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Volume 9
Issue 6
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Fishes, Volume 9, Issue 6 (June 2024) – 25 articles

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11 pages, 3252 KiB  
Communication
Morphological Development and DNA Barcoding Identification of Pholis fangi Larvae and Juveniles in the Yellow Sea
by Shouhai Liu, Haijing Zhang, Xiao Ji, Xiaojia Peng, Yutao Qin and Weimin Yao
Fishes 2024, 9(6), 213; https://doi.org/10.3390/fishes9060213 (registering DOI) - 3 Jun 2024
Abstract
Pholis fangi is a small, bottom-dwelling fish species endemic to the Yellow Sea and Bohai Sea in China. While previous research has focused on its population biology and molecular structure, little is known about the early developmental stages of this species. In this [...] Read more.
Pholis fangi is a small, bottom-dwelling fish species endemic to the Yellow Sea and Bohai Sea in China. While previous research has focused on its population biology and molecular structure, little is known about the early developmental stages of this species. In this study, larval and juvenile P. fangi specimens were collected from the Sheyang Sea Area, Jiangsu Province, in 2017. Morphological features were examined using microscopy, and DNA barcoding was conducted to confirm species identification. The research documented detailed changes in yolk sac, fin development, and melanophore distribution patterns across larval and juvenile stages of P. fangi. Comparative analysis with other Pholis species revealed that melanophore distribution is a key distinguishing characteristic, allowing effective differentiation between larval and juvenile stages, as well as between Pholis species. This study provides valuable insights into the early life history of P. fangi, contributing to a better understanding of the genus Pholis. The findings demonstrate the utility of combining traditional morphological observation and molecular techniques for accurate species identification, particularly during the critical larval and juvenile developmental phases. Full article
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17 pages, 4522 KiB  
Article
The Zootechnical Performance, Health State Modulation, Morphology, and Intestinal Microbiome of Nile Tilapia Juveniles Fed with a Functional Blend of Immunostimulants Associated with a Diet High in Soybean Meal
by Lúvia Souza de Sá, Gabriela Tomas Jerônimo, Thiago Soligo, Eduardo Yamashita, Débora Machado Fracalossi, Maurício Laterça Martins and José Luiz Pedreira Mouriño
Fishes 2024, 9(6), 212; https://doi.org/10.3390/fishes9060212 (registering DOI) - 3 Jun 2024
Abstract
The aim of this study was to evaluate the effect of supplementing feed with a functional mixture of immunomodulators, including β-glucans, nucleotides, ascorbic acid, and alpha-tocopherol, associated with a diet with lower levels of animal protein (11.5%) and higher levels of soybean meal [...] Read more.
The aim of this study was to evaluate the effect of supplementing feed with a functional mixture of immunomodulators, including β-glucans, nucleotides, ascorbic acid, and alpha-tocopherol, associated with a diet with lower levels of animal protein (11.5%) and higher levels of soybean meal (43.5%), on the zootechnical performance, health, hematological and immunological parameters, intestinal morphology, centesimal composition, and intestinal microbiome of juvenile Nile tilapia (initial weight 1.88 g ± 0.25 g, mean ± standard deviation). Two isocaloric and isoproteic diets (35% crude protein) were formulated, one with the inclusion of the immunostimulant functional mixture (40 kg·t−1), composed of 150 mg·kg−1 of nucleotides, 1000 mg·kg−1 of β-glucans, 1000 mg·kg−1 of ascorbic acid (vitamin C), and 20 mg·kg−1 of alpha-tocopherol (vitamin E), and another without. The combined supplementation of nucleotides, β-glucans, ascorbic acid, and alpha-tocopherol resulted in a 59.95% increase in final weight, 64% weight gain, 66% daily gain, a 21.31% decrease in feed conversion rate, and double the retention of body protein. Supplementation also improved intestinal morphology and modulated the intestinal microbiome, increasing Chao-1 diversity. Transmission electron microscopy confirmed that fish fed with both diets exhibited intact intestinal mucosal membranes. Supplementation did not alter the hematological and immunological parameters, suggesting that there was no overstimulation of the fish’s immune system. This work allows us to evaluate the effect of reducing the use of animal protein in the diets of fish, along with the effects of nucleotides, β-glucans, ascorbic acid, and alpha-tocopherol. Together, these compounds can provide fish with the necessary tools to achieve optimal health and growth. Full article
(This article belongs to the Special Issue Relationship between Nutrition and the Immune Response of Fish)
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16 pages, 3344 KiB  
Article
Compatibilities of Cyprinus carpio with Varied Colors of Robotic Fish
by Xiaoshuang Huang, Ying Zhang, Xinjun Chen, Xianghong Kong, Bilin Liu and Shuxia Jiang
Fishes 2024, 9(6), 211; https://doi.org/10.3390/fishes9060211 - 3 Jun 2024
Abstract
Visual selection plays a fundamental role in various aspects of animal behavior, such as colony formation, maintenance, defense, and courtship. This study investigated the effect of bionic robot fish color on carp behavior based on physiological characteristics that were observed during behavioral experiments. [...] Read more.
Visual selection plays a fundamental role in various aspects of animal behavior, such as colony formation, maintenance, defense, and courtship. This study investigated the effect of bionic robot fish color on carp behavior based on physiological characteristics that were observed during behavioral experiments. Through computer image processing and analysis of light attenuation, we observed changes in the number and positioning of carp with bionic robotic fish of different colors (white, red, blue, green, and yellow). The results indicated that (1) the attenuation coefficient of visible light in freshwater was red > yellow > green > blue; (2) the order of the average change in the number of carp responding to different colors of robotic fish was white > red > green > yellow > blue, and carp were more sensitive and responsive to white and red robotic fish; and (3) the order of the distances between different colors of robotic fish and carp was white < yellow < blue < green < red, and white and yellow robotic fish were more attractive to carp. Therefore, the use of white or yellow robotic fish for relevant operations can reduce disturbance to fish schools. Full article
(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)
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12 pages, 1717 KiB  
Article
The Effects of Different Concentrations of Hydrogen−Rich Water on the Growth Performance, Digestive Ability, Antioxidant Capacity, Glucose Metabolism Pathway, mTOR Signaling Pathway, and Gut Microbiota of Largemouth Bass (Micropterus salmoides)
by Yin Yuan, Huixiang Li, Songwei Chen, Yongchun Lin, Jiangyuan Peng, Junru Hu and Yongsheng Wang
Fishes 2024, 9(6), 210; https://doi.org/10.3390/fishes9060210 - 1 Jun 2024
Abstract
Hydrogen−rich water (HRW) is widely recognized for its growth promoting, antioxidant, and anti−inflammatory properties. However, little is known about the role of HRW in aquaculture. This study aims to investigate how different concentrations of HRW affect the growth performance, digestive ability, antioxidant capacity, [...] Read more.
