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Axel Temming - One of the best experts on this subject based on the ideXlab platform.
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spatial and temporal distribution patterns of brown shrimp Crangon Crangon derived from commercial logbook landings and vessel monitoring data
Ices Journal of Marine Science, 2020Co-Authors: Katharina Schulte, Volker Siegel, Marc Hufnagl, Torsten Schulze, Axel TemmingAbstract:In this study, logbook, landings, and vessel monitoring system data of German brown shrimp (Crangon Crangon L.) fishers were combined to analyse spatial and temporal distribution patterns. Landings per unit effort (LPUE) were standardized to the efficiency level of a reference vessel. The standardization altered the spatial–temporal patterns of the LPUE as the vessels differed by a factor of up to 4.7. LPUE data were separated into two size classes according to sieve fractions. Small brown shrimps were characterized by LPUE values increasing early in the year in shallow waters, especially in estuaries in July. Subsequently, peak LPUE values are reached at the end of September in all depths, but with vari-able spatial patterns between years. LPUE data indicate a general outward migration between early summer and winter. In winter, large shrimp shows a clear increase in LPUE with depths mainly in regions adjacent to the Dutch coast and a reversed pattern close to the Danishcoast. The large size class in winter—which consists mainly of mature or egg-bearing females—showed high LPUE values along two persistent diagonal bands in the German Bight. These patterns could lead to local recruitment overfishing, if fishermen are aware of such patterns.
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predictive framework for codend size selection of brown shrimp Crangon Crangon in the north sea beam trawl fishery
PLOS ONE, 2018Co-Authors: Juan Santos, Axel Temming, Thomas Neudecker, Bent Herrmann, Daniel Stepputtis, Claudia Gunther, Bente Limmer, Bernd Mieske, Sebastian Schultz, Marc HufnaglAbstract:The brown shrimp (Crangon Crangon) fishery is of great socio-economic importance to coastal communities on the North Sea. The fishery is exploited by beam trawlers often using codends with very small mesh sizes, leading to concerns about catch rates of undersized shrimp. However, little information is available on codend size selection, making it difficult to provide scientifically based advice on alternative codend designs. Therefore, this study establishes a predictive framework for codend size selection of brown shrimp, based on a large selectivity dataset from 33 different codend designs tested during four experimental fishing cruises, during which more than 350,000 brown shrimp were length measured. Predictions by the framework confirm concerns about the exploitation pattern in the fishery, because the retention probability of undersized shrimp reaches 95% with the currently applied designs. The framework predictions allow the exploration of obtainable exploitation patterns depending on codend design. For example, increasing codend mesh size to 25±29 mm would reduce the retention rate of undersized shrimp to a maximum of 50%, depending on codend mesh type.
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Are the RNA:DNA ratio and dry-weight-at-length suitable growth proxies for brown shrimps (Crangon Crangon)?
Consejo Superior de Investigaciones Científicas, 2018Co-Authors: Marc Hufnagl, Axel TemmingAbstract:Growth rates are of fundamental interest for studying population dynamics of species when no age information is available. In these cases in situ growth proxies must be identified and validated, and here we tested whether RNA-DNA ratio (RD) and dry weight condition (DWC) can act as such proxies for the shrimp Crangon Crangon. Growth rates (mm d–1) were determined for male and female shrimps (20 to 67 mm) reared at five different temperatures (5°C to 25°C) and caught in two different months (May, July). Due to the potential interactive effects of the factors sex, size, temperature and time, different statistical analysis were applied to test for linear interactions (factorial analysis of mixed data, FAMDs), nonlinear additive effects (generalized additive models, GAMs) and nonlinear interactions (nonlinear regression combined with GAMs). The FAMD indicated positive correlations between length, month and growth rate. A positive correlation between DWC and sex and between RD and temperature was also indicated. RD was not significant in the GAM but a nonlinear link between length, temperature and growth was found. Finally, an extended Bertalanffy growth model was fitted to sex-specific growth rates and in a second step a GAM was fitted to the differences (residuals) between observed and predicted growth. RD again had no significant explanatory power for growth and, although it is a commonly used growth proxy, we concluded that it is not a suitable index for evaluating length growth of C. Crangon
