Long-term variation in common dolphin diet in relation to prey abundance

Marine Ecology Progress Series

Alfredo López¹  Imogen German¹  Diana Correia¹  Jose Martinez Cedeira¹  Mara Caldas¹  M. Begoña Santos¹  Fiona L. Read¹  Francisco Velasco¹  Graham J. Pierce¹ 

关键词: Diet selection;    Sardine;    Hake;    Blue whiting;    Feeding ecology;    Zero-inflated models;   

DOI  :  10.3354/meps10233

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: Understanding the effects of changes in prey abundance on predators is essential to predict responses of marine ecosystems to perturbation and ensure sustainable fishing. As abundant top predators feeding largely on commercially exploited fish, common dolphins Delphinus delphis are expected to be affected by fluctuations in fish abundance. Previous studies variously suggest that common dolphins show a preference for energy-rich species or that they are opportunistic predators. In the latter case, the intensity of predation on all prey species would be expected to vary in proportion to their abundances. If such relationships are seen for only a few prey species, and the importance of other species varies inversely with the abundance of these ‘preferred’ prey, this would indicate selective feeding. We suggest that studies on diet at the population level can provide insights into such individual-level foraging decisions. We analysed stomach contents from 514 stranded and by-caught common dolphins in Galicia (NW Spain), collected over 2 decades. The most important prey were sardine, blue whiting and hake. Using zero-inflated generalised additive models to deal with non-linear relationships and the high number of zeros in prey count data, we tested for evidence of ‘preference’ for the main prey species, as well as confirming the existence of ontogenetic, spatial and seasonal variation in diet. Relationships between diet and annual prey abundance do not conclusively confirm either opportunistic or selective predation, but there is more evidence for the former. Lack of evidence for selective predation on energy-rich sardine could be due to current low stock levels.

【 授权许可】

Unknown