HISTORY OF THE AMERICAN MENHADEN. 73 



cal Society, is regarded to have been from 58° to 59° during the week end- 

 ing August 19, but on the 21st, when the nets were shot, the temperature 

 had fallen to 55°, aud this was the first night the herring were caught. 

 They were found low in the nets during the prev'alence of warm weather 

 between Northumberland and Peterhead. 



" The Meteorological Society of Scotland have for two or three years 

 had this capriciousness in the movements of the herring under special 

 investigation, and in the past year the deep-sea thermometers provided 

 to the society by the Marquis of Tweeddale, its president, for test- 

 ing the temperature of the sea, were again sent out by the Fishery 

 Board to their officers, and the temperature obtained at different periods 

 of the herring fishery. Daily registers of the weather were kept and 

 other particulars furnished to the society, both by the district fishery 

 ofiicers and by Samuel McDonald, esq., commander of the " Vigilant," 

 fihhery-cruiser. From the registers and the information thus supplied, 

 the following conclusions have in the mean time been drawn by the 

 committee of the society : 



" From the observations of the catch of herrings and the tempera- 

 ture of the sea off the east coast of Scotland, during the two seasons of 

 1874 and 1875, it is seen (1) that the temperature of the sea from the 

 middle of August to the close of the fishing season was continuously and 

 considerably higher in 1875 than 1874 ; and (2) that the catch of her 

 rings was continuously and considerably lower during 1875 than during 

 the same period of 1874. 



"Another result is this : If there be a district where, from any cause, 

 the temperature of the sea is lower than in surrounding districts, in 

 that district the catch of herrings is heavier ; and conversely, if there 

 be a district where, from any cause, the temperature of the sea is higher 

 than in surrounding districts, in that district the catch of herrings is 

 less. Among the causes which bring about a local increase or decrease 

 of sea-temperature, the chief are clouded or clear skies in respective dis- 

 tricts, according as these occur during the day or during the night. 

 These local variations in the temperature of the sea in their bearings on 

 the catch of herrings have been shown by the observations both of 1874 

 and 1875. 



"Another important point is the relations of surface temperature to 

 bottom temperature, and the relations of the deepest parts of the sea to 

 the positions of the fishing grounds. It is found, for instance, that when 

 the surface temperature is high — higher than lower down — the fish, if 

 any be caught, strike the nets far down, in such a way as to lead to the 

 supposition that a good deal of failure may often arise from the nets not 

 going deep enough. The fish prefer, apparently, so far as the inquiry 

 has gone, the lower to the higher temperature. The herring committee 

 are most desirous of carrying out this line of inquiry into greater detail, 

 if some of the fishermen could be induced to take the trouble of observ- 

 ing the temperature of the sea at the surface and also at the depth at 

 which the fish strike the nets. 



