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Fishes (ISSN 2410-3888) is an international peer-reviewed scientific open access journal on fishes published quarterly online by MDPI.
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Latest Articles
Organochlorine Pesticide Residues and Microbiological Quality Assessment of Dried Barb, Puntius sophore, from the Northeastern Part of Bangladesh
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Fishes 2018, 3(4), 44; https://doi.org/10.3390/fishes3040044 - 9 November 2018
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.
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Description of the Annual Reproductive Cycle of Wreckfish Polyprion americanus in Captivity
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Fishes 2018, 3(4), 43; https://doi.org/10.3390/fishes3040043 - 19 October 2018
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.
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Outbreak of Mortality Associated with Acipenser Iridovirus European (AcIV-E) Detection in Siberian Sturgeon (Acipenser baerii) Farmed in Sweden
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Fishes 2018, 3(4), 42; https://doi.org/10.3390/fishes3040042 - 16 October 2018
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.
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Assessing the Viability of Reintroduction of Locally Extinct Migratory Fish Brycon orbignyanus: Successful Growth, Dispersal and Maturation
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Fishes 2018, 3(4), 39; https://doi.org/10.3390/fishes3040039 - 1 October 2018
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.
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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
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Fishes 2018, 3(4), 38; https://doi.org/10.3390/fishes3040038 - 28 September 2018
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.
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Invasive Rainbow Trout (Oncorhynchus mykiss) Are Not Affected by Different Land Uses in a Multi-Use, Mediterranean Climate Landscape
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Fishes 2018, 3(4), 37; https://doi.org/10.3390/fishes3040037 - 26 September 2018
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.
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Underwater Soundscape Monitoring and Fish Bioacoustics: A Review
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Fishes 2018, 3(3), 36; https://doi.org/10.3390/fishes3030036 - 12 September 2018
Abstract
Soundscape ecology is a rapidly growing field with approximately 93% of all scientific articles on this topic having been published since 2010 (total about 610 publications since 1985). Current acoustic technology is also advancing rapidly, enabling new devices with voluminous data storage and
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Soundscape ecology is a rapidly growing field with approximately 93% of all scientific articles on this topic having been published since 2010 (total about 610 publications since 1985). Current acoustic technology is also advancing rapidly, enabling new devices with voluminous data storage and automatic signal detection to define sounds. Future uses of passive acoustic monitoring (PAM) include biodiversity assessments, monitoring habitat health, and locating spawning fishes. This paper provides a review of ambient sound and soundscape ecology, fish acoustic monitoring, current recording and sampling methods used in long-term PAM, and parameters/metrics used in acoustic data analysis.
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Spawning Induction of First-Generation (F1) Greater Amberjack Seriola dumerili in the Canary Islands, Spain Using GnRHa Delivery Systems
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Fishes 2018, 3(3), 35; https://doi.org/10.3390/fishes3030035 - 5 September 2018
Abstract
The development of a sustainable aquaculture industry requires the closing of the life-cycle of a potential species in captivity, and the establishment of breeding selection programs using hatchery-produced breeding stocks. The greater amberjack Seriola dumerili is a cosmopolitan pelagic species that has been
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The development of a sustainable aquaculture industry requires the closing of the life-cycle of a potential species in captivity, and the establishment of breeding selection programs using hatchery-produced breeding stocks. The greater amberjack Seriola dumerili is a cosmopolitan pelagic species that has been considered as a good candidate for the species diversification of aquaculture production in the Mediterranean region. However, commercial production is still very limited due to bottlenecks in reproduction, larval rearing and management control during grow out. The aim of the present study was to examine the reproductive development of hatchery-produced greater amberjack and to develop a spawning induction protocol based on the use of gonadotropin releasing hormone agonist (GnRHa) in a controlled-release delivery system. The results showed that hatchery-produced greater amberjack undergo normal gametogenesis and can be induced to undergo maturation, ovulation and spawning after multiple administrations of GnRHa implants, over an extended spawning period lasting from May to September in the Canary Islands, Spain. The use of GnRHa-delivery systems resulted in multiple spawns of fertilized and viable eggs. Egg production was high and egg quality adequate for the implementation of larval rearing for commercial purposes. The handling required to administer the GnRHa implants during the prolonged spawning season did not result in any negative effect on the welfare and reproductive performance of the fish based on evaluation of several biochemical parameters. The developed reproduction control method shows great potential to advance the commercial production of greater amberjack, by enabling the use of hatchery-produced broodstocks for further breeding selection.
