The world's biological diversity is declining for the first time since the catastrophe of 65 million years ago which wiped out the dinosaurs and half of Earth's other species. The reason for the current catastrophe is our species' increasing expansion of territory and use of resources at the expense of other species and their habitats. As these pressures continue to rise, extinction rates are also predicted to rise.
New Zealand may have 80,000 species of native animals, fungi and plants, only about 30,000 of which have been described and named. The major groups are the insects and fungi, each with a possible 20,000 species, and the nematode worms, with more than 10,000 species.
Plants and large animals account for barely 5,000 native species in total: about 2,300 vascular plants; about 1,100 mosses and liverworts; about 190 land and freshwater vertebrates (mostly birds and reptiles); approximately 1,200 marine fishes; about 60 seabirds; and about 40 marine mammals (only four of which breed in our waters).
The biodiversity of our micro-organisms is poorly understood, though the known species include about 3,700 algae (a quarter of which are seaweeds while the rest are single- celled plankton and periphytons) and about 2,600 protozoans (e.g. amoeba, giardia etc.).
New Zealand's biodiversity is more primitive in character than that of many other countries, having a limited representation of higher plants and animals (e.g. angiosperms and mammals), but a high representation of older plants and animals (e.g. mosses, liverworts, ferns, flatworms, snails, spiders, wingless crickets, solitary bees, leiopelmid frogs, sphenodon reptiles and ratite birds). Many species are endemic (found only in New Zealand).
In only 700-800 years (about 30 generations), humans and their accompanying animals have eliminated 32 percent of the endemic land and freshwater birds (43 species and 9 subspecies), 18 percent of the endemic seabirds (4 species out of 22), 1 of the 29 freshwater fish, 3 of the 7 frogs, possibly 3 of the 64 reptiles, 1 of the 3 bats, possibly 11 of the 2,300 vascular plants, and at least 12 invertebrates, such as snails and insects. The numbers of most surviving species and subspecies have been heavily reduced.
Today, nearly 1,000 animals, plants and fungi have been identified as threatened (some 800 species and 200 subspecies). Among the threatened species are: more than 200 fungi (5 percent of known species); nearly 200 vascular plants (10 percent); 85 non-vascular plants (8 percent); 150 vertebrate animals (58 percent); and at least 285 invertebrate animals (1-2 percent). One of the worst affected groups is our endemic land and freshwater birds, three-quarters of which (37 out of 50 species) are now threatened.
The main threats to most species are: insufficient habitat and fragmented habitat caused by the predominance of farms, roads and settlements which now claim 63 percent of the total land area and more than 90 percent of the lowland area; human predation, which puts pressure on some species through hunting, fishing, gathering and collecting; and introduced pests and weeds which prey on native species, compete with them, or damage their habitat. Many declining species are still paying the 'extinction debt' incurred by earlier deforestation and drainage.
Most of the New Zealand landscape is now ecologically hostile to many native species. Although nearly 30 percent of the land area is protected in the conservation estate, most of this is on steep and mountainous land. Lowland forests, dunelands, streams, wetlands and subalpine tussock grasslands are under-represented in our protected areas.
Alien species threaten a third of our protected forests (1.8 million hectares) and put pressure on smaller reserves and individual species. Those which cause the most damage are: possums, which now number about 70 million; goats and deer, whose numbers appear to be rising; rats, stoats and feral cats; trout; and introduced weeds. New Zealand now has as many introduced conifers and flowering plants in the wild as it has native species (almost 2,000). About 200 of these are harmful to native plants.
A small number of introduced crop, livestock and biocontrol species are vital to New Zealand's agriculture, horticulture and forestry industries. Specially bred strains and varieties are continually being improved or developed for New Zealand conditions. The breeding programmes need access to a wide range of exotic genetic material. However, while some New Zealand-based gene and seed collections are of world significance, many are poorly documented and stored, and several are deteriorating.
Of the 1,200 or so marine fish in our Exclusive Economic Zone (EEZ), nearly 100 are rockpool species (60 percent of them endemic) and about 1,100 are sea-dwelling species (5 percent endemic). More than 100 sea-dwelling species (10 percent) are fished commercially, though this will soon increase to about 160 species (15 percent). Forty-two species (4 percent), divided into about 150 'stocks', are harvested through a quota management system (QMS) which aims to maintain the stocks at their level of maximum sustainable yield (MSY), which is roughly 25-60 percent of their original biomass.
