SEA-FISHERIES LABORATORY. 203 



Einar Lea with regard to the scales of the herring, and 

 which has been criticised by Miss Hosa Lee,* has not 

 been employed, so that it seems likely that the results of 

 this investigation may be relied upon. 



All the plaice examined have been reported upon in 

 former papers in these Reports. We may consider, first 

 of all, those fish which were caught during the months of 

 October to March, both included. These are they which 

 had ceased to grow — for taking into account all the evi- 

 dence available from these measurements, and from the 

 results of the marking experiments, it seems highly 

 probable that growth proceeds only during the months 

 April to September, and is considerable only during May, 

 June, and July. In considering the Tables XXII-III, it 

 must, therefore, be borne in mind that we are supposing 

 that the plaice in question are those caught at the middle 

 of the season of no growth — that is, at the end of 

 December. The error of age is, therefore, plus or minus 

 three months. But since plaice do not grow during the 

 months October to March, and since we may assume (in 

 the meantime, at least) that the mean spawning period is 

 about the end of March, it would appear that the mean 

 or modal lengths deduced from Tables XXII and XXIII 

 represent the lengths of the fish in each age-group at the 

 end of each complete year of life. 



Table XXIII then gives the numbers (actual 

 numbers and percentages in each grouping) of those 

 plaice in which both sex and age have been deter- 

 mined. Table XXII gives similar data for all the 

 plaice examined, including those in which the sex 

 was not ascertained : in this Table the sexes are 

 grouped together. It is doubtful whether it is worth 



* " An investigation into the methods of growth determination in Fishes." 

 Publications de Circonstance. Cons. Perm. Interned. Explor. de la Mer. 

 No. 63, Nov., 1912. 



