then divided into three groups: FM Control, which was not exposed to thermal treatments, and FM 70 °C and FM 140 °C, which were exposed for 1 h to the respective temperatures of its descriptions. A conventional FM-based (FM with 64% CP produced at 110 °C) control diet was used as a basal diet. In the experimental groups, 30% of the basal diet was replaced by one of the tested FMs. No differences in apparent total tract digestibility (ATTD) were observed between FM Control and 70 °C. Protein ATTD of FM 140 °C as well as Arg ATTD were lower compared to FM Control and 70 °C. The same effect was observed for His and Asp ATTD. The current study showed that thermal treatment affects FM macronutrient and amino acid ATTD. Full article

(This article belongs to the Section Nutrition and Feeding)

16 pages, 4164 KiB

Open AccessEditor’s ChoiceArticle

Sea Bass (Dicentrarchus labrax) Tail-Beat Frequency Measurement Using Implanted Bioimpedance Sensing

by Vincent Kerzerho, Mohamed-Moez Belhaj, Serge Bernard, Sylvain Bonhommeau, Tristan Rouyer, Fabien Soulier and David J. McKenzie

Fishes 2024, 9(10), 399; https://doi.org/10.3390/fishes9100399 - 1 Oct 2024

Viewed by 1143

Abstract

Estimating tailbeat frequency (TBF) is a crucial component of fish swimming kinematics and performance, particularly because it provides information about energetics and behavioral responses to environmental cues. The most commonly used technique for TBF estimation is based on accelerometers. This paper proposes a [...] Read more.

Estimating tailbeat frequency (TBF) is a crucial component of fish swimming kinematics and performance, particularly because it provides information about energetics and behavioral responses to environmental cues. The most commonly used technique for TBF estimation is based on accelerometers. This paper proposes a novel approach using bioimpedance technology. This is the first time bioimpedance has been measured in a freely moving animal. This was made possible by implanting a flexible electrode in the back muscle of seabasses and having them in a swimming tunnel. The experiment first demonstrates that it is possible to measure bioimpedance in an immersed fish despite the high conductivity of seawater. An agreement analysis was then performed to compare a video-based reference measurement of TBF with the newly proposed approach. Several bioimpedance settings, such as the configuration and the extracted electrical parameters, were considered. Data analysis highlights that a 4-point setup for modulus impedance measurement at frequencies over 10

k

Hz

provides the best agreement (r > 0.98 and CCC > 0.97) with the video-based approach. These results attest to the significant benefits of integrating bioimpedance sensors in biologgers, especially considering the complementary parameters that can be extracted from bioimpedance measurements, such as length, weight, condition index, and fat content. Full article

(This article belongs to the Special Issue Technology for Fish and Fishery Monitoring)

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14 pages, 2494 KiB

Open AccessEditor’s ChoiceArticle

Virtual Sensing of Nitrite: A Novel Control for Safe Denitrification in Recirculating Aquaculture Systems (RASs)

by Anneliese Ernst, Christian Steinbach, Kai Wagner and Uwe Waller

Fishes 2024, 9(10), 398; https://doi.org/10.3390/fishes9100398 - 1 Oct 2024

Cited by 1 | Viewed by 3465

Abstract

Recirculating aquaculture system (RAS) technology is seen worldwide as a solution for sustainable fish production. However, there are still deficiencies in the process technology imperiling consistent operation and thus economic results. Drawbacks are linked to essential processes of the water treatment systems such [...] Read more.

Recirculating aquaculture system (RAS) technology is seen worldwide as a solution for sustainable fish production. However, there are still deficiencies in the process technology imperiling consistent operation and thus economic results. Drawbacks are linked to essential processes of the water treatment systems such as denitrification. Nitrogenous waste needs to be removed from RAS process water to maintain an adequate production environment for fish and to mitigate the environmental impact of discharged process water. At present, denitrification lacks reliable process control, especially regarding the organic carbon feed to heterotrophic denitrification processes. An investigation into heterotrophic denitrification in an experimental RAS resulted in the discovery of a virtual sensor based on measurements of the oxidation reduction potential (ORP). The virtual sensor responds to an insufficient carbon feed to denitrification. It is based on the oxidation of nitrite in an ozone-enhanced foam flotation installed downstream of the denitrification. The sensor essentially delivers a binary signal denoting either a complete or an incomplete denitrification process. The virtual sensor can be used for reliably controlling heterotrophic denitrification. It requires an upgraded process chain employing ozone-enhanced foam flotation (protein skimmer) downstream of the denitrification. However, the virtual sensor does not require any additional instrumentation. Full article

(This article belongs to the Special Issue Advances in Recirculating and Sustainable Aquaculture Systems)

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16 pages, 6641 KiB

Open AccessEditor’s ChoiceArticle

Assessing the Effects of Guiera senegalensis, Pluchea odorata, and Piliostigma reticulatum Leaf Powder Supplementation on Growth, Immune Response, Digestive Histology, and Survival of Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) Juveniles before and after Aeromonas hydrophila Infection

by Paul M. Ndour, Jean Fall, Maria J. Darias, Domenico Caruso, Marc Canonne, Elodie Pepey, Sophie Hermet, Sokhna K. L. Fall, Malick Diouf and Samira Sarter

Fishes 2024, 9(10), 390; https://doi.org/10.3390/fishes9100390 - 28 Sep 2024

Viewed by 926

Abstract

The effects of three medicinal plants in the feeds of juvenile Nile tilapia (Oreochromis niloticus) were investigated on growth, survival, immunity, and digestive histology at various inclusion levels: (A) Guiera senegalensis at 0, 1, 2, 4, and 8%; (B) Pluchea odorata [...] Read more.

The effects of three medicinal plants in the feeds of juvenile Nile tilapia (Oreochromis niloticus) were investigated on growth, survival, immunity, and digestive histology at various inclusion levels: (A) Guiera senegalensis at 0, 1, 2, 4, and 8%; (B) Pluchea odorata at 0, 0.5, 1, 2, and 4%; (C) Piliostigma reticulatum at 0, 1, and 2%; and (D) a mixture of the three at 0, 1, and 2%. After 28 days of feeding, fish were infected with Aeromonas hydrophila for 12 days. The results showed that, except for G. senegalensis, the inclusion of the medicinal plants, alone or combined, enhanced the immune response. The diet with 4% P. odorata significantly increased plasma lysozyme and bactericidal activities without affecting feed conversion efficiency or growth. Despite improved immunity, none of the treatments enhanced post-infection survival rates. However, fish fed the 1% mixture showed healthier livers and intestines, with reduced cell swelling and normal lipid deposits, followed by the 2% mixture and the control. These results highlight the potential benefits of incorporating P. odorata and the plant mixture into the diets of Nile tilapia juveniles for enhancing their immune response against A. hydrophila. Full article

(This article belongs to the Section Sustainable Aquaculture)

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13 pages, 9028 KiB

Open AccessEditor’s ChoiceArticle

Rapid Real-Time Prediction Techniques for Ammonia and Nitrite in High-Density Shrimp Farming in Recirculating Aquaculture Systems

by Fudi Chen, Tianlong Qiu, Jianping Xu, Jiawei Zhang, Yishuai Du, Yan Duan, Yihao Zeng, Li Zhou, Jianming Sun and Ming Sun

Fishes 2024, 9(10), 386; https://doi.org/10.3390/fishes9100386 - 28 Sep 2024

Cited by 2 | Viewed by 1319

Abstract

Water quality early warning is a key aspect in industrial recirculating aquaculture systems for high-density shrimp farming. The concentrations of ammonia nitrogen and nitrite in the water significantly impact the cultured animals and are challenging to measure in real-time, posing a substantial challenge [...] Read more.

Water quality early warning is a key aspect in industrial recirculating aquaculture systems for high-density shrimp farming. The concentrations of ammonia nitrogen and nitrite in the water significantly impact the cultured animals and are challenging to measure in real-time, posing a substantial challenge to water quality early warning technology. This study aims to collect data samples using low-cost water quality sensors during the industrial recirculating aquaculture process and to construct predictive values for ammonia nitrogen and nitrite, which are difficult to obtain through sensors in the aquaculture environment, using data prediction techniques. This study employs various machine learning algorithms, including General Regression Neural Network (GRNN), Deep Belief Network (DBN), Long Short-Term Memory (LSTM), and Support Vector Machine (SVM), to build predictive models for ammonia nitrogen and nitrite. The accuracy of the models is determined by comparing the predicted values with the actual values, and the performance of the models is evaluated using Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RMSE) metrics. Ultimately, the optimized GRNN-based predictive model for ammonia nitrogen concentration (MAE = 0.5915, MAPE = 28.95%, RMSE = 0.7765) and the nitrite concentration predictive model (MAE = 0.1191, MAPE = 29.65%, RMSE = 0.1904) were selected. The models can be integrated into an Internet of Things system to analyze the changes in ammonia nitrogen and nitrite concentrations over time through aquaculture management and routine water quality conditions, thereby achieving the application of recirculating aquaculture system water environment early warning technology. Full article

(This article belongs to the Special Issue Advances in Recirculating and Sustainable Aquaculture Systems)

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13 pages, 2275 KiB

Open AccessEditor’s ChoiceArticle

Fish Stock Status and Its Clues on Stocking: A Case Study of Acanthopagrus schlegelii from Zhanjiang Coastal Waters, China

by Hagai Nsobi Lauden, Xinwen Xu, Shaoliang Lyu, Alma Alfatat, Kun Lin, Shuo Zhang, Ning Chen and Xuefeng Wang

Fishes 2024, 9(10), 381; https://doi.org/10.3390/fishes9100381 - 26 Sep 2024

Cited by 2 | Viewed by 1131

Abstract

Global fisheries face overfishing challenges, endangering fish stock and biodiversity. While hatchery release stocking programs aim to bolster fish populations, their effectiveness remains uncertain due to challenges in data acquisition, such as obtaining stocking details and differentiating between wild and stocked individuals. This [...] Read more.

Global fisheries face overfishing challenges, endangering fish stock and biodiversity. While hatchery release stocking programs aim to bolster fish populations, their effectiveness remains uncertain due to challenges in data acquisition, such as obtaining stocking details and differentiating between wild and stocked individuals. This study evaluates the stock status of black sea bream (Acanthopagrus schlegelii) released in Chinese hatchery programs since the 1980s. Samples from Zhanjiang fish markets (January 2019–October 2021) underwent analysis using the length–weight relationship (LWR), length-based spawning potential ratio (LBSPR), and length-based Bayesian (LBB) methods. The male and female LWRs were W = 0.0188L^2.9725 and W = 0.016L^3.0284, respectively, and the observed condition factors indicated good health. The estimates imply that the region is conducive to species survival and can sustain its stocking programs. The LBSPR (SPR = 0.21 (0.17–0.25)) and LBB (B/B_MSY = 1.1 (0.718–1.34), B/B₀ = 0.37 (0.253–0.473)) results suggest a rebuilding population capable of replenishing to more sustainable levels. However, F/M and net selectivity estimates indicate that fishing practices target juvenile fish, limiting the reproductive potential of A. schlegelii. These findings underline the need for enhanced management strategies, including delayed harvesting and the use of size-specific fishing gear, to ensure the long-term sustainability of the species. Full article

(This article belongs to the Special Issue Assessment and Management of Fishery Resources)

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25 pages, 1111 KiB

Open AccessEditor’s ChoiceReview

Systematic Review of Multi-Species Models in Fisheries: Key Features and Current Trends

by Pablo Couve, Nixon Bahamon, Cristian M. Canales and Joan B. Company

Fishes 2024, 9(10), 372; https://doi.org/10.3390/fishes9100372 - 24 Sep 2024

Viewed by 1577

Abstract

In the context of ecosystem-based fisheries management (EBFM), multi-species models offer a potential alternative to traditional single-species models for managing key species, particularly in mixed-fishery settings. These models account for interactions between different species, providing a more holistic approach to fisheries compared to [...] Read more.

