PROPAGATION AND GROWTH OF HERRING. 649. 



bears a strong resemblance to other small fish; bream, perch, crucian, 

 &c., which also press close against each other and cause a great com- 

 motion in the water when they spawn. For some days in the begin- 

 ning of spring only milters are caught, but as soon as spawning com- 

 mences milters and spawners are caught containing loose milt and roe. 

 When si)awning is over, both milters and spawners seek the deep." 



After the eggs of the herring have been laid and have become impreg- 

 nated, some time elapses before they are hatched; this time varies accord- 

 ing to the temperature of the spawning-i^lace. The somewhat conflicting 

 observations on this subject seem to point to a varying incubation-season 

 for the different races. G. J. SundevaWs opinion is probably correct, that 

 ''fish do not have a regular hatching- time for their eggs like birds." ^^ 

 This conscientious observer says that on the coast of Stockholmliin, the 

 eggs of those herrings which spawn there, are generally hatched in about 

 14 days or a little more, but may, when the temperature of the water is 

 higher (say upwards of 08° r.),be even hatched in 3 days."*^ Ekstrom 

 reports that on the coast of Morko hatching takes about 14 days."*^ From 

 the Sli-fiord, which has been examined by the German Fishery commis- 

 sion, it is reported that the hatching of the herring eggs during spring- 

 time, when the temj)erature was, comparatively speaking, high (18 to 2(P 

 C.=64.4°-68o F.) took only about 8 to 10 days.^^ The same observation 

 has been made by Kroyer regarding the herrings on the coast of Denmark.^ 



■^Stockholms Idns Egl. HushdUnings-iSdUskaps handlingar, VI, Stockholm, 1855, p. 158. 



^'^Kgl. Svenslca FetenskapsAcademiensJiandlingai; 1, 1, 1855, p. 17, — See Stockliolms lans 

 Kgl. HzishdUnnigs-Sallskaps handlingar, VI, p. 195, where it says : The development of 

 the eggs progresses rapidly. During August they are often hatched in 3, or at most 

 5-6 days. With a water temperature of 14-15° = 57°-59° F., the eggs have been hatched 

 in 6-8 days. During May it took 6-8 days to hatch them." These observations have 

 been repeated by Widegren in his treatise ^' Ndgra ord om silljiske samt om sillens eller 

 Strommingcna rdtta berednitig till handelsvara" (Kgl. Landirvks Academiens Tidsskrift, X, 

 Stockholm, 1871. — Tidsskrift for Fiskeri, VI, p. 68. — Circulare des deutschen Fischerie 

 Vereins, 1872, IV, p. 106. — United States Commission of Fish and Fisheries. Report for 

 1873-74 and 1874-75, Washington, 1876, p. 186.— Report on the herring fisheries of Scot- 

 land. London, 1878, p. 182.) 



*^Die Fische in den Scheeren von Morko. Berlin, 1835, p. 221. 



^Circulare des deutschen Fischer ei-Vereins, 1874, !>. 268. Later Professor Kupffer has 

 given the followingresults of the above-mentioned comission : ''The roe of the autumn- 

 herring, with a lower temperature (48.2°-51.8°F.) and a saltness of about 2 per cent., 

 develops in exactly the same time and shows the same phenomena as the Sli-sjiring her- 

 ring with a higher temperature (57.2°-68°F.) and a saltness of only 0.5 per cent.; the 

 development of the eggs in the Western Baltic goes on independent of the temperature 

 of the water and its saltness in about 7 days, counting from the time of impregnation; 

 the majority of the eggs are hatched in 7 days, some of them even in 6 days, although 

 the hatching of an indeterminable percentage of eggs may be delayed a few days." 

 (Jahreslericht, IV-VI, p. 31-32). — Dr. H. A. Meyer adds the following information, based 

 ot) more recent and complete observations : *' that with a temperature of 38.3°F. the, 

 development of the egg takes about 40 days, with a temperature of 44.6°-46.4°F. about 

 ^, and with a temperature of B0O-51.8°F. about 11 days; but that the influence of the 

 Ifemperature on the roe of the spring-herring does not differ from its influence on the 

 roe of the ajitjjnm-herring." — Jahresbe/i-icht, IV-VI, p. 240.) 



^Danmarks Fiske, III, p. 170. 