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annual brown shrimp Crangon Crangon biomass production in northwestern europe contrasted to annual landings
Ices Journal of Marine Science, 2016Co-Authors: Ingrid Tulp, Axel Temming, Volker Siegel, Katharina Schulte, Chun Chen, Holger Haslob, Josien Steenbergen, Marc HufnaglAbstract:The brown shrimp (Crangon Crangon) fishery is economically one of the most important fisheries in the North Sea. Fishing is unregulated, apart from the number of licenses and technical measures. The fishery has long been considered sustainable in terms of the effect on the target species, even though annual stocks are not regularly assessed. Average landings constantly increased annually and since 2000 have been 40% higher than in the 1980s and 1990s. Because brown shrimp lack a clear age structure and reproduce almost year-round, an agebased stock assessment is not possible. In the absence of a formal estimate of stock size, it is difficult to judge whether current fishing practices can still be considered sustainable. Here, we use annual survey data collected during peak occurrence in late summer to obtain a depth- and area-stratified, swept-area estimate for the period 1970–2015. The resulting estimate of the total commercial-size shrimp biomass varied between 4000 and 21 000 tonnes over the years. Both parametric and non-parametric methods arrived at very similar results. In combination with length-based mortality estimates (as a proxy for production/biomass ratio), knowledge on the seasonal occurrence, catchability, gear efficiency, and their variation, total adult annual biomass production was estimated. Values ranged between 38 000 and 216 000 tonnes and overlapped at the lower end with total annual commercial landings, which varied between 8000 and 38 500 tonnes, indicating that in some years (1977, 1998, 2007), the larger part of the total brown shrimp production was harvested. Annual brown shrimp landings have gradually increased since the series started, whereas no trend in standing biomass and production was detected. Concurrent with the increase in landings, natural mortality of shrimp by predation has diminished. Considering the increase in fishing pressure and unknown consequence if natural predators recover or shrimp recruitment decreases, the lack of management for the brown shrimp fishery needs to be reconsidered.
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behavioral thermoregulation of the common brown shrimp Crangon Crangon l throughout the seasonal cycle
Journal of Experimental Marine Biology and Ecology, 2016Co-Authors: Stefan Reiser, Axel Temming, Marc Hufnagl, Andre Eckhardt, Jenspeter HerrmannAbstract:Abstract Ectothermic organisms rely on behavioral thermoregulation to modulate their body temperature and the final thermal preferendum (FTP) paradigm (FTPP) postulates that a given species holds a species-specific FTP. The FTPP, however, has been challenged by a considerable amount of recent findings on vertebrate ectotherms, indicating that the FTP is not as static as originally postulated but can be modulated by various factors. In contrast to vertebrates, evidence from invertebrate ectotherms is far more limited. To test for the validity of the FTPP and to study whether behavioral thermoregulation in a marine invertebrate varies seasonally, thermal preferenda of the common brown shrimp ( Crangon Crangon , L.) were determined through a 14 month period. Thermal preferenda of males and females of different size groups were measured in an annular chamber system (4–25 °C) using the gravitational method for thermal preference testing. The results revealed that brown shrimp behaviorally selected a wide range of temperatures and did not show a single or constant thermal preferendum. Thermal preference was modulated following a seasonal pattern suggesting the existence of distinct seasonal preference zones rather than a species-specific preference temperature. Brown shrimp selected low temperatures during winter, however, a difference of 5 °C in preferred temperature was observed between a cold and a relatively mild one. Highest thermal preferenda did not coincide with field water temperatures but were observed after field water temperatures exceeded the annual temperature peak. Besides season, body size of brown shrimp significantly affected thermal selection and small individuals selected higher temperatures compared to large ones. A significant interaction of body size and water temperature at which the shrimp were caught was detected. The study further provides evidence that cohort identity as well as female reproductive state may affect thermal preference as well. The results of the study reveal that thermal selection in brown shrimp is complex, not static and that preference temperature can be modulated by various factors, representing the first evidence for a marine invertebrate ectotherm.
Marc Hufnagl - One of the best experts on this subject based on the ideXlab platform.
