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Fishes, Volume 9, Issue 7 (July 2024) – 32 articles

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18 pages, 862 KiB  
Article
Effects of Rewilding Aquaculture Time on Nutritional Quality and Flavor Characteristics of Grass Carp (Ctenopharyngodon idellus)
by Qianyun Han, Jiajie Hu, Weicong Pan, Jin Yu, Xiaoguo Ying, Jinpeng Weng, Weiye Li and Xudong Weng
Fishes 2024, 9(7), 275; https://doi.org/10.3390/fishes9070275 - 11 Jul 2024
Abstract
Wild fish are preferred by consumers primarily for their superior sensorial qualities, including taste and texture. However, their limited availability often results in higher prices. Considering this, we explored the possibility of enhancing the quality of earthen pond aquaculture fish by transferring them [...] Read more.
Wild fish are preferred by consumers primarily for their superior sensorial qualities, including taste and texture. However, their limited availability often results in higher prices. Considering this, we explored the possibility of enhancing the quality of earthen pond aquaculture fish by transferring them to a near wild environment. This study investigated how rewilding time affects the physical properties, nutritional composition, and volatile profile of grass carp muscle. The results showed that compared to the 0M group, the crude protein content in grass carp muscle did not change significantly (p > 0.05) as the rewilding time increased to 6 months. Meanwhile, the significant increase in hardness and springiness (p < 0.05) indicated that the textural characteristics of muscle, which were key sensory and physical indices of muscle quality, were improved. Although the 6M group showed a 58.93% reduction in crude fat content compared to the 0M group, it retained the highest docosahexaenoic acid (DHA) content. Sensory evaluation demonstrated that as the rewilding time increased, the fishy and grassy odors of the rewilding grass carp diminished. Furthermore, cluster heatmaps and partial least squares discriminant analysis (PLS-DA) revealed that cultured grass carp and rewilding grass carp at three time points exhibited differences in various indicators. The variable importance in projection (VIP) showed that volatile flavor compounds (acetone, propionaldehyde-D, 1-penten-3-ol) and hardness were key factors in distinguishing between them. Therefore, extending the rewilding time can potentially enhance the acceptability of cultured grass carp by improving the physical properties, nutritional quality, and volatile profile of the muscle. This approach may provide a new pathway for fish aquaculture. Full article
(This article belongs to the Section Nutrition and Feeding)
32 pages, 7815 KiB  
Article
From Waters to Fish: A Multi-Faceted Analysis of Contaminants’ Pollution Sources, Distribution Patterns, and Ecological and Human Health Consequences
by Nicoleta Damir, Valentina Coatu, Diana Danilov, Luminita Lazăr and Andra Oros
Fishes 2024, 9(7), 274; https://doi.org/10.3390/fishes9070274 - 11 Jul 2024
Viewed by 151
Abstract
This study presents an extensive evaluation of the contamination levels in fish, mollusks, water, and sediments in the Black Sea over eight years, from 2016 to 2023. The primary aim was to determine the concentrations and distribution patterns of heavy metals (HMs), polychlorinated [...] Read more.
This study presents an extensive evaluation of the contamination levels in fish, mollusks, water, and sediments in the Black Sea over eight years, from 2016 to 2023. The primary aim was to determine the concentrations and distribution patterns of heavy metals (HMs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and other persistent organic pollutants (POPs) in fish, water, and sediments of the Black Sea, and their implications for marine ecosystem health and human safety. Data were collected through scientific cruises and the methodology involved systematic sampling across different regions of the Romanian Black Sea, followed by rigorous laboratory analyses to identify and quantify the presence of contaminants. The study also examined the temporal trends of these pollutants, providing insights into their sources, pathways, and persistence in the marine environment. Additionally, the research assessed the bioaccumulation of contaminants in various biota, offering a critical perspective on food safety and potential risks to human consumers. The findings revealed significant spatial insights, highlighting areas of concern that require immediate attention and action. Notably, industrial discharge, agricultural runoff, and historical pollution hotspots were identified as major sources of contamination. This research underscores the need for enhanced monitoring and regulatory frameworks to mitigate pollution sources and safeguard the Black Sea ecosystem, advocating for sustainable practices and effective management strategies to preserve marine resources in the Black Sea. Full article
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8 pages, 246 KiB  
Opinion
Data Review on the Variation in Sensitivity to Aquaculture Chemotherapeutants in Some Crustacean Life Stages
by Sarah Marteinson, Melanie Kingsbury and Dounia Hamoutene
Fishes 2024, 9(7), 273; https://doi.org/10.3390/fishes9070273 - 11 Jul 2024
Viewed by 169
Abstract
Aquaculture chemotherapeutants used to control sea lice in finfish aquaculture can disperse into the marine habitat and have the potential to affect non-target species like crustaceans. Some of the compounds used (especially in Canada) include in-feed drugs such as emamectin benzoate (EMB), and [...] Read more.
Aquaculture chemotherapeutants used to control sea lice in finfish aquaculture can disperse into the marine habitat and have the potential to affect non-target species like crustaceans. Some of the compounds used (especially in Canada) include in-feed drugs such as emamectin benzoate (EMB), and ivermectin (IVER), as well as bath pesticides such as azamethiphos (AZA) and hydrogen peroxide (HP). Despite the paucity of data, crustacean life cycle stages appear to have varying sensitivities to these compounds. This data review sets out to examine the intraspecies variation in sensitivity within life stages for lobster (Homarus) and prawn (Pandalus) species. Despite limited information, it appears that prawn eggs, adults, and juveniles are less sensitive to AZA and EMB compared with larvae, whereas for lobster the opposite is true: adults and juveniles are more sensitive than larvae to AZA (there was insufficient data to assess EMB). For HP, the sensitivity of prawn eggs appears comparable to larvae, but hatching success data suggest that this important stage of development is less impacted than eggs themselves as indicated by one study. These differences are important considerations for toxicity threshold determination processes and risk assessments, which ideally are environmentally relevant, and highlight the need for more data. Full article
(This article belongs to the Special Issue The Effects of Contaminants from Aquaculture on Aquatic Environments)
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13 pages, 871 KiB  
Article
The Effects of Water Flow Speed on Swimming Capacity and Energy Metabolism in Adult Amur Grayling (Thymallus grubii)
by Cunhua Zhai, Yutao Li, Guanyu Zhu, Wenjie Peng, Qiuxu E, Ying Zhang and Bo Ma
Fishes 2024, 9(7), 272; https://doi.org/10.3390/fishes9070272 - 10 Jul 2024
Viewed by 292
Abstract
The present study aimed to explore whether water flow velocity could affect the swimming ability and overall energy metabolism of wild Amur grayling (Thymallus grubii). Swimming performance was assessed by measuring critical swimming speed (Ucrit), burst speed (Uburst [...] Read more.
