58 
In 1902* Mr. Douglas, Beadnell, labelled and liberated 100 
lobsters and 12 were recovered. But this percentage is more than 
likely too small, for of one group of 10, 8 were recaptured, and we 
have reason for believing that some of the labels were destroyed 
through ignorance. The fishing strength of the fishermen may be 
estimated to be about 20 per cent., and any other losses so far as the 
mature lobster is concerned must be so small as to be negligible. 
The population of adult lobsters on the Northumberland coast may 
therefore be said to be about 200,000. 
From the considerations on page 43 it appears that the relative 
numbers of the sexes are, males, 42 ; females, 58 ; the latter including 
19 in the berried or spawn-bearing condition. 
Our 200,000 lobsters may therefore be said to consist of 84,000 
males and 116,000 females, of which latter 38,000 are berried or 
ova-bearing lobsters. 
If we may be allowed to assume then that there are 38,000 berried 
lobsters in the population of the Northumberland coast, and that 
each of these hatches 40,000 larvae, the total annual contribution of 
larvae is 1,520,000,000. 
We have estimated, however, that to keep up the adult population 
an annual survival at maturity, or about five years after hatching, 
of 40,000 is demanded. This is a survival of 1 in 38,000, or *003 per 
per cent. — 1 lobster for each berried female. 
2. — Crabs. — In similar manner the average annual catch of 
crabs on the Northumberland coast, for the ten years ending 
1904, is 1,437,136, say 1,600,000. 
In 1903f Mr. Douglas liberated, after marking, 145 crabs, and 
14 were recovered, 9*7 per cent. The proportion is more than 
probably too small for the same reasons as in the case of the lobster. 
For example out of one lot of 32, 6 were recaptured. It may also 
be stated that the whole experiment did not take up a year, and the 
crabs used had recently cast. Williamson only obtained about a 
10 per cent, return of the crabs he had marked at Dunbar and 
neighbourhood, and more than likely for the same reasons the 
recaptures do not in his case either, accurately measure the fishing 
strength of the fishermen. We may be allowed to assume again 
that the fishermen are liable to catch about 20 per cent. 
jf 
Rep. Northd. Sea Fish. Com., 1902, p. 40. 
t Rep. NortM. Sea Fish. Com., 1903. 
