Fishes

21 pages, 2300 KiB

Open AccessEditor’s ChoiceArticle

Evaluating the Sampling Design of a Long-Term Community-Based Estuary Monitoring Program

by Jess A. Kidd, Monica Boudreau, Robert C. Bailey, Michael R. van den Heuvel, Mark R. Servos and Simon C. Courtenay

Fishes 2021, 6(3), 27; https://doi.org/10.3390/fishes6030027 - 2 Aug 2021

Cited by 1 | Viewed by 3315

Abstract

Community-based monitoring programs (CBMPs) are a cost-effective option to collect the long-term data required to effectively monitor estuaries. Data quality concerns have caused some CBMP datasets, which could fill knowledge gaps for aquatic ecosystems, to go unused. The Community Aquatic Monitoring Program (CAMP) [...] Read more.

Community-based monitoring programs (CBMPs) are a cost-effective option to collect the long-term data required to effectively monitor estuaries. Data quality concerns have caused some CBMP datasets, which could fill knowledge gaps for aquatic ecosystems, to go unused. The Community Aquatic Monitoring Program (CAMP) is a CBMP that has collected littoral nekton assemblage data from estuaries in the southern Gulf of St. Lawrence since 2003. Concerns with the CAMP sampling design (station placement and numbers) have prevented decision-makers from using the data to inform estuary health assessments. This study tested if CAMP’s sampling design that accommodates volunteer participation provides similar information as a scientific sampling approach. Six CAMP stations and six stations selected using a stratified random design were sampled at ten estuaries. A permutational-MANOVA revealed nekton assemblages were generally not significantly different between the two sampling designs. The current six CAMP stations are sufficient to detect the larger differences in species abundances that may indicate differences in estuary condition. The predicted increase in precision (2%) with twelve stations is not substantive enough to warrant an increased sampling effort. CAMP’s scientific utility is not limited by station selection bias or numbers. Furthermore, well-designed CBMPs can produce comparable data to scientific studies. Full article

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18 pages, 1422 KiB

Open AccessEditor’s ChoiceArticle

Integrating Literature, Biodiversity Databases, and Citizen-Science to Reconstruct the Checklist of Chondrichthyans in Cyprus (Eastern Mediterranean Sea)

by Ioannis Giovos, Fabrizio Serena, Dimitra Katsada, Athanasios Anastasiadis, Adi Barash, Charis Charilaou, Jason M. Hall-Spencer, Fabio Crocetta, Alexander Kaminas, Demetris Kletou, Mary Maximiadi, Vasileios Minasidis, Dimitrios K. Moutopoulos, Roxani Naasan Aga-Spyridopoulou, Ioannis Thasitis and Periklis Kleitou

Fishes 2021, 6(3), 24; https://doi.org/10.3390/fishes6030024 - 26 Jul 2021

Cited by 9 | Viewed by 7292

Abstract

Chondrichthyans are apex predators influencing the trophic web through a top-down process thus their depletion will affect the remaining biota. Notwithstanding that, research on chondrichthyans is sparse or data-limited in several biogeographic areas worldwide, including the Levantine Sea. We revise and update the [...] Read more.

Chondrichthyans are apex predators influencing the trophic web through a top-down process thus their depletion will affect the remaining biota. Notwithstanding that, research on chondrichthyans is sparse or data-limited in several biogeographic areas worldwide, including the Levantine Sea. We revise and update the knowledge of chondrichthyans in Cyprus based on a bibliographic review that gains information retrieved from peer-reviewed and grey literature, Global Biodiversity Information Facility (135 records of at least 18 species) and the Ocean Biodiversity Information System (65 records of at least14 species), and the citizen science project Mediterranean Elasmobranchs Citizen Observations (117 records per 23 species). Our updated checklist reports 60 species that account for about 70% of the Mediterranean chondrichthyan biota. The list includes 15 more species than the previous checklist and our study reports three new species for Cyprus waters, namely the blackmouth catshark Dalatias licha, the round fantail stingray Taeniurops grabatus, and the sawback angelshark Squatina aculeata. Our research highlights the need for conservation measures and more studies regarding the highly threatened blackchin guitarfish Glaucostegus cemiculus and the devil ray Mobula mobular, and stresses the importance for training a new generation of observers to strengthen the knowledge and conservation of elasmobranchs in the region. Full article

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19 pages, 1059 KiB

Open AccessEditor’s ChoiceArticle

Growth, Chemical Composition, Histology and Antioxidant Genes of Atlantic Salmon (Salmo salar) Fed Whole or Pre-Processed Nannochloropsis oceanica and Tetraselmis sp.

by Solveig Lysfjord Sørensen, Ateshm Ghirmay, Yangyang Gong, Dalia Dahle, Ghana Vasanth, Mette Sørensen and Viswanath Kiron

Fishes 2021, 6(3), 23; https://doi.org/10.3390/fishes6030023 - 23 Jul 2021

Cited by 10 | Viewed by 4503

Abstract

New sustainable feed ingredients are a necessity for the salmon aquaculture industry. In this study, we examined the effect of pre-extrusion processing of two microalgae, Nannochloropsis oceanica and Tetraselmis sp., on the growth, fatty acid content in the flesh and health of [...] Read more.

New sustainable feed ingredients are a necessity for the salmon aquaculture industry. In this study, we examined the effect of pre-extrusion processing of two microalgae, Nannochloropsis oceanica and Tetraselmis sp., on the growth, fatty acid content in the flesh and health of Atlantic salmon. The fish were fed one of the following five diets for nine weeks: (1) CO: a fish meal-based control (basal) diet, (2) NU: a Nannochloropsis diet, (3) NE: a pre-extruded Nannochloropsis diet, (4) TU: a Tetraselmis diet, and (5) TE: a pre-extruded Tetraselmis diet. The algae-incorporated diets contained 30% of the respective microalgae. Our results showed that the best growth performance was achieved by the CO diet, followed by the NE diets. Feeding of unprocessed Nannochloropsis and Tetraselmis resulted in a significant reduction in enterocyte vacuolization compared to the CO feeding. A significant effect of processing was noted in the fillet fatty acid content, the intestine and liver structure and the expression of selected genes in the liver. The expression of antioxidant genes in both the liver and intestine, and the accumulation of different fatty acids in the fillet and liver of the extruded algae-fed groups, warrants further investigation. In conclusion, based on the short-term study, 30% inclusion of the microalgae Nannochloropsis oceanica and Tetraselmis sp. can be considered in Atlantic salmon feeds. Full article

(This article belongs to the Special Issue Integration of Nutrition and Physiology in Aquatic Animals)

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13 pages, 1287 KiB

Open AccessEditor’s ChoiceArticle

Dynamics of Two Anadromous Species in a Dam Intersected River: Analysis of Two 100-Year Datasets

by Ulisses M. Azeiteiro, Mário J. Pereira, Amadeu M. V. M. Soares, Heitor O. Braga, Fernando Morgado, Magda C. Sousa, João M. Dias and Carlos Antunes

Fishes 2021, 6(2), 21; https://doi.org/10.3390/fishes6020021 - 5 Jun 2021

Cited by 8 | Viewed by 4454

Abstract

Long-term time-series datasets are key for assessing the population dynamics of fish species with economic interest. This study examines two 100-year datasets for sea lamprey Petromyzon marinus and allis shad Alosa alosa from the Minho River. This basin on the Iberian Peninsula is [...] Read more.

Long-term time-series datasets are key for assessing the population dynamics of fish species with economic interest. This study examines two 100-year datasets for sea lamprey Petromyzon marinus and allis shad Alosa alosa from the Minho River. This basin on the Iberian Peninsula is home to one of the largest populations at the southern distribution limit of these critically endangered anadromous fish species. Besides assessing the importance of the environmental drivers of fish capture data (temperature, salinity, upwelling, precipitation, and climatic oscillation), this study also assesses how dam construction affected these populations using intervention analysis—A statistical tool to detect significant breakpoints in time series data. Results showed contrasting trends between sea lamprey and allis shad, with the number of captured fish from the first progressively improving from 1914 to 2017, and the latter recording a significant decline over time. Although no significant correlations were detected between fishing data and environmental variables, some of the identified breakpoints in the time series data matched the dates when the major dams in Minho River were built. Other historical activities associated with mining might explain the notable changes detected in the trends, while issues associated with illegal, unreported, and unregulated capture data are also discussed. Full article

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13 pages, 1768 KiB

Open AccessEditor’s ChoiceArticle

Effect of 3-Aminobenzoic Acid Ethyl Ester Methanesulfonate (MS-222) on Quality of Marine Cultured Turbot (Scophthalmus maximus) during Simulated Transport in Water

by Jie Cao, Qi Wang, Jun Mei and Jing Xie

Fishes 2021, 6(2), 20; https://doi.org/10.3390/fishes6020020 - 19 May 2021

Cited by 10 | Viewed by 3737

Abstract

This study evaluated the effect of different concentrations (20, 40 and 60 mg/L) of 3-aminobenzoic acid ethyl ester methanesulfonate (MS-222) on the quality changes in turbot during simulated transport in water. The results showed that the ammonia nitrogen content in the transportation water [...] Read more.

This study evaluated the effect of different concentrations (20, 40 and 60 mg/L) of 3-aminobenzoic acid ethyl ester methanesulfonate (MS-222) on the quality changes in turbot during simulated transport in water. The results showed that the ammonia nitrogen content in the transportation water of each sample increased significantly, and the dissolved oxygen level decreased. The dissolved oxygen content in MS-222-treated samples was higher than that of control group (CK) samples. For turbot flesh quality, simulated transport in water led to a decrease in moisture, fat and protein contents in all samples. The MS-222-treated turbot samples showed higher pH values, glycogen contents, springiness and chewiness values and lower lactic acid contents comparing with the CK samples during simulated transport in water. In addition, the fresh and bitter amino acids in the muscle of turbot increased in each treatment group compared to the non-transported fish at the end of the simulated transport. The results showed that MS-222 treatment could retard the turbot transport stress and improve the quality of turbot during simulated transport in water. Full article

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13 pages, 1952 KiB

Open AccessEditor’s ChoiceArticle

Effects of Different Densities of Sea Grape Caulerpa lentillifera on Water Quality, Growth and Survival of the Whiteleg Shrimp Litopenaeus vannamei in Polyculture System

by Khanh Van Ly, David Kamau Murungu, Dung Phuong Nguyen and Ngoc Anh Thi Nguyen

Fishes 2021, 6(2), 19; https://doi.org/10.3390/fishes6020019 - 5 May 2021

Cited by 10 | Viewed by 7701

Abstract

The integrated aquaculture-seaweed system has been identified as a bio-mitigation strategy to overcome environmental damage, improve the efficiency of nutrient use, maintain good water quality, and ensure the system’s sustainability. This study was conducted to determine the appropriate density of sea grape ( [...] Read more.

The integrated aquaculture-seaweed system has been identified as a bio-mitigation strategy to overcome environmental damage, improve the efficiency of nutrient use, maintain good water quality, and ensure the system’s sustainability. This study was conducted to determine the appropriate density of sea grape (Caulerpa lentillifera) in polyculture with whiteleg shrimp (Litopenaeus vannamei) in the same culture tank. Five treatments were randomly designed in triplicate tanks where shrimp was monocultured (without sea grape) as a control treatment and four polyculture treatments with different seaweed density levels (0.5, 1, 1.5, and 2 kg m⁻³) for 56 days. The results showed that polyculture of shrimp and sea grape significantly reduced the concentrations of total ammonia nitrogen (TAN), nitrite (NO₂⁻), nitrate (NO₃⁻), and phosphate (PO₄³⁻) in the rearing tanks and significantly improved (p < 0.05) the growth rate (6.67–6.76% day⁻¹), survival (73.3–78.5%), and production of shrimp (3.44–3.87 kg m⁻³) compared to monoculture (6.24% day⁻¹, 54.8%, and 2.02 kg m⁻³, respectively). Applying shrimp and sea grape polyculture at a density of 1 kg m⁻³ provided a relatively better shrimp performance and feed conversion ratio than other seaweed densities, although not significantly different among polyculture treatments. The findings suggested that sea grape could be used at densities of 0.5–2 kg m⁻³ in polyculture with whiteleg shrimp, of which 1 kg m⁻³ resulted in higher production and feed efficiency. Full article

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12 pages, 27488 KiB

Open AccessEditor’s ChoiceArticle

Molecular Characterization of Hsp47 in Grass Carp (Ctenopharyngodon idella) and Its Correlation with Type I Collagen in Response to Fish Aerobic Exercise

by Xiao Liang, Ying Wan, Zhiyuan Shen, Yanmei Liu, Dapeng Li, Li Li, Rong Tang and Xi Zhang

Fishes 2021, 6(2), 17; https://doi.org/10.3390/fishes6020017 - 23 Apr 2021

Cited by 7 | Viewed by 3433

Abstract

Heat shock protein 47 (Hsp47) is a collagen-specific molecular chaperone that is indispensable for molecular maturation of collagen. In this study, hsp47 and hsp47-like cDNAs were cloned and characterized in grass carp (Ctenopharyngodon idella). The cDNAs were 1212 and 1218 base [...] Read more.