The present study aimed to explore whether water flow velocity could affect the swimming ability and overall energy metabolism of wild Amur grayling (Thymallus grubii). Swimming performance was assessed by measuring critical swimming speed (Ucrit), burst speed (Uburst), and oxygen consumption rate (MO2) based on the stepped velocity test method. Our results showed that the absolute values of Ucrit and Uburst tended to increase with body length. In contrast, the relative values of Ucrit and Uburst tended to decrease and increase, respectively. MO2 in Amur grayling was elevated with increasing velocity, suggesting relatively high swimming efficiency. We also measured the biochemical indices related to energy metabolism. Lactate dehydrogenase, hexokinase, and pyruvate kinase activities significantly increased (p < 0.05). Hepatic glycogen, glucose, and muscle glycogen contents decreased with the increasing trend of velocity (p < 0.05), the lactic acid contents of the blood and muscles increased significantly with the increase in velocities (p < 0.05), and changes in creatine phosphate content showed no significant difference (p > 0.05). The results not only denote the relationship between body size and swimming speed but also show the effects of water flow velocity on energy metabolism in Amur grayling. The results provide basic data for the construction of fish passage. Full article
(This article belongs to the Section Biology and Ecology)
31 pages, 9522 KiB  
Article
Hepatic Transcriptomic Responsiveness of Polar Cod, Boreogadus saida, to Ocean Acidification and Warming
by Sarah Kempf, Heidrun Sigrid Windisch, Kristina Lore Kunz, Hans-Otto Pörtner, Felix Christopher Mark and Magnus Lucassen
Fishes 2024, 9(7), 271; https://doi.org/10.3390/fishes9070271 - 10 Jul 2024
Viewed by 364
Abstract
Background: This study was part of a larger comprehensive project (BIOACID) addressing the physiological resilience of Polar cod, Boreogadus saida, to ocean acidification and global warming and aimed to unravel underlying molecular mechanisms of the observed physiological responses. Methods: Fish were acclimated [...] Read more.
Background: This study was part of a larger comprehensive project (BIOACID) addressing the physiological resilience of Polar cod, Boreogadus saida, to ocean acidification and global warming and aimed to unravel underlying molecular mechanisms of the observed physiological responses. Methods: Fish were acclimated long-term to three CO2 concentrations comprising control conditions (390 ppm) and two projected climate scenarios (780 ppm and 1170 ppm). Each CO2 treatment was combined with four temperatures: 0, 3, 6, and 8 °C. Here, we focused on the hepatic transcriptomic profiles from these previously physiologically characterized fish. Results: Generally, we did not detect signs of a classical stress response. Consistent with functional observations, warming induced much stronger molecular responses compared to elevated PCO2, but an interaction between both factors existed to some extent. Gene ontology analysis revealed a strong response in lipid, amino acid, and protein metabolism. With increasing temperature, we observed a shift away from lipid metabolism, while carbohydrate metabolic pathways remained stable. Conclusions: Although we found Polar cod to be quite resilient to ocean acidification, temperature will remain a critical parameter for this valuable Arctic keystone species, and the question remains as to whether the observed acclimation strategies can be implemented in its natural habitat, especially when food supply is limited. Full article
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20 pages, 2658 KiB  
Article
Identifying Potential Critical Angel Shark Areas in Türkiye, Eastern Mediterranean Based on New Records of Squatina spp. Identified through Fisher Engagement
by Aylin Ulman, Cat A. Gordon, Ali R. Hood, Melanie Warren and Daniel Pauly
Fishes 2024, 9(7), 270; https://doi.org/10.3390/fishes9070270 - 8 Jul 2024
Viewed by 621
Abstract
This study presents new records of three Critically Endangered angel shark species (Family: Squatinidae) occurring in the Eastern Mediterranean—Smoothback Angelshark S. oculata Bonaye, 1840, Sawback Angelshark S. aculeata Cuvier, 1829, and Angelshark S. squatina (Linnaeus, 1758). The supporting data serves to highlight three [...] Read more.
This study presents new records of three Critically Endangered angel shark species (Family: Squatinidae) occurring in the Eastern Mediterranean—Smoothback Angelshark S. oculata Bonaye, 1840, Sawback Angelshark S. aculeata Cuvier, 1829, and Angelshark S. squatina (Linnaeus, 1758). The supporting data serves to highlight three potential Critical Angel Shark Areas (CASAs) in Türkiye: Fethiye Bay, Çanakkale Strait (i.e., Dardanelles), and Antalya Bay. These data also demonstrate that female S. oculata may mature at a smaller size than prior published estimates of length at first maturity. This new dataset provides details of 23 S. squatina specimens, 52 S. oculata specimens, and 5 S. aculeata specimens, totalling 80 recent angel shark specimens found in Turkish waters mostly sent to us from small-scale fishers who had incidentally caught angel sharks. Also presented are four capture-induced parturition events in Turkish waters onboard fishing vessels, thus providing details on internal yolk sacs, reproductive habitats, and indications of spawning season. Our dataset presented here spans from 2018 to 2023 and suggests that mature adults of S. squatina and S. oculata still occur in Turkish waters, in Fethiye Bay and Çanakkale, respectively. Due to elevated chances of fishers encountering Critically Endangered angel sharks in Türkiye, we suggest that fishers are trained in handling and safe-release methods, to ensure reduced incidents of capture-induced parturition, and improved post-release survival. This study demonstrates that bottom set nets set by small-scale fishers pose less risk to mortality for angel sharks as they are almost always encountered alive after a usual 12 h soak time, suggesting that bottom trawling in critical habitats should be better regulated (or phased out) to help improve national angel shark conservation initiatives. Full article
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13 pages, 10219 KiB  
Article
Effects of Exogenous Hormones on Spawning Performances, Serum Gonadotropin and Sex Steroid Hormone in Manchurian Trout (Brachymystax lenok) during Sexual Maturation
by Yucai Pan, Gefeng Xu, Tianqing Huang, Wei Gu, Enhui Liu and Gaochao Wang
Fishes 2024, 9(7), 269; https://doi.org/10.3390/fishes9070269 - 8 Jul 2024
Viewed by 401
Abstract
The objective of this study was to investigate the effects of salmon gonadotropin releasing hormone analog (S-GnRH-A) and human chorionic gonadotropin (HCG) on the serum levels of gonadotropins (GtHs) and sex steroid hormones in Manchurian trout during sexual maturity. Females in the treatment [...] Read more.