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Air Exposure in Catshark (Scyliorhinus canicula) Modify Muscle Texture Properties: A Pilot Study
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Fishes 2018, 3(3), 34; https://doi.org/10.3390/fishes3030034 - 4 September 2018
Abstract
Sharks are captured by tons for human consumption. Improving the quality of their meat will produce fillets that may have a higher economic value in the market, and thus be beneficial for the management of this fishery. In other animal species destined for
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Sharks are captured by tons for human consumption. Improving the quality of their meat will produce fillets that may have a higher economic value in the market, and thus be beneficial for the management of this fishery. In other animal species destined for human consumption, a negative relationship between pre-slaughtering stress and meat quality has been demonstrated. By studying the commercial small-spotted catshark (Scyliorhinus canicula), this work aimed at linking pre-slaughter handling of captured sharks and muscle fillets quality. An experimental group of adult and subadult living catsharks captured by hand and exposed to air (for 18 min, which is the minimum time this species is exposed to air in the fishing deck during fisheries procedures), and an undisturbed group, were evaluated. After air exposure, catsharks returned to water for recovery. Muscle lactate and water content were quantified after acute exposure (for 18 min), 5 h and 24 h. This challenge elicited stress responses in the muscle such as increased lactate levels and immediate dehydration, followed by recovery of lactate levels and overhydration. Muscle consistency, a relevant variable describing quality of seafood according to its ability to be swallowed by the consumer, paralleled muscle water content changes. The results indicated for the first time that handling alive sharks exposed to air results in muscle fillets with different texture properties. Whether these changes in muscle texture induce higher quality fillets has yet to be proven. Our recommendation is to minimize time of air exposure experienced by sharks when captured, including fast slaughtering instead of leaving them to die by asphyxia, as current on-board procedures.
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Administration of Probiotics in the Water in Finfish Aquaculture Systems: A Review
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Fishes 2018, 3(3), 33; https://doi.org/10.3390/fishes3030033 - 22 August 2018
Abstract
Over the last few decades, the contribution of aquaculture to animal protein production has increased enormously, and the sector now provides almost half of the fish and shellfish consumed worldwide, making it a major food producer. Nevertheless, many factors, including infections, pollution, and
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Over the last few decades, the contribution of aquaculture to animal protein production has increased enormously, and the sector now provides almost half of the fish and shellfish consumed worldwide, making it a major food producer. Nevertheless, many factors, including infections, pollution, and stress, may result in significant economic losses. The aquaculture industry will not be totally successful without the therapeutic and preventive means to control all these factors. Antibiotics (long used in aquaculture practice) have tended to aggravate the problem by increasing antibiotic resistance. Concomitantly, probiotics have widely been suggested as eco-friendly alternatives to antibiotics. However, the way in which probiotics are applied in aquaculture is a key factor in their favorable performance. The aim of this review was to examine the current state of probiotics administration through the water in finfish aquaculture. The review also attempts to cover the research gaps existing in our knowledge of this administration mode, and to suggest the issues that need to be investigated in greater depth.
