Stocks ‘very healthy’

Press, 23 November 1976, Page 1

Stocks ‘very healthy’

While both official and unofficial ' sources agree that illegal dealing is rife, just what effect it is having on the crayfish population of New Zealand waters is not clear. It seems that it may not be as harmful as has been thought by some, even when it comes to scrubbing cravfish tails. According to Dr J. L. McKoy, of the Fisheries Research Division in Wellington, crayfish stocks are very healthy in New Zealand, and are likely to stay that way. Dr McKoy is heading a Ministry of Agriculture and Fisheries survey of crayfish, investigating both the biological and ecological side and how the popu-

lation responds to fishing rates. He said the question of whether it was being fished out had to be looked at from two points of view—biological and economical. Biologically, the stocks are most unlikely to be fished out to the point of non-recovery. This is a world-wide pattern, due largely to the method of taking the crayfish — relying on the fish going into the pots. Also, large areas off New Zealand are not being fished because the water is too deep or the numbers are too low. “The individual fisherman does not get as many in a day as he used to, but that is because there are

more fishermen,” Dr McKoy said. There is a pattern in exploiting crayfish. When the operation starts the yield increases for a number of years,. peaks, and then declines for a number of years before levelling out.

This happened first in Fiordland in the mid-19505. The pattern was repeated in the Chatham Islands, but it was completed much more quickly. Dr McKoy said the reason for this was that in Fiordland exploitation techniques were developed as they went along. In the Chathams the techniques and bigger boats were all ready, so there was much more actual fishing.

“The tragedy of the Chathams was the tremendous amount of overcapitalisation. So much capital should not have been poured in at once on boats and equipment at the start of the boom. Had the Ministry had some control the benefits could have been extended over many years.” A crayfish, which can live up to 50 years, takes from seven to 10 years to mature to the stage where it can legally be taken. Each female lays from 125,000 to 250,000 eggs a year. It is impossible to say how many on average reach maturity but the number is obviously less than 100.