Hydrogen−rich water (HRW) is widely recognized for its growth promoting, antioxidant, and anti−inflammatory properties. However, little is known about the role of HRW in aquaculture. This study aims to investigate how different concentrations of HRW affect the growth performance, digestive ability, antioxidant capacity, mTOR signaling pathway, and gut microbiota of juvenile largemouth bass. We randomly assigned 360 fish (13.73 ± 0.1 g) to three treatments. The control group was maintained in regular water, while the treatment groups were treated with different concentrations of H2 dissolved in water, which were H1 (179.65 ± 31.95 ppb) and H2 (280.65 ± 64.43 ppb), respectively. Through an analysis of the three treatments, it was found that H1 significantly increased the final body weight, weight gain rate, specific growth rate, and survival rate, and reduced the feed conversion ratio (p < 0.05). In addition, the trypsin activity was significantly increased in the intestine (p < 0.05), and the expression of genes related to the glucose metabolism (pk and pepck) and mTOR (tor, akt, s6k1, 4ebp1, and ampka) signaling pathways were significantly increased in the liver in H1 (p < 0.05). The relative abundance of Blautia in the gut microbiota (p < 0.05) was significantly increased in H1. Therefore, these results indicated that H1 can significantly improve growth performance, promote intestinal digestion, activate the glucose metabolism pathway and mTOR signaling pathway, and increase the abundance of beneficial bacteria in the gut of largemouth bass. These findings provided valuable support for the application of HRW to support the healthy aquaculture of largemouth bass. Full article
(This article belongs to the Section Physiology and Biochemistry)
18 pages, 3401 KiB  
Article
Environmental Influences on Illex argentinus Trawling Grounds in the Southwest Atlantic High Seas
by Delong Xiang, Yang Li, Keji Jiang, Haibin Han, Yuhan Wang, Shenglong Yang, Heng Zhang and Yuyan Sun
Fishes 2024, 9(6), 209; https://doi.org/10.3390/fishes9060209 - 1 Jun 2024
Abstract
To understand the spatial temporal distribution characteristics of Illex argentinus caught by trawl fishing vessels in the Southwestern Atlantic Ocean and their relationship with key marine environmental factors, this study analyzed the temporal and spatial changes in the fishing ground center of trawl [...] Read more.
To understand the spatial temporal distribution characteristics of Illex argentinus caught by trawl fishing vessels in the Southwestern Atlantic Ocean and their relationship with key marine environmental factors, this study analyzed the temporal and spatial changes in the fishing ground center of trawl vessels at the ten-day scale from December 2019 to May 2022, combining Chinese trawl fishing log data marine environmental data with satellite remote sensing marine environmental data. Utilizing the Maxent model, ten-day intervals were used as the temporal scale, and ten marine environmental factors, including sea surface temperature, sea surface height, sea surface salinity, chlorophyll concentration, temperature at 50 m and 100 m depth, and the meridional and zonal velocities of ocean currents were quantitatively analyzed to explore the correlation between the spatial distribution of catch and environmental factors. The study reveals that the trawl fishing grounds for Illex argentinus are divided into southern and northern grounds. The southern grounds first appear near 45°20′ S in December, gradually moving southeastward in February and March. The northern grounds do not appear until April, near 42° S in the high seas. On the ten-day time scale, the central fishing grounds of Illex argentinus show significant spatial variability but minor interannual differences. The Maxent model results indicate that sea surface temperature and chlorophyll a concentration are the key environmental factors influencing the spatial and temporal variability of the high seas trawl fishing grounds for most of the time, with high environmental contribution rates during the fishing season. While the range of suitable habitats with an HSI > 0.6 identified by the Maxent model varies significantly between years, a pattern is observed where the range expands at the start and end of the fishing season and contracts during the peak fishing season. This suggests that a more concentrated range of suitable habitats is conducive to accurate predictions of trawl fishing grounds, enabling efficient fishing operations. Full article
(This article belongs to the Section Biology and Ecology)
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17 pages, 2268 KiB  
Review
Tropical Shrimp Biofloc Aquaculture within Greenhouses in the Mediterranean: Preconditions, Perspectives, and a Prototype Description
by Dimitrios K. Papadopoulos, Maria V. Alvanou, Athanasios Lattos, Kosmas Ouroulis and Ioannis A. Giantsis
Fishes 2024, 9(6), 208; https://doi.org/10.3390/fishes9060208 - 1 Jun 2024
Abstract
Biofloc technology (BFT) offers an innovative eco-friendly approach that is particularly applicable in shrimp farming. Penaeus vannamei is the most important seafood species in terms of global economic value. Nevertheless, its increasing global demand highlights the necessity for sustainable production of P. vannamei [...] Read more.
Biofloc technology (BFT) offers an innovative eco-friendly approach that is particularly applicable in shrimp farming. Penaeus vannamei is the most important seafood species in terms of global economic value. Nevertheless, its increasing global demand highlights the necessity for sustainable production of P. vannamei shrimps outside their native range, assuring the avoidance of genetic pollution risk. Towards this direction, the present study focuses on the feasibility of tropical shrimp species aquaculture in indoor systems evaluating BFT application in temperate zones. The achievability of P. vannamei cultivation inside greenhouses in temperate latitudes is thoroughly examined and a representative experimental biofloc setup for P. vannamei within a greenhouse in Northern Greece is demonstrated. Nevertheless, there are two major limitations, related to economy and ecology, namely the energy demand for high seawater temperature and the fact that most reared shrimps are non-indigenous species setting risk for genetic pollution, respectively. To overcome the former, energy-saving measures such as tank and greenhouse insulation in combination with a microclimate chamber construction were implemented to optimize water temperature at minimal cost. Concerning the latter, there is clear evidence that P. vannamei populations cannot be established in the Mediterranean, setting aside any environmental risk. Overall, based on the developed and tested pilot prototype, employment of optimal management practices, innovative manufacturing and clean energy alternatives, and the utilization of ecosystem services could reduce the environmental impact and maximize the profitability of biofloc operations. These actions could probably permit sustainable and economically viable farming of P. vannamei employing BFT within greenhouses in the Mediterranean. Full article
(This article belongs to the Special Issue Advances in Shrimp Aquaculture)
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14 pages, 2280 KiB  
Article
Influence of Feeding, Temperature and Photoperiod on Purple Sea Urchin (Paracentrotus lividus) Gonad Development
by João Araújo, Margarida Gamboa, Ioannis Choulis, Ana Candeias-Mendes, Elsa Cabrita, Pedro Pousão-Ferreira and Florbela Soares
Fishes 2024, 9(6), 207; https://doi.org/10.3390/fishes9060207 - 1 Jun 2024
Abstract
Understanding and controlling reproductive cycles and gonad maturation in cultivated species are crucial in aquaculture. The sea urchin Paracentrotus lividus, known for its edible gonads, requires careful maturation control for both reproduction and commercialization. This study explores the impact of temperature, photoperiod, [...] Read more.
