157 - 



SECTION II 



The present investigations and observations 



I. Investigations of the "Thor" in 1903 and 1904 



In the years 1903 and 1904 I undertook an extensive series of investigations on the 

 fish young in the waters around the Faeroes and Iceland as also on the routes 

 from Denmark to these islands, with the Danish research-steamer "Thor". The aim 

 of these investigations was to throw light on the distribution of the young of food- 

 fishes right from the first pelagic developmental stages and to ascertain the condi- 

 tions of the occurrence of the various species. At the same time there was 

 the task to find the young of various important food-fishes the early stages of which had 

 not yet been discovered. 



The investigations for the pelagic stages were made by means of horizontal hauls 

 with a large plankton net and especially with Petersen's young fish trawl, whilst the 

 bottom stages were sought for both with the last-mentioned apparatus and various others 

 (a small ottertrawl with small-meshed net round the cod- end, Norwegian shrimp trawl 

 and Danish eel seine). 



In 1903 and 1904 550 stations in all were visited and several hauls were made at 

 most of them. The most northerly of the stations lay at 67° 19' N., 17°55' W., the most 

 southerly at 55°56' N., 12°39' E., the most westerly at 65°33' N., 29°19' W., the most 

 easterly at 55°56' N., 12°39' E., from which it will be seen that the region within which 

 the 1903 and 1904 investigations were undertaken was very wide. It should be remarked 

 however that no investigations were made during the two years mentioned 

 in the part of the Atlantic which lies to the south of 60° N. L. and west of 5° W. L. 



During these investigations the pelagic young of practically all the North European 

 useful fishes were taken and of most in great numbers. The last was not the case 

 however as regards the common eel {Anguilla vn/garis), only a single specimen ^ of 

 whose larval form {Leptocephalus brevirostris), hitherto known only from the Mediter- 

 ranean, was taken in the two years (1903 and 1904). This was found on May 22nd, 

 1904 at 10 p.m. to the west of the Faeroes (6l°2r N., io°5g' W., depth : ca. 1300 meters) 

 in a 15 minutes haul with Petersen's young-fish trawl near the surface. The temperature 

 of the surface water was 8oO° C. In order to convince myself that only one specimen 

 was present, I then made two hauls each of V2 an hour, one near the surface the other 

 deeper down (with 180 meters wire out). Neither of the two hauls gave any Leptoce- 

 phali. The course was then set towards the south coast of Iceland and investigations 

 were made at several stations on the way, without any Leptocephali being taken however. 

 At the end of the "Thor's" cruise in the middle of September 1904 the result was thus 

 that only a single specimen of Leptocephahis brevirostris was brought home, in spite 

 of the fact we had been working such good fishing apparatus (especially Petersen's 



' This discovery lias already been mentioned by C. G. JOH. PETERSEN in "Meddelelser fra Kommissionen 

 for Havundersogelser" Serie Fiskeri, Bd. i, No. 5, Kjobenhavn, 1905- "Larval eels (Leptocephalus brevit-os- 

 tris of the Atlantic coasts of Europe." 



