Feeding behavior and trophic interaction of three shark species in the Galapagos Marine Reserve

PeerJ

article

Diego Páez-Rosas¹  Paul Insuasti-Zarate³  Marjorie Riofrío-Lazo¹  Felipe Galván-Magaña⁴ 

[1] Galapagos Science Center, Universidad San Francisco de Quito;Unidad Técnica San Cristóbal;Programa de Maestría en Manejo Sustentable de Biorecursos y Medio Ambiente, Universidad de Guayaquil;Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional

关键词: Feeding behavior;    Stable isotopes;    Trophic niche breadth;    Galapagos islands;    Sharks;   

DOI  :  10.7717/peerj.4818

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

There is great concern about the future of sharks in Ecuador because of the lack of biological knowledge of most species that inhabit the region. This paper analyzes the feeding behavior of the pelagic thresher shark (Alopias pelagicus), the blue shark (Prionace glauca) and the silky shark (Carcharhinus falciformis) through the use of stable isotopes of carbon and nitrogen (δ13C and δ15N), with the aim of determining the degree of interaction between these species in the Galapagos Marine Reserve. No interspecific differences were found in use of oceanic vs. inshore feeding areas (δ13C: Kruskal–Wallis test, p = 0.09). The position in the hierarchy of the food web where A. pelagicus feeds differed from that of the other species (δ15N: Kruskal–Wallis test, p = 0.01). There were no significant differences in δ13C and δ15N values between males and females of the three species (Student’s t-test, p 0.05), which suggests that both sexes have a similar feeding behavior. A specialist strategy was observed in P. glauca (trophic niche breadth TNB = 0.69), while the other species were found to be generalist (A. pelagicus TNB = 1.50 and C. falciformis TNB = 1.09). The estimated trophic level (TL) varied between the three species. C. falciformis occupied the highest trophic level (TL = 4.4), making it a quaternary predator in the region. The results of this study coincide with the identified behavior in these predators in other areas of the tropical Pacific (Colombia and Mexico), and suggest a pelagic foraging strategy with differential consumption of prey between the three species. These ecological aspects can provide timely information when implementing in conservation measures for these shark species in the Tropical Pacific and Galapagos Marine Reserve.

【 授权许可】

CC BY