126 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



those of future years, it will be necessary to pay due 

 regard to the probable errors, but in the meantime we 

 may say that of all the plaice caught by a 6-inch trawl- 

 net in Rock Channel, about 64 per cent, were less than 

 8 inches long. 



Six-inch trawl-mesh catches : Near 

 M e r s e y B a r. — There are few of such catches recorded, 

 but it will be seen at once by a glance at the tables that 

 a rather different class of plaice are taken in this part 

 of the Mersey area. The modal lengths vary from about 

 18 to 21 cms. Roughly speaking, we may say that the 

 modal length is about 8 inches. Then about 46 per 

 cent, of the plaice are less than 8 inches long, as compared 

 with about 64 per cent, in the Rock Channel area. But 

 the dispersion of the sizes in the Bar catches is much 

 greater than in the catches made in the former area, and 

 quite a fair proportion of medium-sized fish are taken. 



Six-inch catches: Horse Channel. — 

 Sample catches were made in this area during the months 

 June to November inclusive, and the numbers of fish 

 taken are large enough to enable us to form a reliable 

 opinion as to the effect of this means of capture. The 

 modal lengths vary from 18'3 to 21*5 cms., and are 

 significantly greater than in the Rock Channel ground. 

 The curves are in all cases bi-modal ones, and, as in the 

 case of the catches made near the Mersey Bar the 

 dispersion is much greater than that exhibited by the 

 catches in the small-fish area. The proportion of plaice 

 less than 8 inches long in the catch is about two-thirds 

 in June, and falls to about one-quarter in September. 

 Then, as the result of fishing-out, perhaps also of emigra- 

 tion into deeper water, the proportion of fish under 

 8 inches in length rises, and is about 40 per cent, in 

 November. 