Heat shock protein 47 (Hsp47) is a collagen-specific molecular chaperone that is indispensable for molecular maturation of collagen. In this study, hsp47 and hsp47-like cDNAs were cloned and characterized in grass carp (Ctenopharyngodon idella). The cDNAs were 1212 and 1218 base pairs long, respectively, and included an open reading frame encoding 403 and 405 amino acids. The molecular phylogeny based on the deduced amino acid sequences indicated that the correct sequences of the hsp47 and hsp47-like cDNA were obtained and the deduced proteins clustered distinctly into teleost clades. Primary structure analysis and characterization of Hsp47 and Hsp47-like shared the basic structure and biofunctions of Hsp47 in vertebrates. The spatial pattern of gene expression revealed that hsp47 and hsp47-like were relatively ubiquitous in different tissues and highly expressed in heart and skin. The expression levels of hsp47 and hsp47-like and type I collagen mRNAs varied similarly in different tissues. Type I collagen content increased significantly with the increase of water velocity in the muscle of grass carp in response to aerobic exercise. Among the gene expression changes of hsp47, hsp47-like, col1a1 and col1a2 in muscle that occurred in response to aerobic exercise, the change of type I collagen was most strongly correlated with hsp47 expression. Additionally, col1a1 showed the highest correlation with hsp47-like and col1a2 showed the highest correlation with hsp47. These findings suggest that grass carp Hsp47 and Hsp47-like are closely related to type I collagen synthesis. This study firstly suggests fish aerobic exercise can improve type I collagen content and Hsp47 gene expression in muscle of grass carp. Full article

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13 pages, 2233 KiB

Open AccessEditor’s ChoiceArticle

Wound-Induced Changes in Antioxidant Enzyme Activities in Skin Mucus and in Gene Expression in the Skin of Gilthead Seabream (Sparus aurata L.)

by Cristóbal Espinosa-Ruíz and María Ángeles Esteban

Fishes 2021, 6(2), 15; https://doi.org/10.3390/fishes6020015 - 18 Apr 2021

Cited by 16 | Viewed by 4208

Abstract

This study investigated the antioxidant enzyme activities in the skin mucus of gilthead seabream (Sparus aurata L.) at 3 and 7 days post-wounding (dpw). The expression levels of the genes that encode stress proteins (grp170, grp94, grp75, sod [...] Read more.

This study investigated the antioxidant enzyme activities in the skin mucus of gilthead seabream (Sparus aurata L.) at 3 and 7 days post-wounding (dpw). The expression levels of the genes that encode stress proteins (grp170, grp94, grp75, sod and hsp70) and skin regeneration-related proteins (tf, igf1, tgfb1, der1, apo1 and erdj3) in the skin also were determined. Mucus and skin samples were obtained from the left and right flanks of non-wounded and wounded fish. In both flanks of the wounded fish, catalase and glutathione reductase activities in the skin mucus increased (p < 0.05) at 3 and 7 dpw (100 ± 31% and 111 ± 25%, respectively), whereas superoxide dismutase activity increased (p < 0.05) only at 7 dpw (135 ± 15%). The expression levels of stress proteins in the skin of the wounded flank of the wounded fish mainly increased at 7 dpw (grp170 increased to 288 ± 85%, grp94 to 502 ± 143%, grp75 to 274 ± 69%, sod to 569 ± 99%, and hsp70 increased to 537 ± 14%) (p < 0.05). However, the expression levels of the tissue regeneration-related genes varied depending on the flank investigated, on the experimental time, and on the gene studied. To the best of our knowledge, this is the first work to determine the effect of a wound in different skin parts of the same fish. Full article

(This article belongs to the Special Issue New Insights on Fish Immunology)

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11 pages, 2435 KiB

Open AccessEditor’s ChoiceArticle

Effects of Wastewater Treatment Plant Effluent in a Receiving Stream on Reproductive Behavior of Fathead Minnows (Pimephales promelas)

by Joseph M. Leese, Julia McMahon and Joseph C. Colosi

Fishes 2021, 6(2), 14; https://doi.org/10.3390/fishes6020014 - 12 Apr 2021

Cited by 5 | Viewed by 2676

Abstract

Wastewater treatment plant effluents contain a variety of endocrine disrupting chemicals (EDCs), including chemicals with estrogenic activity such as 17β-estradiol (E2), 17α-ethinyl estradiol (EE2), and nonylphenols. These substances can affect both behavior and physiology in vertebrate animals. To explore the presence and effects [...] Read more.

Wastewater treatment plant effluents contain a variety of endocrine disrupting chemicals (EDCs), including chemicals with estrogenic activity such as 17β-estradiol (E2), 17α-ethinyl estradiol (EE2), and nonylphenols. These substances can affect both behavior and physiology in vertebrate animals. To explore the presence and effects of these EDCs in a natural setting, juvenile and adult male fathead minnows, Pimephales promelas, were held in cages upstream and downstream of the effluent site of a wastewater treatment plant for 21 days and subsequently tested for changes in reproductive behaviors and production of vitellogenin. Additionally, estrogenic activity in the stream was measured using a yeast bioassay. Estrogenicity was found to be significantly higher downstream of the wastewater effluent when compared to levels upstream. Vitellogenin levels did not show a correlational pattern with levels of estrogenicity in the water, but two measures of reproductive behaviors occurred significantly less often in downstream males than upstream males. This suggests that a brief (three-week) exposure to stream water containing wastewater treatment plant effluent can bring about changes in reproductive behavior of fish and that behavior may be more sensitive to low levels of environmental endocrine disruptors than vitellogenin production. Full article

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7 pages, 949 KiB

Open AccessEditor’s ChoiceCommunication

Black Caviar Perturbs Reflection of Russian Geography: A Research Note of Aquaculture-Triggered Place Naming Puzzle

by Dmitry A. Ruban and Vladimir A. Ermolaev

Fishes 2021, 6(2), 13; https://doi.org/10.3390/fishes6020013 - 6 Apr 2021

Cited by 3 | Viewed by 3530

Abstract

Black caviar is often thought to be a typically Russian luxurious food product. Recently, its production has extended due to sturgeon aquaculture development. The analysis of the geographical affinities of the full-cycle companies and their aquaculture-sourced black caviar implies that the majority of [...] Read more.

Black caviar is often thought to be a typically Russian luxurious food product. Recently, its production has extended due to sturgeon aquaculture development. The analysis of the geographical affinities of the full-cycle companies and their aquaculture-sourced black caviar implies that the majority of them employs the Russian Caviar brand and/or refers to the Russian traditions and history. However, names, brands, and/or product positioning of several companies tend to mention geographical objects associated with the tradition places of black caviar production (Astrakhan, the Caspian Sea, and the Volga River), whereas these companies are located in the other, sometimes remote places (with distances over 1000 km). Such marketing solutions of black caviar producers perturb reflection of the Russian geography. The geographical indication (place of origin) of this fish product needs improvement, which is a task for companies, state, and professional societies. Full article

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12 pages, 1438 KiB

Open AccessEditor’s ChoiceArticle

Mechanism of Delayed Convulsion in Fish: The Actions of Norepinephrine in Spinal Cord

by Cheng-Linn Lee, Yuri Kominami and Hideki Ushio

Fishes 2021, 6(2), 12; https://doi.org/10.3390/fishes6020012 - 31 Mar 2021

Cited by 3 | Viewed by 5756

Abstract

Cranial spiking (CS) is among the most popular slaughtering methods for delaying the rigor mortis progress of fish muscles. However, it may cause a convulsion (subsequently referred to as delayed convulsion), which undermines the meat quality and taste. This study aimed to elucidate [...] Read more.

Cranial spiking (CS) is among the most popular slaughtering methods for delaying the rigor mortis progress of fish muscles. However, it may cause a convulsion (subsequently referred to as delayed convulsion), which undermines the meat quality and taste. This study aimed to elucidate the mechanism underlying the delayed convulsion and examine its influence on ATP consumption. Ten carps, nine tilapias, ten rainbow trouts, two ayus, three greenling, thirty-five red seabreams, two striped jack and two stone flounders underwent CS around the medulla oblongata area, which induced different delayed convulsion profiles specific to each species. To investigate the norepinephrine (NE) actions related to delayed convulsion, 27 red seabreams, a representative fish species that exhibits delayed convulsion, were treated with a monoamine-depleting agent, reserpine, or with a monoamine oxidase inhibitor, pargyline, two hours before CS. Spinal cord destruction (SCD) was employed to completely prevent spinal cord functions of the fish in another group. Compared with the control group (CS only), the reserpine, pargyline, and SCD groups showed significantly inhibited delayed convulsion and ATP consumption. This suggests that delayed convulsion is the main ATP-consuming response. Our findings suggest that delayed clonic convulsion in red seabreams is associated with the rapid decrease in spinal cord NE levels, which triggered the rebound motor neuron hyperactivity. Full article

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13 pages, 298 KiB

Open AccessEditor’s ChoiceArticle

Effects of Dissolved Potassium on Growth Performance, Body Composition, and Welfare of Juvenile African Catfish (Clarias gariepinus)

by Lisa Carolina Wenzel, Sebastian Marcus Strauch, Ep Eding, Francisco Xose Presas-Basalo, Berit Wasenitz and Harry Wilhelm Palm

Fishes 2021, 6(2), 11; https://doi.org/10.3390/fishes6020011 - 28 Mar 2021

Cited by 10 | Viewed by 5497

Abstract

Optimal crop production in aquaponics is influenced by water pH and potassium concentrations. The addition of potassium hydroxide (KOH) into the recirculating aquaculture system (RAS) may benefit aquaponics by increasing the water pH for better biofilter activity and supplementing K for better plant [...] Read more.

Optimal crop production in aquaponics is influenced by water pH and potassium concentrations. The addition of potassium hydroxide (KOH) into the recirculating aquaculture system (RAS) may benefit aquaponics by increasing the water pH for better biofilter activity and supplementing K for better plant growth and quality. We investigated the growth, feed conversion, body composition and welfare indicators of juvenile African catfish (Clarias gariepinus) treated with four concentrations of K (K0 = 2, K200 = 218, K400 = 418, and K600 = 671 mg L⁻¹). While growth, feed conversion and final body composition were unaffected, the feeding time and individual resting significantly increased with increasing K⁺. The swimming activity and agonistic behavior were reduced significantly under increased concentrations of K⁺. Leftover feed and the highest number of skin lesions were observed under K600. We suggest that K⁺ concentrations between 200 and 400 mg L⁻¹ can improve the welfare status of juvenile African catfish. This enables the application of KOH in RAS to supply alkalinity to achieve optimum nitrification at minimum water exchange and improve the nutritional profile of the process water with benefits for the welfare status of African catfish and aquaponics plant production and quality. Full article

(This article belongs to the Special Issue Environmental Impacts of Land-Based Aquaculture)

20 pages, 2239 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Numeric Simulation Demonstrates That the Upstream Movement of Invasive Bigheaded Carp Can Be Blocked at Sets of Mississippi River Locks-and-Dams Using a Combination of Optimized Spillway Gate Operations, Lock Deterrents, and Carp Removal

by Daniel Patrick Zielinski and Peter W. Sorensen

Fishes 2021, 6(2), 10; https://doi.org/10.3390/fishes6020010 - 26 Mar 2021

Cited by 10 | Viewed by 4445

Abstract

Invasive bigheaded carp are advancing up the Upper Mississippi River by passing through its locks-and-dams (LDs). Although these structures already impede fish passage, this role could be greatly enhanced by modifying how their spillway gates operate, adding deterrent systems to their locks, and [...] Read more.

