SEA-FISHERIES LABORATORY. 139 



urinations. It is to be noted that there are nq. marked 

 differences between the lengths of the males and females 

 of each Group : what differences there are are often 

 reversed. It is also to be noted that the differences 

 between the modal lengths of Age-Groups I and II 

 are very slight, amounting to only 3 to 4 cms. I expected 

 that the average growth during the third year of life 

 would have been greater than is indicated by the above 

 figures. 



Quite a different plaice population is contained on 

 the grounds off Rhyl, round Great Orme's Head, and in 

 Bed Wharf Bay. Here the fish belonging to Age- 

 Group I are far less in proportion to the older fish than 

 on the Lancashire fishing grounds. So few fish of this 

 group were contained in the sample sent to me that I 

 have not attempted to estimate their modal leng'ths ; the 

 figures are, however, given in detail in the tables. On 

 the other hand, Age-Group III is represented in sufficient 

 numbers to enable the modal lengths to be determined. 



Age-Group II. Beaumaris Bay and adjacent 

 grounds. 



July: Males, 19 - 5 cms. long; females 20 cms. long. 

 Nov.-Dec. : Males, 23 cms. long; females, 23 cms. long. 



Age-Group III. Beaumaris Bay and adjacent 

 grounds. 

 Nov.-Dec. : Males 27 cms. long; females, 29 cms. long. 

 5. LENGTH AND WEIGHT. 



The object of determining the weight of the plaice 

 taken on the various fishing grounds was to find a 

 numerical expression for the " condition " of the fish, 

 both with regard to season and fishing ground. One 

 knows very well when a plaice is " in condition " from 



