115 



JOHS. SCHMIDT 



most of the Atlantic waters but little difference between the temperatures 

 at the surface and at the depths (ca. 50 — 200 meters) where the majority 

 of the species spawn, wc tan draw from the temperatures at the surface some con- 

 clusion as to the temperatures under which spawning occurs. It should be mentioned at 

 once however, that the data are generally somewhat too low in the winter and 

 spring, just when the majority of the species spawn. The reason for this is that the 

 observations at these coastal stations are made in quite shallow water close to the land, 

 and the cooling of the surface water from contact with the air in winter is greater there 

 than further out to sea in a little deeper water, where under the surface waters cooled by 

 the air there is warmer water which rises up as the surface waters sink. This condition 

 will have greater importance at the coastal stations furthest north, as for example at the 

 Westman Isles on South Iceland, where the coast is washed by Atlantic water and where 

 simultaneous observations show that the surface water's a little further out to sea have a 

 somewhat higher temperature in winter and spring than those at the coasts 



' Concerning relatively low temperatures in shallow water, see also I. N. Nielsen: Contribution to 

 the Hydrography of the N.E. Part of the Atlantic Ocean (Meddel. Kom. Havunders., Hydrografi, Bind I, 

 No. 9, p. 10, 12, 1907). 



^ The average temperatures for Iceland and the Eseroes have been calculated from the daily records 



15* 



