Alarming Decrease In Calves Prompts Fears For Endangered Hector’s Dolphin
Low observations of Hector’s dolphin calves, and dolphins much further out to sea than usual in early summer, have raised fears for this endangered species only found in New Zealand waters.
The concerning summer comes after another delay in the announcement of the Threat Management Plan review for Māui and Hector’s dolphin protection. A decision on the review was expected to be announced late last year, but it has been delayed again while ministers consider public feedback. An announcement on the Plan is now expected in the coming months.
Black Cat Cruises Chief Executive Paul Milligan says, “There is now even more reason for the Government to ensure increased protection for Hector’s dolphins is written into the Threat Management Plan.”
Milligan says in early summer Black Cat’s tour boats have had to go further out for dolphin interactions than usual, with significantly fewer calves seen.
“We would normally expect to see dolphins right into Akaroa Harbour, but this summer we’ve often had to leave the harbour and go past the Akaroa Heads to find dolphins,” says Milligan.
“We’re trying to understand why this is happening. Is it a one-off summer, or is this change in their dispersal and breeding a long-term issue? If the latter, it would be a serious concern for the fate of these incredible dolphins.”
Black Cat Cruises reached out to their research partners from Otago University, Zoology Professor Liz Slooten and Marine Science Professor Steve Dawson, who recorded an “alarming decrease” in calf observations this season – less than one percent of all dolphins seen, the lowest number in three decades. The average is normally just over four percent.
“It’s a real worry, it took us all by surprise. We kept saying to each other, where are all the calves this year? Many days we didn’t see any calves, which is unheard of in January,” says Professor Slooten.
“With such a low number of new calves this season, it doesn’t leave much room for any threat to their survival. Every breeding season a number of calves, as well as pregnant females, don’t survive due to natural mortality or threats from human impact, like bycatch.
“It just shows how variable their breeding can be and that any threat to these dolphins will have a significant impact on their population.”
Professor Slooten says the low calf numbers coincided with a highly unusual summer, including lower than normal sea temperatures, changes to dolphin feeding habits and markedly different distribution patterns. In summer, dolphins normally stay close to the shore to feed and have their calves, but this year the Hector’s have been much further offshore.
Scientists are now trying to find out what’s causing the unusual breeding and migration patterns.
“Normally in January the water temperature is around 16-18 degrees, but this year it’s been around 13-14 degrees. While the difference might seem small, it can have a significant impact on our marine species,” says Professor Slooten.
“The cooler temperatures have meant that their food source is further away from the shore. The fish they eat have come into shore to spawn much later than usual, about four to six weeks later. So the fish have been more dispersed, and in turn, the dolphins have followed.”
Professor Slooten says the risks to dolphin survival increase when they are forced to spend more time further out to sea to find their prey species.
“They are much more likely to get caught in set nets and trawl fishing operations. This could be a very bad year for bycatch of Hector’s dolphins.”
Paul Milligan from Black Cat Cruises says the priority must be on achieving the right outcome – which is increased protection for Hector’s dolphins written into the Threat Management Plan.
“If the delays means the Government is having the right conversations then that’s a good thing,” says Milligan. “The survival of this unique species will depend on how far the increased protection measures go.”
· Hector’s dolphins and their sub-species Māui dolphins are the only cetacean (whales and dolphins) species endemic to New Zealand. They are most often seen in the waters around Banks Peninsula, the South Island West Coast, and Te Waewae Bay in Southland. Although endangered and with a declining population, relatively high numbers around Banks Peninsula make it almost certain that every eco-tourism trip taking people to see or swim with the dolphins will find and see them. This makes the trips very popular and generates huge awareness of the species and their environment.
· During the last two decades the International Union for Conservation of Nature status of Hector’s has changed from ‘Vulnerable’ to ‘Endangered’, which means the species is considered very likely to become extinct. There has been an ongoing population decline of -74 percent during the past three generations (approx. 30 years), which is projected to continue (-50 percent during the coming three generations).
· Compounding the problem is that Hector’s dolphins only breed once every two to three years, so any death in the population is very hard to replace.
· Black Cat Cruises is a long-term partner of NZ Whale and Dolphin Trust, and sponsors its research by Otago University professors Steve Dawson and Liz Slooten and their students, including the recent purchase of a new outboard for their research vessel.
· Black Cat Cruises supports the Threat Management Plan review and actively participated in its consultation phase last year. The company is calling for the Government to ensure increased protection for Hector’s dolphins is written into the Threat Management Plan.
· Specifically, Black Cat Cruises is asking the Government to:
- Extend the Banks Peninsula Marine Mammal Sanctuary (introduced in 1988 and extended in 2008) to cover more of the South Island coastline
- Ban set nets in the harbours
- Extend the current commercial fishing exclusion area out to a depth of 100 metres (around 32 km).
· Black Cat Cruises undertook the first ever research into the specific economic value of dolphin tourism to both New Zealand and Canterbury. The research revealed that Hector’s dolphin eco-tourism is worth almost $25 million to the New Zealand economy each year, with another $3-$6 million in associated tourist activity. This also sustains the equivalent of 476 jobs in the national economy.
· During the last decade Black Cat Cruises has received many national and international tourism awards and has been recognised as New Zealand’s first true eco-tourism operator. It is acknowledged by the Department of Conservation for its safe and sustainable marine mammal activities, rated the top wildlife activity in New Zealand in an AA survey, and was listed as one of the top 10 marine mammal experiences by Lonely Planet in 2014.