SEA-FISHERIES LABORATORY. 213 



tlie fishermen would refrain from fishing on such small 

 plaice grounds if they were prevented from landing the 

 bulk of the fish caught. Now, these grounds are largely 

 exploited by second-class sailing trawlers. The imposition 

 of a size-limit can only be justified by postulating that the 

 fish that would otherwise be taken by unrestricted trawling 

 will remain alive in the sea, migrate to other grounds and 

 grow to a size at which their commercial value will 

 become very considerably greater. This migration occurs, 

 although we may not be prepared to say that all the fish, 

 which the imposition of a size-limit would leave uncaught, 

 will survive and grow at the normal rate : it is likely that 

 " thinning-out " the plaice population of these grounds 

 by trawling leads to the more rapid growth of the 

 survivors. Suppose, however, that the migration and 

 growth of the plaice left uncaught by the proposed restric- 

 tion proceed as suggested in this report. Then we save the 

 fish which would have been caught by the second class 

 vessels to be caught by the smacks working offshore, and 

 in the Beaumaris-Red Wharf area, in the winter months. 

 Following up the same argument we see that a size- 

 limit of 20' 5 cms. would prevent some 40 to 50 % of plaice 

 living in the Red Wharf Bay area from being landed 

 during the months of June to October, supposing that it 

 were worth while to trawl on these grounds during this 

 period. It would prevent the landing of some 20 % to 30 % 

 of the plaice caught during the months of November to 

 January, but this would probably not prevent trawling 

 with nets of 6-inch mesh, for it would still be profitable 

 for the smacks to work on these grounds even if they were 

 obliged to return (dead or alive) to the sea all the plaice 

 Less than 20'5 cms. taken by them. It might then be 

 urged that a size-limit of 205 cms. effective in preventing 

 trawling on the Nelson Buoy grounds would be ineffective 



