A recent global assessment of shark populations at 371 coral reefs in 58 countries found no sharks at almost 20% of reefs and alarmingly low numbers at many others.
The study, which involved over 100 scientists under the Global FinPrint project, gave New Zealand a good score card. But because it focused on coral reefs, it included only one region Rangit?hua (Kermadec Islands), a pristine subtropical archipelago surrounded by New Zealand’s largest marine reserve.
It is a different story around the main islands of New Zealand. Many coastal shark species may be in decline and less than half a per cent of territorial waters is protected by marine reserves.
In New Zealand, there are more than a hundred species of sharks, rays and chimaeras. They belong to a group of fishes called chondrichthyans, which have skeletons of cartilage instead of bone.
Some 55 per cent of New Zealand’s chondrichthyan species are listed as not threatened by the International Union for Conservation of Nature (IUCN). Not so encouraging is the 32 per cent of species listed as data deficient, meaning we don’t know the status of their populations. Most species (77 per cent) live in waters deeper than 200 metres.
Seven species are fully protected under the Wildlife Act 1953. They are mostly large, migratory species such as the giant manta ray. Some are threatened with extinction according to the IUCN, including great white sharks, basking sharks, whale sharks and oceanic white tip sharks.
Historically, basking sharks were caught as bycatch in New Zealand fisheries and seen in their hundreds in some inshore areas. Sightings of these giant plankton-feeders suddenly dried up over a decade ago. We don’t know why.
Eleven chondrichthyan species are fished commercially in New Zealand under the quota management system. Commercial fisheries for school shark, rig and elephant fish took off from the 1970s and now catch around 8,000 tonnes per year in total.
Finning of sharks has been illegal throughout New Zealand since 2014.
Most of New Zealand’s shark fisheries are considered sustainable. But a sustainable fishery can mean sustained at low levels and we must tread carefully. School shark was recently added to the critically endangered list after the collapse of fisheries in Australia and elsewhere, and there’s a lot we don’t know about the New Zealand population.
Down To Earth 2020