Ixiv 



Thirty-third Annual Report 



In ni08t of the hauls a small-meshed net was used outside the cod- 

 end, in oi'der to catch the smaller fishes which esca])ed through its 

 meshes. 



The great majority of the fishes caught were individually measured, 

 the sizes being recorded, while large numbers were opened and the 

 condition of the reproductive organs ascertained and noted. Observa- 

 tions were also made in many cases on the contents of the stomachs, 

 in order to determine the food upon which the fishes subsist. These 

 records are being worked up for publication. 



Migrations and Groivth of Fishes. 



As stated in last .Report, marking experiments on the plaice were 

 carried on for the ten years from 1904 to 1913, but were discontinued 

 last year for the reasons explained. During the year, 550 plaice which 

 had been marked in previous years, were recaptured. The parti- 

 culars with regard to the plaice marked in each of the ten years, and 

 the percentage of recaptures (to the end of 1914) are as follows : — 



Year. 



1904 

 1905 

 1906 

 1907 

 1908 

 1909 

 1910 

 1911 

 1912 

 1913 



Number 

 Liberated. 

 310 

 245 

 40 

 13 

 259 

 336 

 1915 

 1733 

 2165 

 1345 



Number 

 Recaptured. 

 101 

 89 

 12 

 6 



67 



65 

 996 



889 

 1198 

 638 



8361 



4061 



Percentage 

 Recaptured. 



32-6 



36-4 

 (300) 

 (46-1) 



25-9 



19-3 



52-0 



51-3 



55-3 



47- 4 



48- 6 



As the table shows, the percentage of recaptures has varied some- 

 what in different years, the mean for the ten years (up to the end of 

 1914) being 48-6. As many of the marked fishes liberated in any one 

 year are recaptured over a number of years (it may be for four or five 

 years), there is little doubt the percentage will be yet increased. It 

 will be observed that the percentage of recaptures for the year 1912 

 amounted to as much as 55*3. In some of the experiments the per- 

 centage was very much higher, as much as over 75 per cent. 



A detailed Report on the results of the marking experiments from 

 1904 to 1909 was published in 1913, and another Report dealing with 

 the later experiments is now^ being prepai'cd. 



The main objects of the marking experiments are to ascertain 

 (1) the migrations of the fishes ; (2) the growth ; (3) the intensity of 

 fishing operations. With reference to the movements of the marked 

 plaice, it is necessary to draw a distinction between those which have 

 reached the size of maturity and those which have not. The latter 

 do not, as a rule, move far from their ordinary feeding grounds, and 

 they do not appear to take any very definite direction in such move- 

 ments as they make. The former, on the other hand, undertake often 