In the context of ecosystem-based fisheries management (EBFM), multi-species models offer a potential alternative to traditional single-species models for managing key species, particularly in mixed-fishery settings. These models account for interactions between different species, providing a more holistic approach to fisheries compared to traditional single-species management. There is currently no comprehensive list or recent analysis of the diverse methods used to account for species interactions in fisheries worldwide. We conducted a systematic review to objectively present the current multi-species models used in fisheries. The systematic search identified 86 multi-species models, which were then evaluated to assess their similarities. Employing a clustering analysis, three distinct groups were identified: extensions of single-species/dynamic multi-species models, aggregated ecosystem models, and end-to-end/coupled and hybrid models. The first group was among the most diverse, owing to their ability to integrate biological components, while maintaining an intermediate level of complexity. The second group, primarily defined by the EwE method, features an aggregated biomass pool structure incorporating biological components and environmental effects. The third cluster featured the most complex models, which included a comprehensive representation of size and age structure, the ability to incorporate biological components and environmental effects, as well as spatial representation. The application of these methods is primarily concentrated on small pelagic and demersal species from North America and Europe. This analysis provides a comprehensive guide for stakeholders on the development and use of multi-species models, considering data constraints and regional contexts. Full article

(This article belongs to the Special Issue Fisheries Stock Assessment and Modeling)

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19 pages, 1358 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Socially Acceptable Feed Formulations May Impact the Voluntary Feed Intake and Growth, but Not Robustness of Nile Tilapia (Oreochromis niloticus)

by Rodrigo Mendes, Paulo Rema, Jorge Dias, Ana Teresa Gonçalves, Rita Teodósio, Sofia Engrola, Francisco J. Sánchez-Vázquez and Luís E. C. Conceição

Fishes 2024, 9(9), 361; https://doi.org/10.3390/fishes9090361 - 16 Sep 2024

Cited by 1 | Viewed by 2395

Abstract

Society is becoming more demanding with aquaculture’s environmental footprint and animal wellbeing. In order to potentially mitigate these concerns, feed formulations could be based on eco-efficient (circular economy-driven) or organic ingredients. This study aimed to investigate the growth performance, feed utilization, and health [...] Read more.

Society is becoming more demanding with aquaculture’s environmental footprint and animal wellbeing. In order to potentially mitigate these concerns, feed formulations could be based on eco-efficient (circular economy-driven) or organic ingredients. This study aimed to investigate the growth performance, feed utilization, and health status of juvenile Nile tilapia (Oreochromis niloticus) when fed with such feeds. The growth trial lasted for 8 weeks, and fish had an initial weight of 31.0 ± 0.5 g (mean ± SD). Fish were fed until visual satiation, in quadruplicate, with one of three isonitrogenous and isoenergetic experimental feeds: a commercial-like feed without fishmeal (PD), a diet based on ingredients compatible with organic certification (ORG), or a feed formulated using circular economy-driven subproducts and emergent ingredients (ECO). Fish fed ECO showed a tendency for decreased feed intake, while ORG fish significantly reduced their intake compared to those fed PD. Consequently, fish fed ECO (62.7 ± 5.4 g) exhibited almost half the growth than those fed PD (107.8 ± 6.1 g), while ORG fish almost did not increase their weight (32.7 ± 1.3 g). ECO and ORG diets had a lower digestibility for protein, lipid, and energy when compared to PD. Feed utilization of fish fed ECO or ORG was also lower than those fed PD. From the health-related genes analyzed, only glutathione reductase (gsr) showed statistically significant differences, being more expressed in fish-fed ECO than those fed PD. Thus, even when such novel formulations induced extreme effects on voluntary feed intake, their impact was noted only in fish growth, but not in robustness. Full article

(This article belongs to the Special Issue Welfare and Sustainability in Aquaculture)

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16 pages, 15478 KiB

Open AccessEditor’s ChoiceArticle

Natural Bacterial Co-Infection in Farmed European Sea Bass Intended for Experimental Research in Sicily, Southern Italy: Pathological Findings

by Simone Palazzolo, Claudio Gervasi, Jessica Maria Abbate, Emil Gjurčević, Rosa Falleti, Maria Giovanna Piro, Giovanni Lanteri, Carmelo Iaria and Fabio Marino

Fishes 2024, 9(9), 360; https://doi.org/10.3390/fishes9090360 - 13 Sep 2024

Viewed by 1161

Abstract

In mariculture facilities, bacterial infections pose significant production challenges, with potentially catastrophic impacts on fish species. Bacterial co-infections are a widespread phenomenon in the natural marine environment, although their impact on aquatic organisms remains poorly investigated. This study aimed to detail the pathological [...] Read more.

In mariculture facilities, bacterial infections pose significant production challenges, with potentially catastrophic impacts on fish species. Bacterial co-infections are a widespread phenomenon in the natural marine environment, although their impact on aquatic organisms remains poorly investigated. This study aimed to detail the pathological findings associated with a natural bacterial co-infection caused by three different pathogens, namely Photobacterium damselae subsp. piscicida, Tenacibaculum maritimum and Vibrio sp., as the cause of mass mortality in European sea bass. The fish had been reared in open-net cages in Sicily and later transferred for experimental research purposes to a user establishment after immunization with an inactivated vaccine. Macroscopic, cytological and histopathological examinations were performed on 109 animals, and bacterial species were identified by the 16S rRNA gene. Overall, ulcerative skin lesions, necrotizing myositis and tail rot with occasional tail loss were associated with tenacibaculosis and vibriosis, while P. damselae subsp. piscicida mainly caused granulomatous inflammation in the spleen and head kidney. Finally, an injection site reaction due to the oil-adjuvanted vaccine administered intraperitoneally was observed in the abdominal fat. Understanding the impact of bacterial pathogens is essential to manage the health and welfare of farmed fish, and the importance of a good health monitoring program cannot be overstated to avoid outbreaks and the possible emergence of new pathogens due to the intensification of the production systems, antibiotic resistance and climate changes. The study would also highlight the importance of the quarantine period when animals supplied for research come from aquaculture farms and how the main goal in the near future should be to better define the procedures to provide completely pathogen-free animals. Full article

(This article belongs to the Section Welfare, Health and Disease)

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9 pages, 219 KiB

Open AccessEditor’s ChoiceArticle

ARISA: Collection of Health Information at Farm Level in Spanish Fish Farming

by Ana Muniesa, Imanol Ruiz-Zarzuela, Miguel Peribañez, Ignacio de Blas and Bernardo Basurco

Fishes 2024, 9(9), 357; https://doi.org/10.3390/fishes9090357 - 12 Sep 2024

Viewed by 612

Abstract

The adequate collection of health information at the farm level is the first step in good health management. The objective of this study was to analyze how Spanish fish farms collect their census, disease occurrence, and mortality data through their farm record books [...] Read more.

The adequate collection of health information at the farm level is the first step in good health management. The objective of this study was to analyze how Spanish fish farms collect their census, disease occurrence, and mortality data through their farm record books and how they use them for reporting to competent authorities. Comparing and contrasting farm books between regions (autonomous communities) revealed a lack of standardization and substantial differences in the reporting. Therefore, this study points out the need to improve and standardize, at the national level, the design of fish farm record books in order to ensure the better collection of farm census data on mortality and disease occurrence, which may facilitate the production of epidemiological reports and the early detection of emerging diseases at the national level. Full article

(This article belongs to the Section Welfare, Health and Disease)

26 pages, 2070 KiB

Open AccessEditor’s ChoiceReview

Vitamin A in Fish Well-Being: Integrating Immune Strength, Antioxidant Capacity and Growth

by Yauheni Shastak and Wolf Pelletier

Fishes 2024, 9(8), 330; https://doi.org/10.3390/fishes9080330 - 22 Aug 2024

Cited by 2 | Viewed by 4927

Abstract

This review synthesizes the multifaceted role of vitamin A in fish well-being, encompassing immune function, antioxidant capacity and growth regulation, providing a comprehensive understanding of its significance in fish diets and implications for aquaculture. Key objectives include exploring the role of vitamin A [...] Read more.

This review synthesizes the multifaceted role of vitamin A in fish well-being, encompassing immune function, antioxidant capacity and growth regulation, providing a comprehensive understanding of its significance in fish diets and implications for aquaculture. Key objectives include exploring the role of vitamin A in fish immunology, growth impact, oxidative stress status, and future directions. Vitamin A is critical for immune cell development, enhancing both innate and adaptive immune responses. It maintains mucosal integrity and modulates phagocytic activity, crucial for pathogen defense. Growth regulation is influenced by vitamin A through cellular differentiation and morphogenesis, essential for tissue and skeletal development. Studies indicate that vitamin A supplementation improves growth metrics and body composition across various fish species. Vitamin A also combats oxidative stress by scavenging free radicals, enhancing antioxidant enzyme activity, and inducing autophagy, thus protecting cellular components from oxidative damage. Interactions with other vitamins like E, D, and C highlight the importance of balanced nutrition in aquaculture. Integrative management practices, including nutritionally balanced diets, optimal water quality, stress reduction, and environmental enrichment, are recommended to maximize fish health and productivity through adequate vitamin A utilization. Full article

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15 pages, 1880 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Elasmobranch Mark–Recapture Experiment off the Balearic Islands: Insight into Scyliorhinus canicula Growth, Mobility, and Population Size

by Francesca Ferragut-Perello, Paula Sánchez-Zulueta, Sergio Ramírez-Amaro, Maria Teresa Farriols, Noemi Pasini, Beatriz Guijarro, Cristina Rodríguez-Cabello and Francesc Ordines

Fishes 2024, 9(8), 315; https://doi.org/10.3390/fishes9080315 - 9 Aug 2024

Cited by 2 | Viewed by 2004

Abstract

Despite the high diversity of elasmobranch fishes in the Balearic Islands, knowledge of their biology and population dynamics is still scarce. A recent mark-and-recapture experiment off the Balearic Islands tagged 3738 individuals of 23 shark and batoid species during MEDITS and CANAL bottom [...] Read more.

