350 



KEPOET ON THE PROBABLE AGES OF YOUNG FISH. 



sively that fish may live in the sea for monthS; with scarcely any 

 increase in size, just as some of the flounders out of a number kept 

 by me in captivity. Some of my captive flounders were only 

 about 2 inches in length when one year old ; these plaice taken 

 at Humberstone in January were of the same length, and must 

 have been at least eight months old, while they may have been more. 



It is not easy to infer from the data given in the table, the average 

 size or the limits of growth of the plaice in their second year. In 

 the entry for May 20th we have a large number of specimens cer- 

 tainly over a year old, and the greater number of these are 6^ to 

 8^ inches long. The flounders I reared in captivity were mostly 

 from 4 to 6 inches long at one year of age, and as the plaice in the 

 North Sea is a much larger fish, and these were taken some months 

 after the principal spawning season, these specimens may all have 

 been in their second year only. But on the other hand, it is certain 

 that some fish at two years old are not bigger than others at one 

 year, so that it is impossible to say whether some fish in their third 

 year may not be present in this lot. 



The maximum growth for a plaice of fourteen to sixteen months 

 old is difficult to fix with •the evidence at present available. The 

 maximum observed by me in the flounder at one year was 7| 

 inches, and as the plaice in the North Sea reaches 28 inches 

 in length, while the flounder's maximum length is 16 or 17 

 inches, individual plaice might reach 12^ inches in sixteen months. 

 I have accordingly estimated the age of the specimens of May 16th 

 from the Denmark coast at twelve to sixteen mouths ; a conclusion 

 supported by the fact that they were all immature. But some of 

 these specimens may be in their third year. 



It will be seen from the entry of March 30th, of fish taken in 

 the Humber by a shrimp trawler, that many plaice occur, only 4, 5, 

 or 6 inches long, which ai'e certainly a year old. 



Pleuronectes flesus, the Flounder. 



Date of 

 capture. 



April 25 



April 28 

 May 14 



No. of 

 specimens. 



3 

 3 

 1 



Several 



4 

 2 



Length in Length in pro,,able age 

 centimetres. I inches. iiuuauic <.n>= 



6-3— 8-4 j2i— 3^ 

 11-4— 12-4 ' 4^— 4| 



23-5 I 9i 

 About 22-8 I About 9 



5-9— 9-1 i2^»j— 31 

 10-8, 15-9 ! 41, 6A 



I i 



9-5, 12-5 3|,4| ; 



1 year 

 2 or 3 years 



1 year 



1 year 



Locality and mode of capture. 



Cleetborpcs to Humberstoue 

 Sands; shrimp shove-net. 



i- Cleethorpes Sands J shove-net. 

 Humberstone Sands; cart-trawl, 



