Meeting Abstract

P3.40  Sunday, Jan. 6  The feeding ecology of the pygmy (K. breviceps) and dwarf (K. sima) sperm whale inferred from diet and stable isotope analyses. STAUDINGER, M.D.; MCALARNEY, R.J.*; MCLELLAN, W.A.; PABST, D.A.; University of Missouri Columbia; University North Carolina Wilmington; University North Carolina Wilmington; University North Carolina Wilmington mcalarneyr@uncw.edu

A paired approach of stomach content and stable isotope analyses was used to characterize the foraging ecology of pygmy (K. breviceps) and dwarf (K. sima) sperm whales in the mid-Atlantic, utilizing samples collected from stranded specimens along the Virginia and North Carolina coasts. Contents were identified to the lowest taxonomical level possible and prey size estimated using published equations. Whale δ¹³ C and δ¹⁵ N values were used to estimate trophic level and foraging area. Both species were found to feed opportunistically in the mesopelagic and bathypelagic zones and squids from families Histioteuthidae, Enoploteuthidae, Cranchidae and Ommastrephidae dominated their diets. While sample sizes were not equivalent, pygmy sperm whales exhibited a more diverse diet than did dwarf sperm whales. Relative prey sizes were equivalent in the diets of pygmy and dwarf sperm whales, and the majority (≥90%) were small (≤5%) relative to predator body size. Pianka’s index value show high dietary overlap across whale species (O_n=0.92) and sexes (O_n=0.96). Pygmy sperm whale muscle δ¹⁵ N values tended to be enriched, and δ¹³ C tended to be depleted, relative to those of the dwarf sperm whale, although no statistical differences between species were detected. Collectively, these results suggest that the feeding ecologies of the pygmy and dwarf sperm whales are similar in the mid-Atlantic.