SEA- FISHERIES LABORATORY. 211 



and that of the sample, — and then endeavouring to 

 " weight " the means of the several cm. groups accordingly. 

 Until the data are more numerous, and until the samples 

 are more regularly taken it does not seem worth while 

 undertaking this work. 



The material that we do possess does, of course, 

 differ in the composition of the catches of fish made on 

 the various grounds, and these differences are very much 

 what one would suspect to exist. For instance, a rough 

 estimate of the proportions of Age-Groups I to III in the 

 catches made on the Nelson Buoy grounds during May to 

 August, and on the Beaumaris-Red Wharf grounds during 

 October to January gives the following figures : — 



Nelson Buoy. 



Beaumaris, Red Wharf Bays. 



Age- Group I. 

 Age- Group II. 

 Age- Group III. 



16% 

 72% 

 11% 



11% 

 75% 

 13% 



These show that the plaice population on the latter 

 grounds is an older one — very slightly older — than on 

 the former grounds. But no age-groups beyond the third 

 are considered, for the numbers of the larger fish received 

 are too small to utilise with confidence. It is, however, 

 the case that the larger and older fish are far more 

 numerous on the North Wales than on the Lancashire 

 ground, but with respect to the younger groups the differ- 

 ence does not appear to be a great one. What we have is a 

 native population which in both cases has approximately 

 the same length distribution, but with, in the case of the 

 winter fishery, a distinct population of older fish super- 

 added by migration from other grounds. 



