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Fishes, Volume 3, Issue 4 (December 2018)

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Cover Story (view full-size image) We followed the reproductive cycle in captivity of wreckfish Polyprion americanus, a late-maturing [...] Read more.
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Open AccessArticle Trade-Offs Underwater: Physiological Plasticity of Rainbow Trout (Onchorhynchus mykiss) Confronted by Multiple Stressors
Received: 13 August 2018 / Revised: 5 November 2018 / Accepted: 11 December 2018 / Published: 16 December 2018
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Abstract
Organisms have evolved mechanisms to partition the available resources between fitness-relevant physiological functions. Organisms possess phenotypic plasticity to acclimate to changing environmental conditions. However, this comes at a cost that can cause negative correlations or “trade-offs”, whereby increasing investments in one function lead
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Organisms have evolved mechanisms to partition the available resources between fitness-relevant physiological functions. Organisms possess phenotypic plasticity to acclimate to changing environmental conditions. However, this comes at a cost that can cause negative correlations or “trade-offs”, whereby increasing investments in one function lead to decreased investments in another function. The aim of the present study was to investigate the prioritization of resource allocation between growth, pathogen defense, and contaminant response in juvenile rainbow trout (Oncorhynchus mykiss) exposed to changes of resource income or expenditure. We performed a multifactorial experiment with three resource-impacting stressors—limited food availability, a parasitic infection, exposure to a vitellogenesis-inducing contaminant—and combinations thereof. Treatment with the individual stressors evoked the expected responses in the respective physiological target systems—body growth, immune system, and hepatic vitellogenin transcription—but we found little evidence for significant negative relations (trade-offs) between the three systems. This also applied to fish exposed to combinations of the stressors. This high phenotypic flexibility of trout in their resource allocation suggests that linear resource allocations as mechanisms of phenotypic plasticity may be too simplistic, but it also may point to a greater capacity of ectothermic than endothermic vertebrates to maintain key physiological processes under competing resource needs due to lower maintenance costs. Full article
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Open AccessArticle Narrowing the Range of Environmental Salinities Where Juvenile Meagre (Argyrosomus regius) Can Be Cultured Based on an Osmoregulatory Pilot Study
Received: 26 September 2018 / Revised: 13 November 2018 / Accepted: 10 December 2018 / Published: 13 December 2018
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Abstract
Aquaculture in Europe aims to diversify and optimize fish farming. The meagre (Argyrosomus regius) arose as a promising species due to its fast growth rates and flesh quality. Thus, it is currently being produced in several Mediterranean countries, mainly in sea-cages
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Aquaculture in Europe aims to diversify and optimize fish farming. The meagre (Argyrosomus regius) arose as a promising species due to its fast growth rates and flesh quality. Thus, it is currently being produced in several Mediterranean countries, mainly in sea-cages and salt-marshes. However, although meagre naturally spend the first years of life in brackish waters, to date it is cultured in seawater. Here, we show that juveniles may not successfully face either freshwater or hyper-osmotic environments as high as 55 ppt salinity. We found that 55 ppt induced catabolism and mobilization of energy metabolites stored in the liver, probably to maintain its osmotic balance. Furthermore, we found that osmoregulatory tissues such as gills managed to maintain plasma osmolality levels without differences in meagre acclimated at 5, 12 and 39 ppt salinity. Our results demonstrate the euryhaline capacity of this species, highlighting that juveniles may be cultured in a wider range of salinities rather than just at seawater. Future studies should focus on optimal environmental salinities for the growth of A. regius juveniles, including long-term experiments limited to the range of 5 ppt to full-strength seawater. Minimizing fish energy consumption in osmoregulation could be economically beneficial for the aquaculture industry in Europe. Full article
(This article belongs to the Special Issue Diversification of Aquaculture with New Fish Species)
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Open AccessReview Potential Human Health Applications from Marine Biomedical Research with Elasmobranch Fishes
Received: 31 October 2018 / Revised: 20 November 2018 / Accepted: 20 November 2018 / Published: 6 December 2018
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Abstract
Members of the subclass of fishes collectively known as elasmobranchs (Class Chondrichthyes, Subclass Elasmobranchii) include sharks, skates, rays, guitarfish, and sawfish. Having diverged from the main line of vertebrate evolution some 400 million years ago, these fishes have continued to be successful in
