Successful breeding for New Zealand’s Doubtful Sound dolphins

16/12/2011 09:25:06 Bottlenose dolphins in Doubtful Sound
December 2011. Doubtful Sound's resident pod of bottlenose dolphins have had the best two breeding seasons for some time.

Over the last two summers, the dolphins have had the most surviving calves for more than a decade. This gives the Department of Conservation (DOC), Otago University researchers, and the local tourism industry optimism about their future.

DOC's marine mammal ranger Kath Blakemore said alarm has been raised about the rapid rate of decline this well-researched population has been undergoing in recent years. Calf survival rates have been low since around 2002. This is more critical as research shows that this small group of dolphins lives separately from others, living almost exclusively within Doubtful Sound. 

16 calves born - 11 survived
Sixteen calves have been born over the last two summers and 11 of these have survived so far. Otago University researcher, Shaun Henderson said that in 20 years of the University's research there has only been one other year with more calves born. If most of these calves survive it will be a significant boost to the population.

"While we don't know the reason for this increased rate of births, everyone involved is hoping this trend continues," Mr Henderson said.

Dolphin watching rules
Since 2009, DOC has been working with boat operators to implement a set of rules for vessel use in Doubtful Sound to minimise any potential impacts from the dolphins interacting with boats. In addition, a research programme has begun to explore some of the other potential causes of the decline, such as genetics, habitat modification, broad-scale climate changes and diet.

The commitment from the Doubtful Sound tourism industry to work alongside DOC and others to help these dolphins has been encouraging. All boat operators, private or commercial, must be familiar with the protection guidelines before heading into Doubtful Sound. These are readily available from the DOC website or your local DOC office. The guidelines aim to reduce the amount of time dolphins spend interacting with boats so they can spend more time doing what dolphins should naturally do.