Invasive bigheaded carp are advancing up the Upper Mississippi River by passing through its locks-and-dams (LDs). Although these structures already impede fish passage, this role could be greatly enhanced by modifying how their spillway gates operate, adding deterrent systems to their locks, and removing carp. This study examined this possibility using numeric modeling and empirical data, which evaluated all three options on an annual basis in both single LDs and pairs under different river flow conditions. Over 100 scenarios were modeled. While all three approaches showed promise, ranging from 8% to 73% reductions in how many carp pass a single LD, when employed together at pairs of LDs, upstream movement rates of invasive carp could be reduced 98–99% from current levels. Although modifying spillway gate operation is the least expensive option, its efficacy drops at high flows, so lock deterrents and/or removal using fishing/trapping are required to move towards complete blockage. Improved deterrent efficacy could also offset the need for more efficient removal. This model could help prioritize research and management actions for containing carp. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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9 pages, 522 KiB

Open AccessEditor’s ChoiceCommunication

Acceptance of a Protein Concentrate from Alfalfa (Medicago sativa) by Yellow Perch (Perca flavescens) Fed a Formulated Diet

by Jessica Coburn, M. Scott Wells, Nicholas B. D. Phelps, T. Gibson Gaylord and Deborah A. Samac

Fishes 2021, 6(2), 9; https://doi.org/10.3390/fishes6020009 - 25 Mar 2021

Cited by 1 | Viewed by 3464

Abstract

The majority of plant proteins used in aquatic feeds are derived from seed meals, which may contain antinutritional factors. Protein concentrates from plant foliage have received less attention in fish feeding trials. Alfalfa protein concentrate (APC) is derived from fresh alfalfa foliage that [...] Read more.

The majority of plant proteins used in aquatic feeds are derived from seed meals, which may contain antinutritional factors. Protein concentrates from plant foliage have received less attention in fish feeding trials. Alfalfa protein concentrate (APC) is derived from fresh alfalfa foliage that contains approximately 52% protein and is low in fiber. A feeding trial was done to assess growth and feed efficiency responses of yellow perch (Perca flavescens) fed a formulated diet with 180 g/kg APC replacing all fishmeal compared to a control isonitrogenous diet with fishmeal. Yellow perch accepted the APC diet but gained weight at a lower specific growth rate (−0.07% per day) and had an elevated feed conversion ratio (+0.32 g feed/g growth) than fish on the control diet containing fishmeal. There was no impact on survivorship or condition nor differences in fillet yield or composition in fish on the diet with APC compared to the control fishmeal diet. These findings indicate that although replacing fishmeal with APC in a perch diet resulted in slower growth rates, the APC was accepted and has promise as a sustainable protein in aquatic feeds. Full article

(This article belongs to the Special Issue Integration of Nutrition and Physiology in Aquatic Animals)

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9 pages, 2916 KiB

Open AccessEditor’s ChoiceArticle

Upwelling Impact on Sardinella lemuru during the Indian Ocean Dipole in the Bali Strait, Indonesia

by Daduk Setyohadi, Umi Zakiyah, Abu Bakar Sambah and Adi Wijaya

Fishes 2021, 6(1), 8; https://doi.org/10.3390/fishes6010008 - 16 Mar 2021

Cited by 14 | Viewed by 4399

Abstract

Understanding the impact of Indian Ocean Dipole (IOD) on fishery around Indonesia is important as the fishery resources are small compared to the demand. In this study, we analyzed the effect of positive and negative phases of IOD on chlorophyll-a concentration and the [...] Read more.

Understanding the impact of Indian Ocean Dipole (IOD) on fishery around Indonesia is important as the fishery resources are small compared to the demand. In this study, we analyzed the effect of positive and negative phases of IOD on chlorophyll-a concentration and the catch of Sardinella lemuru in the Bali Strait. Data are based on field surveys in the Bali Strait during the positive and negative phase of IOD and Sea Surface Temperature (SST) and Sea Surface Chlorophyll (SSC) obtained from the analysis of satellite images. The results suggest that SSC concentration in the strait significantly correlates with the positive and negative phase of IOD, possibly through a change of upwelling and downwelling there. It is suggested that the change of phytoplankton biomass due to positive IOD would result in an increase of Sardinella lemuru in the Bali Strait. This research has direct implications as important information for the government in planning lemuru fisheries management in the Bali Strait based on oceanographic studies and climate phenomena. Full article

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11 pages, 1195 KiB

Open AccessEditor’s ChoiceArticle

Slight Increases in Salinity Improve Muscle Quality of Grass Carp (Ctenopharyngodon idellus)

by Xi Zhang, Zhiyuan Shen, Tianpeng Qi, Rujuan Xi, Xiao Liang, Li Li, Rong Tang and Dapeng Li

Fishes 2021, 6(1), 7; https://doi.org/10.3390/fishes6010007 - 24 Feb 2021

Cited by 20 | Viewed by 4358

Abstract

Fish muscle quality is an important parameter in the aquaculture industry. In this study, we analyzed and compared the muscle quality of grass carp (Ctenopharyngodon idellus) cultured at salinities of 0‰, 3‰, and 6‰ (GC0, GC3, GC6). There was no significant [...] Read more.

Fish muscle quality is an important parameter in the aquaculture industry. In this study, we analyzed and compared the muscle quality of grass carp (Ctenopharyngodon idellus) cultured at salinities of 0‰, 3‰, and 6‰ (GC0, GC3, GC6). There was no significant difference in crude protein and crude fat content of muscle between GC0 and GC3. Crude fat was significantly lower in GC6 compared to the other groups. GC3 and GC6 had higher hydroxyproline content, which suggested that these groups had higher collagen content. GC3 and GC6 had higher contents of free amino acids and umami amino acids than GC0, but there was no significant difference in sweet or sour amino-acid content among groups. GC3 and GC6 had better texture properties, including hardness, gumminess, chewiness, resilience, and springiness, than GC0. GC3 had the highest water-holding capacity among the groups. As the salinity increased, the diameter of muscle fibers decreased and the sarcolemma showed a thickening trend. These results suggest that a slight increase in salinity (i.e., 3‰) can effectively improve the muscle quality of grass carp. Full article

(This article belongs to the Special Issue Environmental Impacts of Land-Based Aquaculture)

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17 pages, 2937 KiB

Open AccessEditor’s ChoiceReview

Eradication of the Invasive Common Carp, Cyprinus carpio from a Large Lake: Lessons and Insights from the Tasmanian Experience

by Jonah L. Yick, Chris Wisniewski, John Diggle and Jawahar G. Patil

Fishes 2021, 6(1), 6; https://doi.org/10.3390/fishes6010006 - 23 Feb 2021

Cited by 14 | Viewed by 7658

Abstract

Common carp (Cyprinus carpio, L. 1758) are the most abundant pest fish species in Australia, detrimental to ecosystem integrity and values, and in need of suitable management solutions. In January 1995, this destructive pest was discovered in two large, connected Tasmanian [...] Read more.

Common carp (Cyprinus carpio, L. 1758) are the most abundant pest fish species in Australia, detrimental to ecosystem integrity and values, and in need of suitable management solutions. In January 1995, this destructive pest was discovered in two large, connected Tasmanian lakes—Lakes Crescent (23 km²) and Sorell (54 km²). After an initial assessment, carp were immediately contained to these waters using screens to prevent their escape down-stream, followed by swift legislation to enforce closure of the lakes to the public. Assessment and evaluation of carp numbers occurred throughout the eradication program, with effort focused on Lake Crescent. Beginning with undirected removal, techniques progressively evolved to more sophisticated targeted removal with assistance from biotelemetry, in conjunction with gill netting and electro-fishing. Real-time population estimates and in situ observations resulted in a detailed cumulative understanding of carp population dynamics, behaviour and seasonal habitat choice. This allowed strategic deployment of fences to block access to marshes, and the installation of steel traps within the fences. These gears specifically prevented spawning opportunities, while concurrently capturing mature fish. Following 12 years of adaptive and integrated effort, 7797 carp (fry, juvenile and adult) were captured from Lake Crescent, with the last carp being caught in December 2007. The subsequent 14 years of monitoring has not resulted in the capture of any carp, confirming the successful eradication of carp from Lake Crescent. These management practices have been successfully replicated in the larger Lake Sorell, where 41,499 carp (fry, juvenile and adult) have been removed. It is now estimated that there are few, if any carp remaining. Collectively, the techniques and strategies described here were reliable, and can be applied as a model to control or eradicate pest populations of carp in freshwater lakes elsewhere. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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26 pages, 7051 KiB

Open AccessEditor’s ChoiceArticle

Survival, Growth, and Development in the Early Stages of the Tropical Gar Atractosteus tropicus: Developmental Critical Windows and the Influence of Temperature, Salinity, and Oxygen Availability

by Gil Martínez, Emyr Peña, Rafael Martínez, Susana Camarillo, Warren Burggren and Alfonso Álvarez

Fishes 2021, 6(1), 5; https://doi.org/10.3390/fishes6010005 - 12 Feb 2021

Cited by 8 | Viewed by 4915

Abstract

Alterations in fish developmental trajectories occur in response to genetic and environmental changes, especially during sensitive periods of development (critical windows). Embryos and larvae of Atractosteus tropicus were used as a model to study fish survival, growth, and development as a function of [...] Read more.

Alterations in fish developmental trajectories occur in response to genetic and environmental changes, especially during sensitive periods of development (critical windows). Embryos and larvae of Atractosteus tropicus were used as a model to study fish survival, growth, and development as a function of temperature (28 °C control, 33 °C, and 36 °C), salinity (0.0 ppt control, 4.0 ppt, and 6.0 ppt), and air saturation (control ~95% air saturation, hypoxia ~30% air saturation, and hyperoxia ~117% air saturation) during three developmental periods: (1) fertilization to hatch, (2) day 1 to day 6 post hatch (dph), and (3) 7 to 12 dph. Elevated temperature, hypoxia, and hyperoxia decreased survival during incubation, and salinity at 2 and 3 dph. Growth increased in embryos incubated at elevated temperature, at higher salinity, and in hyperoxia but decreased in hypoxia. Changes in development occurred as alterations in the timing of hatching, yolk depletion, acceptance of exogenous feeding, free swimming, and snout shape change, especially at high temperature and hypoxia. Our results suggest identifiable critical windows of development in the early ontogeny of A. tropicus and contribute to the knowledge of fish larval ecology and the interactions of individuals × stressors × time of exposure. Full article

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14 pages, 1074 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Evaluating Coexistence of Fish Species with Coastal Cutthroat Trout in Low Order Streams of Western Oregon and Washington, USA

by Kyle D. Martens and Jason Dunham

Fishes 2021, 6(1), 4; https://doi.org/10.3390/fishes6010004 - 30 Jan 2021

Cited by 6 | Viewed by 4668

Abstract

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the [...] Read more.

