192 American Fisheries Society 



The Baltic towns of the Hanseatic League were de- 

 pendent in part upon the herring industry and after a 

 century of great growth and prosperity fell into decline 

 at the middle of the fourteenth century. Their prosper- 

 ity was the accompaniment of the presence of great 

 shoals of herring off the Island of Riigen in the Baltic. 

 Their decline was caused in part by the failure of the 

 herring industry and the supposed migration of the 

 herring to the North Sea which has since been the centre 

 of the industry. Schouwen (on the Netherland coast of 

 the North Sea) appears to have been frequented by the 

 herring shoals in preference to Rugen. The rapid growth 

 of the Netherland cities, their supremacy and final 

 separation from the Hanseatic League followed. A little 

 later the herring again changed their haunts choosing 

 the coast of Norway where both Norsemen and Nether- 

 landers caught them. The Beukelszoon method of curing 

 herring having come into use, nearness to home was no 

 longer a necessity. The Norse fisheries flourished until 

 1587 when an "apparation of a gigantic herring 

 frightened the shoals away." Thus it appears that the 

 development of the herring industry in each locality led 

 to the apparent desertion of the locality by the fish, 

 though the migrations assumed by historians may be 

 doubted. Was this due to the contamination of the sea 

 by the cities, or merely to over catch? Whichever may 

 have been the case it is certain that contamination will 

 not invite runs of the herring. The common assumption 

 that the sea is so large that pollution can not have a 

 significant role is rendered entirely untenable by the 

 greatly increased sensitiveness of the marine fishes as 

 compared with the fresh water ones. 



These unexpected differences in the character of the 

 water near the surface and the sensitiveness of animals 

 to it, are only excelled by the marked differences among 

 animals of the same species from different depths.* Uni- 

 formity of physiological characters has been commonly 

 assumed. It has been customary since the early writings 



* For a full account of the experiment see Puget Sound Marine Sta- 

 tion Publications, Vol. I. 



