of the Fishery Board for Scotland. 



179 



VIII. — ON THE RATE OF GROWTH OF FISHES. By T. W. 

 Wemyss Fulton, M.D., F.R.S.E., Superintendent of Scientific 

 Investigations. 



(Plates XII., XIII.) 



Contents. 



introduction. 



Species Dealt With, 

 Methods, 



Comparison Between Different Species, ... 



Influence of External Conditions, 



A Law of Growth, 

 Plaice (Pleuronectes platessa), 

 Common Dab (P. limanda), ... 

 Hounder {P. flesus) ... 

 Lemon Dab (P. microcephalus), 

 Long Rough Dab (Drepanopsetta platessoides), 

 Turbot {Rhombus (Bothus) maxtmvs), 

 Brill (Rhombus kevis), 

 Cod (Gadus callarias), 

 Haddock (G. teylefinus) 

 Whiting (G. merlangns), 

 Grey Gurnard (Trigla gumardvs), ... 

 Tables of Measurements, I.-XXV., ... 



Introduction. 



For a considerable number of years special attention has been devoted 

 to the study of the grovvtli of fishes by the scientific department of the 

 Board. In 1889, I began observations on this subject by Iwo methods, 

 (1) by marking fishes (plaice, dabs, lemon dabs, brill, turbot, cod, &c.) by 

 attaching to them brass labels bearing a number, the method which is 

 now so largely used in connection with the international investigations, 

 and then returning them alive to the sea ; in the case of the herring, by 

 removing a portion of the caudal fin ; (2) by keeping the fishes in tanks, 

 and noting the changes that occurred from time to time in their length 

 and weight.* 



Since then very many fishes have been dealt with by another method — 

 viz., by collating the measurements of large numbers of each species, by 

 which the earlier series or generations can be separated from one another 

 and the rate of growth ascertained, the measurements grouping themselves 

 into curves or waves. This method was used to a limited extent by 

 Miescher Ruesch in his classic studies on the salmon of the Rhine, and 

 by other observers, as Ljungman, in studying the grovvtli of the herring. 

 These observers, however, did not classify the measurements in a scientific 

 manner, which was first done by Dr. C. G. J. Petersen, who thus placed 

 an important method at the service of investigators. 



Species Dealt With. 



In the course of my investigation on growth during recent years, a large 

 number of fishes have been dealt with — viz., nearly 209,000, belonging to 

 21 species. The results in regard to many of them have been given in a 



* "An Experimental Investigation on the Migrations and Rate of Growth of the Food- 

 Fishes," Eleventh Annual Report, Part III., p. 117. 



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