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Fishes, Volume 6, Issue 4 (December 2021) – 42 articles

Cover Story (view full-size image): Lagoon soft bottoms are key habitats within coral reef seascapes. Coral reef fish use these habitats as nurseries, feeding grounds and transit areas. At present, most soft-bottom sampling methods are destructive (trawling, longlining, hook and line). We developed a remote, unbaited 360° video sampling method (RUV360) to monitor fish species assemblages in soft bottoms. Then, 534 videos were taken to assess the efficiency of the RUV360. The results are consistent with the known characteristics of the lagoon soft-bottom fish assemblages of New Caledonia. We provide future users with general recommendations and reference plots to estimate the proportion of the theoretical total species richness sampled, according to the number of stations or the duration of the footage. View this paper.
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14 pages, 588 KiB  
Article
Effect of Partial Soybean Replacement by Shrimp By-Products on the Productive and Economic Performances in African Catfish (Clarias lazera) Diets
by Ibrahim S. Abu-Alya, Yousef M. Alharbi, Said I. Fathalla, Ibrahim S. Zahran, Saad M. Shousha and Hassan A. Abdel-Rahman
Fishes 2021, 6(4), 84; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040084 - 20 Dec 2021
Cited by 5 | Viewed by 2775
Abstract
The present study was carried out to evaluate the effects of partial replacement of soybean with shrimp by-products (SBp) in African catfish (Clarias lazera) diets on productive (growth, digestibility, body composition, dressing yield, blood parameters, immunity) and economic performances. Therefore, 750 [...] Read more.
The present study was carried out to evaluate the effects of partial replacement of soybean with shrimp by-products (SBp) in African catfish (Clarias lazera) diets on productive (growth, digestibility, body composition, dressing yield, blood parameters, immunity) and economic performances. Therefore, 750 fingerlings (~20.0 g) were distributed into five groups of 150 fingerlings/group with three replicates (n = 50) per group. Group 1 was fed a basal diet, while G2 and G3 were fed diets containing 25% SBp (autoclaved and acid-treated, respectively) as soybean replacer for 12 weeks, while, in G4 and G5, SBp level was 50%. All growth and nutrient utilization parameters (body weight, Wg, ADG, PER, FCR, and digestibility), plasma proteins, and immunity significantly increased in G4 and G5. Anemia screening markers recorded insignificant differences between the tested groups and control one, whereas lipid markers of plasma and fish body decreased by autoclaved SBp and increased by acid-treated SBp. The African catfish body dry matter and crude protein percentages were enriched by the addition of SBp. Replacing the soybean meal decreases diet costs and diet costs/1 kg of weight gain. In conclusion, replacing soybean with SBp (especially 50% acid-treated) positively influenced productive and economic performances with friendly effects to avoid the environmental pollution by these wastes. Full article
(This article belongs to the Special Issue Fish Nutrition and Physiology)
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13 pages, 2962 KiB  
Article
Identification and Expression Characterization of the Smad3 Gene and SNPs Associated with Growth Traits in the Hard Clam (Meretrix meretrix)
by Lulu Fu, Qiudie Chi, Yongbo Bao, Hanhan Yao, Zhihua Lin and Yinghui Dong
Fishes 2021, 6(4), 83; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040083 - 16 Dec 2021
Cited by 1 | Viewed by 1959
Abstract
It has been demonstrated that the sekelsky mothers against decapentaplegic homolog 3 (Smad3) plays an important role in the growth and development of vertebrates. However, little is known about the association between the Smad3 gene and the growth traits of mollusks. [...] Read more.
It has been demonstrated that the sekelsky mothers against decapentaplegic homolog 3 (Smad3) plays an important role in the growth and development of vertebrates. However, little is known about the association between the Smad3 gene and the growth traits of mollusks. In this study, Smad3 from the hard clam Meretrix meretrix (Mm-Smad3) was cloned, characterized, and screened for growth-related single nucleotide polymorphisms (SNPs) in its exons. The full-length cDNA of Mm-Smad3 was 1938 bp, encoding a protein with 428 amino acid residues. The protein sequence included an MH1 (27–135 aa) and MH2 domain (233–404 aa). Promoter analysis showed that the promoter sequence of Mm-Smad3 was 2548 bp, and the binding sites of Pit-1a, Antp, Hb, and other transcription factors are related to the growth and development of hard clams. The phylogenetic tree was divided into two major clusters, including mollusks and vertebrate. The expression level of Mm-Smad3 was predominantly detected in the mantle and foot, while extremely less expression was observed in the digestive gland. The low expression level of Mm-Smad3 was detected at the stages of unfertilized mature eggs, fertilized eggs, four-cell embryos, blastula, gastrulae, trochophore, and D-shaped larvae, whereas an opposite trend was observed regarding the highest expression at the umbo larvae stage (p < 0.05). In the mantle repair experiment, the time-course expression profiles showed that compared to the expression level at 0 h, Mm-Smad3 significantly decreased at 6 h (p < 0.05) but increased at 12 and 48 h. Further, the association analysis identified 11 SNPs in the exons of Mm-Smad3, of which three loci (c.597 C > T, c.660 C > T, c.792 A > T) were significantly related to the growth traits of clam (p < 0.05). Overall, our findings indicated that Mm-Smad3 is a growth-related gene and the detected SNP sites provide growth-related markers for molecular marker-assisted breeding of this species. Full article
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35 pages, 15062 KiB  
Article
Complete Genome Sequences and Pathogenicity Analysis of Two Red Sea Bream Iridoviruses Isolated from Cultured Fish in Korea
by Min-A Jeong, Ye-Jin Jeong and Kwang-Il Kim
Fishes 2021, 6(4), 82; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040082 - 15 Dec 2021
Cited by 3 | Viewed by 2563
Abstract
In Korea, red sea bream iridovirus (RSIV), especially subtype II, has been the main causative agent of red sea bream iridoviral disease since the 1990s. Herein, we report two Korean RSIV isolates with different subtypes based on the major capsid protein and adenosine [...] Read more.
In Korea, red sea bream iridovirus (RSIV), especially subtype II, has been the main causative agent of red sea bream iridoviral disease since the 1990s. Herein, we report two Korean RSIV isolates with different subtypes based on the major capsid protein and adenosine triphosphatase genes: 17SbTy (RSIV mixed subtype I/II) from Japanese seabass (Lateolabrax japonicus) and 17RbGs (RSIV subtype II) from rock bream (Oplegnathus fasciatus). The complete genome sequences of 17SbTy and 17RbGs were 112,360 and 112,235 bp long, respectively (115 and 114 open reading frames [ORFs], respectively). Based on nucleotide sequence homology with sequences of representative RSIVs, 69 of 115 ORFs of 17SbTy were most closely related to subtype II (98.48–100% identity), and 46 were closely related to subtype I (98.77–100% identity). In comparison with RSIVs, 17SbTy and 17RbGs carried two insertion/deletion mutations (ORFs 014R and 102R on the basis of 17SbTy) in regions encoding functional proteins (a DNA-binding protein and a myristoylated membrane protein). Notably, survival rates differed significantly between 17SbTy-infected and 17RbGs-infected rock breams, indicating that the genomic characteristics and/or adaptations to their respective original hosts might influence pathogenicity. Thus, this study provides complete genome sequences and insights into the pathogenicity of two newly identified RSIV isolates classified as a mixed subtype I/II and subtype II. Full article
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17 pages, 2536 KiB  
Article
Fish Upstream Passage through Gauging Stations: Experiences with Iberian Barbel in Flat-V Weirs
by Francisco Javier Sanz-Ronda, Francisco Javier Bravo-Córdoba, Ana García-Vega, Jorge Valbuena-Castro, Andrés Martínez-de-Azagra and Juan Francisco Fuentes-Pérez
Fishes 2021, 6(4), 81; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040081 - 14 Dec 2021
Cited by 3 | Viewed by 2514
Abstract
The monitoring of river discharge is vital for the correct management of water resources. Flat-V gauging weirs are facilities used worldwide for measuring discharge. These structures consist of a small weir with a triangular cross-section and a flat “V”-shaped notch. Their extensive use [...] Read more.