Despite the high diversity of elasmobranch fishes in the Balearic Islands, knowledge of their biology and population dynamics is still scarce. A recent mark-and-recapture experiment off the Balearic Islands tagged 3738 individuals of 23 shark and batoid species during MEDITS and CANAL bottom trawl scientific surveys from June 2021 to August 2023. Retrieval was reported for the sharks Scyliorhinus canicula and Mustelus mustelus, revealing relatively small home ranges for these species (0.2–38.5 km and 7.8–15.3 km for S. canicula and M. mustelus, respectively). Recapture efficiency was higher from scientific surveys than from commercial catches, highlighting potential challenges in collaboration with fishermen and recapture reports. Density estimates obtained from the MEDITS bottom trawl survey suggest a much larger population for S. canicula than estimates from the mark–recapture data, indicating MEDITS density estimates for this species may be overestimated due to its scavenger behavior perhaps favoring individuals searching for discards aggregated in the fishing grounds. This study emphasizes the importance of monitoring, collaborative efforts, and improved reporting mechanisms to enhance our understanding of elasmobranch populations and provide support for sustainable management of these vulnerable marine species. Full article

(This article belongs to the Section Biology and Ecology)

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39 pages, 401 KiB

Open AccessEditor’s ChoiceArticle

Blue Economy Financing Solutions for the Fisheries and Aquaculture Sectors of Caribbean Island States

by Michael Bennett, Antaya March and Pierre Failler

Fishes 2024, 9(8), 305; https://doi.org/10.3390/fishes9080305 - 3 Aug 2024

Cited by 5 | Viewed by 2403

Abstract

This study reviews various financing solutions available for fisheries and aquaculture development in Caribbean small island developing states (SIDS) and Barbados, Grenada, and St. Vincent and the Grenadines. Previously identified financing needs within the fisheries and aquaculture sectors have been matched with the [...] Read more.

This study reviews various financing solutions available for fisheries and aquaculture development in Caribbean small island developing states (SIDS) and Barbados, Grenada, and St. Vincent and the Grenadines. Previously identified financing needs within the fisheries and aquaculture sectors have been matched with the most suitable financing mechanisms. However, the use of blue levies is recommended and applicable in almost every scenario, as they allow these sectors to drive their own development in financing research and conservation projects to their own benefit. The use of “blue tokens” with sufficiently low repayment coupons allows development projects to gather public support for fisheries, thereby increasing the likelihood of the project being successful through community buy-in. The possibility of natural capital being traded as public equities as “Natural Asset Companies” provides the opportunity for development projects to fund themselves. The review concludes that natural capital can be leveraged as the base through which public-private partnerships (PPPs) can facilitate optimal delivery of ecosystem services, benefit multiple stakeholders, and provide numerous development opportunities. An enabling environment for debt and lending with low-interest loan repayments is also applicable to almost every scenario, as it facilitates access to capital finance for infrastructure development and the acquisition of increasingly sustainable fishing equipment. Steps towards generating an enabling environment for financing fisheries and aquaculture in the Caribbean region are also discussed. The establishment of dedicated financing institutions, PPPs, and sufficient data reporting infrastructure for the fisheries and aquaculture industry are essential for driving development in these sectors. Likely, the largest limiting factor in financing Caribbean fisheries and aquaculture industries is a lack of awareness of the range of finance and financing mechanisms available to stakeholders, as well as an enabling environment for financing blue Economy sectors. This review is thus intended to aid financing institutions, Blue Economy developers, and specifically Caribbean fisheries and aquaculture stakeholders and Caribbean governments by raising awareness of the financing mechanisms available, encourage the incorporation of their use in the fisheries and aquaculture industries in the Caribbean, and encourage policymakers to create an enabling environment for financing development in these crucial sectors. Full article

(This article belongs to the Special Issue Fisheries and Blue Economy)

18 pages, 1531 KiB

Open AccessEditor’s ChoiceArticle

RAS-Designed Diets Result in Lower Accumulation of Nitrogen, Phosphorus, and Zinc in Recirculating Aquaculture System Compared with Traditional Flow-Through Designed Diets

by Vegard Øvstetun Flo, Thomas Cavrois-Rogacki, Jon Øvrum Hansen, Jannicke Vigen, Thomas Gitlesen and Odd-Ivar Lekang

Fishes 2024, 9(8), 300; https://doi.org/10.3390/fishes9080300 - 1 Aug 2024

Viewed by 2580

Abstract

A four-week trial was conducted to compare the effects of a conventional flow-through system diet (FTS) and an experimental RAS diet (ERAS) on fish performance, water quality and general system implication in a replicated recirculation aquaculture system (RAS). Six identical RAS, each with [...] Read more.

A four-week trial was conducted to compare the effects of a conventional flow-through system diet (FTS) and an experimental RAS diet (ERAS) on fish performance, water quality and general system implication in a replicated recirculation aquaculture system (RAS). Six identical RAS, each with a total system water volume of 1500 L and cylindrical rearing tanks of 1000 L were stocked with Atlantic salmon (Salmo salar) post-smolts with an average weight of 199.7 ± 28 g, to an average stocking density of 30 kg/m³ and reaching approximately 49 kg/m³ at the trial end. The ERAS diet were composed to inhabit typical RAS feed characteristics compared with the FTS diet, such as a higher fecal stability and reduced protein levels (−12%), but at the same time increased fat content (+8%) to secure similar gross energy levels (22–23 MJ kg⁻¹) between the two diets. Water quality parameters were measured individually. The total accumulation of minerals and metals was analyzed in water from different parts of the system at the start and end of the trial period for both diets. No differences in growth, condition factor, feed conversion rate (FCR), or survival of fish fed the two dietary adaptations were observed. The system using the ERAS diet showed significantly higher pH (+1.2%) and alkalinity (+17%) and lower total ammonia nitrogen (TAN) (−18%) and NO₂⁻ (−46%) compared with the FTS diet. The count of drum filter activations was also significantly lower (−13%) with the ERAS diet. Compared with the FTS diet, the ERAS diet had a lower probability (−4%) of generating particles smaller than 50 μm, and that the RAS was also more effective in removing particles from the drum filter, prompting a lower daily activation of the filter of 22.1 ± 3.0 counts compared with 25.5 ± 3.5 for the FTS diet. Mineral analysis showed a significantly lower accumulation of total phosphorus (TP) (−90%) and dissolved phosphorus (DP) (−92%) in the RAS units using the ERAS diet compared with those using the FTS diet. Compared with a traditional flow-through diet, these results highlight the benefits of using an RAS-adapted diet that matches the energy requirement of flow-through diets regarding water quality, system performance, satisfactory growth, and condition. Full article

(This article belongs to the Topic Feeding Strategies to Improve Sustainability and Welfare in Fish and Poultry Production)

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26 pages, 2732 KiB

Open AccessEditor’s ChoiceReview

Tracking Biomarkers for the Health and Welfare of Aquaculture Fish

by Joana Oliveira, Aires Oliva-Teles and Ana Couto

Fishes 2024, 9(7), 289; https://doi.org/10.3390/fishes9070289 - 19 Jul 2024

Cited by 4 | Viewed by 3382

Abstract

Aquaculture production has been growing consistently over the last few decades to meet the increasing animal protein demand of the human population. However, increased production and rearing intensities raise the challenges of guaranteeing fish health and welfare, which is essential to avoid losses [...] Read more.

Aquaculture production has been growing consistently over the last few decades to meet the increasing animal protein demand of the human population. However, increased production and rearing intensities raise the challenges of guaranteeing fish health and welfare, which is essential to avoid losses and ensure product quality. Biomarkers can provide insights into the fish’s nutritional, physiological, and health status, and aid in the evaluation of early nutritional and physiological imbalances, distress conditions, and pathological diagnosis. The discovery and validation of biomarkers rely mostly on the use of information provided by different parameters, including biochemical, metabolic, or immunologic, as well as several omics, from genomics and transcriptomics to proteomics and metabolomics. In this review, a summary of the main biomarkers used in aquaculture is provided along with an overview of the main omics technologies available for further biomarker research. This review also highlights the need to develop non-lethal biomarkers that can easily and quickly be measured to provide a prompt response to producers. Full article

(This article belongs to the Special Issue Prevention and Control of Aquatic Animal Diseases)

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13 pages, 2271 KiB

Open AccessEditor’s ChoiceArticle

Two Distinct Maternal Lineages of Threespine Stickleback (Gasterosteus aculeatus) in a Small Norwegian Subarctic Lake

by Bård Ove Karlsen, Dhurba Adhikari, Tor Erik Jørgensen, Ida Klykken Hanssen, Truls Borg Moum, Jarle Tryti Nordeide and Steinar Daae Johansen

Fishes 2024, 9(7), 285; https://doi.org/10.3390/fishes9070285 - 18 Jul 2024

Cited by 1 | Viewed by 1323

Abstract

A subarctic Norwegian watercourse is known for its population of threespine sticklebacks (Gasterosteus aculeatus Linnaeus 1758) with unusual pelvic spine polymorphism; the upper lake contains a mixture of specimens that are normal-spined, asymmetric-spined, and spineless. In contrast, the downstream lakes and the [...] Read more.

A subarctic Norwegian watercourse is known for its population of threespine sticklebacks (Gasterosteus aculeatus Linnaeus 1758) with unusual pelvic spine polymorphism; the upper lake contains a mixture of specimens that are normal-spined, asymmetric-spined, and spineless. In contrast, the downstream lakes and the nearby marine site contain only the normal spined morph. We investigated the maternal-line genetic structure in the watercourse using mitogenomics. A total of 242 sticklebacks representing two lakes and a marine site were assessed based on individual and pooled DNA sequencing. While two distinct mitogenome clades were detected in the upper lake (Lake Storvatnet), only one of these clades was present in the downstream lake. The marine site pooled DNA sample, however, contained several mitogenome haplotypes. We present mitogenome sequence features that include gene-specific single nucleotide polymorphisms, molecular phylogeny, and genetic differentiation assessments based on pairwise comparisons of pooled population samples from each site. The Lake Storvatnet mitogenomes belong to two distinct Euro-North American (ENA) clades; one of the ancestral lineages likely corresponds to the original maternal lineage in the watercourse, and the other was introduced more recently. We hypothesize that the second invader carried nuclear genomic features responsible for the observed present-day pelvic spine polymorphism in Lake Storvatnet. Full article

(This article belongs to the Section Genetics and Biotechnology)

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17 pages, 6904 KiB

Open AccessEditor’s ChoiceArticle

From Proliferation to Protection: Immunohistochemical Profiling of Cardiomyocytes and Immune Cells in Molly Fish Hearts

by Giacomo Zaccone, Doaa M. Mokhtar, Alessio Alesci, Gioele Capillo, Marco Albano, Manal T. Hussein, Marialuisa Aragona, Antonino Germanà, Eugenia R. Lauriano and Ramy K. A. Sayed

Fishes 2024, 9(7), 283; https://doi.org/10.3390/fishes9070283 - 16 Jul 2024

Cited by 2 | Viewed by 1092

Abstract

Unlike adult mammalian cardiomyocytes, cardiomyocytes in teleosts display high proliferative capacity throughout adulthood. This study aimed to identify the immunohistochemical profiles of cardiomyocytes and immune cells in the hearts of Molly fish by assessing the immunolabelling expression of key proteins involved in cell [...] Read more.

