THE SALT-WATER FISHERIES OF BOHUSLAN. 167 



season of the year. If tlie cold is too severe, liowever, tlie herrings are 

 Thonght to become torpid. 



The temperature of the air thus seems to exercise its influence chiefly 

 through its extremes, M'hich the herrings cannot well stand, and through 

 its influence on the spavrning of the herrings. During the spawning- 

 process the herrings need a certain even temperature, and, therefore, in 

 case of great heat or cold, go to deeper spawning-places. The temper- 

 ature of the air, therefore, has a much greater influence on the fisheries 

 of spawning herrings than on the common herring-fisheries, whilst the 

 latter are more influenced by wind and current. The influence of the 

 temperature of the air will be more noticeable when fishing is carried 

 on with floating nets than when stationary nets are used. 



As different winds produce a different temperature, and thus exercise 

 an essentially different influence on the herrings, we shall, farther on, 

 when speaking of the influence of the wind, give more data regarding 

 the influence which the temperature of the air has on the herring. 



After a mild winter, and during a mild, early spring, the spawning of 

 those herrings which spawn in spring and the spring-herring fisheries 

 begin somewhat earlier than otherwise. When in spring the air gets 

 warmer the young herrings seek shallow waters, but when cooler weather 

 sets in they return to the deep water. 



14. The pressure of the air, as far as known, only exercises an influence 

 on the herrings through the changes which it produces in the weather 

 and in the direction and force of the wind ; for ail we know regarding 

 the direct influence of the pressure of the air on the sea and thereby on 

 the herrings is the fact that it is not very considerable. Observations 

 which in this respect have been made with regard to other fish are not 

 sufficiently numerous and general to base any certain opinion on them. 



The Meteorological Society of Edinburgh has published the results 

 of their comparison between the observations on the course of the fish- 

 eries made by the superintendents of fisheries during the years 1867-1872, 

 and the simultaneous meteorological observations, from which it appears 

 that the richest hauls were generally made when the barometer was 

 ''high and steady," whilst the fishing was not so good when the barom- 

 eter was "low." Frank BucMand, however, has recently directed atten- 

 tion to an article, by J. Salmon, of Lowestoft, in "Land and Water," 

 January 16, 1862, according to which an "unsteady" barometer had 

 during the autitmn herring-fisheries in the Southern Xorth Sea (the so- 

 called " Yarmouth fisheries ") been favorable to fishing. It is well known 

 that fishing is good when the herrings keep at a moderate depth, and 

 the strength of the wind and the motion of the water are favorable to 

 the use of fishing-apparatus. 



In the Skagerack the lower or higher state of the barometer has a 

 considerable influence on the herring-fisheries, both through its influence 

 on the weather in general and more especially on the wind and the cur- 

 rents of the sea. 