The monitoring of river discharge is vital for the correct management of water resources. Flat-V gauging weirs are facilities used worldwide for measuring discharge. These structures consist of a small weir with a triangular cross-section and a flat “V”-shaped notch. Their extensive use is a consequence of their utility in the measurement of both low and high flow conditions. However, depending on their size, local morphology and river discharge can act as full or partial hydraulic barriers to fish migration. To address this concern, the present work studies fish passage performance over flat-V weirs considering their hydraulic performance. For this, radio-tracking and video-monitoring observations were combined with computational fluid dynamics (CFD) models in two flat-V weirs, using Iberian barbel (Luciobarbus bocagei) as the target species. Results showed that fish passage is conditioned by both hydraulic and behavioral processes, providing evidence for scenarios in which flat-V weirs may act as full or partial barriers to upstream movements. For the studied flat-V weirs, a discharge range of 0.27–8 m3/s, with a water drop difference between upstream and downstream water levels lower than 0.7 m and a depth downstream of the weir of higher than 0.3 m can be considered an effective passage situation for barbels. These findings are of interest for quantifying flat-V weir impacts, for engineering applications and for establishing managing or retrofitting actions when required. Full article
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16 pages, 1690 KiB  
Article
The Relationship between Environmental Factors and Catch Abundance of Hairtail in the East China Sea Using Empirical Dynamic Modeling
by Jinfei Hu, Ping Wang and Hailong Zhang
Fishes 2021, 6(4), 80; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040080 - 13 Dec 2021
Cited by 1 | Viewed by 2263
Abstract
The East China Sea population of hairtail (Trichiurus lepturus, also known as T. japonicus) is a commercially important element of Chinese fisheries. Hairtail has long been widely exploited. Due to overfishing, however, its production declined over the years. One of [...] Read more.
The East China Sea population of hairtail (Trichiurus lepturus, also known as T. japonicus) is a commercially important element of Chinese fisheries. Hairtail has long been widely exploited. Due to overfishing, however, its production declined over the years. One of solutions to this dilemma is to institute reasonable fishery policies. Generally, skillful short-term and long-term prediction of fish catch is a central tool for guiding the development of fishery policy. Accurate predictions require a comprehensive understanding of the relationship between fluctuations in fish catch and variability in both fishing effort and marine environmental conditions. To investigate the combined impact of fishing effort and marine environments on hairtail catch and to develop models to predict hairtail catch, we applied empirical dynamic modeling (EDM) to data on East China Sea fisheries, including hairtail catch, fishing effort, and marine environmental factors. EDM is an equation-free approach that enables the investigation of various complex systems. We constructed all possible multivariate EDM models to investigate the potential mechanisms affecting hairtail catch. Our analysis demonstrates that all key environmental factors (salinity, summer monsoon, sea surface temperature, precipitation, and power dissipation index of tropical cyclones) have an impact on nutrient supply, which we suggest is the central factor influencing hairtail catch. Finally, our comparison of EDM models with parametric models demonstrates that EDM models overwhelmingly outperform parametric models in analysis of these complex interactions. Full article
(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)
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17 pages, 1337 KiB  
Brief Report
Comparative Transcriptome Analysis of Female and Male Fine-Patterned Puffer: Identification of Candidate Genes Associated with Growth and Sex Differentiation
by Binbin Shan, Yan Liu, Changping Yang, Yuan Li, Liangming Wang and Dianrong Sun
Fishes 2021, 6(4), 79; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040079 - 12 Dec 2021
Cited by 3 | Viewed by 2554
Abstract
Sexual growth dimorphism is a common phenomenon in teleost fish. However, the mechanism of this complex phenomenon remains unclear. The fine-patterned puffer (Takifugu poecilonotus; Temminck and Schlegel, 1850) exhibits female-biased sexual size dimorphism similar to other pufferfish. In this study, the [...] Read more.
Sexual growth dimorphism is a common phenomenon in teleost fish. However, the mechanism of this complex phenomenon remains unclear. The fine-patterned puffer (Takifugu poecilonotus; Temminck and Schlegel, 1850) exhibits female-biased sexual size dimorphism similar to other pufferfish. In this study, the transcriptomes of female and male T.poecilonotus were sequenced, 285.95 million raw read pairs were generated from sequence libraries. After identification and assembly, a total of 149,814 nonredundant unigenes were obtained with an N50 length of 3538 bp. Of these candidates, 122,719 unigenes (81.91% of the total) were successfully annotated with multiple public databases. The comparison analysis revealed 10,385 unigenes (2034 in females and 8351 in males) were differentially expressed between different sexes of T.poecilonotus. Then, we identified many candidate growth- and sex-related genes, including Dmrt1, Sox3, Spatas, Prl/Prlr, fabps, Ghr, and Igf1r. In addition to these well-known genes, Fabp4 was identified for the first time in fish. Furthermore, 68,281 simple sequence repeats (SSRs) loci were screened and identified in the transcriptome sequence of T.poecilonotus. The results of our study could provide valuable information on growth- and sex-associated genes and facilitate further exploration of the molecular mechanism of sexual growth dimorphism. Full article
(This article belongs to the Section Genetics and Biotechnology)
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14 pages, 3197 KiB  
Article
Genetic Variability, Population Structure, and Relatedness Analysis of Meagre Stocks as an Informative Basis for New Breeding Schemes
by Orestis Nousias, Konstantinos Tzokas, Leonidas Papaharisis, Katerina Ekonomaki, Dimitrios Chatziplis, Costas Batargias and Costas S. Tsigenopoulos
Fishes 2021, 6(4), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040078 - 10 Dec 2021
Cited by 4 | Viewed by 3008
Abstract
This study evaluates the genetic diversity of different meagre broodstocks sampled in Greece. A multiplex of twelve microsatellite markers was used to genotype 946 fish from eleven stocks and batches used for broodstock selection, and the genetic data was used to calculate genetic [...] Read more.
This study evaluates the genetic diversity of different meagre broodstocks sampled in Greece. A multiplex of twelve microsatellite markers was used to genotype 946 fish from eleven stocks and batches used for broodstock selection, and the genetic data was used to calculate genetic population parameters as well as to investigate the genetic differentiation between stocks. The results from a relatedness analysis were used as the guiding lines for a fine-tuned and overall evaluation of the genetic distance between stocks, and the choice of candidate breeders from some of them. The approach implemented in this study uses well-established population genetics methods to evaluate the selection of breeder candidates in aquaculture commercial conditions utilizing a descriptive genetic data set based on microsatellite analyses, and to outline an efficient methodology for establishing the basis of new breeding schemes. Full article
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14 pages, 1285 KiB  
Article
Molecular Characterization and Nutrition Regulation of the Neutral Amino Acid Transporter ASCT2 in Triploid Crucian Carp
by Zhuangwen Mao, Shengwei Luo, Dafang Zhao, Xiang Zhou, Zilong Zhang, Yangbo Xiao, Shenping Cao, Yonghua Zhou, Shaojun Liu, Jianzhou Tang and Zhen Liu
Fishes 2021, 6(4), 77; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040077 - 09 Dec 2021
Cited by 1 | Viewed by 2104
Abstract
AlaSerCys Transporter 2 (ASCT2), encoded by the SLC1A5 gene, plays an important role in the absorption of glutamine. In this study, the full-length cDNA sequence of ASCT2 was cloned from triploid crucian carp. It encodes 539 amino acid residues and a stop codon. [...] Read more.
