B. The Investigations considered from a practical Point of View. 



The Vest Fiord is one of the most thorouahly investigated of 

 our fiords, speaiiing in a biolog-ical and liydrograpliical sense. And 

 the reason for this is not difficult to understand. The government 

 has found it necessary to send naturalists to the district in whicii a cod 

 fishery is carried on, upon the results of which the income of the 

 country shows an important rise or fall, in proportion to the suc- 

 cess or failure of the catch. The statistics taken have shown that 

 the catch varies quite considerably from one season to another, and 



it has been the aim of the investigating naturalists to discovei- the 

 factors which have an influence on the fate of the fishing. The 

 most important marine animals for us are undeniably cod and her- 

 rings, but in addition to these, there arc many other fish which 

 arc caught in large quantities on the coasts of the counties of 

 Nordland, Tromsø and Finmark.') I will first mention some inverte- 

 brates, which are of economic importance. Then I will deal with 

 the cod fisheries in l^ofoten and Finmark. 



a. Some Invertebrates of economic Importance. 



The animals may be divided into the following groups: — 

 injurious, indifferent, indirectly useful, directly useful, if account 

 only be taken of their useful or baneful relation to mankind. 



A decidedly injurious animal is Myxine ghtfinosa. which sucks 

 out the fish caught in nets and on lines. tSuch forms as Calanus 

 finmarchicus, Boreophaus'm iiicnnis, Xyctiphanes norvegica, many 

 worms, molluscs etc., may be said to be indirectly useful, as they 

 serve as food for edible fish. 



To the du'ectly useful animals, belong first of all those which 

 are eaten by man, then those from which useful products are ob- 

 tained, and lastly those which are used as bait for the edible fish. 

 Only some of those which are directly useful to man shall be men- 

 tioned here. 



Arenicola marina, Lin. 

 This polychæt occurs rather numerously and at many places 

 in muddy beaches, it is dug up by the fishermen and used by them 

 as bait. Similarly too, a fish (Ammodytes tohinnus) is taken and 

 also serves as bait. 



IWtru 'idandlnis, Mi'-LL. 

 The Trondhjem Fiord is the most southerly place, on our 

 coast, where this mussel occurs of sufficient size and in such quan- 

 tities as to give it any economic importance. According to ^'. Storm, 

 it is particulaiiy plentiful on the banks north of Tautra, where it 

 has been dredged for a very long time and has been used as bait. 

 Of late years it has also been taken to Trondhjem and used as 

 food. In the north of Norway, too, this species is a much prized 

 bait, and S. Schneider says that it is eaten by many better-class 

 famOies at Tromsø. The southern limit on our coast for the oc- 

 currence of this species, is the Lyse Fiord, not far from Stav; 

 (59° 3' N.). 



Mytihis cchdis, Lin. 



On our noi-thei'u coasts, this species is as a rule so small that 

 it is not of much use as bait. 



Mod'wla mod'tuhis, Lin. 



At the present time, this is our most important bait-mussel, it 

 is found in large quantities at some places on our northern coasts. 

 It is used as bait on the day fishing lines in Lofoten. The grea- 

 test part of the shell-bait which is used in Lofoten is, however, 

 taken from the fiords in the neighbourhood of Bergen and Stav- 

 anger. This mussel attains to a considerable size in the western 

 fiords. A specimen from Lonevaag (Osterø) was, for instance, 17.;i 

 cm. long and 9.5 cm. wide. The shells held about Vj liter. 



I have measured unusually large specimens from the Sogne 

 Fiord, from 17 to 18.4 cm. In the Oster Fiord, where shells to 

 the value of several thousand kroner have been dredged, I took 

 100 from a heap at Raknes. The most usual measurement of 

 the shells which were sorted out here to be used as articles of 

 commerce, was 10 — 15 cm. In the arctic district of our country. 

 M. modiolus does not attain the size of those in the western fiords. 

 A specimen from Vardo was. however, found to be 11.2 cm. long 

 and 5..3 cm. wide. 



It is quite usual to find the tubes of Pomatocerus iriqucter 

 and various forms of Bryozoa and Hydroida on the shells. On one 

 single occasion, I saw in an aquarium Cancm- payurns crush these 

 shells to eat them. 



In the aquariums of the Bergen liioloLncal Station, we have 

 had M. modiolus for many years, and their mortality has been low. 

 Spawning in these aquariums has been observed on -% 1899, "n 



') Cf. Helland, Lofoten og Vesteraalen, p. 119. 