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the Pacific Northwest have focused solely on the most prevalent species: Coastal cutthroat trout. To examine the potential for interactions of other fishes with coastal cutthroat trout, we conducted an analysis of 281 sites in low order streams located on Washington’s Olympic Peninsula and along the central Oregon coast. Coastal cutthroat trout and juvenile coho salmon were the most commonly found salmonid species within these streams and exhibited positive associations with each other for both presence and density. Steelhead were negatively associated with the presence of coastal cutthroat trout as well as with coho salmon and sculpins (Cottidae). Coastal cutthroat trout most frequently shared streams with juvenile coho salmon. For densities of these co-occurring species, associations between these two species were relatively weak compared to the strong influences of physical stream conditions (size and gradient), suggesting that physical conditions may have more of an influence on density than species interactions. Collectively, our analysis, along with a review of findings from prior field and laboratory studies, suggests that the net effect of interactions between coastal cutthroat trout and coho salmon do not appear to inhibit their presence or densities in small streams along the Pacific Northwest. Full article

(This article belongs to the Special Issue Integration of Nutrition and Physiology in Aquatic Animals)

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15 pages, 1714 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Achieving Sea Lamprey Control in Lake Champlain

by Bradley Young, BJ Allaire and Stephen Smith

Fishes 2021, 6(1), 2; https://doi.org/10.3390/fishes6010002 - 26 Jan 2021

Cited by 4 | Viewed by 4275

Abstract

The control of parasitic sea lamprey in Lake Champlain has been a necessary component of its fishery restoration and recovery goals for 30 years. While adopting the approach of the larger and established sea lamprey control program of the Laurentian Great Lakes, local [...] Read more.

The control of parasitic sea lamprey in Lake Champlain has been a necessary component of its fishery restoration and recovery goals for 30 years. While adopting the approach of the larger and established sea lamprey control program of the Laurentian Great Lakes, local differences emerged that shifted management focus and effort as the program evolved. Increased investment in lamprey assessment and monitoring revealed under-estimations of population density and distribution in the basin, where insufficient control efforts went unnoticed. As control efforts improved in response to a better understanding of the population, the effects of lamprey on the fishery lessened. A long-term evaluation of fishery responses when lamprey control was started, interrupted, delayed, and enhanced provided evidence of a recurring relationship between the level of control effort applied and the measured suppression of the parasitic sea lamprey population. Changes in levels of control efforts over time showed repeatedly that measurable suppression of the parasitic population required effective control of 80% of the known larval population. Understanding the importance of assessment and monitoring and the relationship between control effort and population suppression has led to recognition that a comprehensive, not incremental, approach is needed to achieve effective control of sea lamprey in Lake Champlain. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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18 pages, 1663 KiB

Open AccessEditor’s ChoiceReview

Trends in Growth Modeling in Fisheries Science

by Shane A. Flinn and Stephen R. Midway

Fishes 2021, 6(1), 1; https://doi.org/10.3390/fishes6010001 - 19 Jan 2021

Cited by 37 | Viewed by 9932

Abstract

Growth models estimate life history parameters (e.g., growth rates and asymptotic size) that are used in the management of fisheries stocks. Traditionally in fisheries science, it was common to fit one growth model—the von Bertalanffy growth model—to size-at-age data. However, in recent years, [...] Read more.

Growth models estimate life history parameters (e.g., growth rates and asymptotic size) that are used in the management of fisheries stocks. Traditionally in fisheries science, it was common to fit one growth model—the von Bertalanffy growth model—to size-at-age data. However, in recent years, fisheries science has seen an increase in the number of growth models available and the evaluation of multiple growth models for a given species or study. We reviewed n = 196 peer-reviewed age and growth studies and n = 50 NOAA (National Oceanic and Atmospheric Administration) regional stock assessments to examine trends in the use of growth models and model selection in fisheries over time. Our results indicate that the total number of age and growth studies increased annually since 1988 with a slight proportional increase in the use of multi-model frameworks. Information theoretic approaches are replacing goodness-of-fit and a priori model selection in fisheries studies; however, this trend is not reflected in NOAA stock assessments, which almost exclusively rely on the von Bertalanffy growth model. Covariates such as system (e.g., marine or fresh), location of study, diet, family, maximum age, and range of age data used in model fitting did not contribute to which model was ultimately the best fitting, suggesting that there are no large-scale patterns of specific growth models being applied to species with common life histories or other attributes. Given the importance and ubiquity of growth modeling to fisheries science, a historical and contemporary understanding of the practice is critical to evaluate improvements that have been made and future challenges. Full article

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10 pages, 1061 KiB

Open AccessEditor’s ChoiceArticle

Vertebrae Morphometric Measurement and Ca/P Levels of Different Age European Seabass (Dicentrarchus labrax)

by Vasiliki Nikiforidou, Stefanos Zaoutsos, Nikolaos Vlahos and Panagiotis Berillis

Fishes 2020, 5(4), 37; https://doi.org/10.3390/fishes5040037 - 8 Dec 2020

Cited by 5 | Viewed by 9590

Abstract

The European seabass is one of the most important species of the Mediterranean, specifically Greece. Individuals with different numbers of vertebrae have been reported. This number ranges from 24 to 26 vertebrae. In this study a sample of 73 individual seabass were collected [...] Read more.

The European seabass is one of the most important species of the Mediterranean, specifically Greece. Individuals with different numbers of vertebrae have been reported. This number ranges from 24 to 26 vertebrae. In this study a sample of 73 individual seabass were collected from fish farms and divided into three age groups. The first group included fingerling individuals, the second group, juvenile individuals and the third group, adult individuals. The number and the length of their vertebrae were measured by radiographs. The individuals were divided into subgroups according to their vertebrae number, and from each one the tenth vertebra was taken. Ca and P levels (%) of each tenth vertebra were measured by X-ray spectroscopy (EDS), and the Ca/P ratio was determined. Vertebrae length, Ca and P levels and Ca/P ratio were compared among age groups and among individuals with different numbers of vertebrae. It was shown that the European seabass’s vertebral column can be divided to three sections—cervical, abdominal and caudal—following the striped bass (Morone saxatilis) model. Full article

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23 pages, 3798 KiB

Open AccessEditor’s ChoiceArticle

Case Studies Demonstrate That Common Carp Can Be Sustainably Reduced by Exploiting Source-Sink Dynamics in Midwestern Lakes

by Peter W. Sorensen and Przemyslaw G. Bajer

Fishes 2020, 5(4), 36; https://doi.org/10.3390/fishes5040036 - 4 Dec 2020

Cited by 15 | Viewed by 4720

Abstract

The common carp has been highly problematic in North American ecosystems since its introduction over a century ago. In many watersheds, its abundance appears to be driven by source-sink dynamics in which carp reproduce successfully in peripheral ponds that lack egg/larva micro-predators which [...] Read more.

The common carp has been highly problematic in North American ecosystems since its introduction over a century ago. In many watersheds, its abundance appears to be driven by source-sink dynamics in which carp reproduce successfully in peripheral ponds that lack egg/larva micro-predators which then serve as sources of recruits for deeper lakes. This manuscript describes how carp were sustainably reduced in two chains of lakes by disrupting source-sink dynamics in three steps. First, we ascertained whether lakes had problematic densities of carp that could be explained by source-sink dynamics. Second, ways to control recruitment were developed and implemented including: (i) aerating source ponds to reduce hypoxia and increase micro-predator abundance, (ii) blocking carp migration, and (iii) locating and removing adults from sinks using targeted netting guided by Judas fish. Third, we monitored and adapted. Using this strategy, the density of carp in 3 lakes in one chain was reduced from 177 kg/ha to ~100 kg/ha in 3 years and held constant for a decade. Similarly, adult density was reduced from 300 kg carp/ha in 2 lakes in the other chain to 25 kg/ha. Once carp densities were low, aluminum sulfate treatments became reasonable and once conducted, water quality improved. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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12 pages, 1273 KiB

Open AccessEditor’s ChoiceArticle

Multispecies Fresh Water Algae Production for Fish Farming Using Rabbit Manure

by Adandé Richard, Liady Mouhamadou Nourou Dine, Djidohokpin Gildas, Adjahouinou Dogbè Clément, Azon Mahuan Tobias Césaire, Micha Jean-Claude and Fiogbe Didier Emile

Fishes 2020, 5(4), 35; https://doi.org/10.3390/fishes5040035 - 30 Nov 2020

Viewed by 3551

Abstract

The current study aims at determining the optimal usage conditions of rabbit manure in a multispecies fresh water algae production for fish farming. This purpose, the experimental design is made of six treatments in triplicate including one control T₀, T₁ [...] Read more.

The current study aims at determining the optimal usage conditions of rabbit manure in a multispecies fresh water algae production for fish farming. This purpose, the experimental design is made of six treatments in triplicate including one control T₀, T₁, T₂, T₃, T₄, T₅ corresponding respectively to 0, 300, 600, 900, 1200, 1500 g/m³ of dry rabbit manure put into buckets containing 40 L of demineralized water and then fertilized. The initial average seeding density is made of 4 × 10³ ± 2.5 × 10² cells/L of Chlorophyceae, 1.5 × 10³ ± 1 × 10² cells/L of Coscinodiscophyceae, 3 × 10³ ± 1.2 × 10² cells/L of Conjugatophyceae, 2.8 × 10³ ± 1.5 × 10² cells/L of Bascillariophyceae, and 2.5 × 10³ ± 1.4 × 10² cells/L of Euglenophyceae. During the experiments, the effects of these treatments on abiotic and biotic parameters (chlorophyll-a concentration, phytoplankton density and algal density) of different production media were monitored. Results show that average density of different phytoplankton classes is higher in treatment T₅ (7.91 × 10⁸ ± 6.78 × 10⁷ cells/L) followed by T₄ (5.56 × 10⁸ ± 4.27 × 10⁷ cells/L), T₂ (3.87 × 10⁸ ± 3.10 × 10⁸ cells/L), T₃ (3.79 × 10⁸ ± 3.18 × 10⁸ cells/L, with high significant difference (F _(4,84) = 5, 35, p < 0.00). Chl-a concentration varied from 0.07 ± 0.05 mg/L (T₀) to 14.47 ± 12.50 mg/L (T₅) with high significant differences observed among treatments (F _(5,83) = 3,09, p = 0,01). In addition, fourteen (14) species belonging to eight (8) families, five (5) classes and three (3) phyla were identified in our different production media. During the culture, Chlorophyceae class was the most represented in all treatments with 5 species (36% of the specific diversity) while Euglenophyceae class (7%) was the least represented with only one (01) species. According to these results, treatments T₂ (600 g/m³), T₃ (900 g/m³) and T₄ (1200 g/m³) of dry rabbit manure are those worthy to be recommended as an alternative for a low cost massive production of multispecies freshwater algae that can be easily used by freshwater zooplankton and macroinvertebrates. Indeed, despite the best performances that it shows, treatment T₅, presents important eutrophication’s risks. Full article

(This article belongs to the Special Issue Environmental Impacts of Land-Based Aquaculture)

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15 pages, 51861 KiB

Open AccessEditor’s ChoiceArticle

Morphology, Transcriptomics and In Vitro Model of Skin from Polar Cod (Boreogadus Saida) and Atlantic Cod (Gadus Morhua)

by Elisabeth Ytteborg, Øyvind Johannes Hansen, Vibeke Høst, Sergey Afanasyev, Ireen Vieweg, Jasmine Nahrgang and Aleksei Krasnov

Fishes 2020, 5(4), 34; https://doi.org/10.3390/fishes5040034 - 4 Nov 2020

Cited by 10 | Viewed by 4871

Abstract

Fish skin is a multifunctional barrier tissue with high regeneration capacity that interacts with the surrounding environment and provides protection. Functional importance, high complexity and activity make skin an attractive tissue for studying the effects of environmental challenges and chemical stressors in fish. [...] Read more.

Fish skin is a multifunctional barrier tissue with high regeneration capacity that interacts with the surrounding environment and provides protection. Functional importance, high complexity and activity make skin an attractive tissue for studying the effects of environmental challenges and chemical stressors in fish. The aim of this work was to characterize skin from polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua), and to test cod skin as an in vitro model in exposure studies. Both species have similar skin structures including epidermis, mucous cells, club cells and scales. However, microarchitectural differences were detected; Atlantic cod has a smooth epidermal surface and overlapping scales, whereas polar cod has a folded outer surface and discontinuous scales. Genome-wide microarray found 6.5k genes with expression differences, which suggested more active turnover of proteins, proliferation and motility of cells in skin of polar cod. Hydrogen peroxide (H₂O₂) was used to examine skin responses. Transcriptome response was stronger in the skin of polar cod, with 155 differentially expressed genes. The skin from Atlantic cod was further used to develop a cell culture. H₂O₂ decreased the cell migration rate in a dose-dependent manner, which could indicate reduced skin healing capacity. The results revealed novel skin structures and confirmed that the skin from cod is a promising tissue for evaluation of stressors. Full article

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18 pages, 1679 KiB

Open AccessEditor’s ChoiceArticle

Competition between Invasive Ruffe (Gymnocephalus cernua) and Native Yellow Perch (Perca flavescens) in Experimental Mesocosms

by Raymond M. Newman, Fred G. Henson and Carl Richards

Fishes 2020, 5(4), 33; https://doi.org/10.3390/fishes5040033 - 17 Oct 2020

Cited by 4 | Viewed by 3724

Abstract

Ruffe (Gymnocephalus cernua) were introduced to North America from Europe in the mid-1980s and based on similar diets and habit use may compete with yellow perch (Perca flavescens). To examine competitive interactions between invasive ruffe and native yellow perch, [...] Read more.

