The kiwi of the seas

By Helen Bain

If this many great spotted kiwi were being slaughtered by hunters, there would – quite rightly – be a public outcry.

But when it comes to protecting those species that live in New Zealand’s waters, rather than its forests, it seems we can turn a blind eye to the needless killing of an endangered, endemic animal. Out of sight beneath the ocean waves, it seems, is out of mind.

So it is that the world’s rarest marine dolphin, the Hector’s dolphin, found only in New Zealand, continues to be killed with depressing regularity in set nets.

Once common in New Zealand waters, Hector’s dolphins now number little over 7000 and are listed as endangered by the World Conservation on the Red List of Species Threatened with Extinction. The plight of the North Island sub-species of Hector’s dolphin, the Maui’s dolphin, is even more serious: with an estimated 111 individuals left, it is critically endangered.

Imagine then, if a method of hunting on land was killing significant numbers of great spotted kiwi (numbering more than 10,000) or the kakapo (which numbers 86). Under such a scenario New Zealanders would demand that hunters change their methods to protect our rare and precious native species. Surely we should make the same demands when it comes to protecting our endangered and endemic Hector’s dolphin.

Set nets are a type of gill net widely used in New Zealand waters by recreational and commercial fishers – they also catch and kill nearly everything that swims into them. The figures show that set nets are by far the biggest threat to Hector’s dolphins: they are responsible for more than 70% of deaths where the cause of death is known. Once entangled in the nets, a Hector’s dolphin has little chance of survival. Once submerged, its small lungs (about the size of human lungs) fill with water and it drowns.

Other human-induced threats to Hector’s dolphins, such as trawling, cray pots and boat strike, each account for no more than 10% of known deaths – clearly set nets are the big killer. Given that many entanglements of dolphins in set nets go unreported, the actual number killed by set nets may be much higher than the official figures. And Hector’s dolphins are not the only victims of set nets – other species of dolphin, penguins, seabirds, turtles, orca and seals are also killed.

The impact of set nets on the long-term survival of the Hector’s and Maui’s dolphin is of serious concern. Because – much like the kakapo – the dolphins breed slowly, the threat to their survival as a species is greater. Female dolphins give birth once every 2-4 years and don’t begin breeding till they are 7-9 years old, leaving the population highly vulnerable to human-induced deaths because overall numbers cannot quickly recover.

The population decline of Hector’s dolphin in recent decades has been frightening. They numbered about 26,000 in the 1970s, when set net use began, but plummeted by nearly 20,000 in the last few decades. The Maui’s sub-species in particular hovers on the brink of extinction.

Deaths of Hector’s dolphins in set nets are totally avoidable – virtually every fish species sought commercially or valued by amateur fishermen can be caught by alternative methods, such as line fishing or drag netting. In many countries and states, including many states of the USA, the UK and Australia, set nets are banned or tightly controlled.

In the South Island, Hector’s dolphins are protected from set nets only around Banks Peninsula, and there are controls on set net use from the Waitaki to the Waiau River mouths. Interim measures announced late last year also require amateur fishermen to stay with their nets in some areas off the South Island. The Maui’s dolphin is protected by a set net ban off the north-west coast of the North Island.

However, while these measures have shown that banning set nets can dramatically reduce deaths, they do not go far enough to ensure the dolphins’ survival. The lack of consistency across different areas and sectors means dolphins continue to be killed, even in areas where restrictions are in place.

The largest population of Hector’s dolphin (estimated at 5400) is found off the South Island West Coast and remains unprotected from set nets. The interim measures in the South Island do not protect dolphins from commercial fishing nets – which account for far more deaths than recreational fishing.

The North Island set net ban to protect Maui’s dolphins does not extend into the inner harbours, though the dolphins favour shallow water and Maui’s dolphins have been sighted in three out of five of these harbours, where they remain at risk from set nets.

The only viable solution to realistically protect these vulnerable marine creatures is a national ban on set nets. If we really care about protecting New Zealand’s unique wildlife, we must be as vigilant at sea as we are on land. If we do not take action on set nets to provide the equivalent level of protection to our Hector’s and Maui’s dolphin as we do to our kiwi and our kakapo, we could become the first country to knowingly push a species of dolphin into extinction.

ENDS

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