分隔式桁拖网分隔装置的分隔效率模型

Model for separating efficiency assessment of separator devices rigged in multi-level beam trawls

种类选择性研究是减轻拖网渔业兼捕和抛弃问题的重要方法,利用参数化的模型实现拖网渔具选择性装置渔获性能的解析,不仅有利于装置性能的评价和比较,而且对于优化选择性装置结构、提高装置性能具有重要的意义。根据SELECT模型原理,认为渔获对象接触分隔装置的概率与个体尺寸有关,并使用S型曲线(Logistic曲线)表示接触概率曲线,结合分隔装置的选择曲线,为评价桁拖网分隔装置的分隔效率建立了模型。模型对分隔式桁拖网渔具(60 mm分隔网片)捕获的哈氏仿对虾和短吻舌鳎的渔获数据进行拟合,结果表明,该模型能较好地分析分隔网片的分隔效率。通过对模型的分析,认为模型具有较好的应用性,且模型可根据实际情况进行适当简化;将捕捞对象的接触概率独立于选择性装置选择性能的做法,对于研究网具内捕捞对象行为特性具有一定的参考意义。

Research on species selection is one of important potential measure to alleviate the by-catch and discard problem of trawl fisheries. More and more research showed that parametric models, which have been widely used in analysis of selective devices of trawls, were not only important to assess and compare the performance but indicative to improve the construction of the selective devices. In this paper, a model for assessing the separating efficiency of separator devices rigged in multi-level beam trawl fishing offshore of the East China Sea, in which the size selection of separator panel was taken into account and encounter probability （presented by ogive, Logistic curve） of individual entering trawl was regarded as dependent upon the individual size and then presented by ogive （Logistic curve ）, was developed based on the principle of Select model. Fitness of model for size frequency of Parapenaeposis hardwickii and Cynoglossus abbreviatus caught by multi-level beam trawl rigging separator panel with 60 mm mesh size and the maximum likelihood estimates of parameters showed the model was applicable to assess the separating efficiency of panel. According to the discussion, the model could be applied to the other selective devices and simplified by hypothesis test method according to different situation. Additionally, we think the encounter probability of individual, which was independent of size selection of selective device, could be used to analyse the responding behavior of aquatic animal.