218 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



From the little that is known regarding the periodicity of the great 

 herring-fisheries, it will be clear that the periodical coming and going of 

 the herrings, which on the coast of Bohuslan has been observed for six 

 successive centuries, cannot possibly be purely accidental, although the 

 causes of this phenomenon can so far only be guessed at. All attempts 

 to exi)laiu this phenomenon from accidental causes must therefore be 

 classed with the mythical explanations. 



-' 67. In briefly recapitulating the different scientific theories regarding 

 the migrations of the herrings, it will be found that they may all be ar- 

 ranged under the following heads : 



A. — The theory of a central race of herrings, according to which all her- 

 rings which are in the world belong to one great central race, from 

 which all kinds of herrings, both great and small, come. This the- 

 ory is varied as follows : 



1. This central race of herrings is supposed to live in the ISTorthern 

 Polar Sea, from which large schools emigrate every year to those 

 coasts where herring-fisheries are carried on [Anderson, Pennant, 

 and others). 



2. This central race of herrings is constantly moving through the 

 Northern Atlantic Ocean in a circle, whose extent is regulated by 

 the declination of the sun (Gilpin). 



3. Besides this great central race of herrings living in the I^orthern 

 Atlantic Ocean, causing the great herring-fisheries, smaller local 

 races have separated in course of time, causing the smaller coast- 

 fisheries {Lundheck). 



According to the first two of these three theories there would 

 be no regular migrations, whilst such would take place accord- 

 ing to the thu-d. 

 B. — The theory of separate races of herrings, according to which the dif- 

 ferent fisheries are caused by separate races of herrings, each 

 having its own locality. This theorj^ is varied as follows : 



1. The theory of a coast-race of herrings, considering the herring ex- 



clusively as a bottom-fish. This may again be subdivided : 

 a. Some suppose that there is only one local race of herrings in 

 every place, which, if not driven away by human agencies, always 

 stays near the coast. There is consequently no difference between 

 coast-herrings and sea-herrings, and there are no regular migra- 

 tions [Mlsson). 

 1). Others think that more than one race of herrings may occur in 

 one and the same place. There is consequently a difference be- 

 tween coast-herrings and sea-herrings, and there are regular migra- 

 tions ; but the proper homes even of the sea-herrings are the deep 

 valleys on the bottom of the sea near the coast [Axel Boecic). 



2. The theory of a sea-race of herrings, considering the herring as a 



surface-fish. This theory is also subdivided : 



