64 JOHAN HJORT. M.-N. Kl. 



purpose of spawning, as previously described, they meet, in different 

 years, with different conditions. During some years the sea is warm 

 and salt up to the ver}^ beach, and the swarms of fish may then, un- 

 hindered, proceed up to the beach; other years a deep layer of cold, 

 (under 5 *') and comparatively fresh water, will stretch along the coast. 

 The conditions on the coast are, then, so different from those at the 

 spot the fish have left, that they make a halt. »The fish mope,« they 

 say in the Lofotens, »the Herring want stirring up« is the expression 

 on the West Coast, and the fishery becomes a failure. 



The feeding migrations of the Herring give rise to two fisheries off 

 the Norwegian Coast, viz., the »Fat Herring Fishery« in Nordland, and 

 the »East Coast Fishery« at the mouth of the Christiania Fjord. As 

 yet no hydrographical investigations have been carried out during 

 the Fat Herring Fishery, and I therefore, dare not set forth any 

 theories respecting its dependence on the ocean currents. In lite- 

 rature, there is only to be found Sais' Report on his voyage during 

 the Summer of 1873. In Chap. I, it is stated that, during that year, 

 Sars observed that when the current set strongly towards the coast, 

 the »prey,« the Plankton, drifted in great quantities, and that the Her- 

 ring then, too, appeared. He further reports that the presence of the 

 prey on the Coast of Norivay is very dijferent in different years, and he 

 places this circumstance — and with it also the fishery — in connection 

 with changes in the hydrographical conditions. 



During the East Coast Fishery I had an opportunity of making 

 observations during the Autumn of 1893, and 1894. 



In Chap. II, it is stated that, in November 1893, the Baltic Current, 

 under the influence of heavy westerly gales, was dammed up in Catte- 

 gat and the Christiania Fjord. The Bank Water, as shewn in the Sur- 

 face Chart B, PI. Ill, was met with along the entire West Coast of 

 Norway and far up the Skagerak, on the surface, and from there down 

 to a great depth. Between the islands in the Christiania Fjord the 

 Baltic Water, as a thin layer only a few mètres in thickness, covered 

 the Bank Water, and there was a sharp boundary between the fresh 

 and cold, and the warm and salter waters. Whilst the surface tempera- 

 ture was only 4,8°, the temperature at a depth of 6 mètres was 11.5", 

 and at 38 mètres 12.1 " (see PL V, Fig. 2). The Bank Water, therefore, 



