NEW ZEALAND HAS FOUR SPECIES OF TUNA

Press, Volume CII, Issue 30152, 8 June 1963, Page 8

NEW ZEALAND HAS FOUR SPECIES OF TUNA

Fish Of Great Size And Power [Specially written for “The Press 0 by JAMES SIERS] 'THE tuna has played an important part in our sport fishery. A big yellowfin tuna reaches a size of more than six feet in length. Its power al the end of a line is incredible. But it may be that in time, as fishermen get better sea-going pleasure craft and the movement of the tuna is more accurately plotted, the various species will be enjoyed for sport around our coastline.

Last week-end. Miss M. K. McKenzie,' of the Marine Department, gave some facts and figures on the four species of tuna found around New Zealand.

Speaking at the annual conference of the New Zealand Ecological Society, she said the four species of tuna known to visit our shores regularly are the yellowfin, skipjack, albacore and southern bluefin tuna.

Two other species, the frigate mackerel and the bigeye tuna, Miss McKenzie said, may possibly arrive off the northern. shores in summer.

The New Zealand waters are in the right temperaturerange and overseas charts show the sea around the coasts as tuna habitat. Miss McKenzie said the convergence of currents is

another attraction to tuna. There were three such points about New Zealand. One was in the Fouveax Strait area, another off the Kaikoura coast and a third, north of Auckland, on the northern coast.

The four more common species are divided into two groups—the larger yellowfin, which reaches up to and oyer six feet in length; the smaller southern bluefin, up to an average of 70-801 b; and the smaller skipjack and albacore, which are much the same in length, each about 30 inches long, but fairly heavy in build. The yellowfin tuna are found off the southern coast during the summer. Miss McKenzie showed pictures of some taken in the deep water near the sounds.

In winter, the fish move right up the coast. Miss McKenzif said the skipjack would seem to be the most common species around Hawkes Bay and the • Bay of Plenty. Fishermen trawling for tarekihi with nets have caught tuna on trawling lines in the area. A chart showed where tuna had" been caught by Miss McKenzie. She thinks the first commercial to be used by New Zealand will be the skipjack, which is a topWater fish. The fishing would probably be done off the Bay of Plenty coast, where skipjack are known to come in close in big numbers. Not much seems to be known about the commercially desirable albacore, which has the whitest flesh. But charts show that it does exist in eur waters. The big yellowfin. Miss McKenzie said, did not move south of Cook Strait. All the species are pelagic and this means they are an open-water fish. They rarely penetrate the thermacline, but the fish will go down to a depth of 100 feet or more. Their food consists of bait fish such as anchovies,’ pilchards. mullet and particularly" of any of the smaller fish which have a bright silver marking. The tuna will also feed on squid and crustaceans and no doubt the bigger tuna will feed on bigger fish. The larger tuna are particularly free from predators, although once the fish are hooked on a long line, if sharks or other predators are about, the catch is likely to come up in pieces. Asked about the quantity of tuna around New Zealand, Miss McKenzie said: “The Japanese find it profitable to fish in our waters.