Unlike adult mammalian cardiomyocytes, cardiomyocytes in teleosts display high proliferative capacity throughout adulthood. This study aimed to identify the immunohistochemical profiles of cardiomyocytes and immune cells in the hearts of Molly fish by assessing the immunolabelling expression of key proteins involved in cell proliferation, differentiation, and tissue protection. The cardiac anatomy of Molly fish includes the atrium, ventricle, and bulbus arteriosus. The expression of SOX9, NF-κB, myostatin, and S100 proteins in myocardial cells indicates the proliferative features of the heart in Molly fish. The bulbus arteriosus is characterized by collagenous chambers and smooth muscle cells that express Ach and iba1. The atrium of Molly fish serves as a storage unit for rodlet cells and immune cells. Rodlet cells displayed immunoreactivity to NF-κB, iba1, Olig2, Ach, and S100 proteins, suggesting their roles in the immune response within the heart. Furthermore, telocytes (TCs) have emerged as a significant component of the atrium of Molly fish, expressing Ach, CD68, S100 protein, and iba1. These expressions indicate the involvement of TCs in multiple signaling pathways that contribute to heart architecture. This study delineates the intricate relationship between cardiomyocytes and innate immune cells in Molly fish. Full article

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18 pages, 985 KiB

Open AccessEditor’s ChoiceArticle

Community Structure Characteristics and Changes in Fish Species at Poyang Lake after the Yangtze River Fishing Ban

by Yanping Zhang, Haixin Zhang, Zijun Wu, Mingguang Zhao and Guangpeng Feng

Fishes 2024, 9(7), 281; https://doi.org/10.3390/fishes9070281 - 15 Jul 2024

Cited by 6 | Viewed by 1716

Abstract

To understand the fish community structure characteristics and changes in Poyang Lake after the Yangtze River fishing ban in 2021, seven sampling stations were established, namely in Hukou, Lushan, Duchang, Yongxiu, Nanjishan, Ruihong, and Poyang, for fishery resource surveys between 2020 and 2021. [...] Read more.

To understand the fish community structure characteristics and changes in Poyang Lake after the Yangtze River fishing ban in 2021, seven sampling stations were established, namely in Hukou, Lushan, Duchang, Yongxiu, Nanjishan, Ruihong, and Poyang, for fishery resource surveys between 2020 and 2021. The results showed that 93 fish species were identified, belonging to 11 orders, 20 families, and 61 genera, which was an increase of 4.5% from before the fishing ban. Of these, 52 Cyprinidae species were identified, comprising the highest proportion (55.91%). Four invasive alien species (hybrid sturgeon, Cirrhina mrigala, Piaractus brachypomus, and Mugil cephalus) were identified, and the number of alien species in Poyang Lake was higher than before the fishing ban. Carnivorous and mid-lower-level fish showed a significant increase, accounting for 47.31% and 38.71% of the total species, respectively. Compared with the Yangtze River before the fishing ban, the body length and body weight of the main economic fish in Poyang Lake increased by 6.10–61.26% and by 15.14–291.57%, respectively. In terms of age structure, the proportion of major economically important fish aged 1 or 2 years decreased significantly, while the proportion of older fish increased substantially. There was little difference in the diversity of fish communities at different stations in Poyang Lake. In terms of biodiversity, the Shannon–Wiener index ranged from 2.158 to 2.909, with Poyang having the highest value and Nanjishan the lowest. Margalef’s index ranged from 4.265 to 6.459, with Lushan having the highest value and Nanjishan the lowest. Pielou’s index ranged from 0.617 to 0.822, with Duchang having the highest value and Nanjishan the lowest. Hence, the Yangtze river fishing ban has played an important and positive role in the restoration of fishery resources in Poyang Lake. However, long-term tracking and monitoring are needed to provide information to comprehensively evaluate the ecological impact of the Poyang Lake fishing ban. Full article

(This article belongs to the Special Issue Biodiversity and Spatial Distribution of Fishes)

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20 pages, 5899 KiB

Open AccessEditor’s ChoiceArticle

Impact of Digital Development and Technology Innovation on the Marine Fishery Economy Quality

by Yiying Jiang, Lei Huang, Yang Liu and Shuang Wang

Fishes 2024, 9(7), 266; https://doi.org/10.3390/fishes9070266 - 5 Jul 2024

Cited by 7 | Viewed by 2297

Abstract

The digital economy plays an important role in promoting the high quality and sustainable development of the marine fishery economy. Based on the panel data of the digital economy and marine fishery development from 2011 to 2022, we firstly adopted the entropy method [...] Read more.

The digital economy plays an important role in promoting the high quality and sustainable development of the marine fishery economy. Based on the panel data of the digital economy and marine fishery development from 2011 to 2022, we firstly adopted the entropy method to comprehensively evaluate the economy quality level of the digital economy and marine fishing. Secondly, we constructed a two-way fixed effect model to empirically analyze the impact of digital economy development on the marine fishery economy quality and the mediating role of marine green science and technology innovation, and further explored the regional heterogeneity of the digital economy on the marine fishery economy quality. Several findings emerge. The digital economy and the marine fishery economy quality level was relatively low and showed a fluctuating increase. The development of the digital economy can significantly improve the economy quality of marine fishing, and the conclusion was still valid after considering a series of robustness tests. The digital economy can drive the development quality of the marine fishery economy through marine green technology innovation. This paper proposes fostering the advancement of digital technology in the marine fishery sector, to effectively harness the innovation-driven potential of the digital economy, so as to facilitate the harmonious development of both the marine and digital economies. Full article

(This article belongs to the Special Issue Fisheries Policies and Management)

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15 pages, 9111 KiB

Open AccessEditor’s ChoiceArticle

Integrated Rice–Fish Culture Alters the Bacterioplankton Community and Its Assembly Processes

by Weixu Diao, Julin Yuan, Rui Jia, Yiran Hou, Liqiang Zhang, Bing Li and Jian Zhu

Fishes 2024, 9(7), 254; https://doi.org/10.3390/fishes9070254 - 2 Jul 2024

Cited by 3 | Viewed by 1077

Abstract

The rice–fish co-culture is an important model of carp farming in China; however, research on the dynamics and assembly of water bacterial communities in this system remains limited. Therefore, this study aimed to explore the dynamics and assembly of bacterial communities, as well [...] Read more.

The rice–fish co-culture is an important model of carp farming in China; however, research on the dynamics and assembly of water bacterial communities in this system remains limited. Therefore, this study aimed to explore the dynamics and assembly of bacterial communities, as well as their correlation with environmental factors in paddy water. For these purposes, this study was divided into two groups: a rice–carp co-culture (WRC) group and a rice monoculture (WRM) group, with 20 rice fields in each group. After 60 days of farming, the concentrations of NH₄⁺-N, NO₂⁻-N, TN, and PO₄³⁻ were significantly higher in the WRC group than those in the WRM group. Alpha diversity analysis showed that the Shannon index in the WRC group was significantly decreased compared with the WRM group. At the phylum level, the relative abundance of Actinobacteria significantly increased, while the relative abundance of Proteobacteria and Bacteroidetes significantly decreased in the paddy water of the WRC group. The neutral community model (NCM) indicated that a random process played a dominant role in the construction of bacterial communities in the two groups, and common carp cultivation increased migration rates, thereby affecting community assembly. The co-occurrence network displayed that common carp cultivation led to looser interactions between bacterial communities. In addition, the contents of nutrients significantly affected the abundance of bacteria in paddy water. In summary, carp cultivation decreased the diversity of bacteria and changed the relative abundance of dominant bacteria, thereby affecting the stability and assembly of bacterial communities. Full article

(This article belongs to the Special Issue Aquaculture Ecology and the Environmental Microbiome)

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18 pages, 3368 KiB

Open AccessEditor’s ChoiceArticle

Exploring Growth Patterns of Maurolicus muelleri across Three Northeast Atlantic Regions

by Paula Alvarez, Naroa Aldanondo, Alina M. Wieczorek, Thibault Cariou, Guillermo Boyra, Eduardo Grimaldo, Webjørn Melle and Thor Klevjer

Fishes 2024, 9(7), 250; https://doi.org/10.3390/fishes9070250 - 26 Jun 2024

Viewed by 1646

Abstract

Maurolicus muelleri is an important component of mesopelagic ecosystems; nevertheless, we possess only limited knowledge about its biological features. We collected samples of M. muelleri from six scientific surveys between 2019 and 2021 in three geographical areas in the Northeast Atlantic waters (from [...] Read more.

Maurolicus muelleri is an important component of mesopelagic ecosystems; nevertheless, we possess only limited knowledge about its biological features. We collected samples of M. muelleri from six scientific surveys between 2019 and 2021 in three geographical areas in the Northeast Atlantic waters (from South to North): the Bay of Biscay, the Celtic Sea, and the Norwegian Sea. Geographical variations in otolith growth, fish age, length, weight, and condition, as well as length–weight relationships and von Bertalanffy growth models (VBGMs), were investigated. Length-weight relationships revealed differences associated with the fish’s origin, paralleling the annual and daily otolith growth. VBGM parameters increased progressively northwards, in accordance with Bergmann’s rules. Fish length was positively related to the otolith radio, and Lee’s phenomenon was undetected. The impact of environmental variables, such as temperature and food availability, is debated, with these considered potential drivers of this variability. Populations may belong to separated units, either genetically or morphologically, representing differences in biological parameters as a signal of geographical divergence. Full article

(This article belongs to the Section Biology and Ecology)

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12 pages, 1771 KiB

Open AccessEditor’s ChoiceArticle

Effect of Replacing Fishmeal with Algal Meal on Growth Parameters and Meat Composition in Rainbow Trout (Oncorhynchus mykiss W.)

by Katya Velichkova, Ivaylo Sirakov, Stefka Stoyanova, Apostol Simitchiev, David Yovchev and Kamelia Stamatova-Yovcheva

Fishes 2024, 9(7), 249; https://doi.org/10.3390/fishes9070249 - 26 Jun 2024

Cited by 2 | Viewed by 4594

Abstract

Aquafarms should reduce the use of fishmeal and fish oil in nutritional feed. One such accessible and relatively inexpensive food component that could successfully meet the challenge posed by aquaculture is algae. The objective of the present study was to evaluate the algae [...] Read more.