Ruffe (Gymnocephalus cernua) were introduced to North America from Europe in the mid-1980s and based on similar diets and habit use may compete with yellow perch (Perca flavescens). To examine competitive interactions between invasive ruffe and native yellow perch, individually marked perch and ruffe were placed in mesocosms in a small lake. Mesocosms allowed fish to interact and feed on the natural prey populations enclosed. In the first experiment, four treatments were assessed: 28 perch, 14 perch + 14 ruffe, 14 perch, and 7 perch + 7 ruffe. Yellow perch growth was significantly lower in the presence of ruffe (ANOVA, p = 0.005) than in treatments containing only perch. In a second experiment, an increasing density of one species was superimposed upon a constant density of the other in parallel treatment series. Growth rates of both ruffe and perch declined when ruffe density was increased (t test, p = 0.006). However, neither ruffe nor perch growth was affected by increasing perch density. Total stomach content mass of perch was significantly decreased by ruffe in both years (p < 0.02), but no effects of ruffe on the composition of perch diets were observed. Ruffe growth and food consumption was greater than that of perch for both experiments. Ruffe can outcompete yellow perch when both species depend on a limited benthic food resource. Thus there is reason for concern for the ecological effects of ruffe if they expand their range into Lake Erie or North American inland lakes that contain yellow perch. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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11 pages, 284 KiB

Open AccessEditor’s ChoiceArticle

Digestibility of Local Feed Ingredients in Tilapia Oreochromis niloticus Juveniles, Determined on Faeces Collected by Siphoning or Stripping

by Francis Pius Mmanda, Jan Erik Lindberg, Anna Norman Haldén, Matern S. P. Mtolera, Rukia Kitula and Torbjörn Lundh

Fishes 2020, 5(4), 32; https://doi.org/10.3390/fishes5040032 - 15 Oct 2020

Cited by 13 | Viewed by 6994

Abstract

Eight locally available protein source ingredients in Tanzania were selected for assessment of apparent digestibility (AD) in tilapia Oreochromis niloticus, using faeces samples collected by siphoning or stripping. The selected protein source ingredients were Lake Victoria sardines (FM), brewers spent yeast (BSY), [...] Read more.

Eight locally available protein source ingredients in Tanzania were selected for assessment of apparent digestibility (AD) in tilapia Oreochromis niloticus, using faeces samples collected by siphoning or stripping. The selected protein source ingredients were Lake Victoria sardines (FM), brewers spent yeast (BSY), moringa leaves (ML), freshwater shrimp (FSH), marine shrimp (MSH), cattle blood (CB), duckweed (DW) and fish frames (FF). The AD (%) of dry matter (DM), organic matter (OM) and crude protein (CP) was unaffected (p > 0.782–0.901) by the faeces collection method (i.e., siphoning or stripping), with correlation coefficient (r) of 0.98, 0.99 and 0.93 between AD values for DM, OM and CP, respectively, following siphoning and stripping. The AD (%) of DM, OM, CP and gross energy (GE) in the test ingredients differed (p < 0.0001). The AD (%) of DM and OM was lowest in BSY and DW, followed in increasing order by ML, MSH, FF, FSH and CB. In general, the AD (%) of CP was high (>76%), but with a low value (46%) for DW. The AD (%) of GE was closely correlated (r = 0.96) with the AD of OM. In conclusion, FSH, MSH, CB, FF, BSY and ML have acceptable protein digestibility to be used in tilapia diet formulation. Full article

13 pages, 2853 KiB

Open AccessEditor’s ChoiceArticle

Determining Stingray Movement Patterns in a Wave-Swept Coastal Zone Using a Blimp for Continuous Aerial Video Surveillance

by David Ruiz-García, Kye Adams, Heidi Brown and Andrew R. Davis

Fishes 2020, 5(4), 31; https://doi.org/10.3390/fishes5040031 - 30 Sep 2020

Cited by 8 | Viewed by 5862

Abstract

Stingrays play a key role in the regulation of nearshore ecosystems. However, their movement ecology in high-energy surf areas remains largely unknown due to the notorious difficulties in conducting research in these environments. Using a blimp as an aerial platform for video surveillance, [...] Read more.

Stingrays play a key role in the regulation of nearshore ecosystems. However, their movement ecology in high-energy surf areas remains largely unknown due to the notorious difficulties in conducting research in these environments. Using a blimp as an aerial platform for video surveillance, we overcame some of the limitations of other tracking methods, such as the use of tags and drones. This novel technology offered near-continuous coverage to characterise the fine-scale movements of stingrays in a surf area in Kiama, Australia, without any invasive procedures. A total of 98 stingray tracks were recorded, providing 6 h 27 min of movement paths. The tracking data suggest that stingrays may use a depth gradient located in the sandflat area of the bay for orientating their movements and transiting between locations within their home range. Our research also indicates that stingray behaviour was influenced by diel periods and tidal states. We observed a higher stingray occurrence during the afternoon, potentially related to foraging and anti-predatory strategies. We also saw a reduced route fidelity during low tide, when the bathymetric reference was less accessible due to stranding risk. Considering the increasing threat of anthropogenic development to nearshore coastal environments, the identification of these patterns can better inform the management and mitigation of threats. Full article

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18 pages, 2770 KiB

Open AccessEditor’s ChoiceArticle

An Ecological and Economical Assessment of Integrated Amaranth (Amaranthus hybridus) and Nile Tilapia (Oreochromis niloticus) Farming in Dar es Salaam, Tanzania

by Deogratias Pius Mulokozi, Håkan Berg and Torbjörn Lundh

Fishes 2020, 5(3), 30; https://doi.org/10.3390/fishes5030030 - 18 Sep 2020

Cited by 5 | Viewed by 4881

Abstract

Organic wastes can be recycled in an ecologically sound way in fishponds by applying integrated agriculture and aquaculture systems (IAA). This kind of waste recycling can help to protect the environment from pollution and improve fishpond yields. Additionally, IAA provides an opportunity for [...] Read more.

Organic wastes can be recycled in an ecologically sound way in fishponds by applying integrated agriculture and aquaculture systems (IAA). This kind of waste recycling can help to protect the environment from pollution and improve fishpond yields. Additionally, IAA provides an opportunity for diversification of the output from two or more existing subsystems leading to higher overall farm economic returns. This study explored the potential application of amaranth wastes (AW) as a dietary ingredient for tilapia in a tilapia-amaranths integrated system (ITA). An experimental diet (AD) contained 10% (based on the control diet, CD) inclusion of AW collected from a nearby vegetable market. The experiments included triplicate treatments with; (i) fish fed on AD, where the pond water was used for irrigating the amaranth plants (IAA-fish), and (ii) fish fed on CD, where no pond water was used for irrigating the amaranth plants (non-IAA fish). 90 days after fish stocking, eighteen 4 m² amaranth plots were prepared and treated with (i) tap water without fertilization (control amaranths), (ii) water from IAA-fish pond and organically fertilized (IAA amaranths), and (iii) tap water and inorganically fertilized (non-IAA amaranths). The use of AW improved the fish feed conversion ratio. The overall net income from ITA was 3.2, 2.3, 2.6, and 1.8 higher than from non-IAA amaranths, IAA-amaranths, non-IAA fish, and IAA fish sub-systems respectively. Full article

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14 pages, 1740 KiB

Open AccessEditor’s ChoiceArticle

Geographic-Scale Harvest Program to Promote Invasivorism of Bigheaded Carps

by Wesley W. Bouska, David C. Glover, Jesse T. Trushenski, Silvia Secchi, James E. Garvey, Ruairi MacNamara, David P. Coulter, Alison A. Coulter, Kevin Irons and Andrew Wieland

Fishes 2020, 5(3), 29; https://doi.org/10.3390/fishes5030029 - 1 Sep 2020

Cited by 12 | Viewed by 5009

Abstract

Invasive bigheaded carps, genus Hypophthalmichthys, are spreading throughout the Mississippi River basin. To explore the efficacy of a consumer-based market (i.e., invasivorism) to manage them, we developed a conceptual model and evaluated three harvest approaches—direct contracted removal, volume-based incentives (“fisher-side” control), and [...] Read more.

Invasive bigheaded carps, genus Hypophthalmichthys, are spreading throughout the Mississippi River basin. To explore the efficacy of a consumer-based market (i.e., invasivorism) to manage them, we developed a conceptual model and evaluated three harvest approaches—direct contracted removal, volume-based incentives (“fisher-side” control), and set-quota harvest (“market-side” control). We quantified the efficacy of these approaches and potential population impact in the Illinois River. Contracted removal was effective for suppressing small populations at the edge of the range but cannot support a market. “Fisher-side” removals totaled 225,372 kg in one year. However, participation was low, perhaps due to reporting requirements for fishers. The “market-side”, set-quota approach removed >1.3 million kg of bigheaded carp in less than 6 months. Larger, older fish were disproportionately harvested, which may hinder the ability to suppress population growth. Total density declined in one river reach, and harvest may reduce upstream movement toward the invasion fronts. With sufficient market demand, harvest may control bigheaded carp. However, lack of processing infrastructure and supply chain bottlenecks could constrain harvest, particularly at low commodity prices. Given the geographical scale of this invasion and complicated harvest logistics, concerns about economic dependence on invasivorism that encourage stock enhancement are likely unmerited. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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16 pages, 3398 KiB

Open AccessEditor’s ChoiceArticle

Catch per Unit Effort Dynamic of Yellowfin Tuna Related to Sea Surface Temperature and Chlorophyll in Southern Indonesia

by Budy Wiryawan, Neil Loneragan, Ulfah Mardhiah, Sonja Kleinertz, Prihatin Ika Wahyuningrum, Jessica Pingkan, Wildan, Putra Satria Timur, Deirdre Duggan and Irfan Yulianto

Fishes 2020, 5(3), 28; https://doi.org/10.3390/fishes5030028 - 31 Aug 2020

Cited by 21 | Viewed by 5352

Abstract

Tuna fisheries are the most valuable fisheries in the world, with an estimated market value of at least US$42 billion in 2018. Indonesia plays an important role in the global tuna fisheries and has committed to improve its fisheries management; therefore, a pilot [...] Read more.

Tuna fisheries are the most valuable fisheries in the world, with an estimated market value of at least US$42 billion in 2018. Indonesia plays an important role in the global tuna fisheries and has committed to improve its fisheries management; therefore, a pilot of long-term spatial-temporal data bases was developed in 2012, however none have utilized data to have better understanding for management improvement. In this study, the annual and seasonal variation of large (≥10 kg) Yellowfin Tuna (YFT) catch per unit effort (CPUE) have been investigated and the influence of sea surface temperature (SST) and chlorophyll-a on these variables examined. We used fish landing data from West Nusa Tenggara recorded every month between 2012 and 2017 and analyzed using generalized linear models and generalized additive models. We found a seasonal and annual pattern of tuna abundance affected by SST and chlorophyll-a (chl a) and related to upwelling and El Nino event. These results also suggest that a two-month closure to fishing in August and September in southern Lombok is worth considering by the Government to maximize conservation of stocks due to a high abundance of juveniles emerging during the upwelling months from June to August. Full article

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10 pages, 1940 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Use of Environmental DNA to Detect Grass Carp Spawning Events

by Cari-Ann Hayer, Michael F. Bayless, Amy George, Nathan Thompson, Catherine A. Richter and Duane C. Chapman

Fishes 2020, 5(3), 27; https://doi.org/10.3390/fishes5030027 - 27 Aug 2020

Cited by 16 | Viewed by 4032

Abstract

The timing and location of spawning events are important data for managers seeking to control invasive grass carp populations. Ichthyoplankton tows for grass carp eggs and larvae can be used to detect spawning events; however, these samples can be highly debris-laden, and are [...] Read more.