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spatial and temporal distribution patterns of brown shrimp Crangon Crangon derived from commercial logbook landings and vessel monitoring data
Ices Journal of Marine Science, 2020Co-Authors: Katharina Schulte, Volker Siegel, Marc Hufnagl, Torsten Schulze, Axel TemmingAbstract:In this study, logbook, landings, and vessel monitoring system data of German brown shrimp (Crangon Crangon L.) fishers were combined to analyse spatial and temporal distribution patterns. Landings per unit effort (LPUE) were standardized to the efficiency level of a reference vessel. The standardization altered the spatial–temporal patterns of the LPUE as the vessels differed by a factor of up to 4.7. LPUE data were separated into two size classes according to sieve fractions. Small brown shrimps were characterized by LPUE values increasing early in the year in shallow waters, especially in estuaries in July. Subsequently, peak LPUE values are reached at the end of September in all depths, but with vari-able spatial patterns between years. LPUE data indicate a general outward migration between early summer and winter. In winter, large shrimp shows a clear increase in LPUE with depths mainly in regions adjacent to the Dutch coast and a reversed pattern close to the Danishcoast. The large size class in winter—which consists mainly of mature or egg-bearing females—showed high LPUE values along two persistent diagonal bands in the German Bight. These patterns could lead to local recruitment overfishing, if fishermen are aware of such patterns.
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predictive framework for codend size selection of brown shrimp Crangon Crangon in the north sea beam trawl fishery
PLOS ONE, 2018Co-Authors: Juan Santos, Axel Temming, Thomas Neudecker, Bent Herrmann, Daniel Stepputtis, Claudia Gunther, Bente Limmer, Bernd Mieske, Sebastian Schultz, Marc HufnaglAbstract:The brown shrimp (Crangon Crangon) fishery is of great socio-economic importance to coastal communities on the North Sea. The fishery is exploited by beam trawlers often using codends with very small mesh sizes, leading to concerns about catch rates of undersized shrimp. However, little information is available on codend size selection, making it difficult to provide scientifically based advice on alternative codend designs. Therefore, this study establishes a predictive framework for codend size selection of brown shrimp, based on a large selectivity dataset from 33 different codend designs tested during four experimental fishing cruises, during which more than 350,000 brown shrimp were length measured. Predictions by the framework confirm concerns about the exploitation pattern in the fishery, because the retention probability of undersized shrimp reaches 95% with the currently applied designs. The framework predictions allow the exploration of obtainable exploitation patterns depending on codend design. For example, increasing codend mesh size to 25±29 mm would reduce the retention rate of undersized shrimp to a maximum of 50%, depending on codend mesh type.
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Are the RNA:DNA ratio and dry-weight-at-length suitable growth proxies for brown shrimps (Crangon Crangon)?
Consejo Superior de Investigaciones Científicas, 2018Co-Authors: Marc Hufnagl, Axel TemmingAbstract:Growth rates are of fundamental interest for studying population dynamics of species when no age information is available. In these cases in situ growth proxies must be identified and validated, and here we tested whether RNA-DNA ratio (RD) and dry weight condition (DWC) can act as such proxies for the shrimp Crangon Crangon. Growth rates (mm d–1) were determined for male and female shrimps (20 to 67 mm) reared at five different temperatures (5°C to 25°C) and caught in two different months (May, July). Due to the potential interactive effects of the factors sex, size, temperature and time, different statistical analysis were applied to test for linear interactions (factorial analysis of mixed data, FAMDs), nonlinear additive effects (generalized additive models, GAMs) and nonlinear interactions (nonlinear regression combined with GAMs). The FAMD indicated positive correlations between length, month and growth rate. A positive correlation between DWC and sex and between RD and temperature was also indicated. RD was not significant in the GAM but a nonlinear link between length, temperature and growth was found. Finally, an extended Bertalanffy growth model was fitted to sex-specific growth rates and in a second step a GAM was fitted to the differences (residuals) between observed and predicted growth. RD again had no significant explanatory power for growth and, although it is a commonly used growth proxy, we concluded that it is not a suitable index for evaluating length growth of C. Crangon
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annual brown shrimp Crangon Crangon biomass production in northwestern europe contrasted to annual landings