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Members of the subclass of fishes collectively known as elasmobranchs (Class Chondrichthyes, Subclass Elasmobranchii) include sharks, skates, rays, guitarfish, and sawfish. Having diverged from the main line of vertebrate evolution some 400 million years ago, these fishes have continued to be successful in our ever-changing oceans. Much of their success must be attributed to their uncanny ability to remain healthy. Based on decades of basic research, some of their secrets may be very close to benefitting man. In this short review, some of the molecular and cellular biological areas that show promise for potential human applications are presented. With a brief background and current status of relevant research, these topics include development of new antibiotics and novel treatments for cancer, macular degeneration, viral pathogens, and Parkinson’s disease; potentially useful genomic information from shark transcriptomes; shark antibody-derived drug delivery systems; and immune cell-derived compounds as potential cancer therapeutic agents. Full article
Open AccessArticle Comparative Analysis of the Blood Plasma Metabolome of Negligible, Gradual and Rapidly Ageing Fishes
Received: 9 October 2018 / Revised: 22 November 2018 / Accepted: 30 November 2018 / Published: 4 December 2018
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Abstract
There are a number of different animals that belong to long- and short-lived species and show a various rate of ageing, providing an ideal model to investigate mechanisms of longevity. In this work, a metabolome profiling of blood plasma from fishes with various
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There are a number of different animals that belong to long- and short-lived species and show a various rate of ageing, providing an ideal model to investigate mechanisms of longevity. In this work, a metabolome profiling of blood plasma from fishes with various ageing rates—negligible (Pike Esox Lucius and Sterlet Acipenser ruthenus), gradual (Zander Sander lucioperca and Perch Perca fluviatilis) and rapid (Chum Salmon Oncorhynchus keta and Pink Salmon Oncorhynchus gorbuscha)—was assessed by means of direct infusion to quadrupole time-of-flight mass spectrometry. Of the 2056 distinct m/z features detected by a mass spectrometry metabolic profiling of blood plasma samples, fifteen metabolites in the classes of dipeptides, fatty acids, glycerolipids, phosphoethanolamines and phosphatidylcholines were significantly associated with ageing rate, independent of species differences. This is the first study of the metabolome of fishes with various ageing rate, and this untargeted approach highlighted the metabolic conditions that may serve to assess the ageing process. Full article
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Open AccessReview Oogenesis and Egg Quality in Finfish: Yolk Formation and Other Factors Influencing Female Fertility
Received: 28 August 2018 / Revised: 16 November 2018 / Accepted: 16 November 2018 / Published: 21 November 2018
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Abstract
Egg quality in fishes has been a topic of research in aquaculture and fisheries for decades as it represents an important life history trait and is critical for captive propagation and successful recruitment. A major factor influencing egg quality is proper yolk formation,
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Egg quality in fishes has been a topic of research in aquaculture and fisheries for decades as it represents an important life history trait and is critical for captive propagation and successful recruitment. A major factor influencing egg quality is proper yolk formation, as most fishes are oviparous and the developing offspring are entirely dependent on stored egg yolk for nutritional sustenance. These maternally derived nutrients consist of proteins, carbohydrates, lipids, vitamins, minerals, and ions that are transported from the liver to the ovary by lipoprotein particles including vitellogenins. The yolk composition may be influenced by broodstock diet, husbandry, and other intrinsic and extrinsic conditions. In addition, a number of other maternal factors that may influence egg quality also are stored in eggs, such as gene transcripts, that direct early embryonic development. Dysfunctional regulation of gene or protein expression may lead to poor quality eggs and failure to thrive within hours of fertilization. These gene transcripts may provide important markers as their expression levels may be used to screen broodstock for potential spawning success. In addition to such intrinsic factors, stress may lead to ovarian atresia or reproductive failure and can impact fish behavior, fecundity, and ovulation rate. Finally, postovulatory aging may occur when eggs become overripe and the fish fails to spawn in a timely fashion, leading to low fertility, often encountered during manual strip spawning of fish. Full article
(This article belongs to the Special Issue Fish Reproductive Physiology and Aquaculture)
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Open AccessArticle Organochlorine Pesticide Residues and Microbiological Quality Assessment of Dried Barb, Puntius sophore, from the Northeastern Part of Bangladesh
Received: 13 September 2018 / Revised: 28 October 2018 / Accepted: 5 November 2018 / Published: 9 November 2018
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Abstract
The present study was carried out in the northeastern part of Bangladesh to investigate organochlorine pesticide (OCP) residues in and microbiological quality of dried barb (Puntius sophore). Samples were collected from both producers and retailers from December 2016 to April 2017.