The objective of this study was to investigate the effects of salmon gonadotropin releasing hormone analog (S-GnRH-A) and human chorionic gonadotropin (HCG) on the serum levels of gonadotropins (GtHs) and sex steroid hormones in Manchurian trout during sexual maturity. Females in the treatment group were injected with 20 µg/kg S-GnRH-A and 400 IU/kg HCG, whilst males were injected with half the amount. Blood samples were collected at 0, 5, 10, and 20 days post injection (dpi). The results showed an increase in female follicle-stimulating hormone (FSH) levels in the treatment group at 5 dpi, and from 5 dpi onwards, a difference was observed between the groups, with higher FSH levels in the treatment group compared to the control group. In males, FSH levels showed group differences at only 5 dpi (p < 0.05) and were higher in the treatment group. In females, luteinizing hormone (LH) peaked at 10 dpi in the treatment group, and there were differences between the two groups at 10 dpi and 20 dpi. In males, LH was significantly higher in the treatment group than in the control group at 5 dpi and 10 dpi (p < 0.05). In females, estradiol (E2) was significantly higher in the treatment group than in the control group at 5 dpi and 10 dpi (p < 0.05), whereas in males, the difference between the two groups was only observed at 5 dpi (p < 0.05). The female testosterone (T) level in the treatment group was significantly higher than that of the control group at 5 dpi and 10 dpi (p < 0.05), while T levels were significantly higher in the male treatment group than in the control group at 5 dpi (p < 0.05). The level of 17α–hydroxyprogesterone (17α-OHP) in the females of the treatment group was significantly higher than that of the control group at 5 dpi and 10 dpi (p < 0.05), and 17α-OHP levels were significantly higher in the male treatment group than in the control group at 10 and 20 dpi (p < 0.05). The fish were successfully spawned after S-GnRH-A and HCG injections, and brood amount, fertilization rate, and hatching rate were significantly increased (p < 0.05). This study provides a framework for a better understanding of the mechanisms of exogenous hormone-mediated control of reproduction in Manchurian trout. Full article
(This article belongs to the Special Issue Use of Hormones in Fish Farming)
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15 pages, 836 KiB  
Article
Exposure of Zebrafish Embryos to Morphine and Cocaine Induces Changes in the Levels of Dopamine and of Proteins Related to the Reward Pathway
by Andres Angel Calderon-Garcia, Mercedes Sánchez-Barba and Veronica Gonzalez-Nunez
Fishes 2024, 9(7), 268; https://doi.org/10.3390/fishes9070268 - 5 Jul 2024
Viewed by 380
Abstract
Morphine, a drug of abuse used to treat moderate-to-severe pain, elicits its actions by binding to the opioid receptors. Cocaine is an example of a recreational drug that inhibits dopamine reuptake. The molecular effects of morphine and cocaine have been described in different [...] Read more.
Morphine, a drug of abuse used to treat moderate-to-severe pain, elicits its actions by binding to the opioid receptors. Cocaine is an example of a recreational drug that inhibits dopamine reuptake. The molecular effects of morphine and cocaine have been described in different specific brain regions. However, the systemic outcome of these drugs on the whole organism has not been fully addressed. The aim of this study is to analyse the global effects of morphine (10 μM) and cocaine (15 μM) in the expression of proteins related to the reward pathway. Zebrafish embryos were exposed to these drugs from 5 hpf (hours post-fertilisation) to 6 dpf (days post-fertilisation). Dopamine levels were determined by ELISA, and the expression of Fos proteins, Creb, its activated form p-Creb and tyrosine hydroxylase (Th) were examined by Western blot. Both drugs decreased Th levels at 72 hpf and 6 dpf and modified the expression of Fos family members, pCreb and Creb in a time-dependent manner. Morphine and cocaine exposure differentially modified dopamine levels in 72 hpf and 6 dpf zebrafish embryos. Our results indicate that drugs of abuse modify the expression of several proteins and molecules related to the activation of the reward pathway. Full article
(This article belongs to the Section Physiology and Biochemistry)
12 pages, 1246 KiB  
Article
Morphometric Analysis of Two Shell Color Strains of the Bay Scallop Argopecten irradians
by Xianpeng Huang, Zhenlin Hao, Junxia Mao, Luo Wang, Xubo Wang and Ying Tian
Fishes 2024, 9(7), 267; https://doi.org/10.3390/fishes9070267 - 5 Jul 2024
Viewed by 247
Abstract
In this study, we employed geometric morphometrics (GMs) to analyze the shell shape differences among two mass-selected strains of bay scallops (red shell strain (RS) and black shell strain (BS)) and a control group (CG). The results revealed distinct shell shape differences corresponding [...] Read more.
In this study, we employed geometric morphometrics (GMs) to analyze the shell shape differences among two mass-selected strains of bay scallops (red shell strain (RS) and black shell strain (BS)) and a control group (CG). The results revealed distinct shell shape differences corresponding to shell coloration, with the black shell strain displaying a more elliptical shell compared to the red shell strain. Additionally, the umbonal angle of the red shell strain was smaller than that of the black shell strain, indicating that the black shell strain had a more favorable jet direction that could enhance swimming capabilities. To evaluate the model’s performance in practical applications, leave-one-out cross-validation was carried out on the two shell strains and one control group. The results demonstrated discrimination accuracy rates of 67.44%, 47.62%, and 68.18% for the BS strain, RS strain, and CG, respectively. Similarly, for the right valves, the discrimination accuracy rates were 62.79%, 50.00%, and 75.00% for the BS strain, RS strain, and CG, respectively. Full article
(This article belongs to the Section Aquatic Invertebrates)
20 pages, 5899 KiB  
Article
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
Viewed by 309
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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13 pages, 2894 KiB  
Article
Direct Feedback Regulation of E2, T, and hCG in the Brain–Pituitary–Gonad Axis of Japanese Eel (Anguilla japonica) during Artificial Maturation
by Xiaojian Lai, Shuai Peng, Zhaoren Bai, Le Cao, Huixuan Huang, Yonghua Jiang and Yilei Wang
Fishes 2024, 9(7), 265; https://doi.org/10.3390/fishes9070265 - 5 Jul 2024
Viewed by 402
Abstract
The feedback regulatory effects of estrogen (E2) and androgen (T) on the gonadotropin-releasing hormone (GnRH) and gonadotropin (GtH) within the brain–pituitary–gonad (BPG) axis in eels with undeveloped ovaries were investigated through in vivo studies. However, the regulatory role of the BPG axis only [...] Read more.
