Otter trawling for fish is one of the world’s most productive yet problematic fishing methods due to its bycatch and discards; issues that have been mitigated in some fisheries by developing more selective trawls. This paper systematically reviews efforts published in international peer-reviewed papers over the past 30 years to identify beneficial (and limiting) factors and propose a way forward in this field. In total, 203 papers were assessed, encompassing many of the world’s fishing regions, and involving > 147 species, although 74% of efforts occurred in Europe mainly focussing on haddock (Melanogrammus aeglefinus) (64 papers) and cod (Gadus morhua) (59 papers). Common, simple modifications have involved increasing lateral-mesh openings to match the morphology of unwanted catches via larger diamond-shaped mesh, or simply turning meshes 45° or 90°, either throughout codends or as strategic windows in the posterior trawl. In some fisheries, more complex grids have improved size or species selection. Fewer attempts have been made to modify the anterior trawl, but varying sweep/bridle lengths, horizontal separator panels and longer headropes have realized benefits depending on species-specific behavioural responses. While the utility of many modifications is indisputable, experimental designs (mostly involving covers, but also alternate hauls and paired comparisons) have, in many cases, suffered low replication and/or confounding variables. These deficits may have compromised some results and contributed to repeated efforts in particular fisheries. We conclude that rigorous empirical assessments, initially focusing on the posterior trawl, but eventually encompassing anterior changes, combined with straightforward interpretation of results for stakeholders, are as important as the simplicity and reliability of modifications. Finally, by assessing the utility, applicability, advantages and disadvantages of the modifications developed, we provide a framework which could be followed in future work to reduce bycatch in these fisheries.

由于拖捕和丢弃，水獭拖网捕鱼是世界上生产效率最高但有问题的捕鱼方法之一。通过发展更具选择性的拖网，一些渔业已经缓解了这些问题。本文系统地回顾了过去30年来在国际同行评审论文中发表的成果，以找出有益的（和限制性的）因素，并提出了该领域的前进之路。总共评估了203篇论文，涵盖了世界上许多捕捞地区，涉及147种以上，尽管欧洲有74％的努力主要集中在黑线鳕（Melanogrammus aeglefinus）（64篇论文）和鳕鱼（Gadus morhua）（59篇论文）。常见的简单修改涉及增加侧向网孔，以通过较大的菱形网眼匹配不必要的渔获物的形态，或者简单地将网眼旋转45°或90°（整个编码区中或作为后拖网中的战略窗口）。在某些渔业中，更复杂的网格可以改善尺寸或物种选择。很少有人尝试修改前拖网，但是根据物种特定的行为反应，改变后掠/围栏长度，水平分隔板和较长的头绳已经实现了好处。尽管许多修改的实用性是无可争议的，但在许多情况下，实验设计（主要涉及封面，还包括替代产品和成对的比较）在许多情况下遭受低复制和/或混淆变量的困扰。这些赤字可能损害了某些成果，并助长了某些渔业的反复努力。我们得出的结论是，严格的经验评估最初集中于后拖网，但最终包含前向变化，并结合对利益相关者的直接结果解释，与修改的简单性和可靠性一样重要。最后，通过评估所开发修改的效用，适用性，优缺点，我们提供了一个框架，可以在今后的工作中遵循这些框架，以减少这些渔业中的副渔获物。与利益相关者对结果的直接解释相结合，与修改的简单性和可靠性一样重要。最后，通过评估所开发修改的效用，适用性，优缺点，我们提供了一个框架，可以在今后的工作中遵循这些框架，以减少这些渔业中的副渔获物。与利益相关者对结果的直接解释相结合，与修改的简单性和可靠性一样重要。最后，通过评估所开发修改的效用，适用性，优缺点，我们提供了一个框架，可以在今后的工作中遵循这些框架，以减少这些渔业中的副渔获物。