_ 15 — .TOH. HJOÜT AND C. G. JOH. PETERSEN 



ratus which would lead to a result quicker than the driftnets. Several endeavours have been 

 made to procure such an apparatus, but up to the present always without practical result. If 

 it must be admitted therefore, that the technical part of the investigations has made great 

 progress, there still remains much to be desired. The unevenness of the bottom of the 

 sea offers insuperable difficulties at many places to the use of all apparatus designed for 

 towing on the ground, and if we occasionally remedy this by the use of other apparatus, 

 such as long-lines and set-nets, we do not altogether obtain the wished-for results. 



We have spoken here chiefly of the apparatus for the catch of larger fish, and younger 

 fish in the bottom-stages; but, for the capture of fish in their youngest stages, when they are 

 usually pelagic, the investigations have employed other apparatus with important results. 



We do not feel satisfied with the few young fishes which can be obtained by means of 

 the so-called pelagic net of but small size, and attempts have therefore been made to exchange 

 the tolerably close material of this net for another which has a somewhat wider opening, and 

 the mouth of this net has now been as much enlarged as is possible from the practical stand- 

 point. In order to take more young fish than can be done in vertical hauls, such large nets have been 

 towed for many minutes in a more or less horizontal direction through the masses of water, 

 where the young of the fish concerned were believed to live. In this manner, for example. Dr. 

 Hjort obtained fine collections of young fishes in Norway. Of recent years however, the 

 so-called young- fish trawl — constructed by Petersen and described by Schmidt (Mske- 

 undersegelser ved Island og Fseraerne, pp. 37 — 38, fig. 11) — has been more and more used 

 for the pelagic fishing of young fish in the sea. It is constructed on the principle of the 

 ottertrawl, but the net consists of thickly woven hemp, ca. 19 threads to 3 cm. With this 

 apparatus many hundreds of hauls were made at Iceland and the Feeroes in the years 1903 

 and 1904, and extraordinarily large collections of pelagic organisms, especially fishes, 

 have been brought home. The apparatus was used both at the surface and in great depths, 

 and by a peculiar modification of the lower ends of both the poles which hold the net open, 

 it has been used on the bottom with success, both over soft muddy ground and where the 

 bottom was covered by not too large stones. The youngest bottom-stages of many fishes 

 which have not been taken in any other way, have been obtained with this young-fish trawl, 

 especially of flat-fish. Its fishing-capacity is so great, that many thousands of pelagic young 

 fishes have been taken by it on the shallow coastal banks in the course of 10 — 20 minutes. 

 Further out iu the open sea, on the other hand, the young fish appear to be much less 

 numerous per cubic meter of water; by increasing the duration of the hauls however (to several 

 hours), the success has been attained of catching the eggs and young of characteristically deep- 

 water fishes, concerning which we have hitherto had practically no information, in no small number. 



To the first results of the new investigations in the open sea belonged the obtaining of 

 large collections of pelagic fish eggs which were in part quite unknown in literature, in part 

 wrongly described; before these collections could be worked out in the manner required 

 by the investigations, a purely zoological systematic preliminary investigation of 

 the young fishes has been necessary. Considerable literature concerning the young 

 fishes and theu- determination, existed in various countries certainly, especially in England, Scot- 

 land, Ireland and Germany, and the endeavour has also been made to describe the fish-eggs; for 

 several portions however, a critical revision has been considered necessary, and it was especially 