The feedback regulatory effects of estrogen (E2) and androgen (T) on the gonadotropin-releasing hormone (GnRH) and gonadotropin (GtH) within the brain–pituitary–gonad (BPG) axis in eels with undeveloped ovaries were investigated through in vivo studies. However, the regulatory role of the BPG axis only became apparent during ovary development in the migratory stage. To further elucidate the direct feedback regulation of the BPG axis, female Anguilla japonica underwent artificial induction of vitellogenesis, and the regulation of BPG axis tissues by GtH (human chorionic gonadotropin, hCG), E2, and T was explored through in vitro exposure. The mRNA expression levels of GnRH (mGnRH), GtH (fshb and lhb), and steroid biosynthesis enzymes (cyp11a1, hsd3b, cyp17a1, and cyp17a2) in the diencephalon, pituitary, and ovary, respectively, were determined. The results showed that the expression level of mGnRH in the diencephalon was significantly downregulated by 0.1 IU/mL hCG but upregulated by both 1 nM E2 and higher concentrations of T, suggesting a direct positive feedback regulation of E2 on mGnRH. In the pituitary, the expression levels of fshb and lhb were upregulated by E2, while fshb was suppressed by T. In the ovaries, the expression of cyp11a1 and hsd3b was upregulated by 1 nM E2, whereas T exposure resulted in an opposite effect. Cyp17a1 mRNA levels did not differ significantly with E2 treatment but were upregulated by 1 nM T. These findings suggest that low concentrations of E2 exhibited positive feedback regulation on all three levels (diencephalon, pituitary, and ovary) of the BPG axis, while T showed weaker and differential feedback regulation in BPG axis tissues. Overall, this study’s results revealed the direct feedback regulation of hCG, E2, and T on the BPG axis in eels, a phylogenetic base of teleosts. Full article
(This article belongs to the Special Issue Use of Hormones in Fish Farming)
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13 pages, 2328 KiB  
Article
Structure and Diversity of Microbiomes Associated with the Gastrointestinal Tracts of Wild Spiny Lobsters and Profiling Their Potential Probiotic Properties Using eDNA Metabarcoding
by Muhamad Amin, Hussein Taha, Laila Musdalifah, Muhamad Ali, Alimuddin Alimuddin, Sahrul Alim and Takaomi Arai
Fishes 2024, 9(7), 264; https://doi.org/10.3390/fishes9070264 - 4 Jul 2024
Viewed by 481
Abstract
Microbial communities have been documented as playing many pivotal roles, and contributing to the growth or health performance of animal hosts. Thus, many studies are currently looking for potential beneficial bacteria “probiotics” from diverse environments, including wild species. The present study aimed to [...] Read more.
Microbial communities have been documented as playing many pivotal roles, and contributing to the growth or health performance of animal hosts. Thus, many studies are currently looking for potential beneficial bacteria “probiotics” from diverse environments, including wild species. The present study aimed to investigate the diversity and potential metabolic functions of bacterial communities in the gastrointestinal tract of wild spiny lobsters. The gastrointestinal (GI) tracts of two wild lobster species (Panulirus ornatus and Panulirus homarus) were dissected aseptically and analyzed through high-throughput sequencing, followed by PICRUSt analysis. The results exposed that the most dominant phyla inhabiting both lobster species at the post-puerulus and juvenile stages were Proteobacteria, Firmicutes, Bacteriodota, Patescibacteria, and Verrucomicrobiota, while at the genus level, the GI tracts were mostly dominated by Photobacterium, Candidatus Bacillopora, Vibrio, and Catenococcus at the post-peurulus stage, and Vibrio, Catenococcus, Acanthopleuribacter, Acinetobacter, Pseudoalteromonas, Grimontia, and Photobacterium at the juvenile stage. Further metagenomic prediction analysis discovers many potential probiont properties indicated by the detection of marker genes corresponding to many important metabolic activities, such as antimicrobial compounds (streptomycin, vancomycin, carbapenem, tetracycline, novobiocin, penicillin, cephalosporin, ansamycines, butirosin, and neomycin), antioxidants (e.g., flavonoids and carotenoids), and several important digestive enzymes (e.g., lipase, protease, and amylase). These results suggest that GI tracts of wild spiny lobsters are potential sources to discover novel probionts for aquaculture purposes. Further studies, such as the isolation of the natural product-producing bacteria, or cloning of the beneficial compound-identified genes, are highly recommended to develop novel probiotic strains for aquaculture purposes. Full article
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12 pages, 2840 KiB  
Article
Functional Study on the BMP Signaling Pathway in the Molting of Scylla paramamosain
by Botao Zhong, Huaihua Yu, Shengming Han, Weiwei Song, Zhiming Ren, Chunlin Wang and Changkao Mu
Fishes 2024, 9(7), 263; https://doi.org/10.3390/fishes9070263 - 4 Jul 2024
Viewed by 244
Abstract
In this study, we added LDN-193189 2HCL to inhibit the BMP signaling pathway in Scylla paramamosain and then explored the function of this pathway in molting through the changes in the growth performance and molt-related gene expression. The study findings indicated that the [...] Read more.
In this study, we added LDN-193189 2HCL to inhibit the BMP signaling pathway in Scylla paramamosain and then explored the function of this pathway in molting through the changes in the growth performance and molt-related gene expression. The study findings indicated that the expression of ACVR1, BMPRIB, and Smad1 in Scylla paramamosain was suppressed when the LDN-193189 2HCL concentration in the culture water was 2 µm/L. Subsequently, following a 30-day experiment, there was a significant reduction in the molting frequency, growth rate, and body size of the S. paramamosain larvae. An analysis of the BMP pathway gene expression during the molting phase revealed that the BMP2, BMPR2, and Smad1 genes displayed cyclic expression patterns, while ACVR1, BMP7, and BMPRIB maintained consistent expression levels throughout the molting cycle. Additionally, the expression levels of BMP2, BMPR2, and Smad1 in the inhibition group were significantly lower compared to those in the control group. Furthermore, the inhibition of the BMP pathway led to an increase in the expression of MIH during the intermolt period and a decrease in the expression of EcR during the premolt period. These findings demonstrate that the BMP signaling pathway affects the molting of Scylla paramamosain juvenile crabs by influencing the expression of the critical genes MIH and ECR during molting, offering valuable data for functional research on the BMP signaling pathway in crustaceans. Full article
(This article belongs to the Special Issue Nutrition, Physiology and Metabolism of Crustaceans)
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13 pages, 2554 KiB  
Article
Spatiotemporal Variations in Trophic Diversity of Fish Communities in a Marine Bay Ecosystem Based on Stable Isotope Analysis
by Pengcheng Li, Wan Chen, Kun Wang, Binduo Xu, Chongliang Zhang, Yupeng Ji, Yiping Ren and Ying Xue
Fishes 2024, 9(7), 262; https://doi.org/10.3390/fishes9070262 - 4 Jul 2024
Viewed by 318
Abstract
Climate change has led to significant fluctuations in marine ecosystems. As a component of the food web, the trophic diversity and spatiotemporal changes of fish communities are crucial for understanding ecosystems. In recent years, stable isotope analysis has been increasingly used as a [...] Read more.
