_ 23 — APPENDIX A; PETTERSSON 



in use being purely quantitative were not adapted to tiiis Ivind of study. Previous to the influence of the 



II IT-"! Tijrcijj hydrographical 



commencement of tlie international work, however, the rishery Board tor Scotland and periodicity on 

 the Deutsche Seefischerei-Verein ot Germany had each arranged for the employment of a ">« '"wüng in 



• ■ , 1-1 1 V 11 11 .the North Sea 



new method in collectmg statistics, by which not only the total but also the species, 

 size, gender etc. of the individuals in every catch is recorded. Data thus collected intimate, 

 that the fréquentation of the same fishinggrounds by North-fishes is variable according 

 to the season. Thus the percentage of fuUgrown cod in every catch brought in winter 

 by trawlers from the Dogger Bank into German harbours is double that of summer. 

 The supplement F by Professor Henking, gives instances of this founded on statistic data 

 of the above-described kind and treating both of North-fish and South-fish. According to 

 these the fréquentation of the former is greatest during the ebb of the Atlantic water, 

 that of the latter during the flooding. It suggests a permanent migration of the food- 

 fishes inhabiting the North Sea. It has already been stated, that cod above a certain 

 size quit the Skager Rak and the fjords of Norway during summer, returning there 

 in winter. 



Dr. Hjort's account^ of the cod-migrations in the Norwegian and Barentz Sea as Life-cycius and 

 well as the recent observations by Dr. Schmidt^ of the seas surrounding Iceland give ""^tJ^Tcod ° 

 to hand, that the lifecyclus and migration of the North-fish compass an area of consider- 

 able geographic extent. 



We know that Iceland is surrounded by cold arctic water, a projection of the East- 

 Greenland polar current. In the borderregion of this cold littoral water and the Atlantic 

 current south of Iceland is the spawning-place of the cod in spring (chiefly March and 

 April). The eggs are found only where the temperature of the water is above 5° C. 

 The cold water to the north and east of Iceland is void of spawning cods and cods-eggs. 

 Eggs of certain arctic fish-species take their place. 



The spawning-period over, a large portion at least of the cod go west and northwest 

 following the course of the coast-current and that of the Irminger-current. Later on in 

 summer the fisheries commence on the northcoast of Iceland. The fishfood is here in 

 abundance, the large Copepoda & Schizopoda predominating in the border region of 

 Atlantic and Polar water. The herring shoals now caught with drift-nets during 

 summer on the north- and east-coasts of Iceland seem to undertake wanderings of a 

 similar nature. The fishing for herring commences off" Cape North thence gradually 

 proceeding southeast-wards. Thus in course of summer all food-fishes inhabiting the 

 borderregion: the cod, the herring, the fish-brood north of Iceland pass east-wards. 

 Dr. Schmidt says: "We are here evidently confronted by a general eastward movement 

 the cause of which no doubt is the influence of the warm eastgoing current along the 

 north coast of Iceland during summer." 



The observations made by the Danish Ingolf-expedition 1895—963 have proved the 

 existence during summer of this comparatively warm eastgoing current. 



On the coastbanks of northwestern Iceland the East-Greenland polar current meets 

 and mixes with the last projection of the Atlantic Irminger-current, the water of which 



1 J. Hjort, Fiskeri og Hvalfangst i det nordlige Norge. Bergen, 1902. 



2 J. Schmidt, Fiskenunders0gelser ved Island og Fa^roerne i Sommercn 190^ Skriltcr udgivne al 

 Kommissionen for Havundersogelser. Nr. i. Kobenhavn, 1904. 



3 Den Danske Ingolfexpedition ; II. Martin Knudsen, Hydrografl. Kobenliavn, 1898. 



