Population viability analysis for Hector's dolphin (Cephalorhynchus hectori): A stochastic population model for local populations

Abstract

Mortality of Hector's dolphin (Cephalorhynchus hectori) in gill‐net fisheries is a threat to local populations throughout its range. This population viability analysis extends previous work by exploring a wider range of fishing levels and population growth rates, by incorporating year‐to‐year and environmental variability and by reporting results for smaller population units. Ten of the 16 populations are likely to continue to decline, five are indefinite, and one is likely to increase. All populations subjected to high fishing effort are declining. The only population predicted to increase is partly protected by a marine mammal sanctuary (created in 1988) which reduces the amount of gill‐net fishing. Conservation measures are most urgently needed for the highly threatened North Island population, in particular the dolphins at the northern and southern end of this range.