ABSTRACT Trawling is the main fishing practice worldwide and its ecosystem effects have been raising concern over the past decades. Long-term impacts can be monitored through changes in the trophic structure, and several studies evaluated trophic level (TL) shifts in fish populations between trawled and untrawled environments. However, published results are contrasting. We performed a metanalysis integrating all available studies that evaluated TL shifts in fishes between trawled and untrawled environments and conducted a local study comparing several features of the trophic ecology in two species of fishes. According to the metanalysis, TL does not change significantly with trawling. In contrast, the local study showed higher TLs and broader isotopic niches in the trawled environment. Diet reconstruction indicated a potential consumption of hake, the main discard component, at the trawled environment. All the studies used in the metanalysis were conducted in the Northern Hemisphere, whereas the local study represents the first data available from the Southern Hemisphere. As industrial commercial fisheries in Argentina are relatively recent, it is possible that our data are capturing the initial stage of ecological changes induced by trawling, compared with the historical fisheries located at the Northern Hemisphere.

中文翻译：

---

拖网渔业会影响鱼类的饮食吗？稳定同位素分析方法

摘要 拖网捕捞是世界范围内的主要捕捞方式，其生态系统影响在过去几十年中引起了人们的关注。可以通过营养结构的变化来监测长期影响，一些研究评估了拖网和未拖网环境之间鱼类种群的营养水平 (TL) 变化。然而，公布的结果却大相径庭。我们进行了一项荟萃分析，整合了所有评估拖网和未拖网环境之间鱼类 TL 变化的现有研究，并进行了一项本地研究，比较了两种鱼类的营养生态学的几个特征。根据荟萃分析，拖网捕捞时 TL 没有显着变化。相比之下，当地研究表明，拖网捕捞环境中的 TLs 和同位素生态位更高。饮食重建表明鳕鱼的潜在消费，主要丢弃部分，在拖网捕捞环境中。荟萃分析中使用的所有研究都是在北半球进行的，而本地研究代表了来自南半球的第一批可用数据。由于阿根廷的工业商业渔业相对较新，与位于北半球的历史渔业相比，我们的数据可能捕捉到由拖网捕捞引起的生态变化的初始阶段。