Ices Journal of Marine Science, 2016Co-Authors: Ingrid Tulp, Axel Temming, Volker Siegel, Katharina Schulte, Chun Chen, Holger Haslob, Josien Steenbergen, Marc HufnaglAbstract:The brown shrimp (Crangon Crangon) fishery is economically one of the most important fisheries in the North Sea. Fishing is unregulated, apart from the number of licenses and technical measures. The fishery has long been considered sustainable in terms of the effect on the target species, even though annual stocks are not regularly assessed. Average landings constantly increased annually and since 2000 have been 40% higher than in the 1980s and 1990s. Because brown shrimp lack a clear age structure and reproduce almost year-round, an agebased stock assessment is not possible. In the absence of a formal estimate of stock size, it is difficult to judge whether current fishing practices can still be considered sustainable. Here, we use annual survey data collected during peak occurrence in late summer to obtain a depth- and area-stratified, swept-area estimate for the period 1970–2015. The resulting estimate of the total commercial-size shrimp biomass varied between 4000 and 21 000 tonnes over the years. Both parametric and non-parametric methods arrived at very similar results. In combination with length-based mortality estimates (as a proxy for production/biomass ratio), knowledge on the seasonal occurrence, catchability, gear efficiency, and their variation, total adult annual biomass production was estimated. Values ranged between 38 000 and 216 000 tonnes and overlapped at the lower end with total annual commercial landings, which varied between 8000 and 38 500 tonnes, indicating that in some years (1977, 1998, 2007), the larger part of the total brown shrimp production was harvested. Annual brown shrimp landings have gradually increased since the series started, whereas no trend in standing biomass and production was detected. Concurrent with the increase in landings, natural mortality of shrimp by predation has diminished. Considering the increase in fishing pressure and unknown consequence if natural predators recover or shrimp recruitment decreases, the lack of management for the brown shrimp fishery needs to be reconsidered.
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behavioral thermoregulation of the common brown shrimp Crangon Crangon l throughout the seasonal cycle
Journal of Experimental Marine Biology and Ecology, 2016Co-Authors: Stefan Reiser, Axel Temming, Marc Hufnagl, Andre Eckhardt, Jenspeter HerrmannAbstract:Abstract Ectothermic organisms rely on behavioral thermoregulation to modulate their body temperature and the final thermal preferendum (FTP) paradigm (FTPP) postulates that a given species holds a species-specific FTP. The FTPP, however, has been challenged by a considerable amount of recent findings on vertebrate ectotherms, indicating that the FTP is not as static as originally postulated but can be modulated by various factors. In contrast to vertebrates, evidence from invertebrate ectotherms is far more limited. To test for the validity of the FTPP and to study whether behavioral thermoregulation in a marine invertebrate varies seasonally, thermal preferenda of the common brown shrimp ( Crangon Crangon , L.) were determined through a 14 month period. Thermal preferenda of males and females of different size groups were measured in an annular chamber system (4–25 °C) using the gravitational method for thermal preference testing. The results revealed that brown shrimp behaviorally selected a wide range of temperatures and did not show a single or constant thermal preferendum. Thermal preference was modulated following a seasonal pattern suggesting the existence of distinct seasonal preference zones rather than a species-specific preference temperature. Brown shrimp selected low temperatures during winter, however, a difference of 5 °C in preferred temperature was observed between a cold and a relatively mild one. Highest thermal preferenda did not coincide with field water temperatures but were observed after field water temperatures exceeded the annual temperature peak. Besides season, body size of brown shrimp significantly affected thermal selection and small individuals selected higher temperatures compared to large ones. A significant interaction of body size and water temperature at which the shrimp were caught was detected. The study further provides evidence that cohort identity as well as female reproductive state may affect thermal preference as well. The results of the study reveal that thermal selection in brown shrimp is complex, not static and that preference temperature can be modulated by various factors, representing the first evidence for a marine invertebrate ectotherm.
K. Cooreman - One of the best experts on this subject based on the ideXlab platform.
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Development and application of a duplex PCR assay for detection of Crangon Crangon bacilliform virus in populations of European brown shrimp (Crangon Crangon).