Understanding and controlling reproductive cycles and gonad maturation in cultivated species are crucial in aquaculture. The sea urchin Paracentrotus lividus, known for its edible gonads, requires careful maturation control for both reproduction and commercialization. This study explores the impact of temperature, photoperiod, and diet on gonad development to enhance year-round aquaculture practices. Using two independent cultivation systems, we manipulated environmental conditions to mimic different seasons. Sea urchins were exposed to natural or manipulated temperature and photoperiod conditions and fed either natural (Ulva spp.) or formulated diets. The gonadosomatic index (GI) and histological analysis were used to assess gonad development. The results revealed a clear correlation between environmental conditions, diet, and gonad maturation. Manipulated conditions accelerated maturation, with sea urchins showing advanced stages compared to natural conditions. Furthermore, sea urchins fed formulated diets exhibited higher GI values, indicating enhanced maturation. Histological analysis confirmed accelerated maturation, particularly in females. This study underscores the feasibility of controlling gonad maturation through environmental manipulation and diet, enabling year-round marketable gonad production. Providing formulated diets rich in polyunsaturated fatty acids, notably docosahexaenoic acid (DHA), enhances the commercial value of sea urchins. These findings optimize aquaculture practices for P. lividus, highlighting its adaptability to the maximal production of gonads throughout the year. Full article
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19 pages, 4100 KiB  
Article
Research on Measuring the Bodies of Underwater Fish with Inclined Positions Using the YOLOv8 Model and a Line-Laser System
by Jiakang Li, Shengmao Zhang, Penglong Li, Yang Dai and Zuli Wu
Fishes 2024, 9(6), 206; https://doi.org/10.3390/fishes9060206 - 1 Jun 2024
Abstract
Fish body measurement is essential for monitoring fish farming and evaluating growth. Non-destructive underwater measurements play a significant role in aquaculture management. This study involved annotating images of fish in aquaculture settings and utilized a line laser for underwater distance calibration and fish [...] Read more.
Fish body measurement is essential for monitoring fish farming and evaluating growth. Non-destructive underwater measurements play a significant role in aquaculture management. This study involved annotating images of fish in aquaculture settings and utilized a line laser for underwater distance calibration and fish body inclined-angle calculation. The YOLOv8 model was employed for fish identification and key-point detection, enabling the determination of actual body dimensions through a mathematical model. The results show a root-mean-square error of 6.8 pixels for underwater distance calibration using the line laser. The pre-training YOLOv8-n, with its lower parameter counts and higher MAP values, proved more effective for fish identification and key-point detection, considering speed and accuracy. Average body length measurements within 1.5 m of the camera showed a minor deviation of 2.46% compared to manual measurements. The average relative errors for body length and width were 2.46% and 5.11%, respectively, with corresponding average absolute errors. This study introduces innovative techniques for fish body measurement in aquaculture, promoting the digitization and informatization of aquaculture processes. Full article
(This article belongs to the Special Issue AI and Fisheries)
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20 pages, 712 KiB  
Article
Feed Additives Based on N. gaditana and A. platensis Blend Improve Quality Parameters of Aquacultured Gilthead Seabream (Sparus aurata) Fresh Fillets
by María Isabel Sáez, Alba Galafat, Silvana Teresa Tapia Paniagua, Juan Antonio Martos-Sitcha, Francisco Javier Alarcón-López and Tomás Francisco Martínez Moya
Fishes 2024, 9(6), 205; https://doi.org/10.3390/fishes9060205 - 31 May 2024
Abstract
The aim of this research is to explore the potential effects of two microalgae-based additives included in finishing feeds on the quality and shelf-life of seabream fillets. In a 41-day feeding trial, seabream specimens were fed with experimental aquafeeds containing 10% of the [...] Read more.
The aim of this research is to explore the potential effects of two microalgae-based additives included in finishing feeds on the quality and shelf-life of seabream fillets. In a 41-day feeding trial, seabream specimens were fed with experimental aquafeeds containing 10% of the bioactive supplements. These additives consisted of a blend of Nannochloropsis gaditana and Arthrospira platensis biomass, which was utilized as either raw (LB-CB) or enzymatically hydrolyzed (LB-CBplus). A control group received a microalgae-free diet. The results showed that the functional aquafeeds improved the nutritional profile of seabream fillets, increasing protein and PUFA-n3 contents while reducing the atherogenic index, especially for the LB-CBplus treatment. LB-CBplus also enhanced the texture parameters (hardness and chewiness) of fillets during the initial 5 days under cold storage. Regarding skin pigmentation, fillets showed increased greenish and yellowish coloration compared to control fish, mostly attributed to the inclusion of crude algal biomass (LB-CB). Moreover, diets enriched with microalgae additives effectively delayed muscle lipid oxidation processes under refrigeration for up to 12 days, with LB-CBplus exhibiting higher antioxidant effects. These findings highlight the potential of microalgae-based additives to enhance both the nutritional and organoleptic quality of seabream fillets. Full article
(This article belongs to the Special Issue Effects of Feed Additives on Fish Health and Fillet Quality)
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21 pages, 3320 KiB  
Article
Feature Selection for Explaining Yellowfin Tuna Catch per Unit Effort Using Least Absolute Shrinkage and Selection Operator Regression
by Ling Yang and Weifeng Zhou
Fishes 2024, 9(6), 204; https://doi.org/10.3390/fishes9060204 - 30 May 2024
Abstract
To accurately identify the key features influencing the fisheries distribution of Pacific yellowfin tuna, this study analyzed data from 43 longline fishing vessels operated from 2008 to 2019. These vessels operated in the Pacific Ocean region (0° to 30° S; 110° E to [...] Read more.