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The present study was carried out in the northeastern part of Bangladesh to investigate organochlorine pesticide (OCP) residues in and microbiological quality of dried barb (Puntius sophore). Samples were collected from both producers and retailers from December 2016 to April 2017. A control sample was also prepared in the laboratory with the same raw fish used by the producers to compare the results. Gas chromatography with electron capture detector (GC-ECD) was used to detect and quantify OCP residues. Six samples out of 27 (about 22%) were found to be contaminated with OCP residues. Among these six adulterated samples, four were from retailers and two from producers. Only aldrin was detected in four samples, and in the other two samples both aldrin + dieldrin and aldrin + endrin were detected. Aldrin was found in quantities between 0.332 and 0.967 ppm, dieldrin 0.762 ppm, and endrin 0.828 ppm. All these values were much higher than the maximum residual limit (MRL) of 0.1 ppm. Total plate count (TPC) of producer samples ranged from 5.3 ± 0.02 log cfu g−1 to 5.4 ± 0.03 log cfu g−1 and 6.2 ± 0.02 log cfu g−1 to 6.4 ± 0.02 log cfu g−1 for retailer samples and 5.0 ± 0.03 log cfu g−1 to 5.2 ± 0.04 log cfu g−1 for control samples. Fungal count ranged from 3.2 ± 0.04 log cfu g−1 to 3.5 ± 0.04 log cfu g−1, 3.4 ± 0.04 log cfu g−1 to 3.6 ± 0.03 log cfu g−1, and 2.2 ± 0.05 log cfu g−1 to 2.5 ± 0.03 log cfu g−1 for producer, retailer, and control samples, respectively. All the producer and retailer samples and one-third of the control samples were found to be contaminated with Escherichia coli, whereas Salmonella spp. were detected in amounts of 13.3% in producer samples and 20% in retailer samples and none in the control. In case of Vibrio spp., maximum count was found in retailer samples (13.3%), whereas producer and control samples showed none. The findings of the present study show that the presence of pesticides and poor microbiological quality of dried barb are alarming for consumers in Bangladesh and might cause prolonged disease and impending longstanding risk to human health. Full article
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Open AccessArticle Description of the Annual Reproductive Cycle of Wreckfish Polyprion americanus in Captivity
Received: 10 August 2018 / Revised: 14 September 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
Successful spontaneous reproduction and the production of viable offspring of wild fish in captivity can take some years of adaptation, and may also involve different environmental conditions, sex ratios and densities compared to natural populations. We followed the reproductive cycle of wreckfish Polyprion
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Successful spontaneous reproduction and the production of viable offspring of wild fish in captivity can take some years of adaptation, and may also involve different environmental conditions, sex ratios and densities compared to natural populations. We followed the reproductive cycle of wreckfish Polyprion americanus—a late maturing, deep-sea benthic species—in captivity in three different broodstocks in Spain under natural photoperiod and temperature, and one broodstock in Greece under a constant temperature of 16 °C for two consecutive years, to describe the reproductive cycle of the species and the associated sex steroid hormone profiles. Oogenesis begun in the fall and post-vitellogenic oocytes of 1250 μm were present between March and June. Males were in spermiation condition and produced good-quality sperm throughout the year, regardless of the temperature profile to which they were exposed. Some females completed oogenesis, underwent oocyte maturation, and spawned spontaneously under both constant and fluctuating temperatures. The sex steroid hormones of both males and females followed the already-known profiles during fish gametogenesis, except for 17,20β-dihydroxy-progesterone, which did not seem to be related to either female or male maturation. The female reproductive dysfunctions that were identified included (a) the arrest of oogenesis at the cortical alveoli stage in certain females; (b) the failure to undergo oocyte maturation in others; and (c) the production of large percentages of unfertilized eggs from the females that spawned spontaneously. Our study suggests that reproduction in captivity is possible in wreckfish maintained under typical marine aquaculture conditions, but that reliable spawning and production of high-quality eggs may require some years of adaptation to captivity, before the reproductive dysfunctions will be overcome. Full article
(This article belongs to the Special Issue Fish Reproductive Physiology and Aquaculture)
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Open AccessCase Report Outbreak of Mortality Associated with Acipenser Iridovirus European (AcIV-E) Detection in Siberian Sturgeon (Acipenser baerii) Farmed in Sweden
Received: 5 September 2018 / Revised: 27 September 2018 / Accepted: 5 October 2018 / Published: 16 October 2018
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Abstract
