EATE OF GROWTH OP SOME SEA FISHES. 



231 



The spawning period of the mackerel in the vicinity o£ Plymouth 

 lasts from the middle of May to the end of July, these being its 

 extreme limits. As there is no difficulty in obtaining any number 

 of mackerel during the spawning time, the fish being taken for the 

 market in large numbers in the ripe condition, the evidence avail- 

 able for the determination of the period is abundant. It would be 

 expected that the age of young mackerel could easily be reckoned 

 from such a short and definite spawning season. But I have not 

 found it very easy up to the present time. More abundant data 

 will require to be collected before the question can be satisfactorily 

 answered. In the meantime the few observations in the above 

 table are sufficiently interesting to be recorded, and from them a 

 probable rate of growth can be deduced which may be tested by 

 future observations. 



The specimens of the entry for June 23rd in the table were 

 selected by myself on board a mackerel boat. The boat sailed from 

 Plymouth on June 20th, but the nets were not shot that night 

 because there was not wind enough to enable us to get as far as was 

 necessary. During the whole of the next day we were sailing 

 under a light breeze catching mackerel by hook on whiffing lines. 

 We took 150 in this manner, the bait being a slice from the silvery 

 belly or tail of a mackerel already caught. Some of these mackerel 

 were rather small, but the majority were large, and the great 



