176 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



and maintains that they must give way to storms and strong currents, 

 adding, however, that in that case they either seek shelter or go into 

 deep water. 



From observations made during the English and Scotch fisheries we 

 know that the tide, especially in narrow waters, by the regularly chang- 

 ing currents which it jjroduces, exercises a considerable influence on the 

 herring-fisheries. The richest hauls are made when the current is swift- 

 est, because the floating net is then carried over a greater area. The 

 rising of the tide is generally considered more favorable than its falling, 

 and the herrings have often been observed to swim towards the tide. 



The greatest difliculty in utilizing our observations of the influence of 

 the currents on the herrings, both for science and for the fisheries, is 

 this, that these observations almost exclusively refer to the surface-cur- 

 rents, although there is reason to suppose that deeper currents have 

 often had an influence on the herrings. 



23. Closely connected with and often directly dependent on the cur- 

 remfcs, at least in the North Sea, is the color of the water. A large number 

 of observations made during the so-called "great" herring-fisheries in 

 the open North Sea show that more fish are caught when the water is 

 green than when it is blue. The green color of the water also indicates 

 this in the northern waters, which are richer in "herring-food" and in 

 fish ; and the blue color in the southern waters, where there is less her- 

 ring-food and consequently also fewer herrings. Prof. G. 0. ^Sars^s obser- 

 vations, made during the summer of 1876, show, however, that the rela- 

 tion between the "herring-food " and the color of the water may be exactly 

 the reverse. 



It has already been said above that thick or turbid water is better for 

 fishing than very clear and transparent water. 



24. Eegarding the influence of the greater or less saltness of the water 

 On the herrings there are a number of opinions, some of them directly 

 opposed to the one held by me. Thus it has been supposed that the 

 herrings when spawning sought less salty waters. K. A. Meyer believes 

 that those herrings which are found in the western part of the Baltic 

 and which spawn in spring, prefer sea-water mixed with a good deal of 

 fresh water, and mentions various instances from the Schlei-fiord and 

 other places on the Baltic. But on closer examination this does not seem 

 necessarily to follow from these observations ; but they seem rather to 

 lead us to this conclusion, that the herrings when about to spawn only 

 look to the convenient location of the spawning-places, and that neither 

 a small degree of saltness, as in the Schlei-fiord, nor great saltness, as on 

 the east coastof Scotland, prevents them from selecting a place. Because 

 the sea- water in the fiords is in many places less salty than in the open 

 sea, it does not follow that the herrings during the spawning-season come 

 to the coast on account of the smaller degree of saltness of the water.*^ 



^^XeuGrantz's hypothesis (in which he foEows Pliny) seems more plausible : that the 

 herrings are by their instinct led i;o spawn near the mouths of rivers, as these locali- 

 ties possess great advantages for the young fish, principally plenty of food and shelter. 



