Importance of fisheries discards and experience for seabird behavior and energetics

为了开发大面积分散的海洋资源，信天翁和海燕每天要飞行数百公里，很少照顾它们的幼崽。在具有强烈人为影响的海洋生态系统中，猎物的可得性往往因渔船的存在而改变，这些渔船产生大量废物，如加工鱼类、非目标物种和体型较小的鱼类的内脏。它们不仅为参加渔船的海鸟提供了可预测的丰富食物来源，而且还为获得底栖鱼类提供了一种新的食物来源。因此，在许多渔场，弃物对海鸟的饮食有很大贡献。这对海鸟觅食生态学具有重要意义。本研究的目的是增强我们对行为适应的理解，以应对猎物可用性的变化，以地中海的Scopoli海鸥为例，这种物种既捕食自然猎物，也捕食渔业丢弃的猎物。为了评估渔业废弃物消费的范围和影响，我们将使用GPS跟踪、加速度记录的代谢率测量和非侵入性基因饮食测定相结合的方法。我们将调查海鸥对渔业废弃物的利用是对其自然猎物的低可用性的反应，还是该物种已经适应了定期利用这一资源，而不依赖于其自然猎物的可用性。此外，我们将比较有经验的和新的繁殖者，以评估成年鱼的质量如何影响这种行为，并评估自然猎物和渔场弃物消费的能量平衡。

To exploit marine resources that are scattered patchily over large areas, and often unpredictable, albatrosses and petrels cover hundreds of kilometres per day and attend their chicks infrequently. In marine ecosystems with strong anthropogenic influences, the prey availability is often altered by the presence of fisheries vessels that produce large quantities of discards such as offal from processed fish, non-target species and undersized fish. Not only do they provide a predictable and abundant source of food to seabirds attending fishing vessels, but discards also facilitate access to demersal fish as a novel food source. In many fishery areas, discards thus contribute significantly to the diet of seabirds. This can have important implications on the seabirds foraging ecology. The aim of the present study is to enhance our understanding of behavioural adaptations in response to changes in prey availability, using a case study of Scopoli's shearwater in the Mediterranean Sea, a species that takes both natural prey and fisheries discards. To evaluate the extent and implications of fisheries discard consumption, we will use a combination GPS tracking, measurements of metabolic rates from acceleration logging, and non-invasive genetic diet determination. We will investigate whether the use of fisheries discard by the shearwaters occurs in response to low availability of their natural prey or if this species has adapted to regularly exploit this resource, independently of the availability of their natural prey. Moreover we will compare experienced and novel breeders so assess how the quality of adults influences this behaviour, and evaluate the energetic balance of natural prey and fisheries discard consumption.