Status assessments are available for the rockpool fish, 11 of which are considered threatened, all of them endemic. Assessments are also available for half the QMS stocks (or 2 percent of our total sea-dwelling fish stocks). Most QMS stocks are thought to be still above or near the MSY level and in the 'fishing down' phase. Two species, however, orange roughy and snapper, have some stocks well below the MSY level, while several other species have some stocks recovering from previous overfishing (blue moki, elephantfish), subject to low or declining catches (gemfish, grey mullet, rig), or at risk of depletion given 1995 catch rates (smooth oreo, snapper).
Fishing bycatch (accidental capture or injury of non-target species) kills, on average, several hundred New Zealand seabirds each year, more than 1,000 marine mammals, unquantified tonnes of non-commercial fish species and uncounted communities of sea-floor invertebrates. The highest seabird bycatch is in the southern bluefin tuna fishery, and the highest marine mammal bycatch is in the southern blue whiting, West Coast hoki and southern squid fisheries.
Marine invertebrates depleted by gathering, over-fishing or disease are: toheroa; rock lobsters; Southland paua; and Bluff oysters. Stock recoveries may now be under way for some of these. Little is known of the status of most non-commercial marine invertebrates, but 4 black corals, 1 bryozoan, 1 seastar, 1 lampshell, 1 lobster and 3 crabs are listed as threatened.
Society's responses to the pressures from human predation include:
the Native Plants Protection Act 1934;
the Wildlife Act 1953;
the Marine Mammal Protection Act 1978;
the Fisheries Act 1996; the Conservation Act 1987; and
the Trade in Endangered Species Act 1989, all of which impose varying degrees of control over the harvesting of selected native species.
Society's responses to pressure from habitat loss include:
the preservation of nearly 8 million hectares of publicly owned mountain areas with several thousand hectares of lowland reserves and unoccupied offshore islands, under the Conservation Act 1987, the National Parks Act 1980 and the Reserves Act 1977;
the preservation of approximately 100,000 hectares of habitat on private land through government-funded covenants and purchases, arranged through the Forest Heritage Fund, Nga Whenua Rahui, the Queen Elizabeth II National Trust and the Department of Conservation's Protected Natural Areas Programme;
the protection of 1.1 million hectares of the marine environment (less than 1 percent of our EEZ but almost 7 percent of our territorial sea), made up of: a 750,000-hectare marine reserve around the Kermadec Islands; two marine mammal sanctuaries totalling 335,000 hectares around the Auckland Islands and Banks Peninsula; and 12 other marine reserves, 2 marine parks and 1 special protected area totalling nearly 15,000 hectares of mainland coastal waters (1-2 percent of the waters within 1 kilometre of the mainland);
about 70 ecosystem restoration operations each year as part of the Department of Conservation's 500 species management programmes, including some 40 Species Recovery Programmes;
the attachment of environmental conditions to licences for the 600-plus tourism concessions and several hundred mining and prospecting licences current on conservation land; and
requirements in the Resource Management Act 1991 that decision-makers provide for protection of areas of significant indigenous vegetation, significant habitats of indigenous fauna, and wetlands.
Society's responses to the pressures from alien species include:
more than 600 pest and weed control operations yearly by the Department of Conservation, roughly equally divided between animal pests and noxious weeds, and spanning more than 1 million hectares of conservation land;
pest control programmes, mainly in agricultural areas, by regional councils and the Animal Health Board under the Biosecurity Act 1993; and
testing and risk assessment of introducing new organisms, such as the calici virus, under the Hazardous Substances and New Organisms Act 1996.
Biodiversity research is thinly spread, uncoordinated, and poorly resourced. Although a lot of valuable information exists in disparate databases and publications, little of it is capable of depicting trends over time. Taxonomic expertise in the identification and classification of species is actually in decline.
Initiatives to improve biodiversity research and monitoring are being undertaken through the Department of Conservation's estate monitoring programme, the Ministry of Research Science and Technology's research strategy process, the Ministry for the Environment's indicators programme, and the Crown Research Institutes' databases and research programmes, notably those of Landcare Research and National Institute of Water and Atmospheric Research Ltd (NIWA). A National Biodiversity Strategy is being developed.