Ecology of Hector's dolphin (Cephalorhynchus hectori): Quantifying diet and investigating habitat selection at Banks Peninsula

Hector’s dolphins (Cephalorhynchus hectori) are endangered and endemic to New Zealand. Although their distribution and abundance have been thoroughly described, little is known about Hector’s dolphin ecology. Being small cetaceans living in a cold water environment, Hector’s dolphins have high energy requirements, and prey abundance and movements are often assumed to be a major driver of distribution patterns. This thesis aims to increase our understanding of Hector’s dolphins in a wider ecosystem context, by quantifying their dietary preferences and investigating the influence of prey availability on their habitat selection. Using stomach contents collected from beachcast and bycaught dolphins throughout New Zealand between 1984 and 2006 (n=63), the diet of Hector’s dolphin was quantified for the first time. The dolphins were found to feed throughout the water column, with 29 prey taxa identified in total. Red cod (Pseudophycis bachus), ahuru (Auchenoceros punctatus), arrow squid (Nototodarus sp.), sprat (Sprattus sp.), sole (Peltorhamphus sp.) and stargazer (Crapatalus sp.) were most commonly consumed. Red cod contributed most in terms of mass (37%), while ahuru and Hector’s laternfish (Lampanyctodes hectoris) were consumed in large numbers. Prey length ranged from <1 cm to over 60 cm, but the majority were