l895- ^fo. 9. HYDR-BIOL. STUDIES OF THE NORW. FISHERIES. 65 



during that year flowed from the Xorwegian Channel between all the 

 numerous islands situated at the mouth of the Christiania Fjord. As is 

 shewn by the Chart of Depths III, a deep furrow runs up the middle 

 of the Fjord, which, certainly, above the 60 fathom curve, is a continu- 

 ation of the hollow of the Skagerak. On both sides of this furrow 

 there will be found extensive shallows at a depth of 20 to 30 fathoms, 

 and on these lie thousands of islands and rocks on both sides of the 

 mouth of the Fjord. During the Autumn of 1893, the Herrings went 

 up between all these islands, and still further up the Fjord. 

 According to the Report of the Inspector they were even caught on 

 the Langgrunden (Bank) oft" Horten. From the 12th to 14th Novem- 

 ber, when the fishing at Vallo was good, I found great quantities of 

 the prey of the Herring, Diatomaceæ (Chætoceros), (see Chapter III), 

 and, at the beginning of November, on the stretch from Jomfruland 

 to Tjømo, as well as about the Hvaleroer (Hvaler Islands), there was, 

 according to the statement of the Inspector, a great take of 

 Herrings. 



In the Autumn of 1894, the hydrographical conditions and the fish- 

 ing were ver}' ditterent. The Surface Chart (C) shews us that the Baltic 

 laj'ers were far more widespread than during the previous year. On 

 the other hand, tlie Bank Water was of far less thickness. This was 

 also the case to a great extent, in the deep. I refer to PI. \', Fig. 5, 

 which represents a section off Fredriksværn. As we saw m Chap. 

 II, the Baltic Current was found along the land to a depth of 50 

 mètres, while, several miles to sea, it was of an insignificant thickness. 

 In between the islands, there thus lay a deep layer of cold fresh water 

 (see PI. V, Figs. 3 and 4 about 50 mètres thick. In Chapter III, I 

 pointed out the ver)' interesting circumstance, that the prey of the 

 Herring (Chætoceros) was not met with, during that year, in the upper 

 layers ^o to 10 mètres'. Only by vertical search down to great depth, 

 was the chætoceros first found, and furthest out in the section, PL V, 

 Fig. 5, many miles to sea, was it discovered in great quantities. T/ie 

 occurrence of the Herring was thus identical with that of the Bank 

 Water and the prey of the Herring. The fishery was, to a very great 

 extent, a failure. The herring appeared at sea in great abundance, but 

 would not anywhere venture in between the islands and the land. 

 Above all, no influx is known to have taken place in the Christiania 

 Fjord proper. During my stay at Fredriksværn in December 1894, all 

 the fishermen I spoke to, stated that the Herring lay far out to sea 

 (according to what was stated, 16 to 20 miles), and that boats out 



VitL-Selst. Skritter. M.-X. KL 1895. Jio. 9. 5 



