370 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the adoption of some one will probably come in the future. 

 In 1892 a conference held under the auspices of the 

 National Sea Fisheries Protection Association proposed 

 lOin. as the legal minimum size of marketable Plaice. 

 Following this, in 1893 a Select Committee of the House 

 of Commons recommended 8in. as the limit, being influ- 

 enced by the existing legal sizes in other countries. In 

 France the legal size of Plaice is 5Jin., in Belgium nearly 

 the same, and in Denmark it is 8in. 



It is to be noted that the arguments as to the decline 

 of the Plaice fishery are generally founded on the total 

 weight of fish landed, not on the number of individuals, 

 and this has suggested the ingenious 4k growth-theory " of 

 Petersen* for the betterment of the fishery. In Danish 

 waters the weight of a lOin. Plaice is less than Jib., and 

 that of a 14in. fish is more than twice as much. Now if 

 in the time required for a Plaice to grow from 10 to 14 

 inches the total mortality on the fishery ground is such 

 as to reduce the number of individuals by one-half, the 

 total weight of fish will remain much the same as before. 

 But it is not likely that the mortality will be so great, 

 since the Plaice is singularly free from disease, and at the 

 sizes mentioned its enemies (predatory fishes) are few. It 

 follows then that by deferring their capture until they 

 have grown to 14in. in length a much greater weight of 

 fish will be brought to the market. The utility of a size 

 limit (the most profitable one to be determined by experi- 

 ence) is therefore apparent. Though fewer fish are caught 

 the fishing will become more profitable. The practica- 

 bility of such a measure is greater in Denmark than in 

 Britain, There fish are brought to the market alive and 

 instruments of capture are designed to that end. Small 

 fish taken can therefore be returned to the sea alive. Here, 

 * Petersen — he. xit., p. 48. 



