90 



NOTES ON A FISHING VOYAGE TO THE 



bottom rises, forming a bank or banks, rich in the food of plaice : in 

 one case the Dogger Bank, in the other, this uncharted bank discovered 

 by the fishermen from Hull, and on which my investigations were 

 made. 



Further seawards in both areas, depths are eventually attained 

 which cease to interest the plaice. In this regard, the Barents Sea is 

 more comparable with the North Sea than is Iceland, where the plaice 

 are restricted by the configuration of the sea bottom to a com- 

 paratively narrow coastal zone, throughout their lives. Biologically, 



^ ^ IMMATURE FISH. 



_a « MHTURE FISH. 



VERTICAL LINE (m) MERAGE SIZE 

 AT FIRST MATURITY. 



Fig. 3. — Showing the lengtli frequencies of 895 female plaice from the central grounds of 



the North Sea (Dogger Bank, Clay Deep, etc.). 

 The ordinates at 19, 21, 23, etc., represent the frequencies in 2 cm. size groups 18-19, 



20-21, 22-23 cm. etc. 



for both regions, we have this important standpoint from which a com- 

 parison can be obtained. 



The average size of the females at first maturity ums found to he 40 cm. 

 {ajjproximately), the same as in the central part of the North Sea.* 



Moreover, it is remarkable that out of 2365 and 895 fish from the 

 Barents Sea and the central part of the North Sea respectively, the 

 size of the largest fishes definitely determined as immature should be 

 45 cm. (Cf. Wallace, Fig. 3). 



In order to compare the populations from this standpoint, I have 

 constructed curves of the actual length frequencies of mature and 

 immature female fishes in the two regions (Figs. 2 and 3, pp. 79, 90). 



For the rich material from which that for the central North Sea is 



* Fulton. 20th, 22nd, and 24th Ann. Report. Fishery Board for Scotland, 



Holt. Journ. M. B. A., Vol. ii. 



Kyle. 18Lh Ann. Report. Fishery IJoard for Scotland. 



Wallace, op. cit. 