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Changes in Physicochemical, Microbiological, and Sensory Properties of Sun-Dried Mystus vittatus During Storage at Ambient Temperature
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Fishes 2018, 3(3), 32; https://doi.org/10.3390/fishes3030032 - 20 August 2018
Abstract
The objective of this study was to investigate the changes in physicochemical, microbiological, and sensory properties of sun-dried Mystus vittatus during storage at ambient temperature. The fish was dried under sun exposure on bamboo mats for 5–6 days until the moisture content reduced
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The objective of this study was to investigate the changes in physicochemical, microbiological, and sensory properties of sun-dried Mystus vittatus during storage at ambient temperature. The fish was dried under sun exposure on bamboo mats for 5–6 days until the moisture content reduced to approximately 10–15%. The dried fish was then packed into airtight polyethylene bags and stored at ambient temperature (24 to 29 °C) for 90 days. The physical and sensory properties revealed that the dried fish was acceptable for human consumption for up to 60 days. The pH value slightly decreased from 6.42 to 5.95 during the storage period. The moisture content increased significantly (p < 0.05), while no significant difference was observed for the protein, lipid, and ash contents (on a dry matter basis) with the increase in the storage time. The peroxide value, acid value, and conjugated dienes of the lipids increased significantly during the storage period. The microbial load also increased with the increase in the storage period. The results of this study suggest that the product was slightly oxidized during the storage period and could be stored for up to two months.
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Improved Growth Estimates for Lethrinus harak: Measuring Increments, Adjusting Ages, and Fitting Flexible Growth Models
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Fishes 2018, 3(3), 31; https://doi.org/10.3390/fishes3030031 - 14 August 2018
Abstract
Thumbprint emperor (Lethrinus harak) are a widely distributed, tropical species ranging throughout the Indo-Pacific region. In coastal Tanzania, overfishing is likely occurring and thumbprint emperor are commonly represented in catches. The goal of this study was to estimate age and growth
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Thumbprint emperor (Lethrinus harak) are a widely distributed, tropical species ranging throughout the Indo-Pacific region. In coastal Tanzania, overfishing is likely occurring and thumbprint emperor are commonly represented in catches. The goal of this study was to estimate age and growth to provide basic life history information that may help inform future management. We sampled a total of n = 55 thumbprint emperors from both fishery-dependent and fishery-independent sources. Annular age estimates were improved with measurements of otolith markings. Fish ages ranged from zero to five years. We also evaluated the addition of otolith edge size (a proxy for fractional age) to age estimation, and fit two von Bertalanffy growth models—one for the whole ages and one for the fractional ages—using a flexible Bayesian framework. Growth parameters were similar between the two models, and ultimately,
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On the Finding of the Rare Crab Paragalene longicrura (Nardo, 1868) (Crustacea, Decapoda, Brachyura, Progeryonidae) from Thermaikos Gulf, Northwest Aegean Sea, Greece
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Fishes 2018, 3(3), 30; https://doi.org/10.3390/fishes3030030 - 8 August 2018
Abstract
The finding of a rare crab, Paragalene longicrura, is herein recorded from Thermaikos Gulf. This constitutes the northmost record of the species in Greek waters. The species is only known from sporadic records in the eastern Mediterranean basin. Ecological remarks on the
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The finding of a rare crab, Paragalene longicrura, is herein recorded from Thermaikos Gulf. This constitutes the northmost record of the species in Greek waters. The species is only known from sporadic records in the eastern Mediterranean basin. Ecological remarks on the habitat of P. longicrura and other decapod species are described for the first time for the Mediterranean.
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Increasing Abundance of Silky Sharks in the Eastern Indian Ocean: Good News or a Reason to be Cautious?
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Fishes 2018, 3(3), 29; https://doi.org/10.3390/fishes3030029 - 18 July 2018
Abstract
The silky shark (Carcharhinus falciformis) is the most common shark landed in Indonesian waters, including in the Indian Ocean. However, even though they are frequently caught, there is a lack of information on the population and abundance of silky sharks in
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The silky shark (Carcharhinus falciformis) is the most common shark landed in Indonesian waters, including in the Indian Ocean. However, even though they are frequently caught, there is a lack of information on the population and abundance of silky sharks in the Indian Ocean. Cilacap and Tanjung Luar are two of Indonesia’s shark fishery hotspots, both located on the edge of the Indian Ocean, which is a part of the Indonesian Fisheries Management Area (FMA) 573. The fishers from both places usually have fishing grounds in that particular fisheries management area. This research aims to update the abundance, and to investigate the factors, which influence catches of silky shark in the FMA 573 based on monthly enumeration during 2015–2016. This study found that standardized catch-per-unit-effort (CPUE) or abundance indices of silky shark in the Indonesian FMA 573 increased from 2015 to 2016. We suggested that fish immigration and decreasing fishing pressure may affect the fish abundance. Fisheries management is required to regulate the fishing pressure, such as controlling the number of boats/licenses and the number of trips or fishing gear, as well as initializing spatial and temporal fishing closure.