AlaSerCys Transporter 2 (ASCT2), encoded by the SLC1A5 gene, plays an important role in the absorption of glutamine. In this study, the full-length cDNA sequence of ASCT2 was cloned from triploid crucian carp. It encodes 539 amino acid residues and a stop codon. Phylogenetic analysis revealed that the sequences of the ASCT2 ORF region in cyprinid fishes shared high sequence homology. Comparing the abundance of ASCT2 in different tissues, we found its expression level in muscle was significantly higher than that in intestine (p < 0.05). In addition, the expression levels of ASCT2 also appeared different in diurnal variation. Then we found the addition of 2.5% glutamate in a feeding diet significantly increased the expression levels of ASCT2 in intestine and muscle (p < 0.05). However, in glutamine experiments, the muscle showed the highest expression level of ASCT2 when fish were fed the diet containing 3.0% glutamine (p < 0.05). In vitro, ASCT2 was sensitive to glutamine and its expression level appeared down-regulated when the addition of glutamine was added to 0.1 mg/mL. Finally, we found that the diet with 29% protein level significantly increased the expression level of ASCT2 in intestine (p < 0.05). Nevertheless, different protein sources (fish meal and soybean meal) had no significant effect on the expression levels of ASCT2 in intestine and muscle (p > 0.05). These results provided data for the study of ASCT2 in triploid crucian carp regulated by feeding nutrition, which had a potential application in improving feed formulation in aquaculture. Full article
(This article belongs to the Section Nutrition and Feeding)
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15 pages, 967 KiB  
Review
Probiotics Have the Potential to Significantly Mitigate the Environmental Impact of Freshwater Fish Farms
by Cosmas Nathanailides, Markos Kolygas, Konstantina Choremi, Theodoros Mavraganis, Evangelia Gouva, Kosmas Vidalis and Fotini Athanassopoulou
Fishes 2021, 6(4), 76; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040076 - 08 Dec 2021
Cited by 15 | Viewed by 7430
Abstract
Probiotics for freshwater fish farming can be administered as single or multiple mixtures. The expected benefits of probiotics include disease prophylaxis, improved growth, and feed conversion parameters, such as the feed conversion rate (FCR) and specific growth rate (SGR). In the current work, [...] Read more.
Probiotics for freshwater fish farming can be administered as single or multiple mixtures. The expected benefits of probiotics include disease prophylaxis, improved growth, and feed conversion parameters, such as the feed conversion rate (FCR) and specific growth rate (SGR). In the current work, we review the impact of probiotics on freshwater finfish aquaculture. Data were gathered from articles published during the last decade that examined the effects of probiotics on fish growth, FCR, and water quality in freshwater fishponds/tanks. While the expected benefits of probiotics are significant, the reviewed data indicate a range in the level of effects, with an average reduction in ammonia of 50.7%, SGR increase of 17.1%, and FCR decrease of 10.7%. Despite the variability in the reported benefits, probiotics appear to offer a practical solution for sustainable freshwater aquaculture. Disease prophylaxis with probiotics can reduce the need for antibiotics and maintain gut health and feed conversion. Considering that fish feed and waste are two significant parameters of the aquaculture ecological footprint, it can be argued that probiotics can contribute to reducing the environmental impact of aquaculture. In this direction, it would be beneficial if more researchers incorporated water quality parameters in future aquaculture research and protocols to minimize aquaculture’s environmental impact. Full article
(This article belongs to the Special Issue Environmental Impacts of Land-Based Aquaculture)
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13 pages, 1974 KiB  
Communication
Behavioral Interactions between a Native and an Invasive Fish Species in a Thermally Heterogeneous Experimental Chamber
by Lindsy R. Ciepiela, Ryan M. Fitzpatrick, Samuel T. Lewis and Yoichiro Kanno
Fishes 2021, 6(4), 75; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040075 - 07 Dec 2021
Cited by 1 | Viewed by 2409
Abstract
Mechanisms of the displacement of native fish by nonnative fish can include agonistic behaviors that push native fish species out of their preferred habitat, including their thermal optima. To examine these interactions, we built an experimental thermal preference chamber to evaluate: (1) the [...] Read more.
Mechanisms of the displacement of native fish by nonnative fish can include agonistic behaviors that push native fish species out of their preferred habitat, including their thermal optima. To examine these interactions, we built an experimental thermal preference chamber to evaluate: (1) the thermal preference of native, glacial relict northern redbelly dace Chrosomus eos; (2) if the thermal preference and movement changed in the presence of the invasive western mosquitofish Gambusia affinis; and (3) the direction of agonistic interactions. We hypothesized that G. affinis would express agonistic behavior toward C. eos, because G. affinis is widely recognized as an aggressive invader. Given the temperature range of the experimental chamber, i.e., 20–30 °C, C. eos selected an average of 24.3 °C as its thermal preference. After G. affinis’ introduction, the thermal preference of C. eos increased by 1.7 °C and the movement, given by distance (cm) travelled, increased by 21%. Contrary to our prediction, more agonistic interactions were observed in C. eos toward G. affinis. These results indicate that agonistic behavior of G. affinis toward native fish species may be species- and condition-specific, and may not always be the primary mechanism of native species’ displacement. Biological invasions are a global issue and altered thermal regimes are expected to continue. This study provided the novel approach using of a thermally heterogeneous thermal chamber to examine thermal preferences and aggressive interactions between a native and an invasive species. Future research should examine other life history traits that may be conveying the competitive advantage to G. affinis. Full article
(This article belongs to the Section Biology and Ecology)
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12 pages, 3482 KiB  
Article
Design and Fabrication of an Automatic Fish Feeder Prototype Suits Tilapia Tanks
by Ahmed Mohamed El Shal, Faisal Mohamed El Sheikh and Atef Mohamed Elsbaay
Fishes 2021, 6(4), 74; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040074 - 06 Dec 2021
Cited by 5 | Viewed by 12163
Abstract
The conventional methods of supplying feed to tilapia tanks are ineffective. It is better to find new a automatic feeder saving pellets from crushing and cohesion without hitting pellets during feeding at a predetermined interval of time and an accurate amount of food [...] Read more.
