REPORT ON THE PROBABLE AGES OF YOUNG FISH. 349 



ceeding 3 inches were comparatively few in number. In May only a 

 few specimens of this size were taken. They appear only on one day 

 (or night), May 10th — llth^the number is less than fifty ; the aver- 

 age size of these is a little larger, the greatest number being from 

 2j to 2|. At the beginning of June another outburst appears ; on 

 the 1st only a few are taken, but on the 3rd 235 are taken in the 

 cart-trawl. In July, in the middle of the month a few still smaller 

 specimens are taken, only about 1^ inches long, and as late as the 

 beginning of September we find thirty-eight specimens under 2 

 inches long in the shove-net. Mr. Holt finds that plaice spawn in 

 the North Sea chiefly from the middle of January to the end of 

 March, though a few may spawn earlier or later. I think it is 

 evident that the large number of specimens 2 inches in length taken 

 at the end of April are dei*ived from the eggs shed in January, and 

 are therefore three months old. Those which are larger may be a 

 week or two older or may have grown faster. I have shown in pre- 

 vious papers how variable the rate of growth is. Those which are 

 smaller than 2 inches, may in like manner be younger, or may have 

 grown more slowly. It is difficult to fix the maximum size of speci- 

 mens derived from the immediately preceding spawning season. I 

 have fixed it at 3 inches, referring specimens above this length to 

 the spawning of the previous year. I do not understand why com- 

 paratively few of these young plaice were taken in May. The large 

 number taken at the beginning of June include chiefly those hatched 

 in February and March. Those taken in July and September are 

 few in number, and represent those whose growth has been slow, 

 who have been behindhand in the competition for food, or which 

 are the progeny of the last spawners of the season, of parents which 

 spawned in April or even in May. All these young plaice of the 

 year are taken on the flat sandy shores near Grimsby in shrimp 

 nets, either in the shove-net, which is worked by hand, and has a 

 spread of 10 feet, or by the cart trawl which is towed by a horse. 

 I have shown previously (this Journal, vol. ii. No. 2, p. 99), that 

 plaice of the year occur in June on similar sandy shores near 

 Plymouth. It is evident that the destruction or, at any rate, the 

 capture of plaice fry by shrimpers at the mouth of the Humber must 

 be enormous. 



I have considered the seven specimens taken in sprat stake-nets 

 on January 29th to be remnants of the previous year's brood. Pos- 

 sibly some plaice may spawn in December, but even then the young 

 fish produced could not reach a length of two inches in less than 

 two months. These small fish must, therefore, be derived from the 

 spawning of the previous year, and be eight or nine months old at 

 least. The consideration of such specimens as these shows conclu- 