Infectious disease is a major challenge in aquaculture and poses a constraint for the development of farming of new species. In 2017, Siberian sturgeon (Acipenser baerii) juveniles were imported from Italy to a Swedish farm. Transport conditions were suboptimal. Thirty percent
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Infectious disease is a major challenge in aquaculture and poses a constraint for the development of farming of new species. In 2017, Siberian sturgeon (Acipenser baerii) juveniles were imported from Italy to a Swedish farm. Transport conditions were suboptimal. Thirty percent died during transport and within the first days after arrival. Ten days after arrival, mortalities started to occur again, which prompted initiation of an investigation into the mortalities. Diseased fish were transported live to the National Veterinary Institute (SVA) for necropsy and further analysis. Pathological and histopathological investigation was conducted. Virology was performed on gills and internal organs by cell culture isolation and using specific PCR protocols against nervous necrosis virus (NNV) and Acipenser iridovirus European (AcIV-E). The juveniles displayed neurological signs such as lethargy, inability to maintain an upright position, and erratic swimming. Body condition was below normal, and gills were pale. One fish had petechial hemorrhages on the abdomen and the snout. Two specimens had intestinal hyperemia. Ventricles were air-filled, and swim bladders were deflated. Viral cell cultures gave negative results, but PCR analysis of gills and internal organs detected the presence of AcIV-E. We conclude that AcIV-E was associated with disease and high mortality in the sturgeon juveniles, and stress probably aggravated the course of the infection. Full article
(This article belongs to the Special Issue Viral Diseases of Fish and Shellfish)
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Open AccessReview Biological and Ecological Roles of External Fish Mucus: A Review
Received: 20 September 2018 / Revised: 3 October 2018 / Accepted: 3 October 2018 / Published: 9 October 2018
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Abstract
Fish mucus layers are the main surface of exchange between fish and the environment, and they possess important biological and ecological functions. Fish mucus research is increasing rapidly, along with the development of high-throughput techniques, which allow the simultaneous study of numerous genes
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Fish mucus layers are the main surface of exchange between fish and the environment, and they possess important biological and ecological functions. Fish mucus research is increasing rapidly, along with the development of high-throughput techniques, which allow the simultaneous study of numerous genes and molecules, enabling a deeper understanding of the fish mucus composition and its functions. Fish mucus plays a major role against fish infections, and research has mostly focused on the study of fish mucus bioactive molecules (e.g., antimicrobial peptides and immune-related molecules) and associated microbiota due to their potential in aquaculture and human medicine. However, external fish mucus surfaces also play important roles in social relationships between conspecifics (fish shoaling, spawning synchronisation, suitable habitat finding, or alarm signals) and in interspecific interactions such as prey-predator relationships, parasite–host interactions, and symbiosis. This article reviews the biological and ecological roles of external (gills and skin) fish mucus, discussing its importance in fish protection against pathogens and in intra and interspecific interactions. We also discuss the advances that “omics” sciences are bringing into the fish mucus research and their importance in studying the fish mucus composition and functions. Full article
(This article belongs to the Special Issue Mucosal Health in Aquaculture Organisms)
Open AccessAddendum Addendum: Lindseth, A. and Lobel, P.S. Underwater Soundscape Monitoring and Fish Bioacoustics: A Review. Fishes 2018, 3, 36
Received: 8 October 2018 / Accepted: 8 October 2018 / Published: 8 October 2018
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Abstract
Two videos have been added to the original manuscript [1] as supplementary material together with a description of the recording method.[...] Full article
Open AccessArticle Assessing the Viability of Reintroduction of Locally Extinct Migratory Fish Brycon orbignyanus: Successful Growth, Dispersal and Maturation
Received: 3 August 2018 / Revised: 26 September 2018 / Accepted: 26 September 2018 / Published: 1 October 2018
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Abstract
The reintroduction of threatened fish species in areas where wild populations have been depleted due to anthropogenic impacts is an increasingly popular conservation tool and mitigation policy. Despite the importance of fish reintroduction for conservation purposes, little is known about its efficiency. Here,