The timing and location of spawning events are important data for managers seeking to control invasive grass carp populations. Ichthyoplankton tows for grass carp eggs and larvae can be used to detect spawning events; however, these samples can be highly debris-laden, and are expensive and laborious to process. An alternative method, environmental DNA (eDNA) technology, has proven effective in determining the presence of aquatic species. The objectives of this project were to assess the use of eDNA collections and quantitative eDNA analysis to assess the potential spawning of grass carp in five reservoir tributaries, and to compare those results to the more traditional method of ichthyoplankton tows. Grass carp eDNA was detected in 56% of sampling occasions and was detected in all five rivers. Concentrations of grass carp eDNA were orders of magnitude higher in June, corresponding to elevated discharge and egg presence. Grass carp environmental DNA flux (copies/h) was lower when no eggs were present and was higher when velocities and discharge increased and eggs were present. There was a positive relationship between grass carp eDNA flux and egg flux. Our results support the further development of eDNA analysis as a method to detect the spawning events of grass carp or other rheophilic spawners. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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17 pages, 1034 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Zooplankton Feeding Induces Macroscopical Gonad Malformations in Whitefish (Coregonus ssp.) from Lake Thun, Switzerland

by Daniel Bernet, Thomas Wahli, Christoph Küng and Helmut Segner

Fishes 2020, 5(3), 26; https://doi.org/10.3390/fishes5030026 - 20 Aug 2020

Cited by 1 | Viewed by 3441

Abstract

Alterations in gonad morphology are widespread in wild fish populations. Whitefish (Coregonus spp.) from Lake Thun, Switzerland, display a high prevalence of macroscopical gonad malformations including fusions to the musculature, segmented gonads and intersex condition. The aim of the present study was [...] Read more.

Alterations in gonad morphology are widespread in wild fish populations. Whitefish (Coregonus spp.) from Lake Thun, Switzerland, display a high prevalence of macroscopical gonad malformations including fusions to the musculature, segmented gonads and intersex condition. The aim of the present study was to evaluate whether the gonad morphological changes in Lake Thun whitefish are caused by genetic factors, environmental factors (water, diet) or “gene × environment” interaction. We performed two independent experiments of a three-year duration in which we reared whitefish from fertilization until adulthood and tested the possible causative factors using a matrix design: (i) genetics—comparing the prevalence of gonad malformations in whitefish of different genetic origin reared under identical environmental conditions (same diet, same water, same experimental facility); (ii) environment—comparing the prevalence of gonad malformations in whitefish of the same genetic origin reared in different water sources and/or fed with different diets; and (iii) gene-environment interaction—comparing the prevalence of gonad morphological alterations in relation to the combinations of genetics and environmental factors. Two diets were used for the rearing experiments: either zooplankton collected in Lake Thun which represents the natural diet of whitefish, or an artificial dry food which was used as control. The key finding of this study is that the inducing factor of the gonad malformations is contained in the zooplankton of Lake Thun. Fish fed with this diet developed a significantly higher prevalence of malformations than fish from any other treatment, irrespective of the genetic origin and/or the water source. This result could be repeated in the two independent experiments. Importantly, the prevalence values observed in the experimental fish fed with Lake Thun zooplankton were similar to the prevalence values recorded in free-ranging whitefish in the lake. The findings of this study advance the understanding of the causes of gonad morphological alterations in wild fish populations. Full article

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21 pages, 1613 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Development of Carbon Dioxide Barriers to Deter Invasive Fishes: Insights and Lessons Learned from Bigheaded Carp

by Cory D. Suski

Fishes 2020, 5(3), 25; https://doi.org/10.3390/fishes5030025 - 13 Aug 2020

Cited by 19 | Viewed by 5037

Abstract

Invasive species are a threat to biodiversity in freshwater. Removing an aquatic invasive species following arrival is almost impossible, and preventing introduction is a more viable management option. Bigheaded carp are an invasive fish spreading throughout the Midwestern United States and are threatening [...] Read more.

Invasive species are a threat to biodiversity in freshwater. Removing an aquatic invasive species following arrival is almost impossible, and preventing introduction is a more viable management option. Bigheaded carp are an invasive fish spreading throughout the Midwestern United States and are threatening to enter the Great Lakes. This review outlines the development of carbon dioxide gas (CO₂) as a non-physical barrier that can be used to deter the movement of fish and prevent further spread. Carbon dioxide gas could be used as a deterrent either to cause avoidance (i.e., fish swim away from zones of high CO₂), or by inducing equilibrium loss due to the anesthetic properties of CO₂ (i.e., tolerance). The development of CO₂ as a fish deterrent started with controlled laboratory experiments demonstrating stress and avoidance, and then progressed to larger field applications demonstrating avoidance at scales that approach real-world scenarios. In addition, factors that influence the effectiveness of CO₂ as a fish barrier are discussed, outlining conditions that could make CO₂ less effective in the field; these factors that influence efficacy would be of interest to managers using CO₂ to target other fish species, or those using other non-physical barriers for fish. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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24 pages, 3182 KiB

Open AccessEditor’s ChoiceArticle

Population Genetic Assessment of Anadromous and Resident Striped Bass (Morone saxatilis) in the Roanoke River System, Eastern United States

by Sheila C. Harris, W. Robert Cope, Isaac Wirgin and Eric M. Hallerman

Fishes 2020, 5(3), 24; https://doi.org/10.3390/fishes5030024 - 7 Aug 2020

Cited by 1 | Viewed by 4877

Abstract

Striped bass is the subject of important commercial and sport fisheries in North America. The Roanoke River drainage—especially Smith Mountain Lake, Leesville Lake, and Kerr Reservoir—has popular recreational striped bass fisheries. After construction of five hydroelectric dams, populations became landlocked, declined, and have [...] Read more.

Striped bass is the subject of important commercial and sport fisheries in North America. The Roanoke River drainage—especially Smith Mountain Lake, Leesville Lake, and Kerr Reservoir—has popular recreational striped bass fisheries. After construction of five hydroelectric dams, populations became landlocked, declined, and have been supplemented by stocking. A key basis for responsibly augmenting populations is to characterize genetic variation and incorporate the findings into responsible hatchery and stocking practices. Genetic variation at 12 microsatellite DNA loci was evaluated among 837 striped bass representing 16 collections across the native range; populations from rivers in South Carolina, North Carolina, Chesapeake Bay, and Hudson River were screened to provide context for assessing genetic structure within the Roanoke system. Analysis of population genetic differentiation showed landlocked Roanoke River striped bass to be distinctive. Subject to genetic isolation, high M ratios, and relatively low N_e estimates suggest loss of genetic variation, and relatedness analysis showed heightened frequencies of related individuals. These insights into population genetics, demographics, and existing guidelines for broodstock acquisition and mating designs can inform genetically cognizant hatchery management and stocking for striped bass in the Roanoke River drainage. In particular, we recommend the use of larger numbers of breeders and factorial mating designs to increase the genetic diversity of propagated striped bass stocked within the Roanoke River drainage. Full article

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14 pages, 732 KiB

Open AccessEditor’s ChoiceReview

Zebrafish Models in Neural and Behavioral Toxicology across the Life Stages

by Bruna Patricia Dutra Costa, Layana Aquino Moura, Sabrina Alana Gomes Pinto, Monica Lima-Maximino and Caio Maximino

Fishes 2020, 5(3), 23; https://doi.org/10.3390/fishes5030023 - 31 Jul 2020

Cited by 17 | Viewed by 5814

Abstract

The industry is increasingly relying on fish for toxicity assessment. However, current guidelines for toxicity assessment focus on teratogenicity and mortality. From an ecotoxicological point of view, however, these endpoints may not reflect the “full picture” of possible deleterious effects that can nonetheless [...] Read more.

The industry is increasingly relying on fish for toxicity assessment. However, current guidelines for toxicity assessment focus on teratogenicity and mortality. From an ecotoxicological point of view, however, these endpoints may not reflect the “full picture” of possible deleterious effects that can nonetheless result in decreased fitness and/or inability to adapt to a changing environment, affecting whole populations. Therefore, assessing sublethal effects add relevant data covering different aspects of toxicity at different levels of analysis. The impacts of toxicants on neurobehavioral function have the potential to affect many different life-history traits, and are easier to assess in the laboratory than in the wild. We propose that carefully-controlled laboratory experiments on different behavioral domains—including anxiety, aggression, and exploration—can increase our understanding of the ecotoxicological impacts of contaminants, since these domains are related to traits such as defense, sociality, and reproduction, directly impacting life-history traits. The effects of selected contaminants on these tests are reviewed, focusing on larval and adult zebrafish, showing that these behavioral domains are highly sensitive to small concentrations of these substances. These strategies suggest a way forward on ecotoxicological research using fish. Full article

(This article belongs to the Special Issue Fish as Model Organisms for (Eco)Toxicology and Disease)

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39 pages, 830 KiB

Open AccessEditor’s ChoiceReview

The Application of Single-Cell Ingredients in Aquaculture Feeds—A Review

by Brett D. Glencross, David Huyben and Johan W. Schrama

Fishes 2020, 5(3), 22; https://doi.org/10.3390/fishes5030022 - 16 Jul 2020

Cited by 107 | Viewed by 12129

Abstract

Single-cell ingredients (SCI) are a relatively broad class of materials that encompasses bacterial, fungal (yeast), microalgal-derived products or the combination of all three microbial groups into microbial bioflocs and aggregates. In this review we focus on those dried and processed single-cell organisms used [...] Read more.

Single-cell ingredients (SCI) are a relatively broad class of materials that encompasses bacterial, fungal (yeast), microalgal-derived products or the combination of all three microbial groups into microbial bioflocs and aggregates. In this review we focus on those dried and processed single-cell organisms used as potential ingredients for aqua-feeds where the microorganisms are considered non-viable and are used primarily to provide protein, lipids or specific nutritional components. Among the SCI, there is a generalised dichotomy in terms of their use as either single-cell protein (SCP) resources or single-cell oil (SCO) resources, with SCO products being those oleaginous products containing 200 g/kg or more of lipids, whereas those products considered as SCP resources tend to contain more than 300 g/kg of protein (on a dry basis). Both SCP and SCO are now widely being used as protein/amino acid sources, omega-3 sources and sources of bioactive molecules in the diets of several species, with the current range of both these ingredient groups being considerable and growing. However, the different array of products becoming available in the market, how they are produced and processed has also resulted in different nutritional qualities in those products. In assessing this variation among the products and the application of the various types of SCI, we have taken the approach of evaluating their use against a set of standardised evaluation criteria based around key nutritional response parameters and how these criteria have been applied against salmonids, shrimp, tilapia and marine fish species. Full article

(This article belongs to the Special Issue New Sources of Proteins for Aquaculture Feeds)

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13 pages, 14411 KiB

Open AccessEditor’s ChoiceArticle

Feed and Disease at Olive Flounder (Paralichthys olivaceus) Farms in Korea

by Joo-Young Jung, Soohwan Kim, Kyochan Kim, Bong-Joo Lee, Kang-Woong Kim and Hyon-Sob Han

Fishes 2020, 5(3), 21; https://doi.org/10.3390/fishes5030021 - 14 Jul 2020

Cited by 13 | Viewed by 6298

Abstract

The objective of this study was to conduct field experiments comparing formulated (extruded pellets (E.P)) and raw-fish (moist pellets (M.P)) feeds at two flounder aquaculture farms for six months to obtain the basic data necessary for improving aquafarmers’ awareness of feed-quality issues and [...] Read more.

