— 212 — 



only when the sluices at Trollhättan were opened in the beginning of the present century 

 that the eel-fry came into Lake Wenner ..." 



LiLLjEBORG (Sveriges och Norges Fiskar, III, 1891, p. 392) gives various observations 

 on the immigration of the .eel-fry on the Swedish west coast. It is thus said, that 

 according to C. P. Aström, A. W. Malm, Fil. Trybom and Lilljeborg himself the immi- 

 gration falls in May, June and July and the elvers immigrating have a length of 60— 

 100 mm. 



According to Trybom' so many elvers were found in 3 — 4 feet water below a mill 

 at Segeân near Malmö that the water was coloured quite black with them. 



E. LöNNBERG^ states the following: "in the small streams which flow into the Sound, 

 as early as the beginning of June, I have observed very large quantities of the ascending 

 elvers, no longer than 5 — 10 cm., and the smallest was still so transparent that the ab- 

 dominal organs could be clearly seen. Similar observations have been made at various 

 places along the west coast." 



In addition to the elvers of the first year's group, older fry also run up into the 

 fresh water on the west coast of Sweden, for example at Trollhättan, where Dr. Trybom 

 had 1000 young fry measured in the period from July 24th— Sept. 8th, 1902. The most 

 of these eels measured 20—30 cm., but the lengths varied from 8 to 65 cm.3 



On the Baltic coasts of Sweden the conditions are different. According to Lilljeborg 

 (1. c. p. 392), eel-fry in length from 70—80 mm. were taken on August 24th at Roslagen 

 (Baltic coastal region of Uppland) by Dr. J. 0. v. Friesen and handed over to the Zoolo- 

 gical Museum of Upsala University, but so far as the information goes, it is usually 

 considerably larger eel-fry which run up the Swedish Baltic rivers. Trybom 4 thus writes: 

 "eel-fry of the first year have only rarely been observed in the northern Swedish rivers, 

 although they must occur there 5. In Aug. 1889, for example, large masses of elvers of 

 8 to 13 cm. in length were seen at Ljusnan (in Herjeâdalen) at least. 50 km. from the 

 mouth. Young eels in their second year are however often taken in quantities in the 

 rivers mentioned. I have observed them at Ljusnan and in the Dal River. They are 

 taken in baskets or hoUowed-out "Klötzen" which are set for Petromyzon. In both the 

 rivers named the length of the eel-fry is 23—43 cm. in the period from July till Sep- 

 tember." 



In order to ascertain the conditions, I wrote to the Fisheries Inspector , Dr. Trybom, 

 and asked if information was to hand for recent years with regard to the occurrence of 

 the eel-fry in the Baltic and their ascent in the Swedish rivers, and I may be permitted 

 to quote the following from Dr. Trybom's letter in answer: "what is known regarding 

 the occurrence of the elvers in the Baltic, at least as regards our Swedish coasts, is 

 unfortunately but little. I have often endeavoured to get at the facts with regard to 

 this, but unfortunately with very little success. At Ljusnan (in the neighbourhood of 

 Söderhamn, ca. 61° N. L.) and even right up at lime River I have been informed by 



1 F. Trybom, Nâgra fiskodlingsföretag i Skâne Jren 1883 och 1884 (Malmöhus läns K. Hushallningssälskaps 

 qvartalskrift, 4, 1885, p. 289. 



2 Svensk Fiskeri Tidskrift, 1903, 1, p. 37. 



3 Svensk Fiskeri Tidskrift, 1903, i, p. 36. 



4 Trybom in "Circular" No. i des Deutschen Fischerei-Vereins 1891, p. 30. 



5 As Trybom himself states later, this is by no means to be taken for granted, - 



