THE SALT-WATER FISHERIES OF BOHUSLAN. 199 



have endeavored to prove tliat tiiose races of herrings "which visit the 

 coasts of Bohuslan and Western Norway change their spawning-places 

 periodically, although they could give no reason why it should be so. 

 Axel Boeck, following in part E. Strom and other older authors, also 

 showed that there are several tolerably regular changes in the course of 

 the herring-fishery during the great fishing j^eriods. Later G. 0. Sars 

 has made an ingenious attempt to explain one phase in these changes, 

 viz, the arrival of the herrings at different times during the fishing 

 period, by the varying occurrence of the " herring-food" supj^osed to de- 

 pend mostly on meteorological and hydrological conditions; in the be- 

 ginning, however, he seemed inclined, like Nilsson, to deny the periodicity 

 and to suppose that the visits of the herrings continued without inter- 

 ruption unless checked or hindered by man's interference, but later 

 entertained an opinion which agreed more with that of Boecli. G. Win- 

 ther has also shared Boeckh view in describing the analogous Sound fish- 

 eries, whose changes, however, are less marked. Finally I have at- 

 tempted to explain the periodicity partly by the tendency of the school 

 of herrings to become great through the influence which its size must ex- 

 ercise on the cenobitic conditions in the disproportionately small spawn- 

 ing-places, partly by the greater distance from the spawning-places at 

 which the herrings just on account of the size of the school must seek 

 their food, which depends on supposed periodical changes in the meteo- 

 rological and hydrological conditions. 



47. The great migration periods of the large schools of herrings are 

 marked by very regular changes both in the time of the herrings' an- 

 nual arrival at the coast and in the locahty where they arrive. It must 

 be remembered, however, that all the knowledge we possess of these 

 changes is derived from the fisheries, and that the too exclusive use of ap- 

 paratus only suited to coast-fishing has made the coast-fisheries more 

 prominent than they would have been otherwise. But wherever herring- 

 fisheries are carried on not (m\j near the coast but also with floating nets 

 at a considerable distance from the laud, such as is the case, for example, 

 near the east coast of Scotland, or with purse-nets as on the northeastern, 

 coast of North America, the changes are much less marked and have 

 therefore hitherto almost entirely escaped attention. MacCullocU has 

 some observations on this point chiefly with regard to the fisheries on 

 the eastern coast of Scotland, but it is only recenth' that I among others 

 have directed attention to the fact that the herrings on the eastern coast 

 of Scotland have changed their chief place of visit to a point about 100 

 English mUes farther south, and have left the Moray Fhth, and that they 

 have commenced to come near the coast earher during the season, so 

 that the September fisheries are very insignificant now compared to 

 what they were formerly. On the coasts of Bohuslan and Norway, 

 where fishing is chiefly carried on with seines and stationary nets, such 

 changes have been known from time immemorial. 



48. Thus iProf. Hans Strom in Norway observed tliat the herrings 



