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This is a little known but vital area of current research in New Zealand and worldwide. The crucial question: is fishing as it is practiced here and overseas sustainable in terms of its impacts and natural fish stock's genetics and evolution. There are some dramatic implications and challenges to fisheries management which comes to light from this work.
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This paper discusses the differentiation of genetics in marine populations. It notes that genetic analyses of marine population structure often find only slight geographic differentiation in species with high dispersal potential. Thus, interpreting the significance of this slight genetic signal has been difficult because even mild genetic structure implies very limited demographic exchange between populations, but slight differentiation could also be due to sampling error. The author submits that the examination of genetic isolation by distance, in which close populations are more similar than distant ones, has the potential to increase confidence in the significance of slight genetic differentiation. He notes that direct measurements of mean larval dispersal are needed to understand connectivity in a reserve system, but such measurements are extremely difficult. He concludes that genetic patterns of isolation by distance have the potential to add to direct measurement of larval dispersal distance and can help set the appropriate geographic scales on which marine reserve systems will function well.
Added to archive on 06/22/2007 and placed in the following categories:
Fish Genetics NZ and International |
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In this paper the authors submit that microsatellite analyses of a time series of archived scales demonstrated a significant decline in genetic diversity in a New Zealand snapper population during its exploitation history. They note that effective population sizes estimated both from the decline in heterozygosity and from temporal fluctuations in allele frequency were five orders of magnitude smaller than census population sizes from fishery data. They conclude that if such low NeN ratios are commonplace in marine species, many exploited marine fish stocks may be in danger of losing genetic variability, potentially resulting in reduced adaptability, population persistence, and productivity.
Added to archive on 06/22/2007 and placed in the following categories:
Fish Genetics NZ and International |
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This paper discusses the results of a study where the authors subjected populations of an exploited fish (Menidia menidia) to large, small, or random size-selective harvest of adults over four generations. The authors submit that harvested biomass evolved rapidly in directions counter to the size-dependent force of fishing mortality. They further noted that large-harvested populations initially produced the highest catch but quickly evolved a lower yield than controls. Small-harvested populations did the reverse. These shifts were caused by selection of genotypes with slower or faster rates of growth. They concluse by saying management tools that preserve natural genetic variation are necessary for long-term sustainable yield.
Added to archive on 06/22/2007 and placed in the following categories:
Fish Genetics NZ and International |
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