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Fishes, Volume 5, Issue 3 (September 2020) – 11 articles

Cover Story (view full-size image): Brycen Boettcher (Virginia Department of Wildlife Resources) holds a large striped bass Morone saxatilis which was collected by electrofishing from the James river adjacent to downtown Richmond, Virginia, USA. The James river hosts a large run of anadromous striped bass. The fish was returned to the river to join the spawning run (Photo, courtesy Alan Weaver, Virginia Department of Wildlife Resources). View this paper
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18 pages, 2770 KiB  
Article
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 2 | Viewed by 4259
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  
Article
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 - 01 Sep 2020
Cited by 11 | Viewed by 4351
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  
Article
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 17 | Viewed by 4668
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  
Article
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 13 | Viewed by 3565
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  
Article
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 3065
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  
Review
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 17 | Viewed by 4453
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  
Article
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 - 07 Aug 2020
Cited by 1 | Viewed by 4445
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 Ne 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  
Review
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 15 | Viewed by 4639
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  
Review
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 92 | Viewed by 10591
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  
Article
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 11 | Viewed by 5547
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  
Article
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 10 | Viewed by 4166
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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