Climate change has led to significant fluctuations in marine ecosystems. As a component of the food web, the trophic diversity and spatiotemporal changes of fish communities are crucial for understanding ecosystems. In recent years, stable isotope analysis has been increasingly used as a comprehensive tool for quantitative assessment of trophic diversity to explore spatiotemporal variations in fish community diversity. This study is based on carbon (δ13C) and nitrogen (δ15N) stable isotope analysis using different biomass-weighted isotope diversity indices, including isotopic divergence index (IDiv), isotopic dispersion index (IDis), isotopic evenness index (IEve), and isotopic uniqueness index (IUni). The overall results indicate that IDis, IEve, and IUni values of fish communities were relatively low, while IDiv was relatively high in the Haizhou Bay ecosystem. IDiv, IDis, IEve, and IUni were lower in autumn than in spring; IDiv and IDis were relatively higher in offshore waters, while IEve and IUni were relatively higher in inshore waters. The changes in species composition and intensive pelagic–benthic coupling in Haizhou Bay may lead to significant spatiotemporal variations in the trophic diversity of fish communities in the area. These findings highlight the importance of incorporating trophic relationships into ecosystem models, which will help to enhance our understanding of the complexity of the trophic structure of fish communities. Full article
(This article belongs to the Section Biology and Ecology)
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19 pages, 11600 KiB  
Article
Optimization of Classical Lipase Activity Assays for Fish Digestive Tract Samples
by Héctor Nolasco-Soria, Carlos Alfonso Alvarez-González, Dariel Tovar-Ramírez, Jorge González-Bacerio, Alberto del Monte-Martínez and Fernando Vega-Villasante
Fishes 2024, 9(7), 261; https://doi.org/10.3390/fishes9070261 - 3 Jul 2024
Viewed by 509
Abstract
Fish possess lipases from embryonic development to adulthood. Lipase activity methods vary and significantly differ in terms of the concentration of the substrate used, bile salt, Ca2+, temperature, pH, and type of lipase units, which limits comparative studies. The three most-used [...] Read more.
Fish possess lipases from embryonic development to adulthood. Lipase activity methods vary and significantly differ in terms of the concentration of the substrate used, bile salt, Ca2+, temperature, pH, and type of lipase units, which limits comparative studies. The three most-used substrates are p-nitrophenyl (p-NP), β-naphthyl (β-N) derivates, and emulsified natural oils. These were selected to be redesigned in this study to measure lipase activity under temperature, pH, ion, and bile salt conditions closer to fish physiology, using the appropriate molar absorption coefficient to calculate the lipase units. Cynoscion parvipinnis (CP), Seriola rivoliana (SR), Centropomus viridis (CV), Elop affinis (EA), and Canthidermis maculate (CM) pyloric caeca-intestine extracts were studied. Sodium taurocholate showed the highest activity for intestinal lipases, and the fatty acid length in the substrates changed the lipase hydrolysis rate. The highest lipase activity was obtained with p-NP butyrate and p-NP caprylate in four fish species. Lipase activity was highly activated with Ca2+ (4–7 mM). The β-N absorption spectrum indicates a plateau between 534 and 554 nm for fish lipases. Salmon oil was identified as the most digestible lipid in the four fish species using the in vitro digestibility assay. The lipase zymogram showed an apparent size of 46.3 kDa for CP, 40.2 kDa for SR, 46.2 kDa for CM, 106.6 kDa for EA, and 58.3, 84.6, and 162.1 kDa for CV. Full article
(This article belongs to the Special Issue Advances in Feedstuffs for Sustainable and Innovative Aquaculture)
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12 pages, 1341 KiB  
Article
Population Genetics of the Endemic Hemiculterella wui (Wang, 1935) in the Poyang Lake Basin (China)
by Qin Ma, Mingzheng Li and Huanzhang Liu
Fishes 2024, 9(7), 260; https://doi.org/10.3390/fishes9070260 - 3 Jul 2024
Viewed by 352
Abstract
The Yangtze River floodplain is an area with an extremely rich diversity of fish species. Poyang Lake, as an important part of this river–floodplain system, is a crucial habitat for the survival of fish. However, prolonged human activities, such as environmental pollution and [...] Read more.
The Yangtze River floodplain is an area with an extremely rich diversity of fish species. Poyang Lake, as an important part of this river–floodplain system, is a crucial habitat for the survival of fish. However, prolonged human activities, such as environmental pollution and hydroelectric development, have degraded the habitat in the Poyang Lake Basin, posing threats to fish populations. Understanding genetic diversity is crucial for maintaining fish populations and understanding their dynamics. The genetic diversity of Hemiculterella wui, an economically endemic species in China of subfamily Cultrinae (Cypriniformes: Cyprinidae), has been understudied. This study investigated the genetic diversity and structure of H. wui populations from the Ganjiang, Xinjiang, Fuhe, and Raohe rivers in the Poyang Lake Basin using mitochondrial Cytb gene analysis. Results showed high haplotype diversity but low nucleotide diversity in H. wui’s Cytb sequences. Analysis of molecular variance (AMOVA) showed no significant geographic genetic structure among populations. Haplotype network analysis revealed no clear geographical clustering. Neutrality tests and haplotype nucleotide mismatch distribution indicated that all populations had experienced expansion events. These findings suggest that H. wui in Poyang Lake does not show a distinct geographic structure. However, it is still necessary to monitor the genetic characteristics of H. wui to maintain the genetic diversity of fishes in Poyang Basin, considering the threat of habitat loss and fragmentation to the population. Full article
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9 pages, 2894 KiB  
Editorial
How Current Global Aqua-Nutrition Research Matches the New Industry and Market Demands
by Haiyan Xiong and Houguo Xu
Fishes 2024, 9(7), 259; https://doi.org/10.3390/fishes9070259 - 3 Jul 2024
Viewed by 367
Abstract
As a result of decades of rapid development, aquaculture has become the largest contributor to human seafood consumption [...] Full article
(This article belongs to the Section Nutrition and Feeding)
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26 pages, 8170 KiB  
Article
Knowledge Mapping of the Development Trend of Smart Fisheries in China: A Bibliometric Analysis
by Qiu-Yuan Qin, Jia-Ying Liu, Yong-He Chen, Xin-Ruo Wang and Ta-Jen Chu
Fishes 2024, 9(7), 258; https://doi.org/10.3390/fishes9070258 - 3 Jul 2024
Viewed by 358
Abstract
In recent years, smart fisheries, as an emerging model for fishery development, have become a research hotspot in the fishery and aquaculture industries of many countries. Smart fisheries can be thought of as a system that combines techniques for raising, catching, or selling [...] Read more.
