242 KATE OF GROWTH OF SOME SEA FISHES. 



paper, Matthews had published evidence concerning the spawning 

 season of the sprat which would make these whitebait sprats six to 

 eight months old. These authors do not always bear in mind that 

 the spawning season of the sprat may diner in different places, but 

 Matthews states in the earlier paper { Sprat- fishing, Second Report, 

 Scottish Fishery Board), that he received ripe sprats from Stone- 

 haven, Giiwan, and the Firth of Forth only in May and June. I 

 myself took the pelagic eggs of the sprat in the lower part of the 

 Firth of Forth in May and June. Thus we have in this case, the 

 maximum growth of the sprat, that of one spawned in June, and 

 measuring 2| inches in the following December, 2| inches in six 

 months, and the minimum, that of one spawned in May, and 

 measuring If inches in the following February, If inches in nine 

 months. The authors do not give separate measurements for the 

 separate months of observation. If we take the mean, both of 

 time and size, we have a length of 2-^ inches at seven and a half 

 months of age ; and the paper itself states that over 70 per cent, 

 of the sprats examined wei-e from 2 to 2| inches. The herring at 

 seven and a half months, according to Meyer's results, measures 

 about 3^ inches. 



The observations on the sprats in the Thames whitebait are mor 

 detailed, though by no means so much so as the present subject 

 requires. I have tabulated them as follows : 



Month. 

 February 

 March 

 April 

 May 

 June 



July 



August 



The number of small scaleless sprats gradually increased during 

 the last month, until 90 per cent, of the samples consisted of 



these. 



The young sprat undergoes a metamorphosis from the naked 

 larval form to the silvery scaled form like the herring, and we see 

 that the young larvae which began to appear in the Thames in June 

 reached 8 per cent, of the total number of sprats in July, and 90 

 per cent, of '' the samples " in August. It seems as if the total 

 catch was meant by the latter expression, but the meaning may be. 



