CENSUS OF FISH.

Otago Daily Times, Issue 19146, 14 April 1924, Page 9

CENSUS OF FISH.

VANISHED POPULATION OF THE DOOGKUBAN IC. To take a census of tile small animal life on the sea bed seems a tall order. But in the case of the huge area of the Doggerbank, which measures between its widest, points 250 miles (N.E. to S.W.) and ISO miles (N. to S.) this has been done with useful results for fishermen (says the Daily Mail). The census lakes about eight days, and requires from 200 to 300 samples of the material of tlie sea bottom,- and the most exact sorting and enumeration of the material brought up. Earlier census showed that tho 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 at 4,630,000 millions of young ones and 560.000 millions of adults. The total weight of the Spirula, old and young, excluding the weight, of sheik and water, was 19.000 tons. 15,000 tons of which were babies. This was the net weight of food for plaice and haddock. The survey fust finished shows that on tho old patches there arc very few Spirula left, and they are all adults. There is no new stock. Fifteen thousand tons of food are- no longer