Story: Coastal fish

Page 4. Plankton-feeding open-water fish

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Anchovies, pilchards and sprats

Anchovies, pilchards and sprats are small, silvery pelagic fish of coastal waters.

Anchovies (Engraulis australis) are most common around the North Island and the north-western South Island. These schooling fish are often found in association with pilchards and sprats in open waters.

Pilchards (Sardinops neopilchardus) are widely distributed, but notably scarce on the south-east coast of the South Island. In the past they have also been known as sardines, herrings and bloaters (when canned).

Two very similar sprat species (Sprattus antipodum, Sprattus muelleri) are common around the continental shelf off the South Island, but less common off the North Island. They are commonly preyed on by seabirds and larger fish.

Trevally

The trevally (Pseudocaranx georgianus), known to Māori as araara, is a plankton feeder, most common around the northern North Island where they move in close-packed feeding schools. Stragglers sometimes reach as far south as Banks Peninsula. In summer, they can be seen hunting down krill and other plankton, their backs breaking the water.

Trevally became an important commercial species in the 1960s and 1970s, when schools were targeted by spotter planes. Stocks became overfished, and declined by the 1980s. Recreational anglers make use of the narrow tail, which makes a good ‘handle’ as the fish struggles vigorously when brought aboard.

Jack mackerel

There are three very similar-looking jack mackerels found in New Zealand waters (Trachurus novaezelandiae, Trachurus declivis, and Trachurus murphyi). All species are schooling fish.

The silvery jack mackerel (Trachurus novaezelandiae), restricted to Australasia, is found throughout New Zealand harbours and bays, but is more common in the north-east. The average adult size is 30–40 centimetres.

Trachurus declivis is a slightly larger fish (adults averaging 35–50 centimetres) and is more widely distributed from Australasia up through South-East Asia to Japan.

Trachurus murphyi are larger again, and appear to have invaded New Zealand waters, in the 1980s, from the open ocean. This species is abundant off the Chilean and Peruvian coasts, and it now makes up most of the New Zealand jack mackerel catch.

In the 1980s jack mackerel became an important inshore commercial species, caught by purse seiners – fishing boats that use nets to enclose the fish.

Kōheru

Related to the jack mackerel, but less common, is the kōheru (Decapterus koheru), which is found mainly off northern New Zealand. This small, silvery, plankton-feeding fish uses schooling strategies to avoid predators. When the fish are tightly-packed, their yellow-green side stripes merge, confusing predators. They tend to school below surface waters, and if attacked by marauding kingfish, they will often dive down to the reef.

How to cite this page:

Carl Walrond, 'Coastal fish - Plankton-feeding open-water fish', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/coastal-fish/page-4 (accessed 20 November 2017)

Story by Carl Walrond, published 12 Jun 2006