92 NOTES ON A FISHING VOYAGE TO THE 



the fish dealt with in the Barents Sea were possibly selected naturally 

 by the function of spawning, and that immature fish had not migrated 

 so far seawards to an appreciable extent. I think this is in part 

 probable, and that in the North Sea a similar state of affairs may 

 have once obtained, but has now undergone the following change : — 



Formerly the plaice population was dense on suitable areas, from 

 the nursery grounds out to such a central ground as the Dogger Bank, 

 and the food supply was everywhere restricted. The early influence 

 of man's fishing was to reduce the numbers of the largest fish at pro- 

 portionally the greatest rate, and thus reduce the density of the 

 population on the central grounds. 



Better feeding conditions would now be aff'orded on the central 

 grounds, and to these the younger plaice would tend to move more and 

 more, as the reduction in the numbers of the older individuals became 

 more appreciable. At the present time there seems no doubt that 

 density of population is restricted to the nursery grounds, so it is to the 

 advantage of the individuals to radiate rapidly to the more favourable 

 surroundings off'shore. Thus it may be that the larger of the im- 

 mature plaice extend further seawards than was formerly the case, i.e., 

 emigrate at an earlier age, in consequence of the reduced competition 

 withm the species on the off'shore grounds. 



At any rate, whether it was the case or not in former times, there 

 is now to be found everywhere, and at all times in the North Sea, a 

 proportion of immature fish many times greater than I found this 

 year in the Barents Sea. Even amongst the spawning shoals in the 

 North Sea it is quite usual to find as many immature female fish as 

 mature. 



On the other hand, it may possibly be that we have on this bank in 

 the Barents Sea an accumulated stock of plaice such as the Norwegian 

 investigators* have shown to have existed in suitable areas on their 

 coast, on a much smaller scale. When these spots were first fished, 

 quantities of large plaice were to be obtained. After a few years, 

 however, the population appeared to have been almost entirely fished 

 out, the explanation being that the currents, setting out of the fiords, 

 carry the majority of the floating eggs and young fish to water in 

 which they cannot develop. The capture of the stock is thus out of 

 all proportion to its renewal by natural means, and the decay of the 

 fishery in these particular spots is inevitable. 



From this it would seem to be of the greatest importance for the 

 future welfare of the plaice fishery in the Barents Sea, that steps 

 should be taken to ascertain definitely whether extensive nursery 



* Report on Norwegian Fishery and Marine Investigations. Vol. i. , 1900, i)p. 138-52. 



