Norwegian Institute for Nature Research (NINA), Lillehammer, Norway.
Norwegian Institute for Nature Research (NINA), Department of Terrestrial Ecology, Trondheim, Norway.
PLoS One. 2019 Mar 13;14(3):e0212786. doi: 10.1371/journal.pone.0212786. eCollection 2019.
The general decline of seabird populations worldwide raises large concerns. Although multiple factors are interacting to cause the observed trends, increased mortality from incidental bycatch in fisheries has proven to be important for many species. However, the bulk of published knowledge is derived from longline fisheries, whereas bycatch in gillnet fisheries is less studied and even overlooked in some areas. We present seabird bycatch data from a 10-year time-series of fishery data from the large fleet of small-vessels fishing with gillnets along the Norwegian coast-a large area and fishery with no prior estimates of seabird bycatch. In general, we document high rates of incidental bycatch (averaging 0.0023 seabirds/net, or approximately 0.08 seabirds/fishing trip). This results in an estimated annual bycatch between 1580 and 11500 (95% CI) birds in this fishery. There was a surprisingly high percentage (43%) of surface-feeding seabirds in the bycatch, with northern fulmar being the most common species. Among the diving seabirds caught, common guillemot was most numerous. Our findings suggest that coastal gillnet fisheries represent a more general threat to a wider range of seabird populations, as opposed to longline fisheries where surface-feeding seabird species seem to dominate the bycatch. The bycatch estimates for the Norwegian gillnet-fishery varied in time, between areas, and with fishing depth and distance from the coast, but we found no clear trends in relation to the type of gillnets used. The results enabled us to identify important spatio-temporal trends in the seabird bycatch, which can allow for the development and implementation of more specific mitigation measures. While specific time closures might be an efficient option to reduce bycatch for diving seabirds, measures such as gear modification and reduction in release of wastewater during fishing operation are probably a more effective mitigation approach for reducing bycatch of surface-feeding seabirds.
全球海鸟数量的普遍下降引起了极大的关注。尽管有多种因素相互作用导致了观察到的趋势，但在渔业中因偶然误捕而导致的死亡率增加已被证明对许多物种很重要。然而，大部分已发表的知识来自延绳钓渔业，而刺网渔业中的误捕则研究较少，在某些地区甚至被忽视。我们展示了 10 年期间在挪威沿海小型船只刺网渔业中的渔业数据的时间序列中记录的海鸟误捕数据-这是一个大面积的渔业，以前没有对海鸟误捕的估计。一般来说，我们记录了高比例的偶然误捕（平均每网 0.0023 只海鸟，或每捕鱼航次约 0.08 只海鸟）。这导致该渔业每年的误捕量估计在 1580 至 11500 只（95%置信区间）之间。在误捕中，有高达 43%的海鸟是表面觅食的，北方海雀是最常见的物种。在被捕的潜水海鸟中，普通海鸠数量最多。我们的研究结果表明，沿海刺网渔业对更广泛的海鸟种群构成了更大的威胁，而延绳钓渔业中，表面觅食的海鸟物种似乎占据了误捕的主导地位。挪威刺网渔业的误捕估计值在时间上、地区上、捕鱼深度和离海岸的距离上有所不同，但我们没有发现与使用的刺网类型有关的明显趋势。研究结果使我们能够识别海鸟误捕的重要时空趋势，这可以促进更具体的缓解措施的制定和实施。虽然特定的时间关闭可能是减少潜水海鸟误捕的有效选择，但在捕鱼作业中修改渔具和减少废水排放等措施可能是减少表面觅食海鸟误捕的更有效缓解方法。
