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A D Rijnsdorp - One of the best experts on this subject based on the ideXlab platform.
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evolutionary impact assessment of the north sea Plaice fishery
Canadian Journal of Fisheries and Aquatic Sciences, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, J J Poos, A D RijnsdorpAbstract:There is growing evidence that fishing causes evolution in life-history traits that affect the productivity of fish stocks. Here we explore the impact of fisheries-induced evolution (FIE) on the productivity of North Sea Plaice (Pleuronectes platessa) using an ecogenetic, individual-based model by comparing management scenarios with and without an evolutionary response. Under status-quo management, Plaice evolve towards smaller size at age, earlier maturation, and higher reproductive investment. Current reference points of maximum sustainable yield (MSY) and corresponding fishing-mortality rate (FMSY) that ignore FIE will decrease and cannot be considered sustainable. The nature and extent of the change through FIE depend on fishing effort and selectivity. The adverse evolutionary effects can be reduced — and even reversed — by implementing a dome-shaped exploitation pattern protecting the large fish. The evolutionarily sustainable maximum yield can be obtained by combining such a dome-shaped exploitation...
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nine decades of north sea sole and Plaice distribution
Ices Journal of Marine Science, 2011Co-Authors: Georg H Engelhard, John K Pinnegar, Laurence T Kell, A D RijnsdorpAbstract:Recent studies based mainly on research survey data suggest that within the North Sea, sole Solea solea and Plaice Pleuronectes platessa have exhibited distribution shifts in recent decades—on average southward for sole and northward to deeper waters for Plaice. Various hypotheses may account for such shifts, including climate change effects and more intensive fishing in southern and shallower waters; but the relatively short time-span of datasets analysed so far (� 3 decades) has complicated the separation of these two effects. We have made use of a unique dataset of catch and effort data for British North Sea trawlers; these cover nine decades (spanning the period 1913 – 2007) and are spatially detailed by ICES rectangle (0.58 latitude by 18 longitude). We quantify, for the first time, long-term distribution changes of North Sea sole and Plaice over a period approaching a century, and demonstrate that the distribution shift in Plaice was attributable to climate change rather than to fishing, but that both climate and fishing played a role in the distribution shift of sole. The discussion also highlights the potential impact of additional factors, including eutrophication, prey availability, and habitat modification.
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three dimensional maturation reaction norms for north sea Plaice
Marine Ecology Progress Series, 2007Co-Authors: R E Grift, A D Rijnsdorp, Mikko Heino, Sarah B M Kraak, Ulf DieckmannAbstract:Probabilistic maturation reaction norms (PMRNs) with up to 3 explanatory dimensions were estimated for female North Sea Plaice Pleuronectes platessa. The 3-dimensional PMRNs reported here (1) are the first to be obtained for any organism, (2) reveal the differential capacity of alternative life-history state variables to predict the onset of reproduction, (3) document consistent temporal trends in maturation, and (4) help disentangle the contributions of genetic and plastic effects to these trends. We first show that PMRNs based on age and weight provide slightly more accurate approximations of maturation probabilities than PMRNs based on age and length. At the same time, weight-based PMRNs imply a much wider spread of maturation probabilities than length- based PMRNs. We then demonstrate that including condition as a third explanatory variable improves predictions of maturation probability. The resultant 3-dimensional PMRNs for age-length- condition or age-weight-condition not only show how, at given size and age, maturation probability increases with condition, but also expose how this impact of condition decreases with age and has changed over time. Our analysis reveals several interesting temporal trends. First, it is demonstrated that even after removing plastic effects on maturation captured by age, length, weight and condition, residual trends towards maturation at younger ages and smaller lengths remain. Second, we find that the width of both length- and weight-based PMRNs decreased significantly over time. Third, age and condition are nowadays affecting maturation probabilities less than they did decades ago. We con- clude that Plaice are currently maturing at a very low age, size and body condition, and that the nar- row and steep reaction norms do not allow a strong continuation of the observed trends. The findings obtained are in good agreement with predictions from life-history theory based on the hypothesis of evolutionary change caused by heavy exploitation.
