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首页> 外文期刊>CCAMLR science: journal of the Scientific Committee and the Commission for the Conservation of Antarctic Marine Living Resources >Selectivity of commercial and research trawls in relation to krill
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Selectivity of commercial and research trawls in relation to krill

机译：商业和研究拖网与磷虾的选择性

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This paper describes the results of fishing a single krill aggregation with a commercial trawl RT 72/308 and an Isaacs-Kidd midwater research trawl (IKMT). The commercial trawl catches contained more large krill (35-58 mm) than catches of the research trawl (30-54 mm). The maximum difference in mean length in catches made by both trawls was ?L = 6.2 mm. Statistically significant variability in krill length composition was observed between catches made by the research trawl, while in commercial trawl catches krill length composition hardly varied at all. Statistical analysis of catches showed that when it comes to obtaining representative trawl samples, estimates of length composition in krill catches made using the commercial RT 72/308 trawl are more accurate than those obtained using the IKMT research trawl. The two types of trawl have different catchability characteristics: the research trawl is better at retaining small krill, while the opposite is true for the commercial trawl. Consequently, estimates of krill length based on data obtained using either commercial or research trawls will be biased and contain systematic errors, mainly due to the selectivity properties of the trawls. The various selectivity properties of the trawl used in acoustic surveys have different effects on the accuracy of krill abundance and biomass estimates. Estimates of krill mass density (g/m2) and biomass are less dependent upon the selectivity properties of trawls used in acoustic surveys than are estimates of krill numerical density (numbers/m2) and abundance.
机译：本文介绍了使用商业拖网RT 72/308和艾萨克斯-基德中层研究拖网（IKMT）捕捞单个磷虾集合体的结果。商业拖网渔获物比研究拖网渔获物（30-54毫米）包含更大的磷虾（35-58毫米）。两条拖网渔获物的平均长度的最大差异为ΔL= 6.2 mm。在研究拖网的渔获之间，磷虾长度组成在统计学上具有显着差异，而在商业拖网渔获中，磷虾长度组成几乎没有变化。渔获物的统计分析表明，在获取代表性拖网样本时，使用商业RT 72/308拖网对磷虾渔获物中的长度组成进行估算比使用IKMT研究拖网所获得的更准确。两种类型的拖网具有不同的可捕获性：研究型拖网在保留小磷虾方面更好，而商业拖网则相反。因此，主要是由于拖网的选择性，基于使用商业或研究拖网获得的数据进行的磷虾长度估计会产生偏差，并包含系统误差。声学勘测中使用的拖网的各种选择性属性对磷虾丰度和生物量估计的准确性有不同的影响。磷虾质量密度（g / m2）和生物量的估计与磷虾数值密度（数量/ m2）和丰度的估计相比，对声学调查中使用的拖网的选择性特性的依赖性较小。

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