Estimating fishery-scale rates of discard mortality using conditional reasoning
Estimating fishery-scale rates of discard mortality using conditional reasoning
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DOI：
10.1016/j.fishres.2011.12.004
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发表时间：
2012-08-01
影响因子：
2.4
通讯作者：
Jonsen, Ian D.
中科院分区：
文献类型：
--
作者：
Benoit, Hugues P.;Hurlbut, Thomas;Jonsen, Ian D.
为人口和生态系统评估获得具有代表性的弃物死亡率估计数是非常具有挑战性的。这只能通过回收被标记的被丢弃的个体来直接完成。相反，可以使用船上观察员在丢弃前对个别鱼的活力或身体状况所作的半定量的测量。这种活力措施可以是弃置物死亡率的良好指标，并且由于数据收集方法，还应反映整个渔业的弃置物状况。此外，可以使用已知的影响丢弃死亡率的协变量来预测生命力，从而进行更一般的评估。我们认为，代表性死亡率可以使用至少两种概率的乘积来估计：属于特定活力类别的概率，取决于捕获和捕获处理过程中经历的因素；以及在事件中幸存的概率，取决于释放前的活力。在这里，我们估计了圣劳伦斯湾南部渔业捕获的五种鱼类的死亡率。条件生存概率是通过对实验数据的生存分析得出的，实验中，使用商业捕鱼方法捕获鱼类，并保持以评估短期死亡率（2-3天）。该分析包括一个混合模型，其中包含一小部分未受影响的个体，这似乎适用于副渔获物死亡率研究的数据。基于这项研究和混合模型的机制解释，对丢弃物死亡率的短期监测可能足以表征对许多分类群的长期影响。爱思唯尔B.V.版权所有
Obtaining a representative estimate of discard mortality for population and ecosystem assessments is very challenging. This can only rarely be done directly by recovering tagged discarded individuals. Instead, semi-quantitative measures of individual fish vitality or physical condition, obtained by onboard observers prior to discarding, can be used. Such vitality measures can be a good indicator of discard mortality, and by virtue of the data collection method, should also reflect the condition of discards throughout the fishery. Furthermore, vitality can be predicted using covariates known to affect discard mortality, allowing for a more general assessment. We argue that a representative mortality rate can be estimated using the product of at least two probabilities: that of belonging to a particular vitality class, conditional on the factors experienced during capture and catch handling; and the probability of surviving the event, conditional on pre-release vitality. Here we estimate mortalities for five fish taxa captured in southern Gulf of St. Lawrence fisheries. The conditional survival probabilities were obtained using survival analysis of data from experiments in which fish were captured using commercial fishing methods and held to assess short-term mortality (2-3 days). The analysis included a mixture model with a fraction of unaffected individuals, which appears appropriate for data from bycatch mortality studies. Based on this study and the mechanistic interpretation of the mixture model, short-term monitoring of discard mortality may be sufficient to characterize longer term impacts in a number of taxa. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.