464 SOME RESULTS OF THE INTERNATIONAL FISHERY INVESTIGATIONS. 



Fishery Board, and in America by the Fish Commission, many years 

 ago. It is only since the inception of the International Investigations, 

 however, that it has been carried out on a scale adequate to the 

 furnishing of reliable and useful results. 



Various methods of marking the fish (usually plaice), so as to identify 

 it afterwards, have been practised. In Petersen's method (the one now 

 mostly adopted), a stout silver wire is pushed through the body of the 

 fish just underneath the dorsal fin. One end of this wire passes 

 through a bone button and is looped ; the button is on the lower side of 

 the fish. The other end passes through a hole in a brass disk and is 

 also looped ; the brass disk is on the upper side of the fish and bears a 

 number. Experience has shown that this label can be attached to the 

 plaice in the manner described without permanent damage, and appar- 

 ently without permanent discomfort to the fish. The living fish, being 

 measured and marked, is then put back into the sea, the size and place 

 of liberation being recorded. Most careful arrangements have to be 

 made for the return of marked fishes recaptured by the fishermen, and 

 rewards are paid for these. In Great Britain the reward varies from 

 Is. 6d. to 2s. Obviously success depends on the return of marked fishes 

 recaptured by the fishing vessels, and while the proportion returned is 

 most gratifying, it is still the case that many recaptured marked fishes 

 must escape recognition and return. The first published summary of 

 the results of all the plaice-marking experiments carried on by the 

 various national staffs is given below. 



The " percentage " is the proportion of marked fish recovered within 

 twelve months after the date of liberation. 



Of course, these returns are very incomplete. A large number of 

 fishes have been marked and subsequently recovered since the end of 

 1903, but at the present time the figures are not easily available, and 

 the results have not been collated. The above statement applies to the 

 fish-marking experiments carried on by the naturalists attached to the 

 staff of the International organization. But in addition to these 

 experiments, a large number of plaice and other fishes have been 



