— 223 — 



secutive years 1 placed eel-fry in Gurre Lake, 10,000 each year. In Damhus Lake also 

 10,000 were set out yearly tor several years etc." 



Even though it is by no means maintained, that many more eel- fry cannot be caught 

 per day, in Denmark under other conditions and with other apparatus, I still believe, that 

 fisherman Willumsen's report on his several years' catches with similar simple apparatus 

 to that used in England gives a very good idea of the average conditions here in Den- 

 mark. The reader who knows nothing of the conditions in Denmark will at any rate 

 receive the impression that the quantities taken here are much smaller than for example 

 in the Bristol Channel. 



We come lastly to C, the Swedish Baltic coasts. From what has been said p. 213 

 it is evident, that the young elvers do not seem to ascend the rivers there. At any rate 

 there are very few "montée" and there is no talk of any regular ascent. The fact that 

 Dr. Tkybo.vi has for many years searched for the "montée" on the Swedish Baltic coasts 

 without result, shows sufficiently under any circumstances, that the conditions there are 

 quite difïerent from those in Denmark, and that the phenomenon 'is far from having the 

 same importance as it has with us (and also the Swedish west coast), not to mention the 

 Atlantic coasts. 



The conditions are therefore, that at the three places A, B and C, of which A lies 

 furthest to the west, C furthest to the east, the quantities of ascending elvers are excee- 

 dingly difïerent. At A (Bristol Channel) far more ascend than at B (Denmark) 

 and here again far more than at C (the Swedish Baltic coasts). This 

 means that the numbers decrease as we go from west to east. 



Before giving the eventual biological explanation of these conditions I shall deal with 

 (y) the period at which the eel=fry appear on the different coasts. 



It will be useful, first of all, ere considering the phenomena connected with the 

 ascent of the elvers of the earliest annual group from the sea to the fresh water, to arrive 

 at some understanding of the conditions in regard to the developmental stage previous 

 to that of the true "montée", namely the colourless glass-eels (i. e. Stage 5). 



higher up the river where there are no further hindrances to their passage or sent by railway to distant parts 

 of Sweden. 



The following numt)ers give some notion of the fishery, which however is chiefly for larger fry of later 

 year's ascending groups: 



1900 (i fishing trap) 



17th July — ist August 16,000 specimens 



ist August — 15th August 20,000 — 



I 5th August — 31st August 14,300 — 



ist September — 8th September 3iioo — 



(Greatest catch on one day i . 3,000 specimens) 



I 9 o I (3 fishing traps) 



gth July— 15th July 43,000 specimens 



i6th July — 31st July 373,000 _ — 



ist August — isth August 90,000 — 



19th August — 20th August 4,000 — 



(Greatest catch on one day 56,000 specimens) 



1902 



24th July — Sth September 34,ooo specimens 



(from Nyström, Svensk Fiskeritidskrift, 1903, p. 35.) 