In recent years, smart fisheries, as an emerging model for fishery development, have become a research hotspot in the fishery and aquaculture industries of many countries. Smart fisheries can be thought of as a system that combines techniques for raising, catching, or selling aquatic products to improve production and sustainable development. Smart fisheries are crucial to improving fishery and aquaculture management. In this study, a comprehensive analysis was conducted using bibliometric analysis, the results of which are presented through visual mapping and data charts. This study collected data from the China National Knowledge Infrastructure (CNKI) database and compared it with the WoS database. A total of 949 articles were retrieved on topics related to smart fisheries, including 579 articles from WoS and 370 articles from CNKI. The results present the visualization and analysis of annual publications, author collaboration maps, research collaboration institutions, keywords, etc. The development of smart fisheries in China is obviously different from that in foreign countries. China attaches great importance to technology and production, while foreign countries focus on environmental issues. Therefore, this study helps us to understand the current research status, research hotspots, and future development directions of smart fisheries, providing certain references for future management. Full article
(This article belongs to the Special Issue Management and Monitoring of Recreational Fisheries)
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27 pages, 3530 KiB  
Article
Ontogenetic, Spatial and Inter-Annual Variability in the Diet of European Hake Merluccius merluccius Linnaeus, 1758, in the North Aegean Sea
by Athanasios Evangelopoulos, Antonios Geropoulos, Nikolaos Kamidis and Emmanouil Koutrakis
Fishes 2024, 9(7), 257; https://doi.org/10.3390/fishes9070257 - 2 Jul 2024
Viewed by 275
Abstract
This study contributes to filling knowledge gaps regarding recent information on the diet of the European hake, Merluccius merluccius Linnaeus, 1758, in the Greek seas, particularly its ontogenetic shifts and its spatiotemporal variability. The trophic preferences of M. merluccius were investigated in the [...] Read more.
This study contributes to filling knowledge gaps regarding recent information on the diet of the European hake, Merluccius merluccius Linnaeus, 1758, in the Greek seas, particularly its ontogenetic shifts and its spatiotemporal variability. The trophic preferences of M. merluccius were investigated in the North Aegean Sea during the summers of 2019 to 2023 with visual stomach content analysis to assess its composition, diversity, and variability across body-size classes, years, and subareas. The identified prey are functionally diverse and in many cases also primary targets for local fisheries. The ontogenetic trophic niche of hake was characterized by two distinct shifts, delineated by 10 and 50 cm body-size thresholds. Cephalopods were a prevalent dietary component for large hake individuals. The intermediate body-size classes demonstrated greater trophic niche breadth concerning prey diversity and absolute prey-size ranges. A feeding strategy characterized by the specialization of individuals was also revealed. The effect of the temporal and spatial context on the hake diet was occasionally correlated with spatiotemporal variations in the sizes of their populations. In conclusion, ontogenetic and spatiotemporal variability in the hake diet were found to be significant and should be considered in the data collection design and analyses of the trophic interactions of the species. Full article
(This article belongs to the Section Biology and Ecology)
15 pages, 8048 KiB  
Article
Effects of High Dietary Starch Levels on the Growth Performance, Liver Function, and Metabolome of Largemouth Bass (Micropterus salmoides)
by Lihui Sun, Jianlin Guo, Qian Li, Jianhu Jiang, Jianming Chen, Lingmei Gao, Bicheng Yang and Jun Peng
Fishes 2024, 9(7), 256; https://doi.org/10.3390/fishes9070256 - 2 Jul 2024
Viewed by 324
Abstract
In this study, we conducted a 16-week feeding trial to investigate the effects of a high-cassava starch diet on growth performance, liver function, and metabolism in largemouth bass (Micropterus salmoides). We formulated five diets containing varying levels of cassava starch: 12%, [...] Read more.
In this study, we conducted a 16-week feeding trial to investigate the effects of a high-cassava starch diet on growth performance, liver function, and metabolism in largemouth bass (Micropterus salmoides). We formulated five diets containing varying levels of cassava starch: 12%, 9%, 6%, 3%, and 0% (termed M12, M9, M6, M3, and M0, respectively). We distributed these diets among largemouth bass with the initial body weight of 83.33 ± 0.55 g via an in-pond “raceway” aquaculture system. Our findings suggest that high level (12%) of cassava starch dietary inclusion adversely affected growth performance metrics such as weight gain rate and specific growth rate, along with feed utilization efficiency indicators, including protein efficiency, protein deposition rate, and the apparent digestibility of dry matter and protein. This negative impact was accompanied by a decrease in intestinal amylase activity. Through further transcriptomic analysis, we identified several key genes associated with carbohydrate metabolism, which underwent changes influencing liver function. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed the involvement of these differentially expressed genes (DEGs) in the tricarboxylic acid cycle (TCA cycle). Comparative metabolomics analysis further indicated that the M9 group showed significant enrichment in pathways related to amino acid metabolism and alterations in the levels of metabolites involved in carbohydrate metabolism. In conclusion, our study demonstrates that incorporating up to 9% cassava starch in the diet can enhance growth performance in largemouth bass by stimulating digestive enzyme activities and promoting glucose utilization. Full article
(This article belongs to the Special Issue Physiological Response Mechanism of Aquatic Animals to Stress)
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10 pages, 1614 KiB  
Communication
Population Dynamics Parameters and Exploitation Status of 55 Commercial Species in Egyptian Red Sea Fisheries: A Key to Sustainable Fisheries
by Sahar F. Mehanna and Mohamed Samy-Kamal
Fishes 2024, 9(7), 255; https://doi.org/10.3390/fishes9070255 - 2 Jul 2024
Viewed by 329
Abstract
Egyptian Red Sea fisheries face the same challenges as most of the world’s fisheries, including overexploitation, habitat loss, IUU fishing, pollution, and climate change. These fisheries are highly diverse with multiple species targeted by multiple fleets, using different fishing gears. Much work has [...] Read more.
