504 AN EXPERIMENT IN THE TRANSPLANTATION OF PLAICE FROM 



54'3°-55-7° on the 2nd, and on July 3rd, up to the time of setting out 

 the fish, the temperature had ranged between 54*5° and 58*0° F. The 

 extremes of temperature these fish experienced thus ranged over 

 24° F., without their appearing to have suffered from the rapidity with 

 which the changes occurred. 



Recapture of the Fish. — The following table gives particulars of 

 the recapture of the individual fishes (see next page). 



The object in selecting the N.W. Eough as the point of liberation 

 for these fish was that, in addition to being in the direct track of our 

 vessel between the Norwegian and English coasts, it was a ground 

 which offered a fair prospect of some of the fishes being returned if 

 they survived. Unfortunately some Grimsby, Hartlepool, and Scar- 

 borough trawlers, engaged in fishing for cod and haddock, chanced at 

 once to visit the area of liberation, and in the first month eight fish 

 were returned. Five more being subsequently recaptured gives the 

 result that within one year 13 or 56"5% have been returned. 



The latter five were caught in the fourth (two specimens), seventh, 

 tenth, and eleventh months after liberation, and without exception 

 show important and unusually rapid growths compared with those 

 which have been observed in the case of North Sea fish of correspond- 

 ing size and sex. 



These growths were accompanied by considerable improvement in the 

 condition from the point of view of the market value of the fish. 



Movements of the Fish. — A feature connected with the move- 

 ments of the last five fish is that all but one had migrated from the 

 deeper water (33 fms.) in which they were liberated, short distances on 

 to the Dogger Bank (20 fms. and less). 



The furthest migrant was E 3880, which was taken on the Eastern- 

 most Shoal, about sixty miles from the point of liberation. Another fish, 

 E 3876, had moved about forty miles in the direction of the Middle 

 Rough and was retaken by a Dutch steam trawler. It is curious to 

 note that the Grimsby trawler which efiected the recapture of the 

 former specimen also took, at the same spot, a plaice (E 778), which I 

 had myself transplanted to the Dogger from the Dutch coast in May, 

 1907. This fish had grown 18-5 cm. 



All the female fish brought from the White Sea appeared to be im- 

 mature, the contrast between such and spent ones, so soon after the 

 northern spawning season, being in most cases very marked without 

 internal examination being absolutely necessary.* 



* A new feature in the biology of the plaice lies in the enormous depth at which the 

 Barents Sea plaice spawn. In May, 1909, Captain Leighton informs me, they were found 

 by our trawlers to be in spawning condition in great masses in 90 to 106 fathoms. 



