G90 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



purpose of spawning, but all the year round. The distribution of the 

 herring in the soa is dependent on the distribution of the small marine 

 animals which form its food. These are all pelagian animals, chiefly 

 small crustaceans which keep more or less near the surface and are well 

 known to our fishermen by the name of " aat." Only when the herring 

 comes to the coast in winter for the purpose of spawning, its migrations 

 are, to begin with at least, independent of the occurrence of " aat." The 

 rest of the year the schools roam about in the outer sea, chiefly seeking 

 that portion where at different times they find the best supply of food. 

 The great schools of herrings may therefore at the approach of winter 

 or when the development of their generative organs drives them toward 

 the coast in order to spawn there, be quite naturally either at a shorter or 

 longer distance from their spawning places, just according to the quan- 

 tity of food found in difi'erent portions of the sea. The professor thinks 

 that this circumstance chiefly causes the fluctuations in our spring her- 

 ring fisheries. As the migrations of the young herrings cojnmeuce long 

 before roe and milt are matui'ed, the great mass of herrings, if near the 

 coast at this time, would reach it so early that they would be obliged to 

 stay here a longer time, and thus naturally get nearer the coast, enter- 

 ing the fiords and inlets. In the opposite case, if the mass of herrings 

 should at that time be at a considerable distance from their spawning- 

 places, such a long period of time would elapse before they reached these, 

 that the spawning process could be i)erformed immediately on their 

 arrival. The herrings would in that case stay only a short time near 

 the coast, and the spawning would chiefly go on on the outer and less 

 accessible banks ; in other words, the spring herring fisheries would be 

 of very short duration or prove an entire failure. 



This in brief is the theory which Professor Sars advanced several 

 years ago, after having carefully examined our coasts, as the only pos- 

 sible scientific explanation of the remarkable irregularities which in 

 course of time have been observed in the spring-herring fisheries. There 

 were however at that time but few facts to support this theory. Sailors 

 and fishermen had occasionally spoken of large masses of hefriugs which 

 showed themselves far out in the open sea immediately before the spring- 

 herring fisheries commenced ; whilst others had at different seasons of 

 the year observed large masses of small crustaceans in various parts of 

 the sea. Regarding this last-mentioned phenomenon we likewise have 

 the testimony of reliable naturalists (Kroyer), and from the very portion 

 of the sea which is chiefly concerned here. But all this information is 

 too scattered to prove in an incontrovertible manner that the open sea 

 is really a fit place of sojourn for the enormous masses of herrings which 

 come near the coast at difi'erent seasons of the year. 



Professor Sars considered it as one of his most important objects on 

 this expedition to examine the distril>ution of the " herring-food." With 

 this view he examined the sea almost every day, frequently several 

 times n day, with the surface-net. The results of these investigations 