The conventional methods of supplying feed to tilapia tanks are ineffective. It is better to find new a automatic feeder saving pellets from crushing and cohesion without hitting pellets during feeding at a predetermined interval of time and an accurate amount of food with a larger surface area covered by pellets. Developing-country fish farmers use manual feeding to be more cost-effective than with costly mechanized feeding, so this research aimed to design and construct an automatic fish feeder prototype to feed tilapia in a recirculation aquaculture system’s tank. The performance of the prototype was studied after it was designed and installed. The dispensed feed operated by a DC motor located underneath the pellet hopper and the feed material was discharged into the tank through a gate in the bottom of the feeder. Three pellet sizes, three rotation speeds, and three feeder heights from the water’s surface were used to test the automatic feeder’s efficiency. The results showed that the optimal speed for the automatic feeder was 14 rpm with a height of 70 cm, resulting in a distribution width of 26.6 cm and a high automatic feeder efficiency of 99.9%. Furthermore, the feeder used very little electricity and saved time, cost, labor, energy, and pellets. Full article
(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)
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9 pages, 477 KiB  
Communication
Hidden Giants: The Story of Bolbometopon muricatum at Ningaloo Reef
by Damian P. Thomson, Anna K. Cresswell, Christopher Doropoulos, Michael D. E. Haywood, Melanie Orr and Andrew S. Hoey
Fishes 2021, 6(4), 73; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040073 - 06 Dec 2021
Cited by 2 | Viewed by 2606
Abstract
Bolbometopon muricatum (bumphead parrotfish, Valenciennes, 1839) is a conspicuous, iconic and ecologically important coral reef fish species. B. muricatum plays an important role in the bioerosion of the reef framework and as a result has been described as both an ecosystem engineer and [...] Read more.
Bolbometopon muricatum (bumphead parrotfish, Valenciennes, 1839) is a conspicuous, iconic and ecologically important coral reef fish species. B. muricatum plays an important role in the bioerosion of the reef framework and as a result has been described as both an ecosystem engineer and keystone species. Despite the complete absence of B. muricatum from 32 years of scientific surveys across the Ningaloo Reef World Heritage Area, we recorded a total of 155 individuals of B. muricatum across 63.2 ha of reef crest surveys, equating to mean density of 2.38 ind/ha. Our observations represent the first record of this iconic species in scientific surveys at Ningaloo and in combination with qualitative observations of B. muricatum by expert witnesses, indicate B. muricatum is likely to have been present in ecologically relevant densities since 2006. The densities of B. muricatum observed at northern Ningaloo in 2021 suggest this species is removing an estimated 13.42 tonnes/ha or 1.34 kg/m2 of calcium carbonate per year, which is broadly comparable with estimates of total parrotfish bioerosion across many reefs in the central Indian and Pacific Oceans. Although not currently afforded elevated conservation status within management plans, B. muricatum possess many life-history characteristics that make them vulnerable to overfishing and may justify consideration for increased protection within the world heritage listed Ningaloo Reef Marine Park. Full article
(This article belongs to the Section Biology and Ecology)
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12 pages, 1165 KiB  
Article
Concentration of Metals in Native and Invasive Species of Fish in the Fluvial-Lagoon-Deltaic System of the Palizada River, Campeche
by María del Refugio Castañeda-Chávez, Fabiola Lango-Reynoso, Gabycarmen Navarrete-Rodríguez and Armando Toyokazu Wakida-Kusunoki
Fishes 2021, 6(4), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040072 - 03 Dec 2021
Cited by 1 | Viewed by 2559
Abstract
Aquatic organisms, such as fish, are important indicators of the bioavailability of metals in coastal environments, demonstrating the capacity of different species to bioaccumulate these metallic elements. The fluvial-lagoon system of the Palizada River is an important ecosystem for its terrestrial and aquatic [...] Read more.
Aquatic organisms, such as fish, are important indicators of the bioavailability of metals in coastal environments, demonstrating the capacity of different species to bioaccumulate these metallic elements. The fluvial-lagoon system of the Palizada River is an important ecosystem for its terrestrial and aquatic biological diversity where fishing is an important productive activity in this system. The objective of this research was to evaluate the concentration of Pb and Cd in the muscle tissue of native and invasive fish species in this area. For this, the digestion of fish muscle samples was carried out with a CEM MARS 5 Digestion Microwave System, while the quantification of metals was performed with an atomic absorption equipment. All analysis muscle samples from native and invasive fish showed Pb and Cd in their content. By sampling site there was a statistically significant difference (p < 0.05), with a maximum Pb concentration of 7.760 µg g−1 at the LLAR site (Laguna Larga). In terms of species, the maximum Cd concentration was obtained in the Cyprinus carpio with 6.630 ± 0.127 and in Pterygoplichthus pardalis with 6.547 ± 0.873 µg g−1 (dry weight). The presence of metals such as Pb and Cd in muscle tissue of native and invasive fish species represents an important bioindicator of environmental exposure in the study area and a potential risk to public health, as these species are commonly consumed. Full article
(This article belongs to the Special Issue Assessment of Fisheries Impact on Species and Marine Ecosystems)
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11 pages, 2179 KiB  
Article
Spatial and Temporal Variability of Parasite Communities: Implications for Fish Stock Identification
by Juan F. Espínola-Novelo and Marcelo E. Oliva
Fishes 2021, 6(4), 71; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040071 - 03 Dec 2021
Cited by 6 | Viewed by 2691
Abstract
The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and [...] Read more.
The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and 2017. To avoid the potential effect of host age in parasite communities, individuals of similar ages were selected: 1123 Engraulis ringens (12–24 months old), 1904 Trachurus murphyi (24–36 months old), and 630 Merluccius gayi (36–48 months old). Most taxa show differences in the prevalence at the spatial and temporal scales, but the prevalence of some larval endoparasites remains constant at the temporal scale. At the spatial scale, an analysis of similarity (ANOSIM) showed differences in the parasite communities of three species; a canonical analysis of principal coordinates (CAP) showed low values of correct allocations (CA; ≈50%) and values of allocation due to chance (AdC) were lower than the CA. At the temporal scale, an ANOSIM showed differences between the three species. A CAP showed low values of CA (≈50–60%) and the AdC was always lower than CA. Samples at the spatial scale were well allocated to their localities or nearby localities, suggesting a spatial stability. Samples from different years were not well discriminated, suggesting temporal variability. Therefore, in studies regarding parasites as a tool for stock identification, temporal variability must be taken into account. Full article
(This article belongs to the Section Fishery Economics, Policy, and Management)
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14 pages, 4902 KiB  
Article
Evolution of the Parvalbumin Genes in Teleost Fishes after the Whole-Genome Duplication
by Subham Mukherjee, Oldřich Bartoš, Kamila Zdeňková, Petr Hanák, Petra Horká and Zuzana Musilova
Fishes 2021, 6(4), 70; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040070 - 01 Dec 2021
Cited by 8 | Viewed by 3518
Abstract
Parvalbumin is considered a major fish allergen. Here, we report the molecular evolution of the parvalbumin genes in bony fishes based on 19 whole genomes and 70 transcriptomes. We found unexpectedly high parvalbumin diversity in teleosts; three main gene types (pvalb-α, [...] Read more.
