SEA-FISHERIES LABORATORY. 195 



fall off in February. This relatively sharp drop in the 

 fishing may be partly artificial. The vessels which 

 exploit these grounds are mostly smacks, and their crews 

 appear to like to stop fishing during the Christmas week. 

 A spell of very bad weather, N.W. to N. winds, will also 

 put a stop to trawling here. But allowing for these 

 " accidental " conditions, it seems to be the case that the 

 plaice actually desert the grounds off Carnarvon and 

 Anglesey some time between November and February. 

 The fishery ceases rather sharply, as will be seen from the 

 figures published by me in last year's Annual Report, 

 pp. 136 et seq. It is not at all like the gradual decline in 

 average catch that we might expect to get when a 

 naturally-occurring fish population is being " fished-out.' 

 In a week or two, as in 1910, the average catch per day's 

 fishing may drop from about 7 cwts. to less than 1 cwt. It 

 seems to be certainly the case that some time about the 

 end of the year the plaice migrate away from the 

 Beauniaris-Red Wharf Bay area. It cannot be too often 

 pointed out that here we have the best possible oppor- 

 tunity for a successful study of the relation between the 

 productivity of a fishery and the physical conditions in the 

 surrounding sea-area. I have tried to indicate what this 

 possible relation is in a former Report,* but, unfor- 

 tunately, the data available are insufficient for the 

 demonstration of close relationships. 



The length-measurements for this fishing ground 

 may be summarised as follows : — 



June. — Under 172 cms. (6| in.) 5 % ; over 216 cms. 

 (8£ in.) 45 % ; between 172 cms. and 21"6 cms. 

 50 %. 



* ' Hydrographie Investigations and the Fisheries of the Irish Sea." 

 Ann. Kept. Lancashire Laboratory for 1912, pp. 99 to 150, 1913. 



