THE SALT-WATER FISHERIES OF BOHUSLAN. 183 



has thus again been brought into prominence, but in a different form 

 and free from all those fanciful ideas which are characteristic of the last 

 century. 



32. Among the biological conditions which exercise a great infincnce 

 on the herrings we must mention the persecutions of their enemies. 



From the observations of the fishermen it is well known that fish-of- 

 prey, especially the codfish, can, by sudden and determined attacks, 

 scatter whole schools of herrings 5 and on the west coast of Norway the 

 small schools which either go by the side of the larger ones or follow 

 them are sujjposed to be chased by codfish. 



Whales and seals seem not to have such an influence on the schools 

 of herrings, and the first mentioned owe it chiefly to their colossal size 

 that they are reported as capable of driving the herrings wherever they 

 please. Even in the old Xorwegian laAvs it was forbidden to kill whales 

 which drove herrings towards the coast during the herring fisheries, and 

 even at much later times various authors have spoken of the whales " as 

 commissioned by Providence to lead or rather drive the herrings to those 

 coasts for which our Lord had destined this blessing''; and have also 

 considered it as a special providence " that the whales and fish-of-prey 

 again cause the herrings to fly to their proper home,- the eternal ice of 

 the Polar seas, whither their enemies could not follow them and disturb 

 them in the peaceful enjoyment of their rest.'' Even in our days the 

 Norwegian fishermen not unfrequently ascribe the failure of the fisheries 

 to the circumstance that the herrings have not been proi)erly chased by 

 the whales and fish-of-prey. That the whales and fish-of-prey follow the 

 herrings instead of leading them, for the sole purpose of devouring them, 

 has long since been proved by Martin^ Jessen, Block, Xilsson, and others. 

 It is quite probable, however, that the whales and fish-of-prey cause the 

 herrings to keep closer together. 



As regards the other larger enemies of the herrings, we know of none 

 which can exercise the slightest influence ou their migrations 5 but they 

 may, as is especially the case with birds, indicate the place v/here her- 

 rings are, and thus be of great importance to the fishermen. 



Among the ertemies of the herring we must undoubtedly also count 

 ma7i. But man's influence on the mode of life and the migrations of the 

 herring is very insignificant in comparison with the above-mentioned 

 larger animals and fish-of-prey. The chief means by wliich man per- 

 secutes the herrings is the different fishing-apparatus, among which only 

 the net influences the course of the herrings to any degi"ee. 



The herrings keep somewhat shy of the nets, and this is tiie reason 

 why darkness, turbid water, or a surface agitated by the wind is most 

 profitable for net-fishing. When the water is turbid, fishing with float- 

 ing nets may occasionally be successful even by day time. If the v.ater is 

 too much agitated, fishing with floating nets will generally be unsuccess- 

 ful. When the herring keep near the surface of the water, but seem 

 unwilling to enter the floating net, they may occasionally be driven into 



