of the Fishery Board for Scotland. 



26h 



VI.— ON THE RATE OF GROWTH OF CERTAIN MARINE 

 FOOD-FISHES. By H. Charles Williamson, M.A., B.Sc, 

 Fisheries' (Woodall) Prizeman, University of St Andrews. 



Mr J. T. Cunningham, M.A., of Plymouth Laboratory, has published 

 several papers upon the rate of growth of sea- fishes.* He gives the 

 measurements and the calculated ages of a number of the young forms of 

 the following species, — Pleuronectes flesus, P. iimanda, P. platessa, P. 

 microcephalics, Solea vulgaris, Solea lascaris, Solea lutea, Solea variegata, 

 Rhombus maximus, Rhombus laevis, Arnoglossus latema, Gadus merlangus, 

 Gadus pollaehius, Gadus luscus, Gadus minutus, Zeus faber, Gadus 

 morrhua, Zeugopterus punctatus, Scomber scomber, Clupea sprattus, Clupea 

 pilcliardus, Engraulis encrasicholus, Clupea alosa, Clupea, finta, Gadus 

 ceglefinus, with notes on Motella, mustela, Mugil chelo, Clupea harengus, 

 Osmerus eperlanus, Anguilla vulgaris, Agonus cataphractus, Cottus 

 bubalis, Callionymus lyra, Gobius minutus, Syngnatlius acus. 



Many of these have been treated very fully. The following notes are, 

 for the most part, upon fishes not described by Mr Cunningham. Two 

 forms, however, the dab and lemon dab, have been examined by him, 

 the former very fully, the latter briefly. 



The specimens here mentioned are those preserved at the Marine 

 Laboratory and the University Museum, St Andrews. The contraction 

 due to the spirit has been neglected. The sizes of several mentioned in 

 the tables were obtained from the notes of Professor M'Intosh. 



An attempt has been made to indicate a greater uniformity in the 

 growth of different individuals of the same species, by keeping carefully 

 in view the 'long period over which spawning in many cases takes place. 

 It is, of course, unlikely that all the specimens got in any particular 

 haul were hatched on the same day or even in the same month. Among 

 the specimens of each form examined the greatest variation in this respect, 

 within the limits of the spawning period, is taken for granted. 



It is probable that among the majority, or even the great majority, of 

 individuals belonging to the same species, the rate of growth is fairly 

 uniform under natural conditions ; and assuming this to be the case, the 

 measurement of a large number of specimens taken at different times 

 should, when considered in connection with the duration of the spawn- 

 ing period, give a pretty accurate indication of the average rate of growth 

 of that species. 



This is what I have attempted to do in this paper, so that it may be 

 possible from the size of a fish to fix its approximate age. 



The Dab. 



{Pleuronectes Iimanda. ) 



The 1 Garland ' found eggs of the dab in March, April and May during 

 1892. They were obtained in greatest number in April. Spawning may, 

 however, go on until the middle of June (M'Intosh). 



Among the specimens preserved at St Andrews, there are four ranging 

 in size from 14-to 17 5 mm., which were obtained in January. At the 

 greatest possible age, these dabs would be about ten months old, i.e., if 

 they were spawned in March. They may not be more than seven months 



* Joum. Marine Biol. Association. 