The objective of this study was to conduct field experiments comparing formulated (extruded pellets (E.P)) and raw-fish (moist pellets (M.P)) feeds at two flounder aquaculture farms for six months to obtain the basic data necessary for improving aquafarmers’ awareness of feed-quality issues and firmly establish and expand the use of formulated feed. According to the results, the M.P group was higher in weight gain, feed efficiency ratio, protein efficiency ratio, and specific growth rate and lower in mortality rate than the E.P group. All cases of mortality were caused by six kinds of disease, four of which (Vibrio sp., Edwardsiella sp., Streptococcus sp., and Scuticociliates) were common to the two groups, whereas Lymphocystis arose only in the M.P group and abdominal inflation only in the E.P group at both farms. As for mortality in the present experiment, the numbers were 1047 at Da-Hae farm and 1167 at Global farm, with more fish dying in the E.P tanks than in the M.P tanks. By multiplying the number of deaths by selling price, the economic losses were $9650 and $10,756, respectively. Therefore, it should be considered an urgent priority to develop flounder-exclusive formulated feed for improved digestion and absorption rate and also to establish a water-quality-improvement management plan. Full article

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12 pages, 914 KiB

Open AccessEditor’s ChoiceArticle

Optimized Live Feed Regime Significantly Improves Growth Performance and Survival Rate for Early Life History Stages of Pangasius Catfish (Pangasianodon hypophthalmus)

by Ngoc-Ut Vu and Truong-Giang Huynh

Fishes 2020, 5(3), 20; https://doi.org/10.3390/fishes5030020 - 28 Jun 2020

Cited by 11 | Viewed by 4893

Abstract

This study aimed to determine the optimal live feed regime (i.e., initial feeding moment, density, and frequency) for maximum growth and survival of pangasius catfish (Pangasianodon hypophthalmus) early life history stages. The first experiment assessed the optimal initial feeding moment (30, [...] Read more.

This study aimed to determine the optimal live feed regime (i.e., initial feeding moment, density, and frequency) for maximum growth and survival of pangasius catfish (Pangasianodon hypophthalmus) early life history stages. The first experiment assessed the optimal initial feeding moment (30, 36, 42, and 48 h post hatching, hph). The second experiment assessed feeding density (3, 5, 8 and 11 individuals per mL, ind/mL) at the optimal initial feeding moment (30 hph) which was the best result from the first experiment. The third experiment assessed optimal feeding frequency (1, 2, 4, and 6 times per day) at the optimal initial feeding moment (30 hph) and density (8 ind/mL) which was drawn upon from the second experiment. All experiments were conducted in 20 L containers containing 20 hph P. hypophthalmus larvae at a density of 10 ind/L and fed rotifers (Brachionus angularis) for 3 days and then water fleas (Moina macrocopa) for 7 days. The first experiment demonstrated that larvae initially fed at 30 hph exhibited a significantly higher survival rate (24%) than larvae initially fed at 36, 42, and 48 hph (19%, 16%, and 16%), respectively. The second experiment demonstrated that larvae fed at 8 and 11 ind/mL densities exhibited significantly higher survival rates (32% and 32%) than larvae fed at 3 and 5 ind/mL densities (13% and 23%), respectively. The third experiment demonstrated that the highest survival rate (66%) was obtained when larvae were fed 6 times per day. These results provide valuable insights regarding the optimal live feed regime for better growth and survival of P. hypophthalmus larvae, which are commercially important and numerously cultured throughout the Mekong Delta region. Full article

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16 pages, 1733 KiB

Open AccessEditor’s ChoiceArticle

Population Genetic Analysis for Stock Enhancement of Silver Sea Bream (Rhabdosargus sarba) in Taiwan

by Te-Hua Hsu, Chang-Wen Huang, Hung-Tai Lee, Yi-Hsuan Kuo, Kwang-Ming Liu, Cheng-Hui Lin and Hong-Yi Gong

Fishes 2020, 5(2), 19; https://doi.org/10.3390/fishes5020019 - 16 Jun 2020

Cited by 10 | Viewed by 3979

Abstract

Stock enhancement is a method for replenishing depleted wild finfish populations by supplementing them with hatchery-raised fish. In Taiwan, silver sea bream (Rhabdosargus sarba) is a predominant commercial species involved in stock enhancement projects. Although management agencies conduct stock enhancement projects, [...] Read more.

Stock enhancement is a method for replenishing depleted wild finfish populations by supplementing them with hatchery-raised fish. In Taiwan, silver sea bream (Rhabdosargus sarba) is a predominant commercial species involved in stock enhancement projects. Although management agencies conduct stock enhancement projects, there are a lot of private releases without records. Stock enhancement is performed by the private aquaculture sector without accurate genetic records, potentially leading to unintended consequences for wild populations. We analyzed the genetics of 459 wild and 701 hatchery-reared specimens from nine batches produced by various hatcheries. Wild and hatchery-reared samples could be considered two separate clades by using a set of stable and informative microsatellite markers including type I (from gene introns and 3′UTR) and type II markers (randomly picked up from genome). Type I microsatellite markers could more sensitively reflect the loss of genetic diversity more than type II markers in the domestication process. All specimens were considered native by using mtDNA COI and microsatellites. The genetic composition of the wild population is relatively simple, and the estimated low contribution rate of the hatchery stock (1.3–10.9%; 6–50/459) indicated a weak but significant genetic effect of stock enhancement. Therefore, establishing standards for the stock enhancement of silver sea bream for more effective supplementation of wild populations is imperative. Full article

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63 pages, 10938 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Yellowstone Lake Ecosystem Restoration: A Case Study for Invasive Fish Management

by Todd M. Koel, Jeffery L. Arnold, Patricia E. Bigelow, Travis O. Brenden, Jeffery D. Davis, Colleen R. Detjens, Philip D. Doepke, Brian D. Ertel, Hayley C. Glassic, Robert E. Gresswell, Christopher S. Guy, Drew J. MacDonald, Michael E. Ruhl, Todd J. Stuth, David P. Sweet, John M. Syslo, Nathan A. Thomas, Lusha M. Tronstad, Patrick J. White and Alexander V. Zale

Fishes 2020, 5(2), 18; https://doi.org/10.3390/fishes5020018 - 12 Jun 2020

Cited by 36 | Viewed by 12558

Abstract

Invasive predatory lake trout Salvelinus namaycush were discovered in Yellowstone Lake in 1994 and caused a precipitous decrease in abundance of native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri. Suppression efforts (primarily gillnetting) initiated in 1995 did not curtail lake trout population growth or [...] Read more.

Invasive predatory lake trout Salvelinus namaycush were discovered in Yellowstone Lake in 1994 and caused a precipitous decrease in abundance of native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri. Suppression efforts (primarily gillnetting) initiated in 1995 did not curtail lake trout population growth or lakewide expansion. An adaptive management strategy was developed in 2010 that specified desired conditions indicative of ecosystem recovery. Population modeling was used to estimate effects of suppression efforts on the lake trout and establish effort benchmarks to achieve negative population growth (λ < 1). Partnerships enhanced funding support, and a scientific review panel provided guidance to increase suppression gillnetting effort to >46,800 100-m net nights; this effort level was achieved in 2012 and led to a reduction in lake trout biomass. Total lake trout biomass declined from 432,017 kg in 2012 to 196,675 kg in 2019, primarily because of a 79% reduction in adults. Total abundance declined from 925,208 in 2012 to 673,983 in 2019 but was highly variable because of recruitment of age-2 fish. Overall, 3.35 million lake trout were killed by suppression efforts from 1995 to 2019. Cutthroat trout abundance remained below target levels, but relative condition increased, large individuals (> 400 mm) became more abundant, and individual weights doubled, probably because of reduced density. Continued actions to suppress lake trout will facilitate further recovery of the cutthroat trout population and integrity of the Yellowstone Lake ecosystem. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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21 pages, 338 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Biocontrol of the Common Carp (Cyprinus carpio) in Australia: A Review and Future Directions

by Kenneth A McColl and Agus Sunarto

Fishes 2020, 5(2), 17; https://doi.org/10.3390/fishes5020017 - 2 Jun 2020

Cited by 16 | Viewed by 6263

Abstract

Invasive pest species are recognized as one of the important drivers of reduced global biodiversity. In Australia, the 267 invasive plant, animal and microbial species, established since European colonization in the 1770s, have been unequivocally declared the most important threat to species diversity [...] Read more.

Invasive pest species are recognized as one of the important drivers of reduced global biodiversity. In Australia, the 267 invasive plant, animal and microbial species, established since European colonization in the 1770s, have been unequivocally declared the most important threat to species diversity in this country. One invasive pest, the common carp (Cyprinus carpio), has been targeted in an integrated pest management plan that might include cyprinid herpesvirus 3 (CyHV-3) as a potential biocontrol agent. The species-specificity of the released virus (and of field variants that will inevitably arise) has been assessed, and the virus judged to be safe. It has also been hypothesised that, because the virulence of the CyHV-3 will likely decline following release, the virus should be used strategically: initially, the aim would be to markedly reduce numbers of carp in naive populations, and then some other, as yet uncertain, complementary broad-scale control measure would knock-down carp numbers even further. Brief results are included from recent studies on the modelling of release and spread of the virus, the ecological and social concerns associated with virus release, and the restoration benefits that might be expected following carp control. We conclude that, while further work is required (on the virus, the target species, environmental issues, and especially the identification of a suitable broad-scale complementary control measure), optimism must prevail in order to ensure an eventual solution to this important environmental problem. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

12 pages, 290 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Nutritional and Growth Effect of Insect Meal Inclusion on Seabass (Dicentrarchuss labrax) Feeds

by María Reyes, María Rodríguez, Juan Montes, Fernando G. Barroso, Dmitri Fabrikov, Elvira Morote and María José Sánchez-Muros

Fishes 2020, 5(2), 16; https://doi.org/10.3390/fishes5020016 - 1 Jun 2020

Cited by 32 | Viewed by 4887

Abstract

Abajo: se repite los tres en el resumen. This work studies the effect of high-level fish meal replacement with insect meal: YW meal (obtained from Tenebrio larvae fed a broiler diet), BSF meal (from hermetia larvae fed broilers diet), BSFm meal (obtained from [...] Read more.

Abajo: se repite los tres en el resumen. This work studies the effect of high-level fish meal replacement with insect meal: YW meal (obtained from Tenebrio larvae fed a broiler diet), BSF meal (from hermetia larvae fed broilers diet), BSFm meal (obtained from hermetia larvae fed discard fish) on growth performance nutritive indices and in vitro digestibility of Dicentrarchus labrax juvenile. Three different insect meals were used: BSF meal from hermetia larvae fed broilers diet; BSF improve (BSFm) obtained from hermetia larvae fed discarded fish; YW meal obtained from the larvae of Tenebrio fed a broiler diet. Five diets were used, a control (C) diet and four experimental diets by replacing fishmeal with insect meal from BSF at 30% and 50% (BSF30 and BSF50) substitutions, BSFm at 50% substitution (BSF50 m) and YM at 50% substitution (YW50). Nutritional and growth indices worsened by including insect meal, especially for hermetia meal at 50% substitution, BSF50 and BSF50 m. The internal organs’ weight reflected the growth of the fish fed each experimental diet. No differences were found in fillet composition. Nevertheless, under our experimental condition, YW replacement obtained better results than both BSF diets. Full article

(This article belongs to the Special Issue New Sources of Proteins for Aquaculture Feeds)

14 pages, 1447 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Study of Fishmeal Substitution on Growth Performance and Shelf-Life of Giltheadsea Bream (Sparusaurata)

by Patricia Zaragozá, Silvia Martínez-Llorens, Isabel Fernández-Segovia, José-Luis Vivancos, Ana Tomas-Vidal, Ana Fuentes, José Vicente Ros-Lis, Ramón Martínez-Máñez and José Manuel Barat

Fishes 2020, 5(2), 15; https://doi.org/10.3390/fishes5020015 - 15 May 2020

Cited by 3 | Viewed by 3221

Abstract

In this work the effect of partial or total replacement of fishmeal by plant protein sources and krill and squid meal on growth performance and shelf-life of gilthead sea bream was evaluated. Plant protein dietswith 50 g kg⁻¹ of krill and 100 [...] Read more.

