i8 THE SILVERY HOSTS OF THE NORTH SEA. 



in Scotland, not only indicates that temperature 

 exercises an important influence upon the fishing ; 

 but, that as the temperature increases, the herring 

 rise from the bottom and swim at a higher level 

 during the spawning period. Thus at Wick, where 

 a deep sea thermometer had been in use for some 

 years, it was observed that when the temperature fell 

 to 53 there was no catch, while when it rose to 55 

 in the day, and 54 at night, fishermen have had the 

 best of catches. Dutch scientists have also found 

 that more fish are caught at a temperature of 12 to 

 14 Celsius, 5 3 '6 to 57-2 Fah., than at any other time. 

 "Dutch herring-boats are therefore always supplied 

 with a thermometer, which enables them to place the 

 net at a proper depth." 



During his stay on the west coast of Norway, 

 Boeck constantly noticed the temperature, and noted 

 down a large number of observations during different 

 years. In his report for 1862, he showed the in- 

 fluence of cold on the herring-fishery. In that year 

 he examined the temperature at different depths. 

 The weather had been calm, but a severe cold had 

 prevailed for some time, by which the temperature 

 of the sea at a depth of ten fathoms had been brought 

 as low as I J or 2, Reaumur, while at a depth of thirty 

 fathoms it was from 3 to 4. He further noticed in 

 the same year that at some of the rich fisheries, when 

 the fishing implements were placed at a depth of ten 

 fathoms below the surface but few herrings were 

 caught ; while others, placed at a depth of from fifty 

 to sixty fathoms, caught a large number. 



