Tuna Prospects Studied In Southern Waters

Press, Volume CIII, Issue 30393, 18 March 1964, Page 3

Tuna Prospects Studied In Southern Waters

(New Zealand Press Association)

WELLINGTON, March 17.

The southern blue fin tuna appear to be present in commercial quantities from mid-January to April, says a Marine Department statement today, after the completion of a South Island tuna liaison tour.

The statement says the tuna are found in temperatures as low as 12 degrees and feed in depths as shallow as five fathoms. Other conclusions reached are:— Tuna appear to be attracted by white lures in preference to other colours. A trolling line of 60 feet appears to be most successful, providing a rubber ' spring is inserted to take the pull of the strike. When the tuna is landed it should be killed by a blow on the head with a mallet; otherwise the flesh will be bruised by the vigorous movement

of the fish on deck. Vessels could fish for tuna in the calm of the sounds, providing the weather is suitable for rounding Puysegur Point.

On January 9 a three-week trip to the Southland fiords was started by the Olwyn on charter to the Marine Department, primarily to assess the potential of southern blue fin and to study their distribution in relation to hydrological conditions in the area.

The Olwyn was equipped with a live-bait tank and gear for pole fishing. She was also rigged to troll eight lines. Surface temperatures in Foveaux Strait were all below average but three tuna strikes were made just before the ship rounded Puysegur point. On January 16, the Olwyn sailed to Dusky Sound, pounded into a confused northerly sea and swell. Surface temperatures averaged 54.5 degrees Fahrenheit and the sea was a murky bottle green colour. Under these conditions, 6001 b of southern blue fin tuna were caught between Dusky and Nancy sounds.

The trolling time was 12 hours. Schools of tuna were sighted at the entrance to Charles and Bligh sounds. At least eight strikes were made in this area. The thermocline was at 120 feet and tuna was caught in depths ranging from five to 70 fathoms.

Much research work was being carried out on the tuna grounds off New Zealand, the Minister of Marine (Mr Scott) said today. “All the work is being directed by the scientific staff of the Department but the vessels employed are either from the Royal New Zealand Navy or are local fishing craft,” he said. The naval research vessel Tui was working off the edge of the continental shelf on the west coast of the South Island.