PROPAGATION AND GROWTH OF HERRING. 645 



vincing proof, however, lias been brought forward for these supposi- 

 tions, which must rather be considered as unsuccessful attemi^ts to ex- 

 plain the fact that herrings which spawn at different seasons of the year 

 occur on the same coast, Avithout having recourse to the supposition that 

 two different races of herrings live in the same water, exposed to entirely 

 similar influences. 



Another opinion has also been advanced, viz, that the herrings only 

 spawn every other year. Although it will be difficult to deny the pos- 

 sibility of such an occurrence, even merely as an exception from the 

 common rule, or owing to special circumstances, and although it must 

 be acknowledged that such a supposition affords a very convenient ex- 

 planation of the relationship and occurrence of the so-called migra- 

 tory herring {straksillen),^^ it must, on the other hand, not be forgotten 

 that there is not sufficient proof for the absolute correctness of the sup- 

 position, and that it brings in its train numerous other difficulties. 

 Nothing of the kind has ever been noticed in other closely-related spe- 

 cies of fish, and it seems perfectly clear that we should not look for any 

 such characteristic in a species of animals whose only shield in the 

 battle for existence is its fecundity. 



In the same way it has also been asserted, in order to prove the occa- 

 sionally quite frequent occurrence of so-called " migratory herrings," that 

 the herrings grow so old that through old age they lose the faculty of 

 propagating the species.^^ But no convincing proof of this assertion 

 has so far been brought forward, although it ought to have been com- 

 paratively easy to obtain such proof. It is not known how often the 

 herring can spawn — in other words, how long it retains and uses its prop- 

 agating faculty. A Scotch fishery commission has, however, expressed 

 the opinion that the herring does not live longer than the time occupied 

 by two to three propagation i)eriods.^ 



Some time before spawning commences the herrings which have 

 hitherto lived rather scattered, begin to gather in large masses, which, 

 with the prmcij)al races of herrings, assume gigantic proi)ortions, and 

 form so-called "herring-mountains," which gradually approach the places 



'iBOECK, " Om. Silden og Sildefiskeriernc," p. 24.— G. O. Saes, " ilorgenhladet," Cliris- 

 tiauia, January 4, 1872, No. 3. — Indbereining omdeiAarene 1870-'73, ansUllede praktislc- 

 videnskahelige Under eogelser," Christiania, 1874, p. 59. — Compare, also, Loberg's entirely 

 different explanation in " Jforges Fiskerier," ^]^. 23-24, and my explanation in my "Pre- 

 Umindr Berdttelse" for 1874-75, p. 11. — Although it is natural to suppose that those 

 herrings which finish their first spawning very early are so much weakened by it that 

 they need an extra year to gain sufficient strength for another spawning — an explana- 

 tion which agrees well with the circumstance that the "migratory herring" is smaller 

 than the large spawning herring — we must, as long as this supposition lacks sufficient 

 proof, and as long as the phenomena which shall be explained by it can be explained 

 in a much less doubtful manner, neverthelesSj reject it. 



s^C. U. Ekstrom, Oefvers. af Kgl. Vet. Akads. ForJuindl." i, 1844, p. 2G. Praktisk 

 afhandling, p. 8. — A. W. Majlm, " Gotcborgs och BohusJdns Kgl. Hushdllnings-Sallska-ps 

 liandlingar," 1857, p. 20. — Lasningfor Fiskare i Bohuslan, Goteberg, 1861, p. 17. 



'•''Report of the Royal Commission on the operation of the acts relating to trawling 

 for herring on the coasts of Scotland, Edinburg, 1863, p. 28. 



