THE SALT-WATER FISHERIES OF BOHUSLAN. 185 



tion regarding the conditions of tlie wcatlicr nnder wliicli the herrings 

 make their appearance in a manner favorable to the floating-net fisheries, 

 whilst they leave us entirely in the dark with regard to many other in- 

 teresting points. 



The great majority of all the observations we possess relate to fishing 

 during the spawning-season ; and it is well known that these fisheries 

 are both richer and more certain than those carried on at other seasons, 

 and have therefore generally been considered more important. The 

 catching of those herrings which have come to the coast to seek food has 

 only recently become more important ; and we therefore do not as yet 

 possess a sufficient number of observations on these fisheries, which is 

 to be deplored, as the herrings when seeking food are much more de- 

 pendent on outward natural conditions than when they are spavming. 



The physical conditions prevailing in certain waters (among them 

 l)rincipally the differences of saltness and climate as being dependent on 

 the weather and the currents of the sea), the geographical location and 

 the orographical and j)etrographical character of the bottom, will of 

 course exercise a great influence on all the organic beings found in these 

 waters, or, in other words, on their whole cenobitic life ; it will be clear 

 therefore that only a complete knowledge of all these conditions, both in 

 the present and in former times, will satisfactorily explain all the phe- 

 nomena presented by the races of herrings belonging to these waters, 

 such as the different spawning-seasons, the varying degree of fatness, 

 flavor, &c., as well as the more or less regular periodical changes in the 

 migrations of the herrings. Unfortunately our knowledge of all these 

 matters is so far very limited ; we thus neither i^ossess very exact knowl- 

 edge regarding the influence of the weather on hydrological conditions, 

 nor regarding the influence of these last-mentioned conditions on the 

 difterent biological conditions. Such knowledge, in order to answer its 

 purpose, should not be confined to one locality, but should extend to a 

 large number of fishing-stations, which would enable us to gain more 

 general and satisfactory opinions regarding the combined influence of 

 physical and biological causes on the herrings and their migrations and 

 consequently on the herring-fisheries. 



In order to obtain such knowledge it will be necessary to have access 

 not only to good orographical and petrographical maps, as well as to 

 synoptic weather statistics, but also to synoi)tic tables of hydrological 

 and biological observations. 



34. After having considered as fully as my limited time would allow, 

 the influence of physical and biological causes on the herrings and the 

 herring-fisheries, I will go over to a more direct representation of the 

 migrations of the herrings, referring, of course, to all the foregoing ob- 

 servations and opinions. 



In order to reach a sufficiently distinct terminology and a more com- 

 plete knowledge of the whole subject, it will be necessary by way of in- 

 troduction to give a brief systematized review of fish as to their place of 