To accurately identify the key features influencing the fisheries distribution of Pacific yellowfin tuna, this study analyzed data from 43 longline fishing vessels operated from 2008 to 2019. These vessels operated in the Pacific Ocean region (0° to 30° S; 110° E to 170° W), with a specific focus on 25 features of yellowfin tuna derived from marine environment data. For this purpose, this study opted for the Lasso regression analysis method to select features to predict Pacific yellowfin tuna fishing grounds, exploring the relationship between the catch per unit effort (CPUE) of yellowfin tuna and multiple features. This study reveals that latitude and water temperature at various depths, particularly the sea surface temperature of the preceding and subsequent months and the temperature at depths between 300 and 450 m, are the most significant features influencing CPUE. Additionally, chlorophyll concentration and large-scale climate indices (ONI and NPGIO) also have a notable impact on the distribution of CPUE for yellowfin tuna. Lasso regression effectively identifies features that are significantly correlated with the CPUE of yellowfin tuna, thereby demonstrating superior fit and predictive accuracy in comparison with other models. It provides a suitable methodological approach for selecting fishing ground features of yellowfin tuna in the Pacific Ocean. Full article
(This article belongs to the Special Issue AI and Fisheries)
13 pages, 7452 KiB  
Article
Exploring Cellular Dynamics in the Goldfish Bulbus Arteriosus: A Multifaceted Perspective
by Doaa M. Mokhtar, Enas A. Abd-Elhafez, Marco Albano, Giacomo Zaccone and Manal T. Hussein
Fishes 2024, 9(6), 203; https://doi.org/10.3390/fishes9060203 - 29 May 2024
Viewed by 135
Abstract
The bulbus arteriosus of goldfish, Carassius auratus, possesses unique structural features. The wall of the bulbus arteriosus is exceptionally thick, with an inner surface characterized by longitudinally arranged finger-like ridges, resulting in an uneven luminal appearance. These ridges are covered by endocardium [...] Read more.
The bulbus arteriosus of goldfish, Carassius auratus, possesses unique structural features. The wall of the bulbus arteriosus is exceptionally thick, with an inner surface characterized by longitudinally arranged finger-like ridges, resulting in an uneven luminal appearance. These ridges are covered by endocardium and encased in an amorphous extracellular matrix. The inner surface of the bulbus arteriosus also contains rodlet cells at different developmental stages, often clustered beneath the endothelium lining the bulbar lumen. Ruptured rodlet cells release their contents via a holocrine secretion process. The high abundance of rodlet cells in the bulbus arteriosus suggests that this is the site of origin for these cells. Within the middle layer of the bulbus arteriosus, smooth muscle cells, branched telocytes (TCs), and collagen bundles coexist. TCs and their telopodes form complex connections within a dense collagen matrix, extending to rodlet cells and macrophages. Moreover, the endothelium makes direct contact with telopodes. The endocardial cells within the bulbus arteriosus display irregular, stellate shapes and numerous cell processes that establish direct contact with TCs. TEM reveals that they contain moderately dense bodies and membrane-bound vacuoles, suggesting a secretory activity. TCs exhibit robust secretory activity, evident from their telopodes containing numerous secretory vesicles. Furthermore, TCs release excretory vesicles containing bioactive molecules into the extracellular matrix, which strengthens evidence for telocytes as promising candidates for cellular therapies and regeneration in various heart pathologies. Full article
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15 pages, 1686 KiB  
Article
Food Web Structure and Ecosystem Functions of the Water Source in the Middle Route of China’s South-to-North Water Diversion Project
by Yuanyuan Zhang, Kaidi Gu, Xinyu Wang, Ji’ao Zhang, Jiaoyang Duan, Zhongjun Hu and Qigen Liu
Fishes 2024, 9(6), 202; https://doi.org/10.3390/fishes9060202 - 28 May 2024
Viewed by 278
Abstract
The Danjiangkou Reservoir is the water source of the middle route of China’s South-to-North Water Diversion Project, encompassing the Dan Reservoir and Han Reservoir. However, little is known about the ecological functions of this important ecosystem. Based on a survey conducted in 2023 [...] Read more.
The Danjiangkou Reservoir is the water source of the middle route of China’s South-to-North Water Diversion Project, encompassing the Dan Reservoir and Han Reservoir. However, little is known about the ecological functions of this important ecosystem. Based on a survey conducted in 2023 in the Dan Reservoir, a mass balance model was constructed using Ecopath with Ecosim 6.6 software to characterize its food web structure and ecosystem properties. The model consisted of 18 functional groups, including producers, consumers, and detritus, covering the entire process of energy flow in the ecosystem. The outputs indicated that the fractional trophic level of functional groups in the Dan Reservoir ecosystem ranged from 1.00 to 3.50. The ecotrophic efficiencies of the main economic fish species were all less than 0.9, and the ecotrophic efficiencies of phytoplankton and detritus were less than 0.5. There were two main food chains: the detritus food chain (39%) and the grazing food chain (61%). The total energy transfer efficiency between trophic levels was only 6.02%, and there was a significant phenomenon of energy transfer blockage between trophic levels II and V. Analysis of the overall characteristics of the ecosystem revealed that the total primary production to total biomass (67.96619), connectance index (0.274), and Finn’s cycling index (2.856) of the Dan Reservoir ecosystem all indicate that the ecosystem is immature, with low nutrient recycling efficiency and poor resistance to external disturbances. This may be related to the low proportion of silver carp and bighead carp in the reservoir and the unreasonable structure of the fish community. Our results suggest that it is necessary to scientifically adjust the structure of the fish community, enhance the proportion of filter-feeding and omnivorous fish to improve the energy flow efficiency, and promote the maturity and stability of the Dan Reservoir. Full article
(This article belongs to the Section Biology and Ecology)
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11 pages, 1671 KiB  
Article
Genetic Characterization of Endangered Sterlet (Acipenser ruthenus, Linnaeus 1758) Gene Bank Broodstock, Natural and Cultured Populations in Hungary
by Gyöngyvér Fazekas, Gyula Kovács, Zsuzsanna J. Sándor, Katalin Bogár, Aliz Géczi and Balázs Kovács
Fishes 2024, 9(6), 201; https://doi.org/10.3390/fishes9060201 - 28 May 2024
Viewed by 239
Abstract
The sterlet (Acipenser ruthenus) is the smallest-bodied endangered species among the six native sturgeon species of the Danube River, and self-sustaining populations still inhabit the Hungarian section of the Danube River and its largest tributary, the Tisza River. Their populations are [...] Read more.