Aquafarms should reduce the use of fishmeal and fish oil in nutritional feed. One such accessible and relatively inexpensive food component that could successfully meet the challenge posed by aquaculture is algae. The objective of the present study was to evaluate the algae meal inclusion of Chlorella and Spirulina sp. in a diet for rainbow trout, evaluating its effects on fish growth, histological parameters and fillet quality. Experiments were carried out to replace 50% and 100% of fishmeal with Spirulina sp. and Chlorella vulgaris in feed for rainbow trout (Oncorhynchus mykiss W.) cultured in a recirculation system. At the end of the experimental period, the highest mean live weight was measured in rainbow trout fed a feed containing 50% algal meal in the feed. The absorptive vacuolization of cells was increased the most and lamina propria was average thickened when fed 50% algae diets. Fat droplets in the hepatocytes were larger in the 50% algae meal fed group, and their nuclei were replaced in the peripheral zone of the cells. Substitution of fishmeal with 50% algal meal in fish feed resulted in a 36.44% reduction in the lipid content of rainbow trout fillets compared to control fish. Full article

(This article belongs to the Special Issue Algae as Aquafeed Ingredients and Additives for Sustainable Aquaculture)

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34 pages, 27775 KiB

Open AccessEditor’s ChoiceReview

Fishes in Marine Caves

by Marcelo Kovačić, Vasilis Gerovasileiou and Robert A. Patzner

Fishes 2024, 9(6), 243; https://doi.org/10.3390/fishes9060243 - 20 Jun 2024

Cited by 1 | Viewed by 2639

Abstract

Fishes in marine caves have attracted limited attention by the scientific community in comparison to subterranean fishes which have lost eyes and pigmentation. They constitute a largely unexplored component of marine fish diversity, except for the relatively well-studied marine caves of the Mediterranean [...] Read more.

Fishes in marine caves have attracted limited attention by the scientific community in comparison to subterranean fishes which have lost eyes and pigmentation. They constitute a largely unexplored component of marine fish diversity, except for the relatively well-studied marine caves of the Mediterranean Sea. These habitats are characterized by steep environmental gradients of decreasing light and decreasing water exchange. The fishes recorded so far in marine caves are not exclusive residents of this habitat and they are also present at least in the other mesolithial habitats. In the Mediterranean marine caves, 132 fishes have been recorded to date, representing about 17% of the total Mediterranean fish species richness. Most of these species are reported from the anterior cave zones where some light still exists, while a smaller number of species are known from the totally dark zones. Among them, 27.3% are accidental visitors, 53.8% are the regular mesolithial visitors and switchers between mesolithion and open water, 5.3% are permanent residents of the mesolithion, but also occur in other habitats, and 13.6% are exclusive permanent residents of mesolithion. Some mesolithial exclusive permanent residents recorded in marine caves share similar morphology, probably as adaptations to these habitats. Full article

(This article belongs to the Special Issue Behavior, Ecology and Evolution of Subterranean Fish)

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16 pages, 5922 KiB

Open AccessEditor’s ChoiceArticle

Comparative Analysis of Enzymatic Activities and Transcriptional Profiles of Various Hepatic Enzymes between Male and Female Yellowfin Tuna (Thunnus albacares)

by Dongge Liu, Hao Yang, Shuisheng Li, Hai Huang, Guangli Li and Huapu Chen

Fishes 2024, 9(5), 184; https://doi.org/10.3390/fishes9050184 - 17 May 2024

Cited by 2 | Viewed by 1754

Abstract

Yellowfin tuna (Thunnus albacares) is a valuable pelagic migratory fish with potential for aquaculture. Despite this, there is limited understanding of the biological and physiological characteristics of this species, particularly regarding sex differences in growth performance. The liver, a crucial organ [...] Read more.

Yellowfin tuna (Thunnus albacares) is a valuable pelagic migratory fish with potential for aquaculture. Despite this, there is limited understanding of the biological and physiological characteristics of this species, particularly regarding sex differences in growth performance. The liver, a crucial organ for digestion and metabolism, plays a significant role in regulating fish growth. This study aimed to compare liver enzyme activities and transcriptome profiles between female and male yellowfin tuna to uncover the molecular mechanisms underlying difference between the sexes. The results revealed that female yellowfin tuna exhibited higher amylase and lipid metabolism enzyme activities, while male yellowfin tuna showed higher glucose-6-phosphate dehydrogenase and antioxidant enzyme activities. Additionally, through Illumina sequencing technology, the study generated 37.74 Gb of clean data and identified 36,482 unique genes (UniGenes) in the liver transcriptome. A total of 2542 differentially expressed genes were found, with enriched Gene Ontology terms and pathways related to metabolic processes, particularly lipid metabolism and transport. These findings suggest that female yellowfin tuna have superior digestive enzyme activities and lipid metabolism, while male yellowfin tuna excel in sugar metabolism, ATP production, and antioxidant defense. This study provides valuable insights into sex differences in yellowfin tuna and could aid in advancing full-cycle aquaculture practices for this species. Full article

(This article belongs to the Special Issue Genetics and Breeding in Aquaculture)

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26 pages, 380 KiB

Open AccessEditor’s ChoiceReview

The Role of Functional Feed Additives in Enhancing Aquaculture Sustainability

by Abigail John Onomu and Grace Emily Okuthe

Fishes 2024, 9(5), 167; https://doi.org/10.3390/fishes9050167 - 5 May 2024

Cited by 14 | Viewed by 6647

Abstract

Aquaculture serves as a source of protein and livelihood and is an alternative to capture fisheries, thereby reducing pressure on the wild. However, aquaculture tends to be limited by sustainability issues, which include overdependency on fishmeal, the high cost associated with fishmeal, the [...] Read more.

Aquaculture serves as a source of protein and livelihood and is an alternative to capture fisheries, thereby reducing pressure on the wild. However, aquaculture tends to be limited by sustainability issues, which include overdependency on fishmeal, the high cost associated with fishmeal, the environmental impact of aquaculture activities, which may be detrimental to aquatic lives and the environment, and the use of antibiotics to treat diseases, which may have an adverse effect in their host or the environment. Efforts are being made toward attaining practical ways to enhance aquaculture sustainability. One such effort is using functional feed additives in feed formulation. Functional feed additives are dietary ingredients incorporated in feed formulations, not only for the usual provision of basic nutritional requirements as offered by traditional feed but also for growth and health enhancement; environmental and economic gain. This review emphasizes the importance of incorporating functional feed additives such as probiotics, prebiotics, symbiotics, and phytogenics. This study evaluates and presents holistic information on functional additives, their roles in enhancing aquaculture sustainability, and the challenges encountered in their application. Full article

(This article belongs to the Special Issue Feed Additives in Aquaculture)

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25 pages, 1351 KiB

Open AccessEditor’s ChoiceReview

Adriatic Sea Fishery Product Safety and Prospectives in Relation to Climate Change

by Edmond Hala and Rigers Bakiu

Fishes 2024, 9(5), 160; https://doi.org/10.3390/fishes9050160 - 28 Apr 2024

Cited by 5 | Viewed by 2182

Abstract

This bibliographic study addresses key aspects related to fishing, product safety, and climate change in the Adriatic Sea region. The examination of product safety focuses on the assessment of contaminants originating from human activities such as industry, mining, agriculture, and household waste disposal. [...] Read more.

This bibliographic study addresses key aspects related to fishing, product safety, and climate change in the Adriatic Sea region. The examination of product safety focuses on the assessment of contaminants originating from human activities such as industry, mining, agriculture, and household waste disposal. The contamination of the aquatic environment has emerged as a pressing global concern, extending to the Adriatic basin. Aquatic organisms, including fish, are prone to accumulating pollutants directly from polluted water sources and indirectly through the food web. The bio-accumulation of potentially hazardous substances, particularly heavy metals, pesticides, PCBs, PAHs, and antibiotic resistance in aquatic organisms, poses a significant threat to human health. Climate change effects will deplete our seafood supply in terms of quantity and safety owing to negative consequences such as higher levels of pollution, parasites, viruses, infections, acidification, and toxicities such as shellfish poisoning. Global food safety strategies should be developed to reduce greenhouse gas emissions and promote environmentally friendly technology, which indirectly affects seafood quality and microbiological safety, especially for the Adriatic Sea, which is part of the Mediterranean Sea, characterized by the most polluted waters in the world. Full article

(This article belongs to the Section Processing and Comprehensive Utilization of Fishery Products)

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13 pages, 5489 KiB

Open AccessEditor’s ChoiceArticle

Assessing Prospects of Integrating Asian Carp Polyculture in Europe: A Nature-Based Solution under Climate Change?

by Oksana Nekrasova, Mihails Pupins, Volodymyr Tytar, Leonid Fedorenko, Oleksandr Potrokhov, Arturs Škute, Andris Čeirāns, Kathrin Theissinger and Jean-Yves Georges

Fishes 2024, 9(4), 148; https://doi.org/10.3390/fishes9040148 - 22 Apr 2024

Cited by 3 | Viewed by 1879

Abstract

Aquaculture’s role in addressing food security has grown, with a spotlight on Asian carp species. Polyculture, i.e. cultivating multiple fish species in a single system, is being increasingly adopted for its resource efficiency and economic benefits. This practice for Asian fish for food [...] Read more.

Aquaculture’s role in addressing food security has grown, with a spotlight on Asian carp species. Polyculture, i.e. cultivating multiple fish species in a single system, is being increasingly adopted for its resource efficiency and economic benefits. This practice for Asian fish for food and ornamental purposes is gaining traction in Europe despite their invasive potential. Rising temperatures due to climate change offer an opportunity for thermophilic Asian carps (Hypophthalmichthys molitrix and Aristichthys nobilis). Using GIS modeling (Maxent), we identified the possible settlement of Asian carp in Northern Europe amidst climate change. We analyzed carp global distribution centers, assessed the potential carp spread in Europe, and evaluated their potential suitability for polyculture systems. By 2050, H. molitrix may extend its range to 58–62° N latitude, with a potential 1.7-fold habitat increase, while A. nobilis, which are more heat-tolerant, may move north to 52–58° N latitude, with a 1.3-fold potential increase. Despite the slight ecological differences in their native habitats, niche modeling indicates that these carp can occupy similar niches in Europe (proven statistically). The eventuality of using Asian species for polyculture in Europe presents both opportunities and challenges in the face of a changing climate as long as invasion risks are prevented. Envisaging such polyculture, yet very carefully for the protection of ecosystems, can help food security. Full article

(This article belongs to the Special Issue Biodiversity and Spatial Distribution of Fishes)

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20 pages, 4343 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Multi-Scale Coral Reef and Seascape Habitat Variables Combine to Influence Reef Fish Assemblages

by Katie T. Sievers, Eva C. McClure, Rene A. Abesamis and Garry R. Russ

Fishes 2024, 9(4), 137; https://doi.org/10.3390/fishes9040137 - 15 Apr 2024

Cited by 1 | Viewed by 2302

Abstract

While benthic characteristics of coral reef habitats are a major driver of the structure of coral reef fish assemblages, non-reef habitats adjacent to coral reefs (e.g., mangroves, seagrass beds, and macroalgal beds) can affect reef fish assemblages. Here, we investigate how reef fish [...] Read more.

