Category New Zealand – temperate

Large reef fish

Blue Moki, Butterfish, Blue Cod, Trumpeter

In July 2003, The Earth Policy Institute and others reported that a recent review of marine fisheries, carried out by Ransom Myers and Boris Worm at Canada’s Dalhousie University, had concluded that a startling 90 percent of the world’s large predatory fish stocks, including tuna, swordfish, cod, halibut and flounder, have disappeared in the past 50 years. The study was carried out over a tenyear period, and attributed the decline to a growing demand for seafood, coupled with an expanding global fleet of technologically efficient boats. In addition to numerical decline, the review also concluded that the surviving members of the reef fish population are only one-fifth to one-half the size of earlier individuals.

With the capacity o...

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Haliotis iris

Whilst abalones are to be found in all of the world’s temperate and tropical seas, the New Zealand blackfoot abalone, or Paua (Haliotis iris), is unique  the waters around New Zealand. This univalve marine mollusc eats seaweed and inhabits rocky, coastal areas at depths between one and fifteen metres. It grazes on seaweed and ranges in size from 7-14cm at maturity, but can grow to a maximum of 18cm.

The cooler South Island waters enable the paua to grow larger here than they do in the warmer north. As a result, most wild paua are harvested from the South, the Chatham and Stewart Islands and from the southern coast of the North Island.

There are two other locally occurring abalone species, also known by the collective Maori name, paua (pronounced pah-wah)...

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Japanese wakame seaweed

The Japanese wakame seaweed, Undaria pinnatifida, which has established itself in several New Zealand locations, is a brown macroalga, and typically grows to 1-3m in length. It is an opportunistic species that forms dense forests and has the potential to outcompete and displace native species of algae.

It has been established since late 1980s in Australia and New Zealand, where it is highly invasive, forming dense forests that change the structure of ecosystems and displace native macroalgal communities. Like other kelp species, wakame consists of a holdfast, a stem (or stipe) and a blade. The central stem grows to 10cm wide and extends for the length of the plant. The blade may be up to 1m wide and extends from the tip of the plant for half to three-quarters the length of the plant...

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Lobsters, like shrimps and crabs, are decapods – literally meaning 10 legs – and can be found in all of the world’s tropical and sub-tropical seas as well as more temperate waters. They are predatory, nocturnal animals with a vividly decorated coat. They are often numerous locally; they linger in crevices (with their long antennae sticking out) during the day and hunt small benthic organisms at night, but they also feed on organic detritus whenever they happen across it. As with all crustaceans, the lobster moults or sheds its shell to grow.

Lobsters have recently suffered a dramatic demographic decline; intensive fishing has annihilated entire populations, especially where tourism abounds.

The lobster families that you may encounter are the spiny rock lobsters, Palinurida...

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Rock barren habitats

The marine habitats in which marine communities live are many and varied and are created, or caused, by a number of physical factors. These factors combine to determine which animal and plant communities can co-exist within a particular habitat, with the interplay of the communities themselves playing a large determining factor.

The physical factors include elements such as temperature, depth, tides and currents, relative salinity, wave action, light or shade, sea-bottom substrate, aspect and inclination. Extreme physical factors, such as a rise in sea temperature can have a significant and sudden impact on habitats, such as the El Nino effect on the coral reefs in the Maldives, where a small rise in sea temperature caused widespread coral bleaching.

In addition to the physical fact...

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