502 REPOET OF COMMISSIONER OP FISH AND FISHERIES. 



change took place in the relation between the solar spots and the tem- 

 perature during the last decade of the eighteenth century, when Bonus 

 Ian, as is well known, had the richest herring fisheries which have ever 

 occurred. As there are also traces of such a change during the latter 

 part of the seventeenth century, it is not improbable that such a change 

 always coincides with the frequent occurrence of the sea herrings on the 

 coast of Bohuslan. 



It is self-evident that this little treatise can by no means claim to 

 have answered satisfactorily the question regarding the causes of the 

 secular periodicity of the great herring fisheries, and more especially of 

 the Bohus Ian fisheries, but it may serve to direct attention to a hitherto 

 not yet attempted way of explaining this dark problem, and to decrease 

 the belief in the old explanation of the periodicity of the herring fisheries 

 of mans disturbing the household of nature by the fisheries. In order 

 to show more fully the coincidence between the herring fisheries and the 

 solar-spots periods, scientists and historians should work hand in hand. 

 It cannot be expected of scientists that for the sake of a few data they 

 should go through the immense collections of documents in our archives 

 or through the whole range of historical literature, and thus gather all 

 the necessary facts from former times ; but these facts should be ob- 

 tained by persons who have made a life work of the study of history. 

 By such work done by the officers of the Boyal Norwegian Archive, it 

 became possible for Axel Boeck to furnish quite a number of new and 

 iLteresting contributions to the history of the Bohuslan fisheries. 



As regards the manner in which a coincidence between such vastly 

 different phenomena as the solar spots and northern lights and the 

 herring fisheries is brought about, we can only point to the influence of 

 the solar spots on the weather and thereby on the currents of the sea. 

 Here we therefore find a rich field for long-continued observations by 

 which the necessary hydrological material should be gathered for prov- 

 ing the actual oceurrence of such regular periodical and secular changes 

 in the direction and intensity of the currents of the sea, by which a 

 change in the occurrence of herring food and the consequent migrations 

 of the large schools of herrings could be explained. It is probable, how- 

 ever, that ere long science will have obtained all the necessary data, so 

 that the greater portion of what is still wanting can be supplied by care- 

 ful calculations. 



In looking at the advantages which our new method of explanation 

 affords we shall, by comparison with the other attempts in this direction 

 mentioned above, find very soon that it is the only way of explaining 

 both the temporary and local regularity in the secular periodicity of the 



solar spots and the mackerel fisheries, as the mackerel are, according to the observa- 

 tions of many fishermen, most frequent when the sky is full of cirro-cumuli, or so- 

 called "mackerel clouds," which are known to be in some way connected with the 

 solar spots. As soon as I have gathered more material I hope to he able to give fuller 

 information on this interesting subject. 





