Fishes in the Hawaiian monk seal diet, based on regurgitate samples collected in the Northwestern Hawaiian Islands

摘要

The critically endangered Hawaiian monk seal, Monachus schauinslandi, is endemic to Hawaii and lives mainly on six reef systems in the NWHI (Ragen and Lavigne 1999). The population, with an estimated 1,202 individuals, is undergoing an unsustainable annual decline of 3.9% (National Marine Fisheries Service 2007). Survival rates of pups and juveniles have declined whereas age of first reproduction of females has increased (Antonelis et al. 2006). A reduction in prey is most likely a significant factor influencing these trends (Antonelis et al. 2006, Stewart et al. 2006). For these reasons, understanding diet and foraging habits is a key component for successful conservation of the Hawaiian monk seal (Parrish et al. 2005). Anecdotal observations and early studies of dive behavior and diet led to the reasonable assumption that monk seals feed primarily in shallow coral reefs (Kenyon and Rice 1959, DeLong et al. 1984, Goodman-Lowe 1998). However, later behavioral studies using seal-mounted video cameras, dive recorders, and satellite tags suggest seals forage in deeper water, primarily in sandy fields and slopes at the edge of atolls and banks (Parrish et al. 2000, 2002, 2005; Parrish and Abernathy 2006; Stewart et al. 2006). Recent preliminary, high-resolution dietary analysis confirms prey associated with the latter habitats are eaten by seals (Longenecker et al. 2006).