The sterlet (Acipenser ruthenus) is the smallest-bodied endangered species among the six native sturgeon species of the Danube River, and self-sustaining populations still inhabit the Hungarian section of the Danube River and its largest tributary, the Tisza River. Their populations are drastically decreasing; however, they still have natural reproduction in these habitats. For the genetic conservation of the species, an ex situ gene bank is maintained in Hungary. The present study aimed to analyze the genetic resources of a gene bank with a near 40-year history and to compare it with natural populations and farmed stocks. Twelve microsatellites were used for population genetics analyses and individual genotyping of 268 specimens from two natural habitats (Danube and Tisza Rivers) and three captive stocks (a gene bank broodstock and two farms). Microsatellites revealed similar patterns among wild populations and gene bank stocks and did not show genetic differentiation (FST: 0.016–0.017) among them. These results confirmed that the gene bank broodstock properly represents the genetic background of the Danube and Tisza populations and is suitable as a source of breeding materials for the restocking programs. Negative trends were detected in the farmed stocks, reflected in reduced polymorphism at a few loci. The results of the principal component analyses indicate the farm stocks’ separation from the wild and gene bank stocks. The present genetic characterization study reveals a valuable captive stock of the endangered sterlet populations and provides unique information about the genetic similarities and differences among farms and wild stocks in Hungary. Our results provide information that contributes to preserving the genetic structure and variability in sterlet populations and supports the management of gene bank broodstock—avoiding inbreeding and preserving the unique genetic background of the Carpathian basin. Full article
(This article belongs to the Section Genetics and Biotechnology)
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20 pages, 2299 KiB  
Article
Assessing Economic Contributions of the Virginia Seafood Industry: An Estimation Framework Utilizing Primary Data
by Fernando H. Gonçalves, Jonathan van Senten, Michael H. Schwarz and Shraddha Hegde
Fishes 2024, 9(6), 200; https://doi.org/10.3390/fishes9060200 - 26 May 2024
Viewed by 590
Abstract
With a focus on seafood industries, this study provides a framework for economic contribution assessments, outlines Virginia’s seafood supply chain components, and evaluates the direct, indirect, and induced economic impacts of Virginia’s seafood industry in 2019. Utilizing an analysis-by-parts method in IMPLAN, primary [...] Read more.
With a focus on seafood industries, this study provides a framework for economic contribution assessments, outlines Virginia’s seafood supply chain components, and evaluates the direct, indirect, and induced economic impacts of Virginia’s seafood industry in 2019. Utilizing an analysis-by-parts method in IMPLAN, primary expenditure data from watermen, aquaculture farmers, processors, and distributors were collected through surveys. The efficacy of obtaining primary data through stakeholder surveys heavily relies on the investigator’s interpersonal skills to establish trust and elucidate the study’s benefits, particularly its potential to inform policy decisions. In 2019, the Virginia seafood industry’s estimated total economic contributions amounted to USD 1.1 billion, supporting 7187 individuals. This impact encompasses 6050 direct jobs, 523 indirect jobs, and 614 induced jobs, primarily benefiting watermen and coastal communities. Furthermore, the industry’s influence extends beyond its immediate economic sphere, supporting diverse sectors such as polystyrene foam manufacturing, boat building, sporting and athletic goods, and commercial and industrial machinery. Wages and salaries disbursed throughout the seafood supply chain ripple to Virginia’s economy, benefiting nondepository credit intermediation, owner-occupied dwellings, and real estate sectors. Future research focusing on seafood sales in restaurants and retail outlets will complete the understanding of the seafood industry’s broader economic impact on the state. Full article
(This article belongs to the Section Fishery Economics, Policy, and Management)
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10 pages, 1651 KiB  
Article
Protective Effects of Roselle Aqueous Extracts against UV-Induced Damage in Zebrafish Fins
by I-Ting Lee, Ching-Yuan Huang, Wei-Lin Su, Tran M. Truong, Chi-Chung Wen, Bo-Chang Wang and Yau-Hung Chen
Fishes 2024, 9(6), 199; https://doi.org/10.3390/fishes9060199 - 26 May 2024
Viewed by 241
Abstract
(1) Background: Roselle (Hibiscus sabdariffa) is a flowering plant reported to have anti-obesity, antioxidant, antibacterial, and anti-inflammatory effects. This study aims to evaluate the UV-absorbing and antioxidant activities of roselle aqueous extracts (RAE) and test the protective effects of RAE against [...] Read more.
(1) Background: Roselle (Hibiscus sabdariffa) is a flowering plant reported to have anti-obesity, antioxidant, antibacterial, and anti-inflammatory effects. This study aims to evaluate the UV-absorbing and antioxidant activities of roselle aqueous extracts (RAE) and test the protective effects of RAE against UV radiation in zebrafish embryos. (2) Methods: DPPH assay and UV-spectrum methods were applied to evaluate the antioxidant and UV-absorbing activities, respectively. The protective effects of RAE were evaluated using fin morphology recording, Kaplan–Meier analysis, and Cox proportional hazards regression. Real-time PCR experiments were also applied to detect both the UV- and RAE-induced gene expressions. (3) Results: Our results show that (i) RAE had UV-absorbing abilities and significantly reduced ROS production in vitro; (ii) the mean times of malformed fins in the UV + RAE (36 and 48 ppm) groups were 3.56 and 4.44 days, respectively, and were prolonged compared to those in the UV-only group (3.36 days); (iii) zebrafish in the UV + RAE (36 and 48 ppm) groups were 0.963 and 0.496 (p < 0.001) times more likely to develop to malformed fins, respectively, than those in the UV-only group; and (iv) the RAE treatment led to the 0.19- to 0.62-fold downregulation of the p53, p21, mdm2, and bcl2 gene expressions, compared to the UV-only group. (4) Conclusions: The UV-protective effects of RAE might derive from both the in vitro UV-absorbing activity and in vivo regulation of the p53, p21, mdm2, and bcl2 gene expressions. Full article
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13 pages, 2747 KiB  
Article
Effect of CRISPR/Cas9 Targets Associated with Iron Metabolism and Its Variation on Transcriptional Regulation of SHK-1 Cell Line as a Model for Iron Metabolism
by Phillip Dettleff, Yehwa Jin, Carolina Peñaloza, Rodrigo Pulgar, Alejandro Sáez, Diego Robledo and Sebastian Escobar-Aguirre
Fishes 2024, 9(6), 198; https://doi.org/10.3390/fishes9060198 - 26 May 2024
Viewed by 406
Abstract
In this study, we investigated the function of a gene associated with iron metabolism using CRISPR-Cas9 and RNA sequencing in SHK-1 salmon cells. Our objective was to understand how different guide RNA (gRNA) sequences against the transferrin gene tf could influence gene expression [...] Read more.