While benthic characteristics of coral reef habitats are a major driver of the structure of coral reef fish assemblages, non-reef habitats adjacent to coral reefs (e.g., mangroves, seagrass beds, and macroalgal beds) can affect reef fish assemblages. Here, we investigate how reef fish assemblages respond to local-scale benthic habitats within a coral reef and larger-scale adjacent seascape features (habitats within 500 m of coral reefs) on Siquijor Island in the Philippines. We examined an abundance of species for the entire reef fish assemblage and within the assemblages of parrotfishes (subfamily Scarinae) and wrasses (family Labridae). Five distinct habitat types were identified in a cluster analysis, which incorporated benthic characteristics within coral reefs and habitats adjacent to coral reefs. We found that the diversity and structure of coral reef fish assemblages were affected by benthic characteristics within coral reefs and also by benthic habitat types adjacent to coral reefs. Individual species responses and juveniles of certain species demonstrated uniquely high abundances in habitat clusters characterized by the non-reef habitats surrounding coral reefs. Considering coral reef habitats and adjacent non-reef habitats as a holistic, interconnected seascape will provide better estimations of the drivers of the structures of coral reef fish assemblages. Full article

(This article belongs to the Special Issue Understanding and Managing the Spatial, Population and Ecological Dynamics of Coral Reef Fish)

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14 pages, 4833 KiB

Open AccessEditor’s ChoiceArticle

Environmentally Friendly and Efficient Methods for Mitigating the Density of Ascidian Fouling in Mediterranean Mussel Farming

by Dimitrios Tsotsios, Dimitrios K. Papadopoulos, Maria V. Alvanou, Ioannis Georgoulis, Athanasios Lattos, Basile Michaelidis, Konstantinos Feidantsis, Ioannis A. Giantsis and John A. Theodorou

Fishes 2024, 9(4), 135; https://doi.org/10.3390/fishes9040135 - 14 Apr 2024

Cited by 4 | Viewed by 1455

Abstract

Ascidian biofouling generates significant challenges to bivalve aquaculture. Their rapid spread across almost every available surface leads to increased maintenance costs and reduced yields in shellfish farming. In addition, ascidians may introduce pathogens or toxins, further compromising the health and marketability of bivalve [...] Read more.

Ascidian biofouling generates significant challenges to bivalve aquaculture. Their rapid spread across almost every available surface leads to increased maintenance costs and reduced yields in shellfish farming. In addition, ascidians may introduce pathogens or toxins, further compromising the health and marketability of bivalve stocks and thereby necessitating strict management strategies to manage these impacts. The aim of this study was the evaluation of different management practices for eliminating ascidian fouling and the identification of the best method for Mytilus galloprovincialis (Lamarck, 1819) aquaculture farms. The effects of different anti-fouling treatments as well as their interactive outcomes were examined by conducting two experiments. Various experimental procedures were applied, including the temporally differential washing of mussels, air exposure and immersion in 50 ppt and 70 ppt salinity solutions, as well as the combination of these applications. All treatments reduced the number of ascidian colonies on mussel socks but at varying proportions. Immersing mussel socks in a 70 ppt salinity solution followed by air exposure for 1 day was the most efficient method and led to a 93% eradication. Full article

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48 pages, 9825 KiB

Open AccessEditor’s ChoiceArticle

Dichichthyidae, a New Family of Deepwater Sharks (Carcharhiniformes) from the Indo–West Pacific, with Description of a New Species

by William T. White, Andrew L. Stewart, Helen L. O’Neill and Gavin J. P. Naylor

Fishes 2024, 9(4), 121; https://doi.org/10.3390/fishes9040121 - 28 Mar 2024

Viewed by 6069

Abstract

The genus Dichichthys was resurrected for five species previously allocated to the genus Parmaturus in the family Pentanchidae. Supraorbital crests on the chondrocranium distinguish Dichichthys from Parmaturus and other members of the family Pentanchidae. A new family, Dichichthyidae, has been proposed to contain [...] Read more.

The genus Dichichthys was resurrected for five species previously allocated to the genus Parmaturus in the family Pentanchidae. Supraorbital crests on the chondrocranium distinguish Dichichthys from Parmaturus and other members of the family Pentanchidae. A new family, Dichichthyidae, has been proposed to contain Dichichthys. The sequence of the NADH2 mitochondrial gene confirms the placement of Dichichthys outside of the Pentanchidae family, as well as separate from the Atelomycteridae and Scyliorhinidae families. Dichichthys albimarginatus was described using a holotype collected off the coast of New Caledonia. A second juvenile specimen collected off the coast of Papua New Guinea was tentatively assigned as D. cf. albimarginatus. Dichichthys bigus is known from the holotype collected in the Coral Sea off the coast of Queensland, Australia. A new, parasite-afflicted underwater observation was reported further north of Queensland. The type species Dichichthys melanobranchus, previously only known from juvenile specimens, was redescribed based on adult specimens. Dichichthys nigripalatum is known from the holotype collected off Sumbawa, Indonesia, and a tentatively identified photo record from West Java. Dichichthys satoi n. sp. is described from the West Norfolk Ridge and off the North Island of New Zealand. Members of the genus Dichichthys have unique curved egg cases which have pliable ridges made up of numerous fibres and long coiled tendrils on the posterior end. Full article

(This article belongs to the Section Taxonomy, Evolution, and Biogeography)

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9 pages, 1482 KiB

Open AccessEditor’s ChoiceArticle

Depth Range Extension for the Misty Grouper Hyporthodus mystacinus Documented via Deep-Sea Landers throughout the Greater Caribbean

by Shannon E. Aldridge, Olivia F. L. Dixon, Christine de Silva, Johanna K. Kohler, Oliver N. Shipley, Brennan T. Phillips, Teresa F. Fernandes, Timothy Austin, Rupert F. Ormond, Mauvis A. Gore and Austin J. Gallagher

Fishes 2024, 9(4), 114; https://doi.org/10.3390/fishes9040114 - 22 Mar 2024

Cited by 3 | Viewed by 2248

Abstract

Misty Groupers (Hyporthodus mystacinus) are one of the largest and most geographically widespread grouper species and one of the few grouper species known to occur at depths greater than 200 m. However, aspects of their basic biology, behavior, and ecology remain [...] Read more.

Misty Groupers (Hyporthodus mystacinus) are one of the largest and most geographically widespread grouper species and one of the few grouper species known to occur at depths greater than 200 m. However, aspects of their basic biology, behavior, and ecology remain poorly understood, leaving significant gaps in our ability to evaluate their functional role throughout the vertical water column, as well as our understanding of their conservation needs in a changing ocean. Through in-situ video observation obtained using deep-sea landers in both The Bahamas and Cayman Islands over multiple years, we documented Misty Grouper occurrence up to 470 m depth in the mesopelagic zone. These observations provide a new depth range extension for the species and illuminate the potential importance of deep-water habitats for large grouper species in the wider Caribbean. Full article

(This article belongs to the Section Biology and Ecology)

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17 pages, 20649 KiB

Open AccessEditor’s ChoiceArticle

Numerical Study of the Hydrodynamic Response of Biodegradable Drifting Fish Aggregating Devices in Regular Waves

by Tongzheng Zhang, Zhiqiang Liu, Junbo Zhang, Xing Su, Junlin Chen and Rong Wan

Fishes 2024, 9(4), 112; https://doi.org/10.3390/fishes9040112 - 22 Mar 2024

Cited by 3 | Viewed by 1577

Abstract

Fish-aggregating devices play a significant role in tuna purse fisheries. The severe marine environment and the large number of non-biodegradable fish-aggregating devices impact structural safety and cause marine litter. Therefore, hydrodynamic performance and the use of biodegradable materials are crucial issues for ensuring [...] Read more.

Fish-aggregating devices play a significant role in tuna purse fisheries. The severe marine environment and the large number of non-biodegradable fish-aggregating devices impact structural safety and cause marine litter. Therefore, hydrodynamic performance and the use of biodegradable materials are crucial issues for ensuring the sustainability of fish-aggregating devices. In this study, a type of virtual biodegradable drifting fish-aggregating device (Bio-DFAD) was designed. Numerical simulations were conducted to investigate the motion responses and relative velocities of Bio-DFADs in regular waves (first- and fifth-order waves). The numerical model was applied based on unsteady Reynolds-averaged Navier–Stokes equations with the realizable k–ε model. For different scenarios of modeling, various conditions were modeled, including the relative length, wave steepness, and diameter of the balsa wood, to analyze their effects on the hydrodynamic response of the Bio-DFADs. The results indicated that the increased relative length, wave steepness, and diameter of balsa wood had a significant influence on the motion response amplitude operators (RAOs) and relative velocity of Bio-DFADs. The results suggested that a relative length (L_F/B = 1.5) and smaller diameter (D_F = 30 mm) were recommended for fewer motion responses and relative velocity. The obtained results provide insight for practical engineering applications of the hydrodynamic design of Bio-DFADs. Full article

(This article belongs to the Section Fishery Economics, Policy, and Management)

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25 pages, 1040 KiB

Open AccessEditor’s ChoiceReview

Polystyrene Micro- and Nanoplastics (PS MNPs): A Review of Recent Advances in the Use of -Omics in PS MNP Toxicity Studies on Aquatic Organisms

by Maria Concetta Eliso, Barbara Billè, Tiziana Cappello and Maria Maisano

Fishes 2024, 9(3), 98; https://doi.org/10.3390/fishes9030098 - 5 Mar 2024

Cited by 12 | Viewed by 2747

Abstract

In recent years, micro- and nanoplastics (MNPs) have represented an emerging threat for the aquatic environment due to their persistence and widespread distribution. Indeed, their small size and increased surface area lead to a high biological reactivity, which can be crucial for the [...] Read more.

In recent years, micro- and nanoplastics (MNPs) have represented an emerging threat for the aquatic environment due to their persistence and widespread distribution. Indeed, their small size and increased surface area lead to a high biological reactivity, which can be crucial for the health status of biota. To date, several studies have investigated lethal and sublethal endpoints of MNPs, while one of the main challenges is to understand their mechanisms of toxicity in a comprehensive manner. With this aim, the field of aquatic ecotoxicology can now benefit from the -omics approaches. This review focuses on the recent advances related to the use of transcriptomics, proteomics, and metabolomics to deeply investigate the molecular and biochemical responses of aquatic organisms, both fishes and aquatic invertebrates, to pristine polystyrene (PS) MNPs. The literature reviewed revealed that transcriptomics and metabolomics are the most frequently used -omic approaches. Overall, the studies taken into consideration shed light on the events triggered by PS MNPs at molecular and cellular levels, identifying as mechanisms of toxicity the pathways involved in oxidative stress, energy metabolism, immune response, and the nervous system. Future studies should therefore focus on the use and integration of multi-omics approaches for a more comprehensive understanding of the mechanisms involved in MNPs toxicity. Full article

(This article belongs to the Special Issue Effects of Plastic (Nano/Micro/Macro) Particles on Fish and Aquatic Invertebrates)

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19 pages, 3139 KiB

Open AccessEditor’s ChoiceReview

Applications of Antimicrobial Photodynamic Therapy in Aquaculture: Effect on Fish Pathogenic Bacteria

by Edith Dube and Grace Emily Okuthe

Fishes 2024, 9(3), 99; https://doi.org/10.3390/fishes9030099 - 5 Mar 2024

Cited by 5 | Viewed by 2712

Abstract

Increased infectious diseases and the reduced effectiveness of antibiotics due to antimicrobial resistance pose global challenges affecting the aquaculture industry. As bacteria increasingly develop antibiotic resistance, research scientists are shifting their focus to technologies such as antimicrobial photodynamic therapy (aPDT), which show potential [...] Read more.