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changes in the spatial distribution of north sea Plaice pleuronectes platessa and implications for fisheries management
Journal of Sea Research, 2007Co-Authors: O A Van Keeken, R E Grift, M Van Hoppe, A D RijnsdorpAbstract:Abstract To protect the main nursery area of Plaice, an area called the ‘Plaice Box’ was closed to trawl fisheries with large vessels in 1989, with the expectation that recruitment, yield and spawning stock biomass would increase. However, since then the Plaice population has declined and the rate of discarding outside the Plaice Box has increased, suggesting an offshore shift in spatial distribution of juvenile Plaice. Using research vessel survey data collected since 1970, the change in distribution of juvenile age groups was analysed in relation to the distance to the coast. Further, a comparison of the distribution of different length classes of Plaice between three historic periods was made (1902–1909; 1983–1987; 1999–2003). A shift towards deeper water of larger-sized Plaice (20–39 cm) is apparent already before the 1980s and may be related to the decrease in the number of competitors or predators. An offshore shift in the distribution of young Plaice occurred in the 1990s most likely in response to higher water temperatures that may have exceeded the maximum tolerance range or increased the food requirements above the available food resources. A decrease in competition with larger Plaice offshore, possibly in combination with increased inshore predation by cormorants and seals, may also have played a role. The offshore shift in distribution has reduced the effectiveness of the Plaice Box as a technical measure to protect the under-sized Plaice from discarding, since an increased proportion of the population of undersized Plaice is moving to the more heavily exploited offshore areas.
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effects of a partially closed area in the north sea Plaice box on stock development of Plaice
Ices Journal of Marine Science, 2000Co-Authors: M A Pastoors, A D Rijnsdorp, F A Van BeekAbstract:The ‘‘Plaice box’’ is a partially closed area in the North Sea, established in 1989 to reduce the discarding of undersized Plaice (Pleuronectes platessa) in the main nursery areas, and thereby to enhance recruitment to the fishery. In contrast to the expected positive effects, yield and spawning stock biomass have decreased. The effects of the Plaice box are evaluated by analyzing the relevant factors and processes (natural and anthropogenic) that affect recruitment. It is shown that the Dutch beam trawl effort has decreased in two phases. During 1989–1993, when the Plaice box was closed only during the second and third quarter, effort was reduced to around 40% of the original level. When the box was also closed in the fourth (1994) and first quarter (1995 onwards), effort decreased to around 6%. The effort reduction would imply a reduction in discard mortality if all other factors had remained constant. However, a reduced growth rate and possibly a higher rate of natural mortality may have counteracted the reduction in fishing effort. The apparent changes in growth and mortality coincided with changes in the North Sea ecosystem that occurred in the early 1990s but may also be related to a response to the change in beam trawl effort. 2000 International Council for the Exploration of the Sea
Ulf Dieckmann - One of the best experts on this subject based on the ideXlab platform.
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evolutionary impact assessment of the north sea Plaice fishery
Canadian Journal of Fisheries and Aquatic Sciences, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, J J Poos, A D RijnsdorpAbstract:There is growing evidence that fishing causes evolution in life-history traits that affect the productivity of fish stocks. Here we explore the impact of fisheries-induced evolution (FIE) on the productivity of North Sea Plaice (Pleuronectes platessa) using an ecogenetic, individual-based model by comparing management scenarios with and without an evolutionary response. Under status-quo management, Plaice evolve towards smaller size at age, earlier maturation, and higher reproductive investment. Current reference points of maximum sustainable yield (MSY) and corresponding fishing-mortality rate (FMSY) that ignore FIE will decrease and cannot be considered sustainable. The nature and extent of the change through FIE depend on fishing effort and selectivity. The adverse evolutionary effects can be reduced — and even reversed — by implementing a dome-shaped exploitation pattern protecting the large fish. The evolutionarily sustainable maximum yield can be obtained by combining such a dome-shaped exploitation...
