NORTH SEA FISH GENSUS.

Hokitika Guardian, 31 March 1924, Page 4

NORTH SEA FISH GENSUS.

VANISHED POPULATION OF DOGGER BANK. LONDON, January' 20. To take a census of the small animal life on the sea bed seems a tall order. But in the case of the huge area of the Dogger Bank which measures between its widest points 250 miles (N.E. to S.W.) and 150 miles (N. to S-) this lias been done with useful results for fishermen. The census takes about S days and requires from 200 to 300 samples of the material of the sea bottom, and the most exact sorting and enumeration of the material brought ui>. Earlier census showed.that the centre of the N.E. edge of the Bank, about 700 square miles in area, was very rich in a small, white bivalve called Spirula subtruncata. This is the food of both plaice and haddock. Patches were found elsewhere, and the whole population on the Dogger was estimated afc-1,080,000 millions of young ones and 500,000 millions of adults. The total weight of the Spirilla, old and young, excluding the weight of shell and water, was 19.C00 tons, 15,000 tons of which were babies. This was the net weight of food for plaice and haddock. Tlie survey iust finished shows that on the old patches there are very few Spirula left, and they are all adults. There is no new stock. Fifteen thousand tons of food are no longer available.