Decadal stability in the distribution of bottlenose dolphins in Dusky Sound/Tamatea, New Zealand

Abstract

ABSTRACT Recreational use of wild spaces is increasingly popular, resulting in a burgeoning tourism industry. Such activities can degrade the environment and disrupt the behaviour and natural function of organisms. A small population of bottlenose dolphins (Tursiops truncatus) is resident in Dusky Sound, New Zealand, a fjord with increasing human use. Dolphins, as top predators, play an important role within ecosystems and are at risk of long-term negative consequences from behavioural changes when exposed to high levels of vessel activity. A better understanding of the distribution of the dolphins in Dusky Sound would provide a framework for developing management within the fjord. Here we describe where dolphins were most frequently found, based on >40,000 km of photo-ID survey effort conducted over 10 years. Kernel density estimation revealed two large core areas that remained consistent over the duration of this study. This information could be used to determine areas within Dusky Sound where human activities around dolphins could be managed to avoid anthropogenically driven detrimental impacts. We suggest the following: (1) establish dolphin protection zones, (2) create a marine mammal sanctuary, (3) extend marine reserve boundaries, and/or (4) lower catch limits for fish within the fjord boundaries.