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Full Water Quality Monitoring of a Traditional Flow-Through Rainbow Trout Farm
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Fishes 2018, 3(3), 28; https://doi.org/10.3390/fishes3030028 - 17 July 2018
Abstract
Traditional freshwater rainbow trout farms are still popular in some European countries such as Poland, France and Ireland. These systems generally operate in flow-through configuration. The impact such production systems might have on water quality remains mostly unknown. The present study was set
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Traditional freshwater rainbow trout farms are still popular in some European countries such as Poland, France and Ireland. These systems generally operate in flow-through configuration. The impact such production systems might have on water quality remains mostly unknown. The present study was set up to fulfil this objective of monitoring water quality on different fish farm locations in order to identify the impacts of the whole farm (comparison of farm inlet and outlet) and at pond scale in order to understand the water quality dynamics and to better understand the impact of multiple water reuse (water passes) in a given pond on water quality. In the absence of any sort of water treatment, an increase in the number of water passes was shown to create an increase in ammonium concentration along the farm. Finally, this traditional flow-through rainbow trout production system was revealed to almost be at its full carrying capacity with respect to internal water quality parameters and fish welfare. To increase fish production, some water treatment techniques (solid/liquid separation, nitrification) would have to be introduced in order to optimize the rearing water quality for fish growth and to minimize the release of pollutants in the receiving water to limit the impact on the environment.
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Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles
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Fishes 2018, 3(3), 27; https://doi.org/10.3390/fishes3030027 - 10 July 2018
Abstract
The application of β-1,3/1,6-glucan derived from yeast at five concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) in formulated diets was evaluated in juveniles for its effects on the growth, survival, digestive enzymatic activity, and expression of genes associated with the immune system (interlukin-10
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The application of β-1,3/1,6-glucan derived from yeast at five concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) in formulated diets was evaluated in juveniles for its effects on the growth, survival, digestive enzymatic activity, and expression of genes associated with the immune system (interlukin-10 (IL-10), transforming growth factor (TGF), occludin (OCC), mucin2 (MUC2), lysozyme (LYS), and nucleotide-binding and oligomerization domain 2 (NOD2)) in tropical gar (Atractosteus tropicus). For the experiment, three replicates of 30 fish per experimental unit (70 L) were cultivated for 62 days. The growth results showed no statistically significant differences in relation to weight and total length between treatments. The activity of digestive enzymes (alkaline proteases, trypsin, leucine aminopeptidase, and amylase) did not show significant differences between treatments, except for chymotrypsin activity, where fish fed 1.0% and 1.5% of β-glucans showed higher activities compared with the rest of the treatments. On the other hand, the analysis of gene expression did not show significant differences between treatments, although a tendency of increase in the expression of IL-10, TGF, MUC2, and OCC was observed with an addition of 1.5% of the prebiotic, but there was a decrease in the fish fed with 2% of the prebiotic. It is possible to include concentrations of between 0.5% and 1.5% of β-glucans in the diets for A. tropicus, with no detectable adverse effects on growth, survival, digestive enzyme activity, or specific gene expression. β-glucan 1,3/1,6 added at 1.0% and 1.5% in the diet significantly increases chymotrypsin activity.