In this study, we investigated the function of a gene associated with iron metabolism using CRISPR-Cas9 and RNA sequencing in SHK-1 salmon cells. Our objective was to understand how different guide RNA (gRNA) sequences against the transferrin gene tf could influence gene expression and cellular processes related to iron uptake. RNA-Seq analysis was performed to evaluate the transcriptomic effects of two distinct gRNA targets with high knock-out (KO) efficiencies for the targeted tf gene in the SHK-1 genome. Our results showed no significant differential expression in transferrin-related transcripts between wild-type and CRISPR-edited cells; however, there were major differences between their transcriptomes, indicating complex transcriptional regulation changes. Enrichment analysis highlighted specific processes and molecular functions, including those related to the nucleus, cytoplasm, and protein binding. Notably, different sgRNAs targeting tf might result in different mutations at DNA levels in SHK-1 salmon cells. Full article
(This article belongs to the Special Issue Aquatic Animal Transgene and Gene Editing Technology)
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15 pages, 773 KiB  
Article
Diets, Condition, and Reproductive Fitness of Slimy Sculpin (Uranidea cognata) after Catastrophic Flooding in Trout Streams in Southeastern Minnesota, USA
by Neal D. Mundahl
Fishes 2024, 9(6), 197; https://doi.org/10.3390/fishes9060197 - 25 May 2024
Viewed by 238
Abstract
Slimy sculpin (Uranidea cognata) inhabit coldwater streams in southeastern Minnesota, USA, many of which were subjected to probable 2000-year flood events in August 2007. Floods scoured streambeds, created new stream channels, and greatly reduced benthic invertebrate communities that serve as the [...] Read more.
Slimy sculpin (Uranidea cognata) inhabit coldwater streams in southeastern Minnesota, USA, many of which were subjected to probable 2000-year flood events in August 2007. Floods scoured streambeds, created new stream channels, and greatly reduced benthic invertebrate communities that serve as the primary food resource for sculpin. Diets and Fulton condition of sculpin in Gilmore Creek (with moderate flooding) and Garvin Brook (with very severe flooding) had been examined just prior to flooding and were re-examined 2 weeks after flooding to assess possible diet and condition changes. Diets, body condition, and reproductive fitness of sculpin were examined 7 months post-flood in these same two streams, plus nearby Trout Run (which also experienced very severe flooding). Sculpin condition declined slightly post-flood in Garvin Brook but improved in Gilmore Creek. Prior to spring spawning, the condition of Garvin Brook sculpin had improved, but Gilmore Creek fish condition had worsened. Sculpin diets were more diverse before and after flooding in Gilmore Creek than in Garvin Brook, although the diets of fish from both streams were dominated (>55%) by midge (Diptera: Chironomidae) larvae. Diets remained largely unchanged before versus after flooding in the more severely flooded Garvin Brook, but they changed in Gilmore Creek, becoming more midge-dominated. Prey number per sculpin stomach declined post-flood in Gilmore Creek but not in Garvin Brook, although the dry mass of prey/fish wet mass declined post-flood in both streams. Pre-spawn sculpin displayed no patterns in reproductive fitness (gonadosomatic index, hepatosomatic index, oocyte number) among the three streams that may have been related to flooding severity the previous summer. Sculpin diets and condition were not altered as expected by flooding, and food resource recovery apparently was rapid enough to prevent longer-term impacts on sculpin condition and reproductive fitness in the streams examined. Full article
14 pages, 956 KiB  
Article
Critically Small Contemporaneous Effective Population Sizes Estimated for Stocks of the African Bonytongue in Western Africa
by Luis A. Hurtado, Mariana Mateos, Isabel C. Caballero, Tofunmi E. Oladimeji, Alphonse Adite, Michael O. Awodiran, Kirk O. Winemiller and Matthew B. Hamilton
Fishes 2024, 9(6), 196; https://doi.org/10.3390/fishes9060196 - 25 May 2024
Viewed by 274
Abstract
Inland capture fisheries play a critical role in supporting food security and livelihoods in Africa. Therefore, it is important to evaluate the genetic health of exploited fish populations. The African bonytongue, Heterotis niloticus, supports important commercial and subsistence fisheries in western Africa. [...] Read more.
Inland capture fisheries play a critical role in supporting food security and livelihoods in Africa. Therefore, it is important to evaluate the genetic health of exploited fish populations. The African bonytongue, Heterotis niloticus, supports important commercial and subsistence fisheries in western Africa. However, sharp declines in stocks have been reported. Herein, we estimate contemporary effective population sizes (Ne) of four Heterotis populations in Nigeria, three in Benin, and five in Cameroon using Linkage Disequilibrium methods. Ne estimates were used to assess genetic short-term (i.e., inbreeding depression) and long-term (i.e., loss of evolutionary potential) risks. Ne point estimates obtained with the best estimator (out of 16), as determined by computer simulations, were <50 (range = 5.1–36.2) for nine of the twelve populations examined, which is below the minimum recommended for avoiding the potential deleterious effects of inbreeding depression (original criterion Ne ≥ 50, revised to Ne ≥ 100); and well below the minimum recommended for populations to retain evolutionary potential (original criterion Ne ≥ 500; revised to Ne ≥ 1000). The lower bound of the confidence interval for two of the remaining populations was below the minimum recommended to retain evolutionary potential (with the point estimate of one of them also below this threshold), and for some methods, values were lower than the minimum recommended to avoid inbreeding depression. Accordingly, our results suggest that urgent conservation and management plans are needed to guarantee the persistence and sustainability of the H. niloticus populations examined. Full article
(This article belongs to the Special Issue Molecular Ecology and Genetic Diversity of Fish)
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15 pages, 319 KiB  
Article
Partial Replacement of Fishmeal with Seafood Discards for Juvenile Penaeus japonicus: Effects on Growth, Flesh Quality, Chemical and Fatty Acid Composition
by Marco Ragni, Maria Antonietta Colonna, Laura Di Turi, Claudia Carbonara, Francesco Giannico, Michela Cariglia, Giuseppe Palma and Simona Tarricone
Fishes 2024, 9(6), 195; https://doi.org/10.3390/fishes9060195 - 24 May 2024
Viewed by 202
Abstract
The present study was designed to assess the influence of fishmeal replacement with increasing percentages of fresh seafood discards (0, 25, 50 and 75%) in diets for Penaeus japonicus on growth performance, physical characteristics and the chemical and fatty acid composition of shrimp [...] Read more.
