Albatrosses Following Fishing Vessels: How Badly Hooked Are They on an Easy Meal?

Fisheries have major impacts on seabirds, both by changing food availability and by causing direct mortality of birds during trawling and longline setting. However, little is known about the nature and the spatial-temporal extent of the interactions between individual birds and vessels. By studying a system in which we had fine-scale data on bird movements and activity, and near real-time information on vessel distribution, we provide new insights on the association of a threatened albatross with fisheries. During early chick-rearing, black-browed albatrosses Thalassarche melanophris from two different colonies (separated by only 75 km) showed significant differences in the degree of association with fisheries, despite being nearly equidistant to the Falklands fishing fleet. Most foraging trips from either colony did not bring tracked individuals close to vessels, and proportionally little time and foraging effort was spent near ships. Nevertheless, a few individuals repeatedly visited fishing vessels, which may indicate they specialise on fisheries-linked food sources and so are potentially more vulnerable to bycatch. The evidence suggests that this population has little reliance on fisheries discards at a critical stage of its nesting cycle, and hence measures to limit fisheries waste on the Patagonian shelf that also reduce vessel attractiveness and the risk of incidental mortality, would be of high overall conservation benefit.

渔业活动对海鸟具有显著影响，其作用途径包括改变食物可获得性，以及在拖网作业与延绳钓布设过程中直接造成海鸟死亡。然而，学界对个体海鸟与渔船之间互动的本质及时空范围仍知之甚少。本研究通过一套整合了海鸟活动与行为精细尺度数据、以及渔船分布近实时信息的观测系统，为阐明受胁信天翁与渔业活动的关联提供了全新视角。育雏早期阶段，来自两个相距仅75公里的不同繁殖种群的黑眉信天翁（black-browed albatrosses，*Thalassarche melanophris*），尽管与福克兰群岛捕捞船队的距离近乎相等，二者与渔业活动的关联程度却存在显著差异。两个种群的多数觅食旅程中，被追踪的个体均未靠近渔船，且在船只附近花费的时间与觅食投入占比均极低。尽管如此，仍有少数个体反复造访渔船，这或许表明它们专门依赖与渔业相关的食物来源，因此面临更高的兼捕误获风险。研究证据表明，该种群在繁殖周期的关键阶段几乎不依赖渔业丢弃物；因此，在巴塔哥尼亚大陆架限制渔业废弃物排放、同时降低渔船对海鸟吸引力与意外死亡风险的保护措施，将带来极高的整体保护效益。