Increased infectious diseases and the reduced effectiveness of antibiotics due to antimicrobial resistance pose global challenges affecting the aquaculture industry. As bacteria increasingly develop antibiotic resistance, research scientists are shifting their focus to technologies such as antimicrobial photodynamic therapy (aPDT), which show potential for treating and controlling fish infections without promoting the development of resistant bacteria. Various photosensitizers (PSs), both natural and synthetic, are under investigation for their application in aPDT within the aquaculture industry. This shift is crucial for the sustainability of the aquaculture industry, which plays a significant role in achieving several of the United Nations (UN) Sustainable Development Goals (SDGs). This review highlights the application of aPDT against fish pathogens in the industry and the types of PSs utilized. It also explores the potential application of this technique for treating and controlling fish infections, along with the advantages and limitations of its use in aquaculture production systems. Finally, a conclusion and future perspectives are provided. Full article

(This article belongs to the Special Issue Prevention and Treatment of Aquaculture Animal Diseases)

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22 pages, 5936 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Water Nitrate Concentration Combined with Elevated Temperature on Rainbow Trout Oncorhynchus mykiss in an Experimental Aquaponic Setup

by Dimitrios K. Papadopoulos, Athanasios Lattos, Ioanna Chatzigeorgiou, Aphrodite Tsaballa, Georgios K. Ntinas and Ioannis A. Giantsis

Fishes 2024, 9(2), 74; https://doi.org/10.3390/fishes9020074 - 13 Feb 2024

Cited by 3 | Viewed by 2841

Abstract

Intensive recirculating systems are a fast-developing sector of aquaculture. While several warm-water fish have been reared in aquaponics, almost no data are available for cold-water species. The determination of nitrate toxicity thresholds in recirculating aquaculture is crucial. Different pollutants are typically more toxic [...] Read more.

Intensive recirculating systems are a fast-developing sector of aquaculture. While several warm-water fish have been reared in aquaponics, almost no data are available for cold-water species. The determination of nitrate toxicity thresholds in recirculating aquaculture is crucial. Different pollutants are typically more toxic at elevated temperatures. We investigated the performance of Oncorhynchus mykiss under two different nitrate levels and two temperatures. We applied a 2 × 2 factorial design, where fish (9.78 ± 0.51 g) were exposed to nitrate concentrations of 40 or 110 mg/L NO₃⁻ and to temperatures of 17 °C or 21 °C for 20 days. This study focused on understanding the physiological responses of rainbow trout to relatively low nitrate levels under heat stress in order to investigate the feasibility of integrating this species into commercial aquaponics. The growth, condition, and expression of genes involved in metabolism, heat shock, antioxidant, and immune response were assessed in the liver, together with the activities of enzymes related to glucose and fatty acid metabolism. High nitrate levels at 17 °C affected the condition but did not alter growth, leading to increased glycolytic potential and, occasionally, a greater reliance on lipid oxidation. Antioxidant defense was mainly induced due to high nitrates and the similar expression patterns of antioxidant genes observed under high nitrate at both 17 °C and 21 °C. Warm exposure decreased condition and growth, leading to greatly reduced glucokinase transcription, irrespective of the nitrate levels. Exposure to 21 °C and high nitrate led to equivalent growth and condition as well as to a milder inflammatory response combined with metabolic readjustments (enhancement of glycolytic and lipid oxidation pathways) compared to the low nitrates at 21 °C. Based on the results, rearing at a temperature close to 21 °C should be avoided for fingerling growth, while NO₃⁻ concentration until 110 mg/L may not have severe impacts on fingerling health and growth at 17 °C. In addition, rainbow trout fingerlings can tolerate a 20-day exposure at 21 °C and NO₃⁻ up to 110 mg/L. Additional factors should always be considered, such as specific water quality parameters, for a comprehensive approach to assessing the feasibility of rainbow trout aquaculture in aquaponics. Full article

(This article belongs to the Special Issue Development of Sustainable Aquaculture Production)

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24 pages, 3575 KiB

Open AccessEditor’s ChoiceArticle

Growth Performance and Environmental Quality Indices and Biomarkers in a Co-Culture of the European Sea Bass with Filter and Deposit Feeders: A Case Study of an IMTA System

by Efthimia Cotou, Helen Miliou, Evanthia Chatzoglou, Eirini Schoina, Nektarios Politakis, Dimitra Kogiannou, Eleni Fountoulaki, Afrodite Androni, Aggeliki Konstantinopoulou, Georgia Assimakopoulou and Cosmas Nathanailides

Fishes 2024, 9(2), 69; https://doi.org/10.3390/fishes9020069 - 8 Feb 2024

Cited by 4 | Viewed by 3702

Abstract

This study aimed to evaluate the efficiency of an integrated multi-trophic aquaculture (IMTA) system comprising co-cultured fed fish and organic extractive species representing three distinct trophic levels as well as the impact and potential utilization of two commercially available fish feeds made up [...] Read more.

This study aimed to evaluate the efficiency of an integrated multi-trophic aquaculture (IMTA) system comprising co-cultured fed fish and organic extractive species representing three distinct trophic levels as well as the impact and potential utilization of two commercially available fish feeds made up of 35% fish meal (FM) and 20% fish meal (LFM) ingredients, using a multi-indicator assessment approach. Significant alterations were observed in growth performance indicators (GPIs), water and sediment quality indices, toxicity tests and biomarkers within the IMTA system. The fish survival, weight gain (WG), and specific growth rate (SGR) were higher in the IMTA system with significantly lower feed conversion ratios (FCRs) and higher feed efficiency (FE) in comparison to the fed fish monoculture system. Yet, organic filter feeders displayed 100% survival, and increased shell growth, while deposit feeders exhibited successful survival and significant weight gain. In the comparison between FM-IMTA and LFM-IMTA, fed fish in FM-IMTA showed higher WG, SGR, and FE with lower FCR. Environmental parameters like temperature, oxygen, and nutrient concentrations fluctuated but generally improved in the IMTA system, indicating lower mesotrophic conditions. Sediment fatty acid profiles differed between systems and toxicity assessments, which suggested a lower impact in IMTA and FM-IMTA systems. The sediment microbial community displayed high similarity within IMTA systems and between FM-IMTA and LFM-IMTA. These findings underscore the potential of IMTA systems for sustainable aquaculture, emphasizing improved growth performance and reduced environmental impact, particularly when using fish meal feeds. Full article

(This article belongs to the Section Environment and Climate Change)

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21 pages, 687 KiB

Open AccessEditor’s ChoiceReview

Use of Algae in Aquaculture: A Review

by Srirengaraj Vijayaram, Einar Ringø, Hamed Ghafarifarsani, Seyed Hossein Hoseinifar, Saman Ahani and Chi-Chung Chou

Fishes 2024, 9(2), 63; https://doi.org/10.3390/fishes9020063 - 1 Feb 2024

Cited by 17 | Viewed by 10646

Abstract

The utilization of algae in aquaculture is environmentally friendly, safe, and cost-effective and can effectively substitute for fish meal and fish oil in aquatic feeds. Incorporating algae as dietary supplements leads to significant enhancements in aquatic animals’ health and also improves the aquatic [...] Read more.

The utilization of algae in aquaculture is environmentally friendly, safe, and cost-effective and can effectively substitute for fish meal and fish oil in aquatic feeds. Incorporating algae as dietary supplements leads to significant enhancements in aquatic animals’ health and also improves the aquatic ecosystem. Algae are rich sources of nutrients and serve as the foundational food source in the aquatic food chain. Currently, 40 different algae species are employed in aquaculture. Furthermore, algae contributes to elevating the overall quality of aquatic feed products. Aquaculture stands as the most vital food production sector globally; however, challenges such as infection outbreaks and aquatic environmental pollution pose significant threats to the sustainable growth of this industry. An alternative strategy for mitigating environmental issues and improving aquatic production involves the utilization of algae. The novelty in the applications of algae in aquaculture stems from their multifaceted roles and benefits, such as their capacity to improve water quality, serve as nutrient-rich feed supplements, and enhance the overall health and productivity of aquatic species. These versatile applications of algae represent a fresh and innovative approach to sustainable aquaculture practices. This review furnishes insights into the use of algae, algae extracts, or components derived from algae to enhance water quality. Additionally, it covers the utilization of algae-based feed supplements, boosting of the immune system, enhanced growth performance, and disease resistance in aquatic animals. Full article

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18 pages, 1555 KiB

Open AccessEditor’s ChoiceArticle

Estimating Cognitive Ability in the Wild: Validation of a Detour Test Paradigm Using a Cichlid Fish (Neolamprologus pulcher)

by Arne Jungwirth, Anna Horsfield, Paul Nührenberg and Stefan Fischer

Fishes 2024, 9(2), 50; https://doi.org/10.3390/fishes9020050 - 27 Jan 2024

Cited by 5 | Viewed by 2702

Abstract

Cognitive abilities vary within and among species, and several hypotheses have been proposed to explain this variation. Two of the most prominent hypotheses regarding the evolution of cognition link increased social and habitat complexity with advanced cognitive abilities. Several studies have tested predictions [...] Read more.

Cognitive abilities vary within and among species, and several hypotheses have been proposed to explain this variation. Two of the most prominent hypotheses regarding the evolution of cognition link increased social and habitat complexity with advanced cognitive abilities. Several studies have tested predictions derived from these two hypotheses, but these were rarely conducted under natural conditions with wild animals. However, this is of particular importance if we aim to link cognitive abilities with fitness-relevant factors to better understand the evolution of cognition. The biggest hurdle to assessing cognition in the wild is to find a suitable setup that is easy to use under field conditions. Here, we set out to evaluate an extremely simple test of cognitive ability for use with a broad range of aquatic animals in their natural habitat. We did so by developing a detour test paradigm in which fish had to detour a clear obstacle to reach a food reward. By altering the difficulty of the task, we confirmed that this setup is a valid test of cognitive abilities in wild groups of a Lake Tanganyika cichlid, Neolamprologus pulcher. Subsequently, we probed specific predictions from the two major hypotheses regarding cognitive evolution using the most difficult test configuration. Specifically, we tested the variation in cognitive abilities among groups of different sizes occupying habitats of varying complexity. We find mixed support for both hypotheses, but we hope that our work inspires future investigations on the evolution of cognition in Lake Tanganyika cichlids. Full article

(This article belongs to the Special Issue Causes and Consequences of Cognitive Variation in Fishes)

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26 pages, 7878 KiB

Open AccessEditor’s ChoiceArticle

Effects of Cold Stress on the Hemolymph of the Pacific White Shrimp Penaeus vannamei

by Jianqiang Zhu, Wenjun Shi, Ran Zhao, Chen Gu, Hui Li, Libao Wang and Xihe Wan

Fishes 2024, 9(1), 36; https://doi.org/10.3390/fishes9010036 - 16 Jan 2024

Cited by 9 | Viewed by 3495

Abstract

Temperature is an important factor in the physiological processes of aquatic organisms and can seriously affect several chemical and biological processes in their bodies, including respiratory metabolism, antioxidant capacity, immune capacity, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were [...] Read more.

