Modelling Survival of Hector's Dolphins around Banks Peninsula, New Zealand

Abstract

In 1988, a marine mammal sanctuary was established around Banks Peninsula to reduce Hector's dolphin entanglement in commercial and recreational gill nets. We describe the application of a multistate mark-recapture model to data from photographic identification surveys to determine the effect of the sanctuary on dolphin survival rates. The model allows sightings to occur in three geographic strata with free movement between strata. Although we found evidence of both area and time effects on sighting probabilities we found no evidence that survival rates depended on area or time. Thus, there was no evidence that dolphin survival rates increased following establishment of the sanctuary. However, power of this test is shown to be low.