of the Fishery Board for Scotland. 



179 



tured without being forwarded to the Fishery Officers or myself, partly 

 from ignorance of the experiments on the part of those who obtained 

 them, and partly from the disinclination of some of the trawlers to assist 

 in the matter. Of the 2586 fishes referred to above as having been 

 marked and liberated, 130 have been re-captured, and particulars obtained 

 about them, the great majority having been sent to me with the brass 

 disc attached. Of the 1490 set free in the Firth of Forth, 55 have been 

 again caught; while 74 of the 1096 liberated in St Andrews Bay have 

 been re-captured. By far the greater number have been plaice. Of the 

 515 plaice marked in the Firth of Forth. 36 have been again obtained; 

 and of the 735 marked in St Andrews Bay, no less than 67 have been 

 re-caught, making a total of 103 marked plaice re-captured, or 8*2 per cent, 

 of those liberated. The number of common dabs which had the labels 

 attached to them was 337, of which 155 were set free in the Firth of 

 Forth, and 182 in St Andrews Bay. The total number again captured 

 was eleven (six from the Firth of Forth, and five from St Andrews Bay), or 

 3*2 per cent, of those replaced in the sea. Of 196 cod dealt with, 10 

 were re-captured, or 5"1 per cent. The only other marked fish obtained 

 were two thornbacks out of 71 ; one turbot out of 4 ; one gray skate 

 amongst 23; and one lemon sole from among 173. None of the long 

 rough dabs were re-captured, although 198 were marked and liberated, 

 and none of the 85 haddocks, or 69 gurnards, or 54 anglers. There is 

 evidence of many fishes having been caught without the label, but with a 

 mark on the tail showing that a label had been attached, and Mr Peter 

 Sim informs me he has caught plaice in this condition as far out as the 

 Bell Rock. 



I. — The Migratory Movements. 



As has been said, the main object of these experiments was to ascertain 

 the migrations which take place among the food-fishes, and an examination 

 of the tabulated results brings out some points of interest. The question 

 may naturally be raised, whether or not the presence of an irritating body 

 in contact with the skin, such as the small brass disc and silk cord used in 

 the experiments, causes material interference with the normal migratory 

 movements of the fish. It is of course difficult or impossible to give a 

 decided answer to this question. But it seems to me that it does not, 

 because in some cases the marked fish have remained, even for long 

 periods, at about the same place, without travelling far, while in other 

 cases specimens of the same species have gone considerable distances ; and 

 in each of these cases the irritation caused by the disc was, so far as can 

 be judged, equal in amount. In considering the movements of the fish in 

 these experiments, it will be well to begin with the plaice. 



1. Plaice. 



As stated above, 103 of the 1250 plaice marked and liberated were 

 recovered, or 8*2 per cent. ; but from the facts described previously as to 

 the insecurity of the aluminium wire at first employed, the fish thus 

 marked may be disregarded, and if that be done then the percentage 

 of re-captures of plaice rises to 9*9 per cent., or nearly one in ten. 

 Particulars in regard to each of the plaice which were recovered are given 

 in the accompanying Table ; but, before discussing these, a few words may 

 be said on certain general aspects. It may be said that the great majority 

 of the specimens marked were immature, e.g., under the size at which 

 sexual maturity is first reached, ranging, as a rule, between 8 and 12 

 inches, the smallest being 6 J inches. Only 132 were above 12 inches, 



