KEPOET OF THE COUNCIL. 491 



of the large spent fish which are then leaving this portion of the sea. 

 It is intended to conduct similar experiments in January, 1910, as 

 the plaice whose movements it is desired to study can usually be 

 obtained in greater numbers earlier in the year. 



Over three thousand fish also were taken in the North Sea and 

 transplanted to other grounds. Of these, 2550 were transplanted to 

 the Dogger Bank, having been procured in about equal numbers on 

 the English, Dutch, and Danish coasts. Plaice taken to the Dogger 

 Bank from the Dutch and Danish coasts in May, 1908, were found, on 

 recapture in December last, to have differed somewhat in their rate of 

 growth. It was accordingly considered advisable to secure comparable 

 data as to the growth rate, on the Dogger Bank, of plaice brought from 

 different localities. During the year 473 plaice were taken to the 

 Devon bays. Twenty-three plaice were brought from the Barents Sea 

 by a member of the staff' on the steam trawler Princess Louise, and 

 notwithstanding the great change in temperature experienced on the 

 voyage, were liberated in apparently good condition in the North Sea. 

 Twelve of these fish have been recovered, and were found to have 

 grown at a rapid rate. 



The following table gives the particulars as to the numbers of plaice 

 recaptured during the year, with the exception of these twelve fish. 



There have thus been recaptured during the year 861 plaice. 



Vitality Experiments. — The plaice caught in ten hauls of the 

 trawl, 3407 in all, were subjected to experiments designed to deter- 

 mine the length of time it is necessary to keep trawled plaice in 

 circulating sea-water, in order satisfactorily to test their condition. 

 While no period was found in all cases sufficient for such tests, the 

 retention of the fish for twenty hours in the tanks, with periodic 

 removal of dead fish, appears greatly to reduce the errors of experi- 

 ment. A discussion of these experiments has been added to the 

 report on the previous Vitality Experiments carried out by the 

 Association, which has now been published. 