In this work the effect of partial or total replacement of fishmeal by plant protein sources and krill and squid meal on growth performance and shelf-life of gilthead sea bream was evaluated. Plant protein dietswith 50 g kg⁻¹ of krill and 100 g kg⁻¹ of squid were supplemented with synthetic amino acidsand at the end of the growing period weight showed no significant differences. The spoilage process of the fish was followed by physicochemical and microbiological measurements together with a colorimetric sensor array (CSA) specially designed for that purpose. The changes in the physicochemical parameters and microbial growth showed that shelf-life of samples were in all cases lower than ninedays. The CSA was not able to show significant differences between both diets, confirming the physicochemical and microbiological results. The fact that the type of feed had no effect on the freshness parameters studied demonstrates that total fishmeal replacement with plant protein blends in the proportions used in this work could be an excellent alternative for feed formulation in aquaculture. Full article

(This article belongs to the Special Issue New Sources of Proteins for Aquaculture Feeds)

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15 pages, 2551 KiB

Open AccessEditor’s ChoiceArticle

Accumulation of Geosmin and 2-methylisoborneol in European Whitefish Coregonus Lavaretus and Rainbow Trout Oncorhynchus Mykiss in RAS

by Petra Lindholm-Lehto, Juha Koskela, Janne Kaseva and Jouni Vielma

Fishes 2020, 5(2), 13; https://doi.org/10.3390/fishes5020013 - 11 May 2020

Cited by 7 | Viewed by 4272

Abstract

Geosmin (GSM) and 2-methylisoborneol (MIB)-induced off-flavors can cause serious problems in a recirculating aquaculture system (RAS), such as delayed harvest and increased production costs, but also damage producers’ reputation. Traditionally, off-flavors have been removed by depuration before harvesting. Rainbow trout (Oncorhynchus mykiss) and [...] Read more.

Geosmin (GSM) and 2-methylisoborneol (MIB)-induced off-flavors can cause serious problems in a recirculating aquaculture system (RAS), such as delayed harvest and increased production costs, but also damage producers’ reputation. Traditionally, off-flavors have been removed by depuration before harvesting. Rainbow trout (Oncorhynchus mykiss) and European whitefish (Coregonus lavaretus) are commercially valuable species produced for consumers, both being suitable for rearing in RAS. In this study, European whitefish and rainbow trout were raised from juvenile up to 240 g (European whitefish) and 660 g (rainbow trout) to monitor the long-term accumulation of off-flavors. The concentrations in fillet of rainbow trout reached 3.6 ng·g⁻¹ (MIB) and 5.6 ng∙g⁻¹¹ (GSM) with lipid content of 22.5%, while for European whitefish up to 3.2 ng·g⁻¹ (MIB) and 3.9 ng·g⁻¹ (GSM) were found with 14.8% in lipid content. Concentrations up to 58 ng·L⁻¹ (MIB) and 49 ng·L⁻¹ (GSM) were found in the circulating water. Based on the results, the accumulation of MIB proceeds at similar pace for both species. In the case of GSM, the accumulation started similarly for both species but proceeded more quickly for rainbow trout after 140 days of the experiment, with a statistically significant difference (p < 0.05). Full article

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17 pages, 4723 KiB

Open AccessEditor’s ChoiceArticle

Alternative Feed Raw Materials Modulate Intestinal Microbiota and Its Relationship with Digestibility in Yellowtail Kingfish Seriola lalandi

by Chinh Thi My Dam, Mark Booth, Igor Pirozzi, Michael Salini, Richard Smullen, Tomer Ventura and Abigail Elizur

Fishes 2020, 5(2), 14; https://doi.org/10.3390/fishes5020014 - 11 May 2020

Cited by 11 | Viewed by 4645

Abstract

Gut microbiota plays a crucial role in nutrient digestibility and fish health. This study aimed to investigate the effects of alternative feed raw materials on the bacterial communities in the distal intestine and its relationship with nutrient digestibility in yellowtail kingfish (YTK), Seriola [...] Read more.

Gut microbiota plays a crucial role in nutrient digestibility and fish health. This study aimed to investigate the effects of alternative feed raw materials on the bacterial communities in the distal intestine and its relationship with nutrient digestibility in yellowtail kingfish (YTK), Seriola lalandi. Two 4-week digestibility trials were conducted to evaluate fish meal (FM), two sources of poultry by-product meal (PBM-1 & PBM-2), blood meal (BLM), faba bean meal (FBM), corn gluten meal (CGM), soy protein concentrate (SPC) and wheat flour (WH). The nutrient digestibility value was determined using the stripping fecal collection method. Bacterial communities were characterized by high-throughput sequencing based on V3-V4 region of the 16S rRNA gene. The most abundant phylum identified in the present study was Proteobacteria. A significant change in the distal intestine was observed in fish fed diets containing CGM and BLM, characterized by a reduction of species richness and diversity. Additionally, significant correlation between nutrient digestibility and intestinal microbiota was observed. Allivibrio, Vibrio, Curvibacter, Ruminococcaceae, and Clostridium were positively correlated, whereas Ralstonia genus was negatively correlated with nutrient digestibility. This study demonstrated that intestinal microbiota could be a useful tool for evaluating the digestibility of feed raw materials; however, further culture-based study is needed to confirm this observation. Full article

(This article belongs to the Special Issue Effects of Dietary Components on the Gut Health of Fishes)

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27 pages, 5228 KiB

Open AccessFeature PaperEditor’s ChoiceReview

A Decade in Review: Alaska’s Adaptive Management of an Invasive Apex Predator

by Kristine Dunker, Robert Massengill, Parker Bradley, Cody Jacobson, Nicole Swenson, Andy Wizik and Robert DeCino

Fishes 2020, 5(2), 12; https://doi.org/10.3390/fishes5020012 - 21 Apr 2020

Cited by 15 | Viewed by 6056

Abstract

Northern pike are an invasive species in southcentral Alaska and have caused the decline and extirpation of salmonids and other native fish populations across the region. Over the last decade, adaptive management of invasive pike populations has included population suppression, eradication, outreach, angler [...] Read more.

Northern pike are an invasive species in southcentral Alaska and have caused the decline and extirpation of salmonids and other native fish populations across the region. Over the last decade, adaptive management of invasive pike populations has included population suppression, eradication, outreach, angler engagement, and research to mitigate damages from pike where feasible. Pike suppression efforts have been focused in open drainages of the northern and western Cook Inlet areas, and eradication efforts have been primarily focused on the Kenai Peninsula and the municipality of Anchorage. Between 2010 and 2020, almost 40,000 pike were removed from southcentral Alaska waters as a result of suppression programs, and pike have been successfully eradicated from over 20 lakes and creeks from the Kenai Peninsula and Anchorage, nearly completing total eradication of pike from known distributions in those areas. Northern pike control actions are tailored to the unique conditions of waters prioritized for their management, and all efforts support the goal of preventing further spread of this invasive aquatic apex predator to vulnerable waters. Full article

(This article belongs to the Special Issue Biology and Control of Invasive Fishes)

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11 pages, 512 KiB

Open AccessEditor’s ChoiceReview

Salmon Louse (Lepeophtheirus salmonis (Krøyer)) Control Methods and Efficacy in Atlantic Salmon (Salmo salar (Linnaeus)) Aquaculture: A Literature Review

by Kristine Cerbule and Jacques Godfroid

Fishes 2020, 5(2), 11; https://doi.org/10.3390/fishes5020011 - 31 Mar 2020

Cited by 8 | Viewed by 5002

Abstract

The salmon louse (Lepeophtheirus salmonis) causes problems in Atlantic salmon (Salmo salar) aquaculture in the Northern Hemisphere, because infestations can result in both a loss of production and in fish mortality. Several types of treatment have been used to [...] Read more.

The salmon louse (Lepeophtheirus salmonis) causes problems in Atlantic salmon (Salmo salar) aquaculture in the Northern Hemisphere, because infestations can result in both a loss of production and in fish mortality. Several types of treatment have been used to control louse infestations, but these have seen varying success. The aim of this review is to examine the efficacy and safety of commonly used treatments (chemical, biological, mechanical, and preventive measures) as documented in peer-reviewed publications. Efficacy is assessed in relation to a reduction in numbers of lice, and safety is assessed as a lack of negative treatment-associated effects on fish health and welfare (Atlantic salmon and/or cleaner fish). Most chemical treatments showed decreasing efficacy over time, together with the use of increasing concentrations as a result of the development of resistance to the treatments by lice. The need for a restrictive use of pesticides to preserve treatment efficacy has been emphasized. The use of cleaner fish was suggested to be effective, with few or no negative effects towards Atlantic salmon. The use of cleaner fish would be preferable to chemical treatment if the farmed fish health and welfare criteria are met. At present, the number of peer-reviewed publications relating to other forms of treatment and prevention are sparse. Full article

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15 pages, 2272 KiB

Open AccessEditor’s ChoiceArticle

Effect of Light–Dark Cycle on Skin Mucosal Immune Activities of Gilthead Seabream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

by Diana Ceballos-Francisco, Alberto Cuesta and María Ángeles Esteban

Fishes 2020, 5(1), 10; https://doi.org/10.3390/fishes5010010 - 24 Feb 2020

Cited by 5 | Viewed by 2867

Abstract

Changes in different immune activities in the skin mucus of gilthead seabream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.) specimens exposed to a constant light–dark photoperiod (12 h L:12 h D) were studied. Samples were collected at 08:00 [...] Read more.

Changes in different immune activities in the skin mucus of gilthead seabream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.) specimens exposed to a constant light–dark photoperiod (12 h L:12 h D) were studied. Samples were collected at 08:00 (light on), 14:00, 20:00 (light off), 02:00, and again at 08:00 to determine immunoglobulin M (IgM) levels, several enzymes related to the immune system, and bactericidal activity. IgM levels were higher during the day in seabream and reached a minimum value at 20:00, but it was hardly affected in sea bass. No significant variations were recorded in the levels of protease and antiprotease. Peroxidase reached its maximum level in seabream at 02:00, the same time that it reached its minimum level in sea bass. Lysozyme showed little variation in seabream, but it was significantly lower at 14:00 than during the rest of the cycle in sea bass. Finally, different interspecific variations on bactericidal activity against Vibrio harveyi were recorded. The findings demonstrate that the immune parameters present in skin mucus of these important fish species are affected by the light–dark cycle and that there are substantial interspecies differences. Full article

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17 pages, 949 KiB

Open AccessEditor’s ChoiceArticle

Sturgeon Meat and Caviar Quality from Different Cultured Species

by Annalaura Lopez, Mauro Vasconi, Federica Bellagamba, Tiziana Mentasti and Vittorio Maria Moretti

Fishes 2020, 5(1), 9; https://doi.org/10.3390/fishes5010009 - 7 Feb 2020

Cited by 17 | Viewed by 6836

Abstract

Sturgeon raw eggs, caviar and meat obtained from different species reared in an Italian production plant were evaluated for their chemical composition, in order to improve their appreciation on the market and to detect any eventual distinctness related to the species. Mainly, fatty [...] Read more.

Sturgeon raw eggs, caviar and meat obtained from different species reared in an Italian production plant were evaluated for their chemical composition, in order to improve their appreciation on the market and to detect any eventual distinctness related to the species. Mainly, fatty acid (FA) profile of eggs and caviar, determined by Gas-Chromatography coupled to Flame Ionization Detection, showed variability in the interspecific comparison, highlighted by chemometric methods (Linear Discriminant Analysis). Generally, all samples showed a prevalence of unsaturated fatty acids with respect to saturated ones, reaching a content of polyunsaturated fatty acids (PUFA) between the 40% and the 50% of total FA. A remarkable presence of n3 series PUFA was detected in all samples and a selective deposition of many FA into eggs’ cellular membranes, yolk lipid and body fat reserves, imputable to the different biological role of single FA during sturgeon reproduction, was evidenced. Chemical composition of sturgeon flesh samples evidenced a high-protein and medium-fat content, characterized by a FA profile of high nutritional value. Moreover, color parameters (redness, yellowness, brightness, Chroma) were measured on sturgeon fillets, showing many species-specific characteristics of sturgeon meat. Full article

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