66 JOHAN HJORT. M.-N. Kl. 



there made good hauls in their drift nets, whilst the fishermen ashore 

 drew empty nets. 



I do not hesitate, therefore, to express my belief that the movements 

 of the Herring during the East Coast Fishery, in the years iSg^ and 

 i8g4, tuere associated with the Bank Water and the salter layers. 



My investigations have, therefore, led me to believe that there exists 

 the most intimate connection between the variable hydrographical con- 

 ditions, and the influx of the migratory fish. It is, furthermore, my be- 

 lief that we may, even now, point out, in any case, some of the factors 

 which, in the sea, determine the variable conditions during the influxions, 

 and these conditions have, in the investigations I have been able to 

 make along the Coast of Norway, proved to be identical with those 

 given by Pettersson and Ekman in their fundamental studies of the 

 Swedish fisheries of Bohuslän, namely the saline contents, temperature 

 (amount of gas) and the Plankton ^ 



It appears to me evident, that continued investigations in the same 

 direction are greatly to be desired, as questions like these require, 

 above everything, a length}' experience. Even if, during the course 

 of a few years, one has been able to observée a constant conformity 

 to rule, continued researchs are, nevertheless, just as much required, 

 as we, in respect to the migrations of the fish, are, naturally, brought 

 face to face with clear questions of experience, concerning Avhich 

 nothing can be known beforehand. Only continued investigations 

 can determine wdthin which boundaries the influence of the currents 

 is perceptible, and zvhich of the contributing factors it is that plays 

 the greatest part. The solution of these problems will be of the 

 greatest gain to our knowledge concerning the influxions on the 

 whole. 



//", in the future, one is desirous of increasing this knoivledge, 

 then at each of the great fisheries, and during the course of several 

 years, carefully instructed people must collect materials, and obtain 



1 See, Grunddragen af Skageracks och Kattegats hydrografi loc. cit. samt Om det 

 hydrogr. tilst. i Bohusl. skärg. o. s. v. loc cit. (Outlines of the Hydrography of the 

 Skagerak and Cattegat, also »Concerning the Hydrographical Conditions of the Archi- 

 pelago (Island belt) of the Bohuslän t). 