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Automatic Discrimination between Scomber japonicus and Scomber australasicus by Geometric and Texture Features
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Fishes 2018, 3(3), 26; https://doi.org/10.3390/fishes3030026 - 27 June 2018
Abstract
This paper proposes a method for automatic discrimination of two mackerel species: Scomber japonicus (chub mackerel) and Scomber australasicus (blue mackerel). Because S. japonicus has a much higher market price than S. australasicus, the two species must be properly sorted before shipment,
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This paper proposes a method for automatic discrimination of two mackerel species: Scomber japonicus (chub mackerel) and Scomber australasicus (blue mackerel). Because S. japonicus has a much higher market price than S. australasicus, the two species must be properly sorted before shipment, but their similar appearance makes discrimination difficult. These species can be effectively distinguished using the ratio of the base length between the dorsal fin’s first and ninth spines to the fork length. However, manual measurement of this ratio is time-consuming and reduces fish freshness. The proposed technique instead uses image processing to measure these lengths. We were able to successfully discriminate between the two species using the ratio as a geometric feature, in combination with several texture features. We then quantitatively verified the effectiveness of the proposed method and demonstrated that it is highly accurate in classifying mackerel.
Full article
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Biochemical, Microbiological, and Sensory Properties of Dried Silver Carp (Hypophthalmichthys molitrix) Influenced by Various Drying Methods
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Fishes 2018, 3(3), 25; https://doi.org/10.3390/fishes3030025 - 25 June 2018
Abstract
An experiment was performed to evaluate the effects of different drying methods with different pre-treatments on the physico-chemical, microbiological, and sensory properties of the silver carp, Hypophthalmichthys molitrix. In order to achieve this objective, the collected fresh fish were dried using traditional (without
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An experiment was performed to evaluate the effects of different drying methods with different pre-treatments on the physico-chemical, microbiological, and sensory properties of the silver carp, Hypophthalmichthys molitrix. In order to achieve this objective, the collected fresh fish were dried using traditional (without any pre-treatment), improved (fish soaked in a 5% salt solution for 10 min and then treated with chili powder (0.3%) and turmeric powder (0.3%)), and solar tunnel (fish soaked in a 5% salt solution for 10 min) drying methods. The results showed that the dried fish produced by the solar tunnel drying method were rehydrated more rapidly than the products produced by the traditional and improved drying methods. The moisture content of the dried H. molitrix was varied from 18.24 to 25.43% on a fresh matter basis. There was no significant (p > 0.05) difference found regarding the protein, lipid, and ash content among the different drying methods on a dry matter basis. The total volatile base nitrogen (TVB-N) contents ranged between 37.58 and 45.03 mg/100 g, and significantly (p < 0.05) the lowest TVB-N was observed in dried fish produced by the solar tunnel drying method. Moreover, the highest peroxide and acid values were found in the traditionally produced dried fish as compared with the fish dried by the improved and solar tunnel drying methods. The aerobic plate count of dried fish ranged from 4.52 to 7.51 log CFU/g. The sensory evaluation results revealed that the solar-dried products showed superior quality than the products produced by the traditional and improved drying methods. The results revealed that the dried fish produced by the solar tunnel drying method provided the best product in terms of physico-chemical, microbiological, and sensory aspects.
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News
30 October 2018
Institutional Open Access Agreement between Bill and Melinda Gates Foundation and MDPI
Institutional Open Access Agreement between Bill and Melinda Gates Foundation and MDPI
Special Issues
Special Issue in
Fishes
Mucosal Health in Aquaculture Organisms
Guest Editor: Carlo LazadoDeadline: 15 November 2018
Special Issue in
Fishes
Fish-borne parasites in era of One Health
Guest Editor: Ivona MladineoDeadline: 15 December 2018
Special Issue in
Fishes
Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean"
Guest Editors: Pedro Miguel Guerreiro, Filipe RibeiroDeadline: 31 December 2018
Special Issue in
Fishes
Fish Reproductive Physiology and Aquaculture
Guest Editors: Yonathan Zohar, Neil DuncanDeadline: 15 February 2019