Diet composition of the Guadalupe fur seal (Arctocephalus townsendi). Where and what do they eat?

Abstract

The Guadalupe fur seal (Arctocephalus townsendi) is a specialist predator feeding on prey present in one trophic level. Data related to the diet of the Guadalupe fur seal are few. It is still unknown where most of the individuals forage or the composition of their diet. On Isla Guadalupe, the San Benito Archipelago and the Farallon Islands, fur seals primarily feed on pelagic and coastal squids. However, differences between colonies were found probably caused by differences in diversity and abundance of prey species over the continental shelf and the pelagic environment, and maybe due to the plasticity of the species in their foraging behavior. Diet composition of the Guadalupe fur seal might reflect adaptations to local and temporal environmental conditions. The aim of this work was to consider historical information, add new information, identify main prey species, and determine where in the marine regions the Guadalupe fur seals feed.

Keywords:

• Guadalupe fur seal
• Arctocephalus townsendi
• diet composition
• Farallon Islands
• fish species
• Isla Guadalupe
• San Benito Archipelago
• squid species

Acknowledgments

We thank “Cooperativa de Pescadores Nacionales de Abulón” who provided logistic support at San Benito Archipelago. Also we thank the support of CONACYT to M.E., and funding from UCSC-MIRTCIAD- Guaymas. The censuses and scat collection were conducted under permit Nº 06801/06 SEMARNAT, México. A special thank to Dr. Mark Olson for all his support, assistance, and guidance.