302 FOUNDERS OF OCEANOGRAPHY. 



in their early youth, perhaps even before undergoing meta- 

 morphosis. Experience shows that all such fears are 

 groundless. In the hatchery at the Port Erin Biological 

 Station young plaice have been reared up to their fourth 

 year, when they had become sexually mature, and had, 

 a year before, in their turn produced spawn for the hatchery. 

 In 1917 there were three generations of plaice living together 

 in the institution — the grandparent spawners, which had 

 been originally wild fish ; the parents, which were hatched 

 in the spring of 1914 and were then spawning (in March, 1917) ; 

 and the young of the third generation, which were developing 

 as normal larvse. The following year (March, 1918) some of 

 the fish hatched in 1914 had again produced fertile spawn 

 — there can be no doubt that they were perfectly normal 

 healthy fish. 



In addition to such operations in hatching and rearing, 

 a further experiment that has been tried with the object 

 of restocking depleted fisheries is the transplanting of young 

 fish from shallow waters where they are present in great 

 quantities (" nurseries "), and perhaps overcrowded, to other 

 deeper fishing-grounds where there is abundance of food 

 and where growth will probably be more rapid. Professor 

 Walter Garstang first showed, some years ago, that small 

 plaice caught in spring on the Dutch inshore grounds and 

 transferred to the richer feeding-ground of the Dogger Bank, 

 in the centre of the North Sea, grew very much more quickly 

 than those left inshore. The following statement as to the 

 result of this experiment is quoted from a recent article by 

 Dr. E. J. Allen :— 



" Plaice 7| inches long, when captured in April on 

 the inshore grounds, were on the average 13f inches long 

 by the following November when transplanted to the 

 Dogger Bank, whereas those that remained on the inshore 

 grounds were only 9-J inches long at the same date. 

 Expressed as weights, the differences are still more striking. 

 Fish of 2 J ounces increased in seven months to 15 ounces 



