Monitoring marine resource exploitation is a key activity in fisheries science and biodiversity conservation. Since research surveys are time consuming and costly, fishery‐dependent data (i.e., derived directly from fishing vessels) are increasingly credited with a key role in expanding the reach of ocean monitoring. Fishing vessels may be seen as widely ranging data‐collecting platforms, which could act as a fleet of sentinels for monitoring marine life, in particular exploited stocks. Here, we investigate the possibility of assessing catch composition of single hauls carried out by trawlers by applying DNA metabarcoding to the dense water draining from fishing nets just after the end of hauling operations (hereafter “slush”). We assess the performance of this approach in portraying β‐diversity and examining the quantitative relationship between species abundances in the catch and DNA amount in the slush (read counts generated by amplicon sequencing). We demonstrate that the assemblages identified using DNA in the slush satisfactorily mirror those returned by visual inspection of net content (about 71% of species and 86% of families of fish) and detect a strong relationship between read counts and species abundances in the catch. We therefore argue that this approach could be upscaled to serve as a powerful source of information on the structure of demersal assemblages and the impact of fisheries.

中文翻译：

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都是鱼成网：用于快速捕捞量评估的元条形码

监测海洋资源开发是渔业科学和生物多样性保护的一项关键活动。由于研究调查既耗时又昂贵，因此，依赖渔业的数据（即直接来自渔船的数据）在扩大海洋监测范围方面起着关键作用。捕鱼船可能被视为范围广泛的数据收集平台，可以充当监视海洋生物（特别是被捕捞种群）的前哨舰队。在这里，我们研究了在拖网作业刚结束（以下称“泥泞”）之后，通过将DNA元条形码应用于从渔网中排出的浓水中来评估拖网渔船单次拖网的渔获物成分的可能性。我们评估了该方法在描绘β多样性和检查捕获物中物种丰度与泥浆中DNA量之间的定量关系（扩增子测序产生的读数计数）之间的定量关系。我们证明，使用雪泥中的DNA识别的组合令人满意地反映了通过目视检查净含量（大约71％的物种和86％的鱼类科）返回的那些，并且检测到捕获数量与物种数量之间的密切关系。因此，我们认为这种方法可以扩大规模，以作为有关沉没式鱼群的结构和渔业影响的信息的有力来源。我们证明，使用雪泥中的DNA识别的组合令人满意地反映了通过目视检查净含量（大约71％的物种和86％的鱼类科）返回的那些，并且检测到捕获数量与物种数量之间的密切关系。因此，我们认为这种方法可以扩大规模，以作为有关沉没式鱼群的结构和渔业影响的信息的有力来源。我们证明，使用雪泥中的DNA识别的组合令人满意地反映了通过目视检查净含量（大约71％的物种和86％的鱼类科）返回的那些，并且检测到捕获数量与物种数量之间的密切关系。因此，我们认为这种方法可以扩大规模，以作为有关沉没式鱼群的结构和渔业影响的信息的有力来源。