480 



REPORT ON TRAWLING AND OTHER INVESTIGATIONS 



Table XXII., shoiving the numhers and sizes of Plaice marlced in Teicjn- 

 mouth Bay, and the nnmbers recovered in successive periods inside 

 and outside the hay. 



It will be seen that the general percentage of recoveries (34 per cent.) 

 is much higher for this bay than for Start Bay, and that half the fishes 

 from 9 to 1 2 inches were recovered ; whereas in the Start Bay ex- 

 periments only a quarter of the fishes of this size, and less than 24 per 

 cent, of the total number liberated, were recaught. 



The fact that none of the thirty-two fishes from 7 to 8 inches were 

 recaught after the first year tends to show that the explanation ad- 

 vanced above, in the Start Bay section, as regards the small percentage 

 of these fishes caught, is not sufficient to account for all the facts. 

 One year's growth (from 3 to 4 inches for fishes of this size) would 

 bring them to a length of 10 to 12 inches, at which size they would 

 be capable, as the records show, of undertaking the ordinary migrations, 

 and would thus be liable to capture by the trawlers outside the bays. 

 The probability is that the rapid growth of fishes of this size causes the 

 fish to suffer injury towards the end of the summer owing to the rigid 

 character of the labels with which they are marked. The fish grow in 

 thickness, but the length of the silver wire connecting the buttons 

 remains the same. The consequence is that the buttons press too 

 severely upon the skin and, by laceration, cause wounds of a serious 

 character, or wear off altogether. I have seen good examples of this 

 in ovir North Sea investigations. The statistics of capture of these 

 small marked fishes should, therefore, be treated cautiously, and the 

 fact that none of the fishes marked of this size-group (7 to 8 inches) 

 have been recaptured after the first year in any of the Devon experi- 

 ments receives an explanation which it would otherwise be difficult to 

 supply. 



Turning again to the table, it should be noticed that fully twice as 

 many fish from this experiment have been recovered outside the bay as 