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The reintroduction of threatened fish species in areas where wild populations have been depleted due to anthropogenic impacts is an increasingly popular conservation tool and mitigation policy. Despite the importance of fish reintroduction for conservation purposes, little is known about its efficiency. Here, we assessed the viability of reintroduction of the endangered migratory fish, Brycon orbignyanus, in an area of the Upper Uruguay River basin where the species has not been reported for more than 30 years. We released 4000 yearling juveniles in the Pelotas River in 2014 and maintained 400 juveniles in captivity as a control population. After three years, a total of 13 individuals was recaptured, of which, 10 were considered sexually mature with first maturation being recorded in animals larger than 42 cm in total body length. The age–length comparison with a control population growth curve showed that recaptured fish were slightly bigger than those in captivity. Furthermore, important ecological attributes as schooling behavior and dispersal capacity were recorded for all recaptured individuals. Combined, our results suggest that the re-establishment of a self-sustained population of locally extinct species B. orbignyanus in the Pelotas River may be successful if sustained over time and supported by conservation policies. Full article
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Open AccessArticle Relative Mass of Brain- and Intestinal Tissue in Juvenile Brown Trout: No Long-Term Effects of Compensatory Growth; with Additional Notes on Emerging Sex-Differences
Received: 8 August 2018 / Revised: 25 September 2018 / Accepted: 26 September 2018 / Published: 28 September 2018
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Abstract
This study investigated whether compensatory growth causes long-term effects in relative brain- or intestine size in a wild, predominantly anadromous, population of brown trout (Salmo trutta). The subject fish belonged to two treatment groups; one group had undergone starvation and subsequent
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This study investigated whether compensatory growth causes long-term effects in relative brain- or intestine size in a wild, predominantly anadromous, population of brown trout (Salmo trutta). The subject fish belonged to two treatment groups; one group had undergone starvation and subsequent growth compensation, while the other were unrestricted controls. The main hypothesis that compensatory growth would negatively affect brain and intestinal size, as a consequence of growth trade-offs during the compensatory phase, could not be supported as no significant differences were detected between the treatment groups. Further exploratory analyses suggested that males and females started to diverge in both brain and intestine size at around 130 mm fork length, with females developing relatively smaller brains and larger intestines. The size at which the differences appear is a typical size for smoltification (saltwater preadaptation), and females tend to smoltify to a higher proportion than males. Smoltification is known to cause a more elongated morphology and relatively smaller heads in salmonids, and the marine lifestyle is associated with rapid growth, which could require relatively larger intestines. Hence, these emerging sex differences could be a consequence of sex-biased smoltification rates. An investigation of wild smolts of both sexes indicated no differences in brain or intestine mass between male and female smolts. Full article
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Open AccessArticle Invasive Rainbow Trout (Oncorhynchus mykiss) Are Not Affected by Different Land Uses in a Multi-Use, Mediterranean Climate Landscape
Received: 1 August 2018 / Revised: 20 September 2018 / Accepted: 21 September 2018 / Published: 26 September 2018
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Abstract
Land use carries implications for freshwater fish conservation. Plantation forestry practices have been shown to have negative impacts on resident fish fauna, but little work has been conducted to assess these impacts on invasive vs. native fish populations. Ten headwater catchments in the
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Land use carries implications for freshwater fish conservation. Plantation forestry practices have been shown to have negative impacts on resident fish fauna, but little work has been conducted to assess these impacts on invasive vs. native fish populations. Ten headwater catchments in the Mediterranean climate zone of Chile were used to assess the impacts of land use (pine plantations vs. native forests) on fish condition (length-weight relationship) and abundance (catch-per-unit-effort (CPUE)) of the invasive trout Oncorhynchus mykiss and the threatened native catfish Nematogenys inermis. Negative impacts on trout condition were associated with a lack of canopy cover and river topology. The presence of N. inermis was associated with catchment factors less favourable to trout. Current environmental regulations and forestry management practices do not appear to create negative pressures on invasive trout from land use practices, despite expectations from the literature. Assessing how land use management regulations impact invasive and native fishes should be a part of species conservation and territorial planning. Full article
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Fishes EISSN 2410-3888 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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