Temperature is an important factor in the physiological processes of aquatic organisms and can seriously affect several chemical and biological processes in their bodies, including respiratory metabolism, antioxidant capacity, immune capacity, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were used to investigate the response of Penaeus vannamei to cold stress. The results indicated that cold stress disrupted nucleotide metabolism and inhibited gluconeogenesis. However, shrimp exhibited response mechanisms in order to enhance cold tolerance, regulating changes in key genes and metabolites in amino acid and lipid metabolism to increase energy supply and protect cell membrane stability. In addition, the response included regulating Ca²⁺ pumps and ion channels to maintain intracellular ion homeostasis and osmotic balance. When the temperature dropped further, oxidative damage occurred due to overwhelming of the antioxidant defense system, and immune function was inhibited. This research provides some references regarding the molecular mechanisms involved in responding to cold stress and potential strategies to improve cold tolerance in P. vannamei; these are important references for studying the cold stress response of shrimp. Full article

(This article belongs to the Special Issue Omics Analysis in Marine Invertebrate Biology)

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19 pages, 17284 KiB

Open AccessEditor’s ChoiceArticle

Immune Cell Profiling in the Ovarian Stroma of a Viviparous Fish during the Breeding Season: A Histological and Immunohistochemical Investigation

by Ramy K. A. Sayed, Doaa M. Mokhtar, Madeha Ahmed Hashim, Ahmed S. Aly, Giacomo Zaccone, Marco Albano, Alessio Alesci and Nada Abdellah

Fishes 2024, 9(1), 10; https://doi.org/10.3390/fishes9010010 - 25 Dec 2023

Cited by 4 | Viewed by 3139

Abstract

The molly fish is a member of viviparous teleosts that are characterized by the fusion of the right and left ovaries during their early embryonic development. This fusion results in a singular and saccular ovary, where the germinal epithelium lines the internal lumen. [...] Read more.

The molly fish is a member of viviparous teleosts that are characterized by the fusion of the right and left ovaries during their early embryonic development. This fusion results in a singular and saccular ovary, where the germinal epithelium lines the internal lumen. The present study aimed to identify the immune cells in the ovarian stroma of Molly fish during the breeding season using histological and immunohistochemical analysis. Histological examination of the ovaries displayed oocytes at all different stages of development and degeneration. The ovocoel, a lymph-filled space, remains in the center of the ovary and branches posteriorly, creating the lumen of the gonoduct. The ovarian wall is composed of three layers: the mesothelium, tunica albuginea, and germinal epithelium. The developing ova were held together by the stroma, which consisted of vascular collagenous connective tissue clustered with immune cells. Immunohistochemical analysis revealed the presence of clusters of macrophages expressing APG5, IL-1β, TGF-β, S100, NF-κB, CD68, Iba-1, and Ach. Monocytes demonstrated positive immunoreactivity for both APG5 and IL-1β, whereas dendritic cells expressed only APG5. Furthermore, rodlet cells exhibited immunoreactivity for S100 protein, IL-1β, NF-κB, CD68, Nrf2, Ach, myostatin, SOX9, and Iba-1. In contrast, stem cells displayed immunoreactivity for Nrf2, myostatin, and SOX9. In conclusion, the ovarian stroma of Molly fish demonstrated a notable presence of immune cells, indicating their active involvement in immune reactions. Full article

(This article belongs to the Section Biology and Ecology)

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14 pages, 7394 KiB

Open AccessEditor’s ChoiceArticle

Expected Climate Change in the High Arctic—Good or Bad for Arctic Charr?

by Martin A. Svenning, Eigil T. Bjørvik, Jane A. Godiksen, Johan Hammar, Jack Kohler, Reidar Borgstrøm and Nigel G. Yoccoz

Fishes 2024, 9(1), 8; https://doi.org/10.3390/fishes9010008 - 23 Dec 2023

Cited by 4 | Viewed by 2479

Abstract

Lakes in the High Arctic are characterized by their low water temperature, long-term ice cover, low levels of nutrients, and low biodiversity. These conditions mean that minor climatic changes may be of great importance to Arctic freshwater organisms, including fish, by influencing vital [...] Read more.

Lakes in the High Arctic are characterized by their low water temperature, long-term ice cover, low levels of nutrients, and low biodiversity. These conditions mean that minor climatic changes may be of great importance to Arctic freshwater organisms, including fish, by influencing vital life history parameters such as individual growth rates. In this study, Arctic charr sampled from two Svalbard lakes (78–79° N) over the period 1960–2008 provided back-calculated length-at-age information extending over six decades, covering both warm and cold spells. The estimated annual growth in young-of-the-year (YOY) Arctic charr correlated positively with an increasing air temperature in summer. This increase is likely due to the higher water temperature during the ice-free period, and also to some extent, due to the winter air temperature; this is probably due to thinner ice being formed in mild winters and the subsequent earlier ice break-up. However, years with higher snow accumulation correlated with slower growth rates, which may be due to delayed ice break-up and thus a shorter summer growing season. More than 30% of the growth in YOY charr could be explained specifically by air temperature and snow accumulation in the two Arctic charr populations. This indicated that juvenile Svalbard Arctic charr may experience increased growth rates in a future warmer climate, although future increases in precipitation may contradict the positive effects of higher temperatures to some extent. In the longer term, a warmer climate may lead to the complete loss of many glaciers in western Svalbard; therefore, rivers may dry out, thus hindering migration between salt water and fresh water for migratory fish. In the worst-case scenario, the highly valuable and attractive anadromous Arctic charr populations could eventually disappear from the Svalbard lake systems. Full article

(This article belongs to the Special Issue Effect of Climate Change on Salmonid Fishes in Rivers)

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15 pages, 7257 KiB

Open AccessEditor’s ChoiceArticle

Identification of “Bathed” Chinese Mitten Crabs (Eriocheir sinensis) Using Geometric Morphological Analysis of the Carapace

by Yiqian Xu, Junren Xue, Hongbo Liu, Tao Jiang, Xiubao Chen and Jian Yang

Fishes 2024, 9(1), 6; https://doi.org/10.3390/fishes9010006 - 21 Dec 2023

Cited by 4 | Viewed by 3271

Abstract

To confirm whether Chinese mitten crabs (Eriocheir sinensis), commonly known as hairy crabs or river crabs, in non-Yangcheng Lake areas undergo morphological convergence with the original crabs in the Yangcheng Lake purse seine and high-standard modified aquaculture ponds after being “introduced” [...] Read more.

To confirm whether Chinese mitten crabs (Eriocheir sinensis), commonly known as hairy crabs or river crabs, in non-Yangcheng Lake areas undergo morphological convergence with the original crabs in the Yangcheng Lake purse seine and high-standard modified aquaculture ponds after being “introduced” or “bathed”-cultured, we employed a geometric morphometrics approach. This approach allowed us to compare and analyze the dynamic changes in the carapace morphology of both the original and “introduced” crabs in Yangcheng Lake and high-standard ponds in Kunshan City at 0, 7, 14, and 30 days after “bathing” culture. The geometric morphological analysis of the carapace was conducted using a system of 35 established landmarks. The stepwise discriminant analysis of the relative distortion score revealed morphological differences between “introduced” and resident original crabs in the Yangcheng Lake area and in high-standard modified ponds after 7, 14, and 30 days of bathing culture. The accuracy of the discriminant analysis was 100%. The results of the geometric morphological visualization demonstrated that the carapaces of the bathed crabs underwent adaptive changes in the water. However, even after one month of bathing culture, the “introduced” crabs in lakes and ponds could not reach the morphological characteristics of the original crabs, i.e., their carapaces did not exhibit the characteristics of the original crabs. Full article

(This article belongs to the Section Sustainable Aquaculture)

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16 pages, 3721 KiB

Open AccessEditor’s ChoiceArticle

Environmental Factors Determine Tuna Fishing Vessels’ Behavior in Tonga

by Siosaia Vaihola and Stuart Kininmonth

Fishes 2023, 8(12), 602; https://doi.org/10.3390/fishes8120602 - 7 Dec 2023

Cited by 7 | Viewed by 2370

Abstract

Comprehending the spatial distribution of human fishing endeavors holds significant importance in the context of monitoring fishery resources and implementing spatial management measures. To gain insights into the spatial arrangement of tuna longline activities within the exclusive economic zones of Tonga and their [...] Read more.

Comprehending the spatial distribution of human fishing endeavors holds significant importance in the context of monitoring fishery resources and implementing spatial management measures. To gain insights into the spatial arrangement of tuna longline activities within the exclusive economic zones of Tonga and their correlation with the marine environment, this study utilizes data from the Tonga Tuna Longline Fisheries spanning from 2002 to 2018. The data are employed to extract information about the spatial distribution of fishing efforts and coupled with 15 marine environmental variables covering both sea surface and subsurface conditions. This study employs boosted regression trees (BRT) and general additive models (GAM) to establish the non-linear relationships between the distribution of fishing effort and marine environmental factors. Furthermore, it examines and analyzes the ecological niche occupied by tuna longline vessels in high-sea environments. The outcomes of the factor analysis indicate that the most important factors influencing the fishing efforts of tuna longliners are the dissolved oxygen content at the sea surface and latitude. These two factors contribute significantly, accounting for 19.06% and 18.62% of the fishing efforts of vessels, respectively, followed by distance to ports, longitude, and dissolved oxygen at 100 m depth, contributing 10.77%, 7.07%, and 6.30%, respectively. The sea surface chlorophyll, ocean current at 100 m depth, and mixed layer depth contributed the least, 3.63%, 2.13%, and 1.72, respectively. In terms of space and time, tuna longliners are more likely to operate in the 18–22° S latitudinal and 172–178° W longitudinal region, and fishing efforts increased in the months from March to August. The spatial distribution of the fishing efforts modeled for fishing vessels in 2018 is predicted to have good spatial distribution with the actual fishing efforts of these vessels. This research aids in comprehending the environmental impacts resulting from shifts in the spatial distribution of tuna longline vessels, offering valuable insights for the effective management of tuna longline fisheries in Tonga. Full article

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