RATE OF GROWTH OF SOME SEA FISHES. 233 



elusion that tliese young mackerel of November are really more than a 

 year old^ and are derived from the spawning not of the immediately 

 preceding summer but of the previous year. I have shown that the 

 scad (Caranx trachurus), which I believe spawns about the same time 

 as the mackerel, is only 2*5 to 3*5 cm. long in September (see my 

 previous paper). The herring is on]y 8 to 9 cm. long in November 

 when spawned in April or May : the adult mackerel is about six 

 inches longer than the adult herring, and therefore there is no 

 reason to believe that it grows to twice the length in less time. 



But the question arises, if these mackerel 16 to 21 cm. are 

 sixteen months old, how can others taken in June and 22 to 23 cm. 

 long be only a year old ? The answer to which is, I think, that 

 there is considerable individual variation in size. It it clear that 

 the single specimen, taken at the end of September and measuring 

 13*8 cm., could not have reached that length in two or three months, 

 and it must have been an unusually small specimen at fourteen 

 months old. 



I hope to test and confirm these conclusions this summer by 

 following the growth of the mackerel fry from the hatching time 

 onwards. Hitherto, mackerel fry from a few weeks upwards have 

 not been taken, but by the use of a large and suitable net we may 

 succeed in capturing them. 



In the early summer the smaller mackerel, those I conclude to 

 be two years old, are found near the coast, while the larger fish are 

 caught out in the open sea. Thus in May last year Plymouth boats 

 were catching mackerel of 12 or 13 inches in length, and about ^ lb. in 

 weight, off Looe Island on the Cornish coast, while the large Lowe- 

 stoft boats were bringing in huge mackerel up to more than 1^ lbs. 

 in weight from off Ushant and eighty miles south-west of Penzance. 



Clujjea harengus, the Herring. 



I have not had many opportunities of studying the growth of the 

 herring, but have thought it would be useful to give an inclusive 

 summary of the evidence which has been recorded by others on 

 the subject. The question has been carefully and successfully in- 

 vestigated by H. A. Meyer, in the Baltic. There is a paper by this 

 observer in the Jahreshericht of the Commission zur Untersuchung 

 der deutsclien Meere, for 1874-75-76, published in 1878. The 

 paper is entitled Observations on the Growth of the Herring in the 

 Western Part of the Baltic. Before Meyer's work various contra- 

 dictory opinions had been expressed concerning the growth of the 

 herring. For instance, the English Royal Commission of 1862, whose 

 report was published in 1863 {Commission on the Ojieration of the 