Parvalbumin is considered a major fish allergen. Here, we report the molecular evolution of the parvalbumin genes in bony fishes based on 19 whole genomes and 70 transcriptomes. We found unexpectedly high parvalbumin diversity in teleosts; three main gene types (pvalb-α, pvalb-β1, and pvalb-β2, including oncomodulins) originated at the onset of vertebrates. Teleosts have further multiplied the parvalbumin gene repertoire up to nine ancestral copies—two copies of pvalb-α, two copies of pvalb-β1, and five copies of pvalb-β2. This gene diversity is a result of teleost-specific whole-genome duplication. Two conserved parvalbumin genomic clusters carry pvalb-β1 and β2 copies, whereas pvalb-α genes are located separately in different linkage groups. Further, we investigated parvalbumin gene expression in 17 tissues of the common carp (Cyprinus carpio), a species with 21 parvalbumin genes in its genome. Two pvalb-α and eight pvalb-β2 copies are highly expressed in the muscle, while two alternative pvalb-α copies show expression in the brain and the testes, and pvalb-β1 is dominant in the retina and the kidney. The recent pairs of muscular pvalb-β2 genes show differential expression in this species. We provide robust genomic evidence of the complex evolution of the parvalbumin genes in fishes. Full article
(This article belongs to the Section Genetics and Biotechnology)
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7 pages, 196 KiB  
Editorial
Introduction to the Biology and Control of Invasive Fishes and a Special Issue on This Topic
by Peter W. Sorensen
Fishes 2021, 6(4), 69; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040069 - 30 Nov 2021
Cited by 4 | Viewed by 2654
Abstract
Across the globe, dozens of species of invasive fish are now found in fresh as well as marine waters, where they alter habitats, compete with native fish for food, and prey on native fishes, exerting both indirect and direct effects on ecosystems and [...] Read more.
Across the globe, dozens of species of invasive fish are now found in fresh as well as marine waters, where they alter habitats, compete with native fish for food, and prey on native fishes, exerting both indirect and direct effects on ecosystems and economies. While efforts to understand and control these species are growing, most are still in their infancy; however, a few examples stand out. This special issue is comprised of 11 notable articles on freshwater invasive fish and is the first to address this topic. This introductory article serves as an introduction to these articles which focus on 5 topics on invasive freshwater fish: (1) the damage they cause (one article); (2) techniques to ascertain their presence (one article); (3) techniques to restrict their movement (one article); (4) strategies to control them (three articles); and (5) lessons learned from ongoing management efforts (five articles). This introduction notes that successful management efforts share a few approaches: (1) they develop and use a deep understanding of local species and their abundance as well as distribution; (2) they focus on reducing reproductive success; (3) they use multiple complimentary control strategies; and (4) they use a long-term approach. Full article
(This article belongs to the Special Issue Biology and Control of Invasive Fishes)
15 pages, 1067 KiB  
Article
Comparative Pharmacokinetics and Tissue Concentrations of Flunixin Meglumine and Meloxicam in Tilapia (Oreochromis spp.)
by Miriam Martin, Stephen Smith, Michael Kleinhenz, Geraldine Magnin, Zhoumeng Lin, David Kuhn, Shawnee Montgomery and Johann Coetzee
Fishes 2021, 6(4), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040068 - 25 Nov 2021
Cited by 5 | Viewed by 3426
Abstract
Evidence of pain perception in fish is well established, but analgesic use in aquaculture is limited. The objective was to investigate the comparative pharmacokinetics of flunixin administered intramuscularly (IM) and meloxicam administered IM or orally (PO) in tilapia. Two hundred and seventy fish [...] Read more.
Evidence of pain perception in fish is well established, but analgesic use in aquaculture is limited. The objective was to investigate the comparative pharmacokinetics of flunixin administered intramuscularly (IM) and meloxicam administered IM or orally (PO) in tilapia. Two hundred and seventy fish were assigned to 1 of 3 treatment groups: flunixin meglumine IM (2.2 mg/kg); meloxicam IM (1 mg/kg); or meloxicam PO (1 mg/kg). Blood and tissue samples were collected from 6 fish per treatment at 14 time points for 10 days. Drug concentrations were determined using ultra-high-pressure liquid chromatography coupled with mass spectroscopy. Plasma concentration versus time data were analyzed with a non-compartmental approach using a commercially available software. Flunixin reached a mean maximum concentration (Cmax) of 4826.7 ng/mL at 0.5 h, had a terminal half-life (T1/2) of 7.34 h, and an area under the concentration–time curve extrapolated to infinity (AUCINF_obs) of 25,261.62 h·ng/mL. Meloxicam IM had a T1/2 of 9.4 h after reaching a Cmax of 11.3 ng/mL at 2 h, with an AUCINF_obs of 150.31 h·ng/mL. Meloxicam PO had a T1/2 of 1.9 h after reaching a Cmax of 72.2 ng/mL at 2 h, with an AUCINF_obs of 400.83 h·ng/mL. Tissue concentrations of both drugs were undetectable by 9 h. Flunixin reached a sufficient plasma concentration to potentially have an analgesic effect, while meloxicam, when administered at the given dosage, likely would not. Full article
(This article belongs to the Section Welfare, Health and Disease)
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14 pages, 2519 KiB  
Article
Using Isotopic Data to Evaluate Esox lucius (Linnaeus, 1758) Natal Origins in a Hydrologically Complex River Basin
by Ryan M. Fitzpatrick, Dana L. Winkelman and Brett M. Johnson
Fishes 2021, 6(4), 67; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040067 - 22 Nov 2021
Cited by 3 | Viewed by 2318
Abstract
Otolith microchemistry has emerged as a powerful technique with which to identify the natal origins of fishes, but it relies on differences in underlying geology that may occur over large spatial scales. An examination of how small a spatial scale on which this [...] Read more.
Otolith microchemistry has emerged as a powerful technique with which to identify the natal origins of fishes, but it relies on differences in underlying geology that may occur over large spatial scales. An examination of how small a spatial scale on which this technique can be implemented, especially in water bodies that share a large proportion of their flow, would be useful for guiding aquatic invasive species control efforts. We examined trace isotopic signatures in northern pike (Esox lucius) otoliths to estimate their provenance between two reservoirs in the Upper Yampa River Basin, Colorado, USA. This is a challenging study area as these reservoirs are only 11-rkm apart on the same river and thus share a high proportion of their inflow. We found that three isotopes (86Sr, 137Ba, and 55Mn) were useful in discriminating between these reservoirs, but their signatures varied annually, and the values overlapped. Strontium isotope ratios (87Sr/86Sr) were different between sites and relatively stable across three years, which made them an ideal marker for determining northern pike provenance. Our study demonstrates the usefulness of otolith microchemistry for natal origin determination within the same river over a relatively small spatial scale when there are geologic differences between sites, especially geologic differences underlying tributaries between sites. Full article
(This article belongs to the Section Fishery Economics, Policy, and Management)
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12 pages, 3228 KiB  
Article
Effects of Different Temperatures on the Antibacterial, Immune and Growth Performance of Crucian Carp Epidermal Mucus
by Bin Wang, Guoxin Ma, Yong Liu, Yafei Wang, Xiaoxue Du, Qiang Shi and Hanping Mao
Fishes 2021, 6(4), 66; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040066 - 22 Nov 2021
Cited by 8 | Viewed by 2980
Abstract
Fish is one of the important sources of energy and protein, and proper water temperature is key to successful fish breeding. The authors of this study evaluated crucian carp growth, mucus antibacterial properties, and immune indicators at 17, 21, 24, 27, and 31 [...] Read more.