Journal of invertebrate pathology, 2018Co-Authors: Benigna Van Eynde, Olivier Christiaens, Daan Delbare, K. Cooreman, Kelly S. Bateman, Grant D. Stentiford, Annette M. Dullemans, Monique M. Van Oers, Guy SmaggheAbstract:Abstract Crangon Crangon bacilliform virus (CcBV) was first discovered in 2004 in European brown shrimp (Crangon Crangon) caught along the English coast. This study describes a duplex PCR assay developed for the detection of CcBV, based on amplification of the lef-8 gene (211 bp) of CcBV and the E75 gene (105 bp) of C. Crangon as an internal amplification control. The lef-8 and E75 primer pairs were designed based on preliminary genome sequencing information of the virus and transcriptomic data available for C. Crangon, respectively. Sequencing of the resulting amplicons confirmed the specificity of this PCR assay and sequence analysis of the lef-8 fragment revealed amino acid identity percentages ranging between 31 and 42% with members of the Nudiviridae, proposing that CcBV may reside within this family. Finally, the duplex PCR assay was applied to samples of C. Crangon hepatopancreas tissue collected along the Belgian coast to screen for the presence of CcBV. The prevalence of CcBV averaged 87%, which is comparable to previous reports of high prevalence, based upon histological analysis, in shrimp collected along the English coast. Development of a specific and sensitive PCR assay to detect CcBV will provide a useful tool for future aquaculture and research programs involving C. Crangon.
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organotins in north sea brown shrimp Crangon Crangon l after implementation of the tbt ban
Chemosphere, 2012Co-Authors: Yves Verhaegen, K. Cooreman, Guy Smagghe, Patrick Roose, T Neudecker, Els Monteyne, I Tulp, K. ParmentierAbstract:The organotin (OT) compounds tributyltin (TBT) and triphenyltin (TPhT) are potent biocides that have been used ubiquitously in antifouling paints and pesticides since the mid-1970s. These biocides are extremely toxic to marine life, particularly marine gastropod populations. The European Union therefore took measures to reduce the use of TBT-based antifouling paints on ships and ultimately banned these paints in 2003. Despite sufficient data on OT concentrations in marine gastropods, data are scarce for other species such as the North Sea brown shrimp (Crangon Crangon), a dominant crustacean species in North Sea inshore benthic communities. The present study provides the first spatial overview of OT concentrations in North Sea brown shrimp. We have compared these data with historical concentrations in shrimp as well as with sediment concentrations. We have also addressed the effect on the shrimp stock and any human health risks associated with the OT concentrations found. TBT and TPhT in shrimp tail
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the brown shrimp Crangon Crangon l ecdysteroid receptor complex cloning structural modeling of the ligand binding domain and functional expression in an ecr deficient drosophila cell line
General and Comparative Endocrinology, 2010Co-Authors: Yves Verhaegen, Luc Swevers, K. Parmentier, Thomas Soin, Pierre Rouge, Wim De Coen, K. CooremanAbstract:cDNAs encoding ecdysteroid receptor (EcR) and retinoid X receptor (RXR) were cloned and sequenced from brown shrimp Crangon Crangon (Crustacea: Decapoda), a common faunal species and commercially important in the North-West European coastal waters. A 3D model of the ligand-binding domain (LBD) of EcR was created and docking of ponasterone A (PonA) was simulated in silico. Finally, we report the transfection of expression plasmids for these receptors in the mutant Drosophila L57-3-11 cell line. Through an ecdysteroid responsive reporter assay we clearly prove the functionality of shrimp ecdysteroid receptor in the transfected L57-3-11 cell line. Our results indicate that the Drosophila L57-3-11 cell line and in silico LBD modeling can be used to study the function of crustacean ecdysteroid receptors and be applied to assess endocrine disrupting effects on non-target crustacean species.
Guy Smagghe - One of the best experts on this subject based on the ideXlab platform.
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Tributyltin: A bottom-up regulator of the Crangon Crangon population?
