168 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



15. Eegarding the influence wiiich fog and liaze have on the lierriugs, 

 we possess scarcely any information except the observation made by 

 the Dntch floating-net fishermen that foggy weather is not favorable to 

 fishing. Fog and haze probably have a similar influence as a cloudy 

 sky, but doubtless they often injure the fisheries by impeding the sailing 

 near the coast. Nothing definite is known concerning the influence 

 which the difl'erent degrees of moisture in the air or the evaporations 

 from the surface of the water may possibly have on the herrings. 



16. The clouds also must be considered. A cloudy sky is generally 

 thought to be favorable to fishing; this idea probably originates in the 

 circumstance that clouds produce a subdued light, which brings the 

 herrings nearer to the surface and renders it more difficult for them to 

 see and escape the fishing-apparatus. During the night clouds will 

 diminish the warmth, the lower regions of the air and the surface of the 

 water will, therefore, become cooler, and by day-time clouds will prevent 

 the upper portions of the water from getting too warm. The greater or 

 less degree of cloudiness by day or night is therefore of considerable 

 importance for the fivsheries, especially during summer. 



17. Eegarding the influence of rain, snow, or hail on the herrings, it 

 will easily be understood tliat this chiefly depends on its connection with 

 other meteorological conditions. When it rains or snows the sky is 

 generally covered with clouds, the pressure of the air is lower and the 

 weather milder (the latter caused, among other things, by latent warmth 

 being set free). Eaiu or snow is therefore generally considered favor- 

 able for fishing. Excessive rains, however, followed by floods, are con- 

 sidered unfavoral)le in Scotland. When rain is accompanied by a 

 thunder-storm or a hurricane, it is of course these last-mentioned phe- 

 nomena which exercise an influence on the herrings and the herring- 

 fisheries. 



That snow should scare the herrings away, as Keucrantz says, cannot 

 be considered as the general rule, although this may occasionally be the 

 case in consequence of local peculiarities (for example, when fishing is 

 going on at a season of the year when a fall of snow would produce a con- 

 siderably lower temperature), but the form in which the '■'■ falling weather'' 

 shows itself (rain or snow) seems to be immaterial. The influence which 

 the fishermen ascribe to the snow remaining on the mountains has been 

 spoken of above. 



18. Of all the outward physical causes, the tcinils doubtless have the 

 most important influence on the mode of life and the migrations of the 

 herrings. This influence of the wind may, however, be occasioned by 

 the diflerent temperature, cloudiness, rain, &c., which it produces, by the 

 influence which it exercises on the force, velocity, and direction of the 

 currents by the considerable changes which it brings about in the height 

 of the water, the motion it produces in the upper layers of the water, 

 and the consequent greater or smaller waves, turbid state of the water, 

 or diff'ereat breaking of the rays of light. This influence of the wind is 



