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首页> 外文期刊>ICES Journal of Marine Science >A method for evaluating the impacts of fishing mortality and stochastic influences on the demography of two long-lived shark stocks
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A method for evaluating the impacts of fishing mortality and stochastic influences on the demography of two long-lived shark stocks

机译：评估捕捞死亡率和随机影响对两种长寿鲨鱼种群的影响的方法

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摘要

Stochastic demographic models were developed for Carcharhinus obscurus and C. plumbeus populations off the west coast of Australia by resampling the input parameters for life tables from empirical biological data collected from commercial target fisheries and fishery-independent surveys. The models were used to examine the effects of multiple scenarios of age-specific survival, derived from the fishing mortality rates estimated from a tagging study on sharks and indirect estimates of natural mortality. In the absence of fishing, median estimates of the rates of intrinsic population increase (r) were 0.025 for both species. Inclusion of the age-specific fishing mortality rates estimated for C. obscurus recruits born in 1994 and 1995 resulted in the median estimates of rdeclining to 0.007 and 0.012, respectively, suggesting that recent harvest levels of mainly neonates by the target fishery were probably sustainable. However, the model also suggested that the population was more susceptible to exploitation of older sharks than was previously believed. The C. plumbeus model indicated that fishing mortality between 2001 and 2004 was probably unsustainable. The increasingly negative trend in median r estimates (from -0.032 to -0.049), and the population's apparently limited capacity for density-dependent compensation through changes in fecundity, somatic growth and longevity, suggests that management intervention is necessary to prevent continued stock depletion.
机译：通过从商业目标渔业和独立于渔业的调查中收集的经验生物学数据，对生命表的输入参数进行重新抽样，为澳大利亚西海岸的暗纹Car鱼和铅青C种群开发了随机人口统计学模型。这些模型用于检查特定年龄生存的多种情景的影响，这些情景源自对鲨鱼的标记研究估计的捕鱼死亡率和对自然死亡率的间接估计。在没有捕鱼的情况下，两种物种的固有种群增长率（r）的中位数估计为0.025。将1994年和1995年出生的暗中隐孢子虫新兵的按年龄划分的捕鱼死亡率包括在内，估计中值分别下降至0.007和0.012，这表明目标渔业最近主要是新生儿的捕捞水平可能是可持续的。但是，该模型还表明，与以前所认为的相比，该种群更容易受到旧鲨鱼的剥削。 C. plumbeus模型表明2001年至2004年之间的捕捞死亡率可能难以为继。中位数r估计值的负趋势越来越大（从-0.032到-0.049），并且由于生育力，体细胞生长和寿命的变化，人口依赖于密度的补偿的能力明显受到限制，这表明管理干预对于防止种群持续枯竭是必要的。

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