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three dimensional maturation reaction norms for north sea Plaice
Marine Ecology Progress Series, 2007Co-Authors: R E Grift, A D Rijnsdorp, Mikko Heino, Sarah B M Kraak, Ulf DieckmannAbstract:Probabilistic maturation reaction norms (PMRNs) with up to 3 explanatory dimensions were estimated for female North Sea Plaice Pleuronectes platessa. The 3-dimensional PMRNs reported here (1) are the first to be obtained for any organism, (2) reveal the differential capacity of alternative life-history state variables to predict the onset of reproduction, (3) document consistent temporal trends in maturation, and (4) help disentangle the contributions of genetic and plastic effects to these trends. We first show that PMRNs based on age and weight provide slightly more accurate approximations of maturation probabilities than PMRNs based on age and length. At the same time, weight-based PMRNs imply a much wider spread of maturation probabilities than length- based PMRNs. We then demonstrate that including condition as a third explanatory variable improves predictions of maturation probability. The resultant 3-dimensional PMRNs for age-length- condition or age-weight-condition not only show how, at given size and age, maturation probability increases with condition, but also expose how this impact of condition decreases with age and has changed over time. Our analysis reveals several interesting temporal trends. First, it is demonstrated that even after removing plastic effects on maturation captured by age, length, weight and condition, residual trends towards maturation at younger ages and smaller lengths remain. Second, we find that the width of both length- and weight-based PMRNs decreased significantly over time. Third, age and condition are nowadays affecting maturation probabilities less than they did decades ago. We con- clude that Plaice are currently maturing at a very low age, size and body condition, and that the nar- row and steep reaction norms do not allow a strong continuation of the observed trends. The findings obtained are in good agreement with predictions from life-history theory based on the hypothesis of evolutionary change caused by heavy exploitation.
Patrick Bayer - One of the best experts on this subject based on the ideXlab platform.
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place of work and place of residence informal hiring networks and labor market outcomes
Journal of Political Economy, 2008Co-Authors: Patrick Bayer, Stephen L Ross, Giorgio TopaAbstract:We use a novel research design to empirically detect the effect of social interactions on labor market outcomes. Using Census data on residential and employment locations, we examine whether individuals residing in the same city block are more likely to work together than those in nearby blocks. We find evidence of significant social interactions. The estimated referral effect is stronger when individuals are similar in sociodemographic characteristics. These findings are robust across specifications intended to address sorting and reverse causation. Further, the increased availability of neighborhood referrals has a significant impact on a wide range of labor market outcomes.
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place of work and place of residence informal hiring networks and labor market outcomes
Journal of Political Economy, 2008Co-Authors: Patrick Bayer, Stephen L Ross, Giorgio TopaAbstract:We use a novel dataset and research design to empirically detect the effect of social interactions among neighbors on labor market outcomes. Specifically, using Census data that characterize residential and employment locations down to the city block, we examine whether individuals residing in the same block are more likely to work together than those in nearby blocks. We find evidence of significant social interactions operating at the block level: residing on the same versus nearby blocks increases the probability of working together by over 33 percent. The results also indicate that this referral effect is stronger when individuals are similar in sociodemographic characteristics (e.g., both have children of similar ages) and when at least one individual is well attached to the labor market. These findings are robust across various specifications intended to address concerns related to sorting and reverse causation. Further, having determined the characteristics of a pair of individuals that lead to an especially strong referral effect, we provide evidence that the increased availability of neighborhood referrals has a significant impact on a wide range of labor market outcomes including employment and wages.
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place of work and place of residence informal hiring networks and labor market outcomes
National Bureau of Economic Research, 2005Co-Authors: Patrick Bayer, Stephen L Ross, Giorgio TopaAbstract:We use a novel research design to empirically detect the effect of social interactions among neighbors on labor market outcomes. Specifically, using Census data that characterize residential and employment locations down to the city block, we examine whether individuals residing in the same block are more likely to work together than those in nearby blocks. We find evidence of significant social interactions operating at the block level: residing on the same versus nearby blocks increases the probability of working together by over 33 percent. The results also indicate that this referral effect is stronger when individuals are similar in socio-demographic characteristics (e.g., both have children of similar ages) and when at least one individual is well attached to the labor market. These findings are robust across various specifications intended to address concerns related to sorting and reverse causation. Further, having determined the characteristics of a pair of individuals that lead to an especially strong referral effect, we provide evidence that the increased availability of neighborhood referrals has a significant impact on a wide range of labor market outcomes including labor force participation, hours and earnings.
R E Grift - One of the best experts on this subject based on the ideXlab platform.