Fish is one of the important sources of energy and protein, and proper water temperature is key to successful fish breeding. The authors of this study evaluated crucian carp growth, mucus antibacterial properties, and immune indicators at 17, 21, 24, 27, and 31 °C. The results indicated that in the range of 17–31 °C, the resistance of epidermal mucus to Vibrio harveyi decreased with temperature rising. At 24 and 27 °C, the activities of lysozyme and catalase significantly increased; alkaline phosphatase activity, superoxide dismutase activity, and total protein concentration first increased and then decreased with rising temperature; the highest values were observed at 24 °C, with increases of 56.55%, 26.64%, and 44.52%, respectively, compared to those under the 17 °C treatment. When the treatment reached 27 °C, the temperature had an effect on the growth and antibacterial properties of crucian carp, and the activities of alkaline phosphatase and superoxide dismutase were significantly reduced. At temperatures of 17–24 °C, the survival rate of crucian carp could reach more than 93%, and at the temperature of 24 °C, the specific growth rate reached the highest value of 43.29%. Therefore, the most favorable temperature for the long-term breeding of crucian carp was found to be 24 °C. This study provides a favorable experimental basis for the establishment of intelligent aquaculture systems and the setting of water environment parameters. Full article
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21 pages, 101898 KiB  
Article
Feasibility Research on Fish Pose Estimation Based on Rotating Box Object Detection
by Bin Lin, Kailin Jiang, Zhiqi Xu, Feiyi Li, Jiao Li, Chaoli Mou, Xinyao Gong and Xuliang Duan
Fishes 2021, 6(4), 65; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040065 - 19 Nov 2021
Cited by 6 | Viewed by 4119
Abstract
A video-based method to quantify animal posture movement is a powerful way to analyze animal behavior. Both humans and fish can judge the physiological state through the skeleton framework. However, it is challenging for farmers to judge the breeding state in the complex [...] Read more.
A video-based method to quantify animal posture movement is a powerful way to analyze animal behavior. Both humans and fish can judge the physiological state through the skeleton framework. However, it is challenging for farmers to judge the breeding state in the complex underwater environment. Therefore, images can be transmitted by the underwater camera and monitored by a computer vision model. However, it lacks datasets in artificial intelligence and is unable to train deep neural networks. The main contributions of this paper include: (1) the world’s first fish posture database is established. 10 key points of each fish are manually marked. The fish flock images were taken in the experimental tank and 1000 single fish images were separated from the fish flock. (2) A two-stage attitude estimation model is used to detect fish key points. The evaluation of the algorithm performance indicates the precision of detection reaches 90.61%, F1-score reaches 90%, and Fps also reaches 23.26. We made a preliminary exploration on the pose estimation of fish and provided a feasible idea for fish pose estimation. Full article
(This article belongs to the Section Sustainable Aquaculture)
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16 pages, 1628 KiB  
Article
Survival and Physiological Recovery after Capture by Hookline: The Case Study of the Blackspot Seabream (Pagellus bogaraveo)
by Ignacio Ruiz-Jarabo, Miriam Fernández-Castro, Ismael Jerez-Cepa, Cristina Barragán-Méndez, Montse Pérez, Evaristo Pérez, Juan Gil, Jesús Canoura, Carlos Farias, Juan Miguel Mancera and Ignacio Sobrino
Fishes 2021, 6(4), 64; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040064 - 17 Nov 2021
Cited by 2 | Viewed by 3027
Abstract
Evaluating the survival of discarded species is gaining momentum after the new European Common Fisheries Policy (Article 15 of the European Regulation No. 1380/2013). This regulation introduced a discard ban, with an exemption for those species with demonstrated high survival rates after their [...] Read more.
Evaluating the survival of discarded species is gaining momentum after the new European Common Fisheries Policy (Article 15 of the European Regulation No. 1380/2013). This regulation introduced a discard ban, with an exemption for those species with demonstrated high survival rates after their capture and release. Candidate species should be evaluated for each fishing gear and geographical area. In this study, we assessed not only survival, but also physiological recovery rates of blackspot seabream (Pagellus bogaraveo) below commercial size captured with a hookline called “voracera” in the Strait of Gibraltar (SW Atlantic waters of Europe). Experiments onboard a commercial fishing vessel were paralleled with studies in controlled ground-based facilities, where the capture process was mimicked, and physiological recovery markers were described. Our results confirmed that hookline capture induced acute stress responses in the target species, such as changes in plasma cortisol, lactate, glucose, and osmolality. However, 90.6% of the blackspot seabreams below commercial size captured with this fishing gear managed to survive, and evidenced physiological recovery responses 5 h after capture, with complete homeostatic recovery occurring within the first 24 h. Based on this study, the European Commission approved an exemption from the discard (EU Commission Delegated Regulation 6794/2018). Thus, the robust methodology described herein can be an important tool to mitigate the problem of discards in Europe. Full article
(This article belongs to the Section Fishery Economics, Policy, and Management)
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15 pages, 1584 KiB  
Article
Effects of Single or Combined Administration of Dietary Synbiotic and Sodium Propionate on Humoral Immunity and Oxidative Defense, Digestive Enzymes and Growth Performances of African Cichlid (Labidochromis lividus) Challenged with Aeromonas hydrophila
by Omid Safari, Mehrdad Sarkheil, Davar Shahsavani and Marina Paolucci
Fishes 2021, 6(4), 63; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040063 - 15 Nov 2021
Cited by 9 | Viewed by 2517
Abstract
The aim of the present study was to investigate the potential effects of dietary synbiotic (SYN) (Pediococcus acidilactici + Galactooligosaccharides; 10 g kg−1), sodium propionate (SP; 5, 10 and 20 g kg−1) and a combination of SYN + [...] Read more.
The aim of the present study was to investigate the potential effects of dietary synbiotic (SYN) (Pediococcus acidilactici + Galactooligosaccharides; 10 g kg−1), sodium propionate (SP; 5, 10 and 20 g kg−1) and a combination of SYN + SP on the growth performance, humoral immunity, antioxidant responses and disease resistance against Aeromonas hydrophila of African cichlid (Labidochromis lividus) fingerlings (0.52 ± 0.05 g) in a feeding trial lasting 63 days. A completely randomized design was run with eight treatments, including 0 (control) and supplemented diets containing SYN + SP (e.g., 10 + 5, 10 + 10, 10 + 20, 0 + 5, 0 + 10, 0 + 20 and 10 + 10). The lowest feed conversion ratio value was observed in fish fed the 5 g kg−1-SP and 10 g kg−1-SYN (p < 0.05). The highest values of protein efficiency ratio and protein productive value were recorded in fish fed the 10 g kg−1-SYN (p < 0.05). Fish fed the 10 g kg−1-SYN diet had the highest activities of immunity (lysozyme, immunoglobulin) and antioxidant responses (glutathione peroxidase and superoxide dismutase) (p < 0.05). After 28 days post-challenge, the highest survival rate (57%) was recorded in the diet containing 10 g kg−1 SYN and 5 g kg−1 SP. The results indicated that the single administration of SYN or combined with SP, especially at the level of 5 g kg−1 of diet, enhanced the survival and growth performances, humoral immune response, antioxidant and digestive enzymes of African cichlid. Full article
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16 pages, 2452 KiB  
Article
Seasonal Changes in Plasma Hormones, Sex-Related Genes Transcription in Brain, Liver and Ovary during Gonadal Development in Female Rainbow Trout (Oncorhynchus mykiss)
by Huiqin Chen, Baoliang Bi, Lingfu Kong, Hua Rong, Yanhua Su and Qing Hu
Fishes 2021, 6(4), 62; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040062 - 12 Nov 2021
Cited by 3 | Viewed by 4281
Abstract
The purpose of this study was to investigate the periodic seasonal changes in endocrine activity and gonadal development of female rainbow trout (Oncorhynchus mykiss) in a high-altitude cold-water environment. The fish were sampled monthly from January to November and the levels [...] Read more.