Egyptian Red Sea fisheries face the same challenges as most of the world’s fisheries, including overexploitation, habitat loss, IUU fishing, pollution, and climate change. These fisheries are highly diverse with multiple species targeted by multiple fleets, using different fishing gears. Much work has been performed in recent years to assess Red Sea fish stocks. However, not all fish stocks in the Egyptian Red Sea are assessed, and those that are assessed only cover 30% of landings. The assessments are unbalanced by area, with the Gulf of Suez being much better covered than the southern Red Sea and Gulf of Aqaba. The results show that most of the analyzed stocks are overexploited. There is an urgent need to take action to protect, conserve, and restore the different fish stocks in different fishing grounds. These actions will ensure the sustainability of the fisheries, making them ecologically friendly and economically and socially efficient. Full article
(This article belongs to the Special Issue Diagnosis and Management of Small-Scale and Data-Limited Fisheries)
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15 pages, 9111 KiB  
Article
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
Viewed by 396
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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16 pages, 6965 KiB  
Article
Spatiotemporal Variation and Predictors of the Purpleback Flying Squid (Sthenoteuthis oualaniensis) Distribution Surrounding the Xisha and Zhongsha Islands during a Fishing Moratorium
by Liangming Wang, Changping Yang, Binbin Shan, Yan Liu, Jianwei Zou, Dianrong Sun and Tao Guo
Fishes 2024, 9(7), 253; https://doi.org/10.3390/fishes9070253 - 1 Jul 2024
Viewed by 278
Abstract
As an economic species widely distributed in the South China Sea (SCS), the purpleback flying squid (Sthenoteuthis oualaniensis) still has a large potential for exploitation, and the variations in its use as a resource are highly correlated with environmental and other [...] Read more.
As an economic species widely distributed in the South China Sea (SCS), the purpleback flying squid (Sthenoteuthis oualaniensis) still has a large potential for exploitation, and the variations in its use as a resource are highly correlated with environmental and other factors. In this study, using a generalized additive model (GAM) and gradient forest analysis (GFA), in conjunction with environmental factors, the distribution of purpleback flying squid surrounding the Xisha and Zhongsha islands during the fishing moratorium period was investigated. The results indicated that catch per unit effort (CPUE) had a gradual increase from May to July 2023 in the primary fishing area surrounded the Xisha Islands during May to June, then moved southward towards 13–15° N after July. CPUE is used as an important indicator to reflect the abundance of the fishery, while the GFA results show that CPUE has a better fit than catch in this study. Therefore, the subsequent analysis focused on CPUE. Longitude and sea surface temperature (SST) were of relative higher importance, followed by sea surface salinity (SSS), latitude, chlorophyll a concentration (Chla), sea surface height (SSH), and mixed layer depth (MLD). Longitude and CPUE had a significant, positive correlation. The CPUE gradually increased with latitude within 14–16° N. The CPUE increased slowly as SST increased from 29.5 to 30.5 °C in the primary fishing area. The Chla in this fishing zone was 0–0.2 mg/m3 and displayed a significant positive association with CPUE. Conversely, SSS, SSH, and MLD had negative correlations with CPUE. These findings will promote the sustainable utilization of purpleback flying squid in the SCS. Full article
(This article belongs to the Special Issue Assessment and Management of Fishery Resources)
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15 pages, 334 KiB  
Article
Possible Metal Burden of Potentially Toxic Elements in Rainbow Trout (Oncorhynchus mykiss) on Aquaculture Farm
by József Lehel, Melinda Plachy, Péter Palotás, András Bartha and Péter Budai
Fishes 2024, 9(7), 252; https://doi.org/10.3390/fishes9070252 - 1 Jul 2024
Viewed by 317
Abstract
Aquaculture products are important parts of human nutrition due to their healthy components; however, they may contain elements that are potentially toxic to consumers. The aim of the study was to detect the concentration of As, Cd, Hg, and Pb by inductively coupled [...] Read more.
Aquaculture products are important parts of human nutrition due to their healthy components; however, they may contain elements that are potentially toxic to consumers. The aim of the study was to detect the concentration of As, Cd, Hg, and Pb by inductively coupled plasma optical emission spectroscopy in rainbow trout (Oncorhynchus mykiss) originated from an aquaculture farm in Italy. The amount of As was 1.65 ± 0.49 mg/kg; however, the total As cannot be evaluated due to the absence of official regulation. The calculated EDI and THQ for the inorganic As content were below the reference values. The level of Cd was higher than the regulated limit in 30% of the samples; however, its EDI and THQ were below the recommended limit. The concentration of Hg was below the regulated maximum limit in all the samples. The detected amount of Pb was above the maximum limit in 10% of the samples; however, EDI and THQ were below the reference dose and recommended value. Despite higher concentrations of Cd and Pb than the official regulated limit, HI was below 1 for adults; thus, the consumption of the investigated rainbow trout is safe, but it was above the official regulated limit for children, resulting in a slight risk, particularly during long-term intake. Full article
8 pages, 2127 KiB  
Article
Acoustic Characteristics of Spawning Biological Sounds of Brown Croaker (Miichthys miiuy)
by Hansoo Kim, Young Geul Yoon, Sungho Cho, Sunhyo Kim, Mira Kim and Donhyug Kang
Fishes 2024, 9(7), 251; https://doi.org/10.3390/fishes9070251 - 29 Jun 2024
Viewed by 239
Abstract
Marine organisms make sounds for various reasons, including spawning and avoidance, which are species-specific. Traditionally, Korean fishermen in the northwest Pacific Ocean have listened for spawning sounds to locate spawning grounds of Brown croaker (Miichthys miiuy), one of the important commercial [...] Read more.