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three dimensional maturation reaction norms for north sea Plaice
Marine Ecology Progress Series, 2007Co-Authors: R E Grift, A D Rijnsdorp, Mikko Heino, Sarah B M Kraak, Ulf DieckmannAbstract:Probabilistic maturation reaction norms (PMRNs) with up to 3 explanatory dimensions were estimated for female North Sea Plaice Pleuronectes platessa. The 3-dimensional PMRNs reported here (1) are the first to be obtained for any organism, (2) reveal the differential capacity of alternative life-history state variables to predict the onset of reproduction, (3) document consistent temporal trends in maturation, and (4) help disentangle the contributions of genetic and plastic effects to these trends. We first show that PMRNs based on age and weight provide slightly more accurate approximations of maturation probabilities than PMRNs based on age and length. At the same time, weight-based PMRNs imply a much wider spread of maturation probabilities than length- based PMRNs. We then demonstrate that including condition as a third explanatory variable improves predictions of maturation probability. The resultant 3-dimensional PMRNs for age-length- condition or age-weight-condition not only show how, at given size and age, maturation probability increases with condition, but also expose how this impact of condition decreases with age and has changed over time. Our analysis reveals several interesting temporal trends. First, it is demonstrated that even after removing plastic effects on maturation captured by age, length, weight and condition, residual trends towards maturation at younger ages and smaller lengths remain. Second, we find that the width of both length- and weight-based PMRNs decreased significantly over time. Third, age and condition are nowadays affecting maturation probabilities less than they did decades ago. We con- clude that Plaice are currently maturing at a very low age, size and body condition, and that the nar- row and steep reaction norms do not allow a strong continuation of the observed trends. The findings obtained are in good agreement with predictions from life-history theory based on the hypothesis of evolutionary change caused by heavy exploitation.
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changes in the spatial distribution of north sea Plaice pleuronectes platessa and implications for fisheries management
Journal of Sea Research, 2007Co-Authors: O A Van Keeken, R E Grift, M Van Hoppe, A D RijnsdorpAbstract:Abstract To protect the main nursery area of Plaice, an area called the ‘Plaice Box’ was closed to trawl fisheries with large vessels in 1989, with the expectation that recruitment, yield and spawning stock biomass would increase. However, since then the Plaice population has declined and the rate of discarding outside the Plaice Box has increased, suggesting an offshore shift in spatial distribution of juvenile Plaice. Using research vessel survey data collected since 1970, the change in distribution of juvenile age groups was analysed in relation to the distance to the coast. Further, a comparison of the distribution of different length classes of Plaice between three historic periods was made (1902–1909; 1983–1987; 1999–2003). A shift towards deeper water of larger-sized Plaice (20–39 cm) is apparent already before the 1980s and may be related to the decrease in the number of competitors or predators. An offshore shift in the distribution of young Plaice occurred in the 1990s most likely in response to higher water temperatures that may have exceeded the maximum tolerance range or increased the food requirements above the available food resources. A decrease in competition with larger Plaice offshore, possibly in combination with increased inshore predation by cormorants and seals, may also have played a role. The offshore shift in distribution has reduced the effectiveness of the Plaice Box as a technical measure to protect the under-sized Plaice from discarding, since an increased proportion of the population of undersized Plaice is moving to the more heavily exploited offshore areas.
Fabian M Mollet - One of the best experts on this subject based on the ideXlab platform.
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evolutionary impact assessment of the north sea Plaice fishery
Canadian Journal of Fisheries and Aquatic Sciences, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, J J Poos, A D RijnsdorpAbstract:There is growing evidence that fishing causes evolution in life-history traits that affect the productivity of fish stocks. Here we explore the impact of fisheries-induced evolution (FIE) on the productivity of North Sea Plaice (Pleuronectes platessa) using an ecogenetic, individual-based model by comparing management scenarios with and without an evolutionary response. Under status-quo management, Plaice evolve towards smaller size at age, earlier maturation, and higher reproductive investment. Current reference points of maximum sustainable yield (MSY) and corresponding fishing-mortality rate (FMSY) that ignore FIE will decrease and cannot be considered sustainable. The nature and extent of the change through FIE depend on fishing effort and selectivity. The adverse evolutionary effects can be reduced — and even reversed — by implementing a dome-shaped exploitation pattern protecting the large fish. The evolutionarily sustainable maximum yield can be obtained by combining such a dome-shaped exploitation...