The National Institute of Water and Atmospheric Research (NIWA) has released Marine Biodiversity of Aotearoa New Zealand, an assessment of life in the waters around New Zealand. The area covered by the findings extends to the 200 nautical-mile boundary of the Exclusive Economic Zone. At 4.2 million square km, New Zealand’s EEZ is one of the largest in the world, and much of it remains undiscovered. The wide range of marine habitats provided by the EEZ’s varied seafloor relief and latitudinal spread make it rich in sea life.
Inventory of New Zealand Marine Life
The report is the result of research work done over the past 10 years, with contributions from authorities around the world. The project’s mission was to review and inventory all of New Zealand’s marine life, “from bacteria to blue whales”. It found that the EEZ is home to 17,135 living species. Groups with over 1,000 species are molluscs (common example shellfish, snails etc), arthropods (crabs, crayfish, shrimps etc), chordates (species with backbones – fish), porifera (sponges) and cnidaria (jellyfish, corals).
Many species occupy New Zealand waters to an extent greater than anywhere else in the world. For instance New Zealand’s 66 black corals represent 41% of the entire known group in the Indo-Pacific Region. Of the 1,387 species of fish in the New Zealand EEZ, approximately half are widespread while 19% are considered endemic. This leads the report to describe the EEZ as containing “a globally unique mix of widespread (semi-cosmopolitan) Indo-Pacific, Australasian, sub-Antarctic and endemic taxa.”
Birds and Mammals in the Marine Environment
Birdlife is abundant in New Zealand waters, with 122 of the country’s 286 avian species classified as marine or maritime - birds that spend “all or almost all of their time feeding in those environments.” Penguins, albatross and petrels are particularly prevalent around New Zealand, with nearly three quarters of the world’s species occurring there. Six types of penguin make New Zealand their home, including the endangered yellow eyed penguin (hoiho), which is found nowhere else. Twelve species of albatross breed in New Zealand.
New Zealand has three pinnipeds - the New Zealand fur seal, the New Zealand sea lion, and the southern elephant seal. The fur seal was hunted almost to extinction in the 1800’s, but is now a common sight on many sites of the coast in its season. The endemic sea lion, the largest breeding colonies of whch are on the sub-Antarctic Auckand Islands, is critically endangered.
The other big mammals that frequent New Zealand waters are of course the cetaceans. The report states that nearly half of all the world’s whales and dolphins have been recorded in the EEZ. They include nine species of baleen whales (blue, humpback, southern right etc.), 17 dolphins (including the endangered and endemic Hector’s, one of the world’s smallest), and 12 of the rarely seen beaked whales. The sperm whale is a more common sight around New Zealand, where all three living species have been recorded.
Alien and Undiscovered Marine Species
Of all the species of marine life identified, 177 are classified as naturalised alien species. These have become established in New Zealand waters primarily as a result of human activity. Some degree of invasion is inevitable given New Zealand’s reliance on sea going vessels for trade.
The report concludes from the study that there are numerous undiscovered species inhabiting the EEZ. Most of these will be the lesser forms of microscopic protozoans, algae and sponges etc. However the report also points out that there has been a doubling of known fish species over the last 15 years. Discoveries continue at about 20 per year, and the assessment concludes there are some 760 species of fish still to be found in the New Zealand EEZ.
Human Impact on New Zealand Waters
The report also touches on historical aspects of human impact on New Zealand’s marine biodiversity. In the seven centuries of human occupation of Aotearoa, 625,00 tonnes of the highly valued snapper species has been taken from the Hauraki Gulf – half of it in the last 70 years. As well as reducing the species biomass twelve-fold over 700 years, that impact has had secondary effects on the habitat through reduced snapper predation of other species. Reference is also made to the effects of whaling. In 1800 there were 27,000 right whales in New Zealand waters, the species reduced by commercial harvest to the brink of extinction a century later.
In also noting the threats that exist to the marine environment from destructive fishing methods, agricultural runoff and climate change amongst other things, the report concludes with mention of the protective measures being taken. The ongoing investment in surveying and monitoring the New Zealand marine eco-system is noted, as are conservation measures.
New Zealand has over 30 ‘no-take’ marine reserves that protect 7.6% of the country’s territorial seas. Unfortunately, the mainland’s coastal water protection is relatively limited, with 99% of reserve area being at the remote Auckland and the Kermadec island groups. There are also areas in the EEZ where commercial fishing is restricted, and three marine parks have been designated.
Reference
Gordon DP, Beaumont J, MacDiarmid A, Robertson DA, Ahyong ST (2010) "Marine Biodiversity of Aotearoa New Zealand." PLoS ONE 5(8): e10905. doi:10.1371/journal.pone.0010905
Brian Cross - Brian is a feelance writer specialising in content for the corporate sector, based in Wellington, New Zealand.
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