86 NOTES ON A FISHING VOYAGE TO THE 



That rich supplies of molluscs were available, was evident from the 

 frequent occurrence of living specimens in the trawl ; the masses of 

 crushed shells in the stomachs of the plaice and catfish ; and, perhaps 

 most important of all, the fine, plump condition of the plaice when first 

 caught. This is a striking contrast to the condition met with a few 

 years ago at Iceland, and reported of the earliest trawling times on 

 the Dogger Bank. 



How sensitive some fishes are to external conditions, when about to 

 spawn, has been pointed out by Schmidt.* The same investigator has 

 found more recently f that plaice marked on the north and east coasts 

 of Iceland, migrate from their cold surroundings towards the warm 

 Atlantic water, when preparing for reproduction. 



As further contributing to our knowledge on this problem, I find 

 that among the Lowestoft fishermen, whose fishing in January and 

 February is almost entirely confined to the spawning plaice of the 

 southermost North Sea, it is common knowledge that in a severe, 

 cold winter, plaice always set in more abundantly, and remain longer, 

 in the deep channels of this region, than is the case when the winter 

 is mild. Hydrographic observations have shown that the water here is 

 of Channel origin, and has a higher temperature at this period tlian 

 any other part of the southern North Sea. 



From the evidence I shall present below, it will be seen that the 

 spawning plaice of the Barents Sea probably seek to the west the more 

 congenial surroundings which their condition demands. 



The Prussian hydrographers| have pointed out how the ramifications 

 of the North Cape current follow well-defined channels along the sea 

 bottom towards the east, and we may perhaps justifiably surmise that 

 the influence extends to the deep water west of the bank on which the 

 present investigations were carried out. 



At any rate, it is the experience of our fishermen that the plaice 

 are found further to the west, and in denser shoals, when they first 

 visit these grounds in June and July, than later in the season. 

 I should estimate, from the condition of the fish taken by the 

 Boman in August, that this year the spawning season terminated 

 in July. 



An analysis of the Roman's hauls of the first two days, relative to 

 their respective positions and depths, reveals features which bear 

 comparison with North Sea grounds at a similar period, viz., just after 



* Jons Schmidt. " Contributions to the Life History of tlie Eel," (Angiiilla vulgaris. 

 Tart.), Rapports et Prods- Vcrbaux, V, p. 234, ct scq., 1906. 



t Marking Experiments on Plaice and Cod in Icelandic IVaters. Meddel. fra Ivomm. 

 f. Havnnders., Serie Fiskeri. IJind ii. No. 6, 1907. 



X Rapports et Proces-Verbaiix, Vol. iii, 1905. Appendix A, pp. 3 and 4. 