Frontiers in Marine Science, 2019Co-Authors: K. Parmentier, Daan Delbare, Guy Smagghe, Yves Verhaegen, Bavo P. De Witte, Stefan Hoffman, Patrick Roose, Ketil Hylland, Thierry Burgeot, Kris CooremanAbstract:The restrictions and the concerted action of the global ban on the use and presence of tributyltin (TBT) in marine applications to protect ecosystems in the marine environment in 2008 was mainly based on the economic impact on shellfish industries and the dramatic extinction of local mollusc populations in the past. In contrast to the vast datasets on effects on molluscs, the knowledge on impacts on species from other taxa remained in the uncertain until almost two decades ago. The assumption on a long-term TBT-mediated pernicious metabolic bottom-up regulation of the crustacean Crangon Crangon population was provoked by the outcome of an EU-project ‘Sources, Consumer Exposure and Risks of Organotin Contamination in Seafood’. This study reported high TBT body burdens in C. Crangon in 2003, at the start of the transition period to the global ban. Experimental research on the TBT impact in C. Crangon focused on agonistic interference with natural ecdysteroid hormones at the metabolic pathways regulating growth and reproduction and the biogeochemical distribution of the chemical. In this paper, metabolic, topical and population-relevant biological endpoints in C. Crangon and other crustaceans are evaluated in relation to the temporal and spatial trends on TBT’s occurrence and distribution in the field during and after the introduction of the tributyltin restrictions and endocrine-related incidents. Arguments are forwarded to relate the German Bight incident on growth and reproduction failure in the C. Crangon population, despite the lack of direct evidence, to the pernicious impact of tributyltin in 1990/91 and previous years. The extreme occurrence of TBT in C. Crangon from other parts of the southern North Sea and evidence on the high body burdens as dose metrics of exposure also feeds the suspicion on detrimental impacts in those areas. This paper further demonstrates the complexity of distinguishing and assessing the individual roles of unrelated stressors on a population in an integrated evaluation at the ecosystem level.
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Development and application of a duplex PCR assay for detection of Crangon Crangon bacilliform virus in populations of European brown shrimp (Crangon Crangon).
Journal of invertebrate pathology, 2018Co-Authors: Benigna Van Eynde, Olivier Christiaens, Daan Delbare, K. Cooreman, Kelly S. Bateman, Grant D. Stentiford, Annette M. Dullemans, Monique M. Van Oers, Guy SmaggheAbstract:Abstract Crangon Crangon bacilliform virus (CcBV) was first discovered in 2004 in European brown shrimp (Crangon Crangon) caught along the English coast. This study describes a duplex PCR assay developed for the detection of CcBV, based on amplification of the lef-8 gene (211 bp) of CcBV and the E75 gene (105 bp) of C. Crangon as an internal amplification control. The lef-8 and E75 primer pairs were designed based on preliminary genome sequencing information of the virus and transcriptomic data available for C. Crangon, respectively. Sequencing of the resulting amplicons confirmed the specificity of this PCR assay and sequence analysis of the lef-8 fragment revealed amino acid identity percentages ranging between 31 and 42% with members of the Nudiviridae, proposing that CcBV may reside within this family. Finally, the duplex PCR assay was applied to samples of C. Crangon hepatopancreas tissue collected along the Belgian coast to screen for the presence of CcBV. The prevalence of CcBV averaged 87%, which is comparable to previous reports of high prevalence, based upon histological analysis, in shrimp collected along the English coast. Development of a specific and sensitive PCR assay to detect CcBV will provide a useful tool for future aquaculture and research programs involving C. Crangon.
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Rearing European brown shrimp (Crangon Crangon, Linnaeus 1758): a review on the current status and perspectives for aquaculture
Reviews in Aquaculture, 2014Co-Authors: Daan Delbare, Kris Cooreman, Guy SmaggheAbstract:The European brown shrimp, Crangon Crangon, is a highly valued commercial species fished in the north-eastern Atlantic, especially the North Sea. The shrimp fisheries are mainly coastal and exert high pressures on the local ecosystems, including estuaries. The culture of the species provides an alternative to supply a niche market I(large live/fresh shrimps) in a sustainable manner. However, after more than a century of biological research on this species, there is still little knowledge on its optimal rearing conditions. C. Crangon remains a difficult species to keep alive and healthy for an extended period of time in captivity. This review is based on a comprehensive literature search and reflects on the current status of experimental rearing techniques used for this species, identifies the problems that compromise the closing of the life cycle in captivity and provides examples on how these problem issues were solved in the culture of commercial shrimp species or other crustaceans. The ability to consistently produce high-quality offspring could initiate the commercial production of this valuable shrimp. A further advantage of the ability to consistently produce high-quality offspring of this species would facilitate research on the development of new bio-assays with this ecologically and economically important species in a wide variety of biochemical and physiological studies.