The purpose of this study was to investigate the periodic seasonal changes in endocrine activity and gonadal development of female rainbow trout (Oncorhynchus mykiss) in a high-altitude cold-water environment. The fish were sampled monthly from January to November and the levels of plasma hormones (estradiol (E2), cortisol and thyroid hormones (THS)) and vitellogenin (VTG) were measured by ELISA. Moreover, the transcriptions of sex-related genes in the ovary, brain, and liver were detected by qRT-PCR. The results showed a seasonal fluctuation of plasma hormones and VTG together with the development of the ovary, which reached a peak from August to October. Similarly, the transcription of hypothalamic gonadotropin-releasing hormone-2 (cgnrh-2), hypothalamic gonadotropin-releasing hormone receptors (gnrhr) and follicle-stimulating hormone (fsh) in the brain varied from January to September, but the highest level was detected in September to November. In addition, the transcription of sex-related genes located in the ovary and liver increased significantly during August to October, accompanied by a continuous increase in the gonadosomatic index (GSI) and a decrease in the hepatosomatic index (HSI). Therefore, plasma hormones and sex-related genes regulate the development and maturation of O. mykiss oocytes with the change in seasons and peaked in November. The results of this study provide a reference for improving the efficiency of the artificial reproduction of O. mykiss. Full article
(This article belongs to the Section Physiology and Biochemistry)
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15 pages, 976 KiB  
Article
Antimicrobial and Toxic Activity of Citronella Essential Oil (Cymbopogon nardus), and Its Effect on the Growth and Metabolism of Gilthead Seabream (Sparus aurata L.)
by Jorge García-Márquez, Andre Barany, Álvaro Broz Ruiz, Benjamín Costas, Salvador Arijo and Juan Miguel Mancera
Fishes 2021, 6(4), 61; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040061 - 12 Nov 2021
Cited by 4 | Viewed by 2792
Abstract
Aquaculture procedures usually induce stress that affects the physiological status of fish. For this reason, the inclusion of additives in fish feeds to palliate stress might be a good alternative. This study aimed to assess the antimicrobial activity of citronella (Cymbopogon nardus [...] Read more.
Aquaculture procedures usually induce stress that affects the physiological status of fish. For this reason, the inclusion of additives in fish feeds to palliate stress might be a good alternative. This study aimed to assess the antimicrobial activity of citronella (Cymbopogon nardus) essential oil (CEO) against bacterial pathogens and to determine its dietary impact on the growth performance of Sparus aurata. In vitro tests confirmed that CEO possesses antimicrobial activity against several fish-specific pathogens. For the in vivo tests, three experimental groups were fed for 60 days with different concentrations of CEO: CTRL (0 mL kg−1 fish feed); CEO1 (1 mL kg−1 fish feed); and CEO2 (2 mL kg−1 fish feed). At the end of the experiment, the physiological status was characterized. Subsequently, the specimens of the CTRL and CEO2 groups were subjected to a challenge with an injection of Poly I:C for immune stimulation. Although S. aurata individuals tolerated CEO inclusion without compromising growth performance, it significantly reduced glycogen in the CEO2 group, concomitant to an increment of total peripheral leucocytes. Moreover, different hematological profiles’ responsive patterns against an inflammatory stimulus were observed. In conclusion, our results suggest that the use of CEO as a fish feed additive can prevent bacterial outbreaks and improve potential in vivo disease resistance in S. aurata without negatively affecting growth. Full article
(This article belongs to the Special Issue Phytochemicals in Aquaculture)
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11 pages, 1073 KiB  
Article
The Standard Deviation Structure as a New Approach to Growth Analysis in Weight and Length Data of Farmed Lutjanus guttatus
by Sergio G. Castillo-Vargasmachuca, Eugenio Alberto Aragón-Noriega, Guillermo Rodríguez-Domínguez, Leonardo Martínez-Cárdenas, Eulalio Arámbul-Muñoz and Álvaro J. Burgos Arcos
Fishes 2021, 6(4), 60; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040060 - 12 Nov 2021
Cited by 1 | Viewed by 2485
Abstract
In the present study, size-at-age data (length and weight) of marine cage-reared spotted rose snapper Lutjanus guttatus were analyzed under four different variance assumptions (observed, constant, depensatory, and compensatory variances) to analyze the robustness of selecting the right standard deviation structure to parametrize [...] Read more.
In the present study, size-at-age data (length and weight) of marine cage-reared spotted rose snapper Lutjanus guttatus were analyzed under four different variance assumptions (observed, constant, depensatory, and compensatory variances) to analyze the robustness of selecting the right standard deviation structure to parametrize the von Bertalanffy, Logistic, and Gompertz models. The selection of the best model and variance criteria was obtained based on the Bayesian information criterion (BIC). According to the BIC results, the observed variance in the present study was the best way to parametrize the three abovementioned growth models, and the Gompertz model best represented the length and weight growth curves. Based on these results, using the observed error structure to calculate the growth parameters in multi-model inference analyses is recommended. Full article
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13 pages, 1024 KiB  
Article
Technical Efficiency and Output Losses in Shrimp Farming: A Case in Mekong Delta, Vietnam
by Keo Sa Rate Thach, Hong Tu Vo and Ji-Yong Lee
Fishes 2021, 6(4), 59; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040059 - 11 Nov 2021
Cited by 3 | Viewed by 3160
Abstract
The conversion from black tiger shrimp farming and crop farming to white leg shrimp production is widespread in Vietnam’s Mekong Delta provinces. However, this conversion trend also contains many risks related to the technical aspects of the production process. The study mainly aims [...] Read more.
The conversion from black tiger shrimp farming and crop farming to white leg shrimp production is widespread in Vietnam’s Mekong Delta provinces. However, this conversion trend also contains many risks related to the technical aspects of the production process. The study mainly aims to estimate the technical efficiency of white leg shrimp farming. It also compares the technical efficiency of white leg shrimp farming between the traditional group that historically has cultivated white leg shrimp and the group that recently converted from black tiger shrimp and crops to white leg shrimp, in order to evaluate the efficiency and adaptability of shrimp farming. Primary data were collected by directly interviewing 99 farmers in traditional areas and 101 farmers in recently converted areas in the study sites and analyzed by using the stochastic frontier method. The calculated technical efficiency was around 72.9 percent, suggesting that farmers could increase their output level by about 27.1%, given constant inputs. There was no difference in the technical efficiency of the two groups, indicating that the converted farms have sufficient adaptability when switching to white leg shrimp farming. The output loss in farmers’ production is still very high, with an average loss of 1973 kg/hectare. Full article
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16 pages, 4552 KiB  
Article
Effects of Food Deprivation Duration on the Behavior and Metabolism of Black Rockfish (Sebastes schlegelii)
by Fengyuan Shen, Zonghang Zhang, Yiqiu Fu, Zhen Zhang, Xin Sun, Jianyu Dong, Xiayang Ding, Muyan Chen and Xiumei Zhang
Fishes 2021, 6(4), 58; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040058 - 06 Nov 2021
Cited by 8 | Viewed by 2835
Abstract
Fish often undergo food shortages in nature, especially for juveniles that are relatively vulnerable in most aspects. Therefore, the effects of food deprivation on fish behavior and physiology are worth exploring. Here, we investigated the behavioral and metabolic adaptations of the juvenile black [...] Read more.