The present study was designed to assess the influence of fishmeal replacement with increasing percentages of fresh seafood discards (0, 25, 50 and 75%) in diets for Penaeus japonicus on growth performance, physical characteristics and the chemical and fatty acid composition of shrimp flesh. Each diet was administered for 108 days, and the trial was assayed in triplicate. The final body weight and the specific growth rate were significantly higher (p < 0.05) in shrimps fed with 75% fishmeal replacement as compared to 25%, while the abdomen weight and the total length were the highest (p < 0.01). Moreover, 75% replacement showed a significantly (p < 0.05) lower value of hardness and a greater crude protein and lipid content as compared to the 0% replacement. The shrimps fed with high levels of seafood discards (50 and 75%) showed a lower saturated fatty acid concentration and, in turn, a greater amount of polyunsaturated fatty acids in shrimp meat significantly (p < 0.05) affected the lower atherogenic and thrombogenic indices. In conclusion, replacing 75% of fishmeal with seafood discards provided satisfactory results. An economic analysis based on ESG indicators and PESTLE methodology is provided in order to show the socio-economic and governance impacts affecting the replacement of shrimps’ diet with fish discard. Full article
(This article belongs to the Section Nutrition and Feeding)
18 pages, 6109 KiB  
Article
Identification and Characterization of microRNAs in Morphological Color Change of Polychromatic Midas Cichlids (Amphilophus citrinellus)
by Guoqiang Wu, Xidong Mu, Yi Liu, Chao Liu, Xuejie Wang, Yexin Yang and Hongmei Song
Fishes 2024, 9(6), 194; https://doi.org/10.3390/fishes9060194 - 24 May 2024
Viewed by 294
Abstract
As a representative genetic and economic trait, pigmentation has a strong impact on speciation and adaptation. However, information and reports on microRNAs (miRNAs) associated with pigmentation remain limited. The Midas cichlid fish, with three typical distinct stages of body color pattern, “black-gray-gold”, is [...] Read more.
As a representative genetic and economic trait, pigmentation has a strong impact on speciation and adaptation. However, information and reports on microRNAs (miRNAs) associated with pigmentation remain limited. The Midas cichlid fish, with three typical distinct stages of body color pattern, “black-gray-gold”, is an ideal model system for investigating pigmentation traits. In this study, miRNA libraries from scale tissues with the attached epidermis of Midas cichlids at three distinct stages of color transformation, black (B), transition (T), and gold (G), were sequenced using Illumina sequencing technology. In total, 53 (B vs. G), 88 (B vs. T), and 57 (T vs. G) miRNAs were differentially expressed between the respective groups. Target genes of the identified miRNAs were predicted, and the results showed that multiple target genes were related to pigmentation and pigment–cell differentiation. The miRNA–mRNA regulatory network suggests that miR-183-x and miR-133-x were predicted to be involved in regulating morphological color changes in Midas cichlids. The results advance our understanding of potential functions of miRNAs in skin pigment differentiation and early skin color fading of fishes. Full article
(This article belongs to the Special Issue Genetics and Breeding in Aquaculture)
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35 pages, 4084 KiB  
Article
Quantifying Variability in Zebrafish Larvae Locomotor Behavior across Experimental Conditions: A Learning-Based Tracker
by Zhuo Zhang, Xinyu Chai, Guoning Si and Xuping Zhang
Fishes 2024, 9(6), 193; https://doi.org/10.3390/fishes9060193 - 23 May 2024
Viewed by 246
Abstract
This study investigated the effects of environmental changes on zebrafish larval behavior, using single-factor and orthogonal experiments to assess locomotion during temperature and pH changes. In single-factor experiments, zebrafish larvae were exposed to variations in temperature (22 to 30 °C) and pH levels [...] Read more.
This study investigated the effects of environmental changes on zebrafish larval behavior, using single-factor and orthogonal experiments to assess locomotion during temperature and pH changes. In single-factor experiments, zebrafish larvae were exposed to variations in temperature (22 to 30 °C) and pH levels (6.0, 7.0, 9.0). The simultaneous temperature and pH changes were investigated by orthogonal tests. In both experiments, each zebrafish larva was recorded in three 5 min videos at different stages (before exposure, during short-term exposure (10 min), and after long-term exposure (60 min)). You Look Only Once (YOLOv5) and Deep Simple Online Real Time Tracking (DeepSORT) models were adopted to develop a zebrafish larva tracking system, and YOLOv5 was improved in two aspects of anchor clustering and network structure. The tracking accuracy of the tracking system for small targets effectively improved, reaching more than 98% MOTA (Multiple Object Tracking Accuracy). Principal Component Analysis (PCA) was employed to extract three behavioral features from 13 motion parameters, namely motion activity, edge behavior, and motion direction preference. Our findings reveal that lower temperatures and acidic conditions both led to a decrease in motion behavioral activity, and the former also increased edge behavior. Conversely, elevated temperatures and alkaline conditions had a muted impact on these behaviors. Interestingly, concurrent changes in temperature and pH significantly altered directional preference. Additionally, we observed that lower temperatures elicited distinct temporal behavioral patterns at a constant pH level. In summary, we recommend the precise control and explicit reporting of ambient temperature and pH in both breeding devices and experimental wells to minimize the environmental impact on zebrafish behavior and enhance experiment repeatability and reliability. Full article
(This article belongs to the Special Issue AI and Fisheries)
16 pages, 4808 KiB  
Article
Exploring Seasonal Variations in Fish Communities: A Study of the Yellow River Estuary and Its Adjacent Waters Using eDNA and Trawl Surveys
by Xiaoyang Wang, Fan Li, Fei Shao, Hongjun Song, Na Song, Xiaomin Zhang and Linlin Zhao
Fishes 2024, 9(6), 192; https://doi.org/10.3390/fishes9060192 - 23 May 2024
Viewed by 293
Abstract
The Yellow River Estuary and its adjacent waters serve as crucial spawning, foraging, and nursery areas for marine organisms, possessing abundant biological resources. Monitoring fish communities provides a baseline for implementing the sustainable utilization of marine resources. In this study, data were collected [...] Read more.
The Yellow River Estuary and its adjacent waters serve as crucial spawning, foraging, and nursery areas for marine organisms, possessing abundant biological resources. Monitoring fish communities provides a baseline for implementing the sustainable utilization of marine resources. In this study, data were collected from 15 spring surface and bottom sites and 17 summer surface sites using eDNA and trawl surveys. The results showed that 37, 40, and 35 fish species were detected using eDNA in the spring (surface and bottom) and summer (surface), respectively, with 38 fish species caught during summer trawling. The dominant species mainly belonged to Engraulidae of Clupeiformes in the spring and Gobiidae of Perciformes in the summer, characterized by smaller-sized, short-lived, and pelagic fish species. The summer surface communities exhibited higher diversity than the spring surface and bottom communities. NMDS analysis revealed a degree of seasonal differences in fish communities and that there may be a lack of vertical stratification in the spring communities. The pH and DO were identified as the key environmental factors affecting the fish community. Additionally, the combination of eDNA and trawl surveys was regarded as a superior survey method. Our study provides valuable information for understanding seasonal fish communities in the Yellow River Estuary and its adjacent waters, contributing to fishery resource management and conservation in the region. Full article
(This article belongs to the Special Issue Assessment and Management of Fishery Resources)
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15 pages, 2148 KiB  
Article
Effect of Organic or Inorganic Fertilization on Microbial Flocs Production in Integrated Cultivation of Ulva lactuca with Oreochromis niloticus and Penaeus vannamei
by Andrezza Carvalho, Hellyjúnyor Brandão, Julio C. Zemor, Alessandro Pereira Cardozo, Felipe N. Vieira, Marcelo H. Okamoto, Gamze Turan and Luís H. Poersch
Fishes 2024, 9(6), 191; https://doi.org/10.3390/fishes9060191 - 23 May 2024
Viewed by 316
Abstract
Different fertilization regimes in biofloc systems influence the predominance of distinct bacterial populations, impacting water quality and organism performance. This study evaluates the growth and nutrient absorption of the macroalgae Ulva lactuca when cultivated in an integrated system with Penaeus vannamei and Oreochromis [...] Read more.
