REPORT OF THE COUNCIL. 319 



Marking Experiments. — Experiments have been systematically 

 carried out in the marking and liberation of fishes, especially plaice 

 and soles, over wide areas, in order to throw light on their migrations 

 and rate of growth, and on the intensity of fishing under modern 

 conditions. Altogether, up to the end of May, 1904, 2,881 fishes had 

 been marked and set free. Of these the majority were liberated in the 

 localities where they were caught, but during the present year about 

 1,200 marked plaice have been transplanted to the Dogger Bank from 

 the English, Dutch, and Danish nursery grounds, in order to test the 

 possibility of their rate of growth being more rapid in parts of the 

 sea where the competition for food is apparently less keen. If these 

 transplantation experiments should be successful, the possibility of 

 restocking exhausted areas in the North Sea will have entered upon 

 a new phase. 



The success of the marking experiments in general is shown by the 

 satisfactory percentage of marked fish which have been returned by 

 the fishermen, by the general consistency of the returns, and by the 

 interesting results obtained in regard to the seasonal migrations of the 

 fish. Of 539 plaice liberated up to the end of May, 1903, the number 

 of recoveries amounted twelve months later to 125, i.e. 23 per cent. 

 The experiments off' the north coast of Holland, referred to in the last 

 Annual Ifeport of the Council, were repeated during the autumn and 

 winter of 1903. The movements of plaice again showed the same 

 southward tendency, and a simultaneous migration in the same 

 direction was exhibited off the English coast. Plaice marked and 

 liberated on the Leman Ground (about fifty miles east of Cromer) on 

 December 10th, were recovered in February off the Suffolk coast, and 

 in March in the English Channel off Winchelsea (a minimum distance 

 of 175 miles). 



Mr. A. Meek, Lecturer in Biology at the Durham College of Science, 

 and Director of the Marine Laboratory at Cullercoats (since destroyed 

 by fire), has kindly co-operated with the Association's staff in the 

 marking experiments, and, in addition to special experiments, liberated 

 about 200 marked plaice on behalf of the Association off the coast of 

 Northumberland during the summer of last year. Most of the fish 

 recovered were recaught locally, but several were subsequently re- 

 covered in Scottish waters, off St. Andrews Bay and the Isle of May. 



Special Experiments. — During the present year special experiments 

 have been made on the vitality of trawl- caught fishes and on the 

 proportion of small fishes which escape through the meshes of the 

 trawl. 



In May, drift-bottles were thrown overboard at intervals along lines 

 between Lowestoft and Heligoland, and between the Wash and the 