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organotins in north sea brown shrimp Crangon Crangon l after implementation of the tbt ban
Chemosphere, 2012Co-Authors: Yves Verhaegen, K. Cooreman, Guy Smagghe, Patrick Roose, T Neudecker, Els Monteyne, I Tulp, K. ParmentierAbstract:The organotin (OT) compounds tributyltin (TBT) and triphenyltin (TPhT) are potent biocides that have been used ubiquitously in antifouling paints and pesticides since the mid-1970s. These biocides are extremely toxic to marine life, particularly marine gastropod populations. The European Union therefore took measures to reduce the use of TBT-based antifouling paints on ships and ultimately banned these paints in 2003. Despite sufficient data on OT concentrations in marine gastropods, data are scarce for other species such as the North Sea brown shrimp (Crangon Crangon), a dominant crustacean species in North Sea inshore benthic communities. The present study provides the first spatial overview of OT concentrations in North Sea brown shrimp. We have compared these data with historical concentrations in shrimp as well as with sediment concentrations. We have also addressed the effect on the shrimp stock and any human health risks associated with the OT concentrations found. TBT and TPhT in shrimp tail
Bent Herrmann - One of the best experts on this subject based on the ideXlab platform.
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testing a size sorting grid in the brown shrimp Crangon Crangon linnaeus 1758 beam trawl fishery
Fisheries Research, 2020Co-Authors: Tiago Veigamalta, Bent Herrmann, Jordan P Feekings, Rikke Frandsen, Ludvig Ahm KragAbstract:Abstract The North Sea brown shrimp (Crangon Crangon Linnaeus, 1758) fishery became Marine Stewardship Council (MSC) certified in 2017. As part of the certification, the fishermen proposed to incrementally increase the mesh size of the codend used from 22 mm to 26 mm. As this increase in mesh size could result in a substantial loss of marketable sized brown shrimp (shrimp with total length equal or higher than 50 mm), a combination of a size sorting grid with a bar spacing of 6 mm and a 22 mm codend was proposed by the Danish fishermen as a possible alternative to the increase in codend mesh size. The objective of the proposed gear was to release shrimp smaller than the marketable size before they reach the codend, while potentially limiting the loss of marketable sized shrimp. Therefore, the aim of this study was to investigate the size selective performance of brown shrimp in the above-mentioned gears. The results showed that the grid reduced catches of shrimp under the marketable size of 50 mm. Moreover, the combination of the grid and a 22 mm diamond mesh codend, with an estimated L 50 of 44.9 mm and a selection range of 15.6 mm, had an overall selective performance similar to that of a 26 mm diamond mesh codend, both for shrimps under and above the marketable size.
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predictive framework for codend size selection of brown shrimp Crangon Crangon in the north sea beam trawl fishery
PLOS ONE, 2018Co-Authors: Juan Santos, Axel Temming, Thomas Neudecker, Bent Herrmann, Daniel Stepputtis, Claudia Gunther, Bente Limmer, Bernd Mieske, Sebastian Schultz, Marc HufnaglAbstract:The brown shrimp (Crangon Crangon) fishery is of great socio-economic importance to coastal communities on the North Sea. The fishery is exploited by beam trawlers often using codends with very small mesh sizes, leading to concerns about catch rates of undersized shrimp. However, little information is available on codend size selection, making it difficult to provide scientifically based advice on alternative codend designs. Therefore, this study establishes a predictive framework for codend size selection of brown shrimp, based on a large selectivity dataset from 33 different codend designs tested during four experimental fishing cruises, during which more than 350,000 brown shrimp were length measured. Predictions by the framework confirm concerns about the exploitation pattern in the fishery, because the retention probability of undersized shrimp reaches 95% with the currently applied designs. The framework predictions allow the exploration of obtainable exploitation patterns depending on codend design. For example, increasing codend mesh size to 25±29 mm would reduce the retention rate of undersized shrimp to a maximum of 50%, depending on codend mesh type.