Different fertilization regimes in biofloc systems influence the predominance of distinct bacterial populations, impacting water quality and organism performance. This study evaluates the growth and nutrient absorption of the macroalgae Ulva lactuca when cultivated in an integrated system with Penaeus vannamei and Oreochromis niloticus in chemoautotrophic and heterotrophic systems. The experiment lasted 45 days and comprised two treatments, each with three replicates: chemoautotrophic—utilizing chemical fertilizers; heterotrophic—employing inoculum from mature biofloc shrimp cultivation, supplemented with organic fertilizers. Each treatment consisted of three systems, each containing a 4 m3 tank for shrimp, 0.7 m3 for tilapia, and 0.35 m3 for macroalgae, with continuous water circulation between tanks and constant aeration. Water quality analyses were carried out during the experiment, as were the performances of the macroalgae and animals. The data were subjected to a statistical analysis. Results revealed an increase in macroalgae biomass and the removal of nitrate (57%) and phosphate (47%) during cultivation, with a higher specific growth rate observed in the chemoautotrophic treatment. Nonetheless, the heterotrophic treatment exhibited higher levels of protein in the macroalgae (18% dry matter) and phosphate removal rates (56%), along with superior maintenance of water quality parameters. Tilapia performance varied across treatments, with a higher final weight and weight gain recorded in the heterotrophic treatment. The recycling of water from an ongoing biofloc cultivation with organic fertilization demonstrated viability for macroalgae cultivation within an integrated system involving shrimp and fish. Full article
(This article belongs to the Special Issue Integrated Aquaculture and Monoculture of Low-Trophic Species)
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12 pages, 1070 KiB  
Article
Effect of Stocking Density on Survival and Growth of Brown Meagre Sciaena umbra (L.) Larvae
by Rémi Millot, Mikaël Demolliens, Jean-José Filippi, Sally Pugliese, Alban Delmas, Alizée Boussard, Loriane Alonso, Adeline Suchel, Emilie Poletti, Jean-François Luca, Reda Hayoun, Laura Gutierrez, Alexandre Vela, Romain Bastien and Antoine Aiello
Fishes 2024, 9(6), 190; https://doi.org/10.3390/fishes9060190 - 22 May 2024
Viewed by 367
Abstract
Successful aquacultural production of juvenile fish requires that the optimal rearing conditions be applied. However, for many fish species, there is a significant knowledge gap concerning these conditions. In this study, we evaluated the effects of stocking density on the survival and growth [...] Read more.
Successful aquacultural production of juvenile fish requires that the optimal rearing conditions be applied. However, for many fish species, there is a significant knowledge gap concerning these conditions. In this study, we evaluated the effects of stocking density on the survival and growth of brown meagre, Sciaena umbra (L.), during rearing trials in an experimental hatchery. This research forms part of a feasibility project to improve the aquacultural production of brown meagre. Four initial larval density treatments (5, 10, 30, and 70 larvae per L) were established. At 0, 9, 17, 22, and 25 days post-hatching, we measured the total length, coefficient of variation in length, and specific growth rate. The physicochemical water parameters remained at satisfactory levels for fish culture throughout the experiment. Lower densities promoted better growth in terms of total length, specific growth rate, and survival. We observed a significant negative correlation between larval density and length growth/survival. Thus, the low larval density treatment yielded the highest survival (48.5% ± 3.46%), growth in final total length (11.9 ± 1.09 mm), and specific growth rate (5.13% ± 0.39% per day). Increased stocking density therefore negatively affects growth and survival, reduces homogeneity, but increases the production of S. umbra larvae. This study helps identify optimal aquaculture conditions for maximizing the production of juvenile S. umbra for ecological restoration. Full article
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13 pages, 1804 KiB  
Article
Production of Flathead Grey Mullet (Mugil cephalus) and Lettuce (Lactuca sativa) in a Coupled Aquaponic System under Suboptimal Water Temperatures
by Enric Gisbert, Sandra Molas, Esteban Hernández, Ricard Carbó and Alberto Ruiz
Fishes 2024, 9(6), 189; https://doi.org/10.3390/fishes9060189 - 21 May 2024
Viewed by 395
Abstract
The combined production of three varieties of lettuce (romaine, iceberg, and red leaf) with flathead grey mullet (Mugil cephalus) was tested in triplicate in three independent coupled aquaponic units with no thermal control. For this purpose, a total of 114 fish [...] Read more.
The combined production of three varieties of lettuce (romaine, iceberg, and red leaf) with flathead grey mullet (Mugil cephalus) was tested in triplicate in three independent coupled aquaponic units with no thermal control. For this purpose, a total of 114 fish (2.5 kg/m3) were stocked in each fish tank (2 m3), and 92 lettuces were planted in the hydroponic unit (6 m2). As no thermal control was included in the design of the aquaponic system, water temperatures declined from maximum values of 20.4 °C to minimum values of 5.0 °C, which directly affected fish growth. However, the conditions imposed by the aquaponic system were suitable for promoting lettuce’s growth and external appearance, as no pests or leaf discoloration were noticed. Lettuce survival was similar among the three tested varieties (98.5 ± 1.7%). The yields for the romaine and iceberg varieties were 384 ± 100 g/lettuce and 316 ± 70 g/lettuce, respectively, and that for the red leaf variety was lower, at 176 ± 75 g/lettuce. Yield values ranged between 3.6 and 4.4 kg/m2 depending on the replicate considered (4.0 ± 0.4 kg/m2). According to present results, each aquaponic unit required ca. 2.6–2.7 L of water per unit of lettuce produced. Full article
(This article belongs to the Special Issue Advances in Sustainable Aquaculture Production Systems)
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