SEA-FISHERIES LABORATORY. 369 



sexes the total number of mature fish can be further cal- 

 culated. Such determinations made from year to year 

 would obviously give the fluctuation of the adult Plaice 

 population. 



Of all the Pleuronectid food fishes the Plaice is the 

 most important by reason of its relatively great abundance 

 and on that account when the probability of the decline of 

 the fishery became evident it was the object of much solici- 

 tude on the part of the fisheries authorities, and many 

 remedial measures have been proposed. In this country 

 the continual destruction of immature fish has been the 

 most obvious danger to the fishery, and the remedies have 

 all been directed to the minimising of this evil. The idea 

 underlying the remedies suggested has been to allow as 

 many fishes as possible the chance of spawning at least 

 once in their lifetime. This destruction of immature fish 

 takes place in every form of fishery. Practically all the 

 fish captured in inshore fishing, whether by trawl or stake 

 net, are immature. Even in the deep sea Grimsby fishing 

 more than half the fish landed are immature. In 1894* 

 of the Plaice landed at that port 7 millions were mature 

 and 9 millions immature. Of the same quantity 9| 

 millions were over 13in. in length and 6| millions under. 

 At first sight therefore it might appear that the imposition 

 of a size limit below which it would be illegal to land the 

 fish would be an effectual remedy. If based on the size at 

 which sexual maturity first occurs this limit would vary 

 for different localities. It is obvious, however, that such 

 a regulation is impracticable, since the Plaice becomes a 

 marketable fish long before it becomes sexually mature. 

 The imposition of such a limit would close the inshore 

 grounds against plaice fishing altogether. 



Other size limits have, however, been proposed, and 

 * Holt— fee. cit., p. 410. 



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