Fish often undergo food shortages in nature, especially for juveniles that are relatively vulnerable in most aspects. Therefore, the effects of food deprivation on fish behavior and physiology are worth exploring. Here, we investigated the behavioral and metabolic adaptations of the juvenile black rockfish Sebastes schlegelii to different durations of food deprivation. In this study, three treatments were set: control group, short-term food deprivation (STFD) group, and long-term food deprivation (LTFD) group. The rearing lasted for six weeks. During this period, videos were recorded three times per week to assess the locomotor activity and aggression. After this, the fishes’ boldness, neophobia, and aggressiveness were assessed using different behavioral assessment devices, while the standard metabolic rate (SMR) was measured by flow-type respirometry. In general, the values of the four indicators (swimming time, the number of turns, movement number, and attack number) for the STFD group were significantly higher than those for the control and LTFD group during the same period of rearing. In a subsequent personality assessment, the STFD group was observed to be significantly bolder in an assessment measuring boldness than the control and LTFD group (indicated by time in the circle, swimming time, number of times through the circle, and frequency in the circle). The LTFD group was observed to be more exploratory in the assessment of neophobia (indicated by duration in the exploratory area, distance from novelty item, and frequency of stay in the exploratory area). Indeed, the LTFD group was observed to be significantly less aggressive in the assessment of aggressiveness than the control and STFD group (indicated by attack number, attack range frequency, first attack, and winner). SMR was noted to be significantly higher in the STFD group than in the control and LTFD group. In conclusion, this study firstly reported the effects of food deprivation duration on the personalities of black rockfish, as well as the behavioral and physiological mechanisms. Thus, we hope to provide insights into the work of stock enhancement. Full article
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17 pages, 2181 KiB  
Article
The Innate Immune Response to Infection by Polyascus gregaria in the Male Chinese Mitten Crab (Eriocheir sinensis), Revealed by Proteomic Analysis
by Yanping Yang, Fengjiao Ma, Juanjuan Dong, Lianxing Li, Ping Ren, Yuning Zhang, Yatao Wu, Yinping Wang, Kai Liu and Fang Zhang
Fishes 2021, 6(4), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040057 - 04 Nov 2021
Cited by 3 | Viewed by 2676
Abstract
The Chinese mitten crab (Eriocheir sinensis) is a representative catadromous invertebrate of the Yangtze River and a commercial species widely cultivated in China. Both cultivated and wild crabs suffer from a variety of parasites and pathogens, which can result in catastrophic [...] Read more.
The Chinese mitten crab (Eriocheir sinensis) is a representative catadromous invertebrate of the Yangtze River and a commercial species widely cultivated in China. Both cultivated and wild crabs suffer from a variety of parasites and pathogens, which can result in catastrophic economic losses in aquaculture revenue. Polyascus gregaria, a parasitic barnacle with a highly derived morphology, is specialized in invading these crabs. This study examines the immunological mechanism in E. sinensis infected with P. gregaria. Tandem mass tags (TMT), a specialized method of mass-spectrometry, was used to analyze the infection by P. gregaria resistance at the protein level. In the hepatopancreas of infected crabs, 598 proteins differentially expressed relating to physiological change, of which, 352 were upregulated and 246 were downregulated. Based on this differential protein expression, 104 GO terms and 13 KEGG pathways were significantly enriched. Differentially expressed proteins, such as ATG, cathepsin, serpin, iron-related protein, Rab family, integrin, and lectin, are associated with the lysosome GO term and the autophagy-animal KEGG pathways, both of which likely relate to the immune response to the parasitic P. gregaria infection. These results show the benefit of taking a detailed, protein-level approach to understanding the innate immune response of aquatic invertebrates to macroparasite infection. Full article
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9 pages, 2159 KiB  
Communication
Carps, Catla catla, Cirrhinus mrigala and Hypophthalmichthys molitrix Are Resistant to Experimental Infection with Tilapia Lake Virus (TiLV)
by Pravata Kumar Pradhan, Dev Kumar Verma, Shrish Chandra Yadav, Atul Krishna Dev, Thangaraj Raja Swaminathan, Anutosh Paria, Rajendran Kooloth Valappil and Neeraj Sood
Fishes 2021, 6(4), 56; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040056 - 01 Nov 2021
Cited by 2 | Viewed by 2881
Abstract
Tilapia tilapinevirus, also known as tilapia lake virus (TiLV), is an emerging fish virus that primarily affects tilapines. However, the virus has also been detected in a few non-tilapines. As tilapia is generally farmed in polyculture systems along with carps in South [...] Read more.
Tilapia tilapinevirus, also known as tilapia lake virus (TiLV), is an emerging fish virus that primarily affects tilapines. However, the virus has also been detected in a few non-tilapines. As tilapia is generally farmed in polyculture systems along with carps in South Asian countries, there is a likelihood that TiLV-infected tilapia can transmit the virus to the co-cultured species. In view of the above, the susceptibility of three carp species, namely catla (Catla catla), mrigal (Cirrhinus mrigala) and silver carp (Hypophthalmichthys molitrix) was evaluated vis-à-vis tilapia, following experimental infection with TiLV. No clinical signs and histopathological alterations could be observed in carps. RT-qPCR revealed that TiLV copy numbers in liver and brain of all the three carps were almost negligible and did not show any increase with time, suggesting that the virus did not replicate in liver and brain, the target organs of TiLV. Further, TiLV could not be isolated from pooled liver and brain tissues of carps using permissive CFF cell line. On the contrary, in tilapia, typical clinical signs and histopathological lesions were observed and there was significant increase in TiLV copy number up to 6 days post-injection. Furthermore, the virus was successfully isolated from pooled liver and brain tissue of infected tilapia. From the above findings, it could be concluded that C. catla, C. mrigala and H. molitrix are resistant to TiLV infection and unlikely to be carriers for this virus. Full article
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10 pages, 1853 KiB  
Review
Foundation and Prospects of Wild Population Reconstruction of Acipenser dabryanus
by Junyi Li, Hao Du, Jinming Wu, Hui Zhang, Li Shen and Qiwei Wei
Fishes 2021, 6(4), 55; https://0-doi-org.brum.beds.ac.uk/10.3390/fishes6040055 - 30 Oct 2021
Cited by 3 | Viewed by 2043
Abstract
Acipenser dabryanus is an endemic fish inhabiting the upper reaches of the Yangtze River in China. It is classified as a first-class nationally protected animal in China and is listed in the International Union for Conservation of Nature (IUCN) Red List of Critically [...] Read more.
Acipenser dabryanus is an endemic fish inhabiting the upper reaches of the Yangtze River in China. It is classified as a first-class nationally protected animal in China and is listed in the International Union for Conservation of Nature (IUCN) Red List of Critically Endangered Species (CR). Recently, there has been a decrease in natural reproduction of A. dabryanus, and the wild population is almost extinct. This paper summarizes the changes observed in the natural population of A.dabryanus and the factors leading to its endangerment. Based on the process of artificial propagation and achievement of relevant protection goals, this paper presents the concept and technical framework for reconstruction of the wild population of A. dabryanus. In addition, by comprehensively reviewing the research findings and existing problems in the resource protection and monitoring of A. dabryanus in recent years, we assessed the possibility of wild population reconstruction and resource restoration for A. dabryanus. Reconstruction and restoration measures for the wild population of A. dabryanus are proposed, with the aim of providing a scientific basis for the reconstruction of the natural population and the improvement and restoration of critical habitat of this species. Furthermore, it is hoped that this paper will serve as a reference for the protection and restoration of other endangered fishes. Full article
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