Marine organisms make sounds for various reasons, including spawning and avoidance, which are species-specific. Traditionally, Korean fishermen in the northwest Pacific Ocean have listened for spawning sounds to locate spawning grounds of Brown croaker (Miichthys miiuy), one of the important commercial fish species. We measured the spawning sounds recorded in October, the croakers’ spawning season (August to October). The mean signal duration with standard deviation was 0.184 ± 0.027 s, and the mean pulse interval was 0.022 ± 0.001 s. The zero-to-peak mean sound pressure level was 165.2 ± 0.7 dB. The peak frequency was 459.2 ± 93.8 Hz, with maximum and minimum frequencies observed at 863.0 ± 225.9 Hz and 231.2 ± 67.9 Hz. The spawning sounds occurred around sunset (16:00–21:00, local time) and only when the water temperature was above 22 °C. These findings help interpret the environmental ecology and manage the fishery resources of the Brown croaker spawning grounds. Full article
(This article belongs to the Special Issue Applications of Passive Acoustics to Fisheries)
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18 pages, 3368 KiB  
Article
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 778
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  
Article
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
Viewed by 712
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
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12 pages, 4976 KiB  
Article
Effects of Acute Temperature Stress on the Expression of Related Genes in the Brain of Opsariichthys bidens
by Qianhui Li, Luomei Xiong, Yechen Zhu, Anrui Zheng and Shanjian Zheng
Fishes 2024, 9(7), 248; https://doi.org/10.3390/fishes9070248 - 25 Jun 2024
Viewed by 750
Abstract
Opsariichthys bidens (O. bidens) is a fish species native to China and sensitive to temperature changes. In this study, the effects of acute temperature stress on brain gene expression in O. bidens were investigated by sampling brain tissues from specimens exposed [...] Read more.
Opsariichthys bidens (O. bidens) is a fish species native to China and sensitive to temperature changes. In this study, the effects of acute temperature stress on brain gene expression in O. bidens were investigated by sampling brain tissues from specimens exposed to three different temperatures (15 °C, 25 °C, and 35 °C) for varying durations of 2 h, 4 h, 6 h, and 8 h. The study focused on analyzing the expression patterns of key genes implicated in neural function and stress response, including brain-derived neurotrophic factor (BDNF), c-FOS, heat shock proteins (HSP70, HSP90), endoplasmic reticulum stress markers (IRE1, GRP78), oxidative stress enzymes (CAT, SOD), and apoptotic regulators (caspase3, Bax). The findings revealed that upon exposure to acute heat stress, the expression levels of the aforementioned genes in the brain of O. bidens were up-regulated within 2 h, peaking at the 4-h mark. Conversely, following acute cold stress, the expression of c-FOS, BDNF, HSP70, HSP90, SOD, and CAT genes increased significantly after 4 h, while caspase3 expression was notably elevated at the 6-h mark, with no significant impact observed on Bax, IRE1, or GRP78 gene expression levels. The study suggested that the brain of O. bidens responds to high temperatures through mechanisms involving neural activation, heat shock proteins, endoplasmic reticulum stress, oxidative stress, and apoptosis. Similarly, adaptation to low temperatures by O. bidens’ brain was associated with neural activation, regulation of heat shock proteins, oxidative stress responses, and apoptotic processes. Overall, this research aimed to elucidate the impact of temperature stress on brain physiology and the adaptive mechanisms of O. bidens at the genetic level, providing a foundational understanding of its temperature adaptation strategies. Full article
(This article belongs to the Section Biology and Ecology)
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14 pages, 964 KiB  
Article
Feeding Behaviour of Seven Icefish Species (Channichthyidae) in the Ross Sea, Antarctica
by Erica Carlig, Davide Di Blasi, Laura Ghigliotti, Andreas Scalas, Andrew L. Stewart and Michela Mortara
Fishes 2024, 9(7), 247; https://doi.org/10.3390/fishes9070247 - 25 Jun 2024
Viewed by 417
Abstract
The Channichthyidae, a monophyletic fish group belonging to the suborder Notothenioidei, are uniquely adapted to the polar environment. However, while their physiology has been extensively studied, studies on their ecology are relatively rare. Here, we investigated the trophic ecology of seven icefish species [...] Read more.
The Channichthyidae, a monophyletic fish group belonging to the suborder Notothenioidei, are uniquely adapted to the polar environment. However, while their physiology has been extensively studied, studies on their ecology are relatively rare. Here, we investigated the trophic ecology of seven icefish species (Chaenodraco wilsoni, Chionobathyscus dewitti, Chionodraco hamatus, Dacodraco hunteri, Neopagetopis ionah, Pagetodes antarcticus and Pagetopsis macropterus) by using the traditional morphometric approach to assess the relationship between form and feeding function. The suction index (SI), the mechanical advantage in jaw closing (MA) and nine morphological traits related to feeding structures have been analysed. Icefish species are characterised by non-protractible, elongate jaws and a wide gape; such morphological features influence the low values of both MA and SI, supporting their ram-feeding habit. The ecomorphological differences among species resulted mainly determined by the anatomical structures related to SI. Such differences do not seem to be determined primarily by the type of prey, as is the case in other taxonomic groups of Notothenioidei, but rather by phylogenetic proximity. A 3D animation was developed to visualise the different feeding modes of two icefish species (C. hamatus and P. macropterus) which are characterised by different approaches to prey. Full article
(This article belongs to the Special Issue Recent Advances in Foraging Behavior of Fish)
14 pages, 1617 KiB  
Article
Trends and Environmental Drivers of Marine Fish Landings in Cuba’s Most Productive Shelf Area
by Yunier Olivera-Espinosa, Yandy Rodríguez-Cueto, Fabián Pina-Amargós, Francisco Arreguín-Sánchez, Manuel J. Zetina-Rejón, Kendra Karr and Pablo del Monte-Luna
Fishes 2024, 9(7), 246; https://doi.org/10.3390/fishes9070246 - 23 Jun 2024
Viewed by 353
Abstract
Marine finfish landings in Cuba have decreased during the last 30 years. However, in Cuba’s most productive fishing region, certain species, including rays, herrings, and snappers, have had increased landings over the past decade. Despite these anomalies, no comprehensive analysis of the interactions [...] Read more.
Marine finfish landings in Cuba have decreased during the last 30 years. However, in Cuba’s most productive fishing region, certain species, including rays, herrings, and snappers, have had increased landings over the past decade. Despite these anomalies, no comprehensive analysis of the interactions among multispecies landing dynamics, environmental factors, and fishing efforts has been carried out. This study estimates the dynamics of multispecies finfish landings between 1981 and 2017 on the southeastern coast of Cuba. A log-normal generalized additive model (GAM) was fit to evaluate the effects of various environmental and effort-related variables on the total landings. During the period analyzed, the finfish landings and fishing effort decreased by 46% and over 80%, respectively. Despite concerns about overfishing, landings per unit of effort (LPUE) increased by 2.8 times. The total fish landings were significantly related to changes in the fishing effort, coastal vegetation, rainfall, chlorophyll-a, and the Southern Oscillation Index (SOI). This study highlights the changing relationship between the landings and fishing effort, suggesting that LPUE may not accurately reflect true stock abundance. The findings of this study will assist in integrating the dynamics of finfish species, ecosystem status, and management actions for Cuba’s most productive fishing zone. Full article
(This article belongs to the Special Issue Assessment and Management of Fishery Resources)
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