[17] 



SCIENTIFIC EXAMINATION OF THE GERMAN SEAS. 



541 



<^py>. 



3.— The different ages of the herring. 



When the young herring leaves the egg it does not have the shape of 

 an old herring; it is much more slender than the old herring (Fig. XIV) 

 and almost as thin as a ribbon. Its dorsal fin is proportionately long, 

 and is placed far 

 back. At this 

 stage of its life the 

 herring may be 

 said to be a larva. 

 The fish retains 

 this sh apeuntil its 

 length exceeds 30 

 to 40 millimeters. 

 As soon as the 

 sexual organs be- 



Cfin to 2T0W rap- The upper figure shows the outline of a spring-herring larva from the 

 , . Schlei, magnified twice. The lower figure shows the outline of an autumn- 



j (I J y indicating herring larva from the Bay of Eckernforde, magnified twice. The lines be- 

 ' _ tween the two figures show the natural size. 



the approach ot 



the spawning season, other changes in the shape of the body can be 



noticed. 



The sexual organs of small herring, measuring less than 210 milli- 

 meters in the Bay of Kiel, are but little developed. In herrings meas- 

 uring 210 to 290 millimeters in length, the sexual organs grow from 

 October till the spawning season in spring. 



As the spermaries grow faster from October to December than the 

 ovaries, the male herrings are during these months thicker than 

 the female ones, whilst from January to April the female herrings look 

 thicker, because during that period their ovaries increase more rapidly 

 than the spermaries of the male fish. 



When the spawn and the spermatozoa approach maturity, the her- 

 rings decrease in size as their quantity of fat diminishes, although even 

 then we occasionally find herrings which in spite of the strong develop- 

 ment contain a large quantity of fat. 



In April the larger herrings whose spawn and milt have been fully 

 matured generally leave the Bay of Kiel and go into the shallow brackish 

 waters of the Schlei, and their places in the Bay of Kiel are occupied 

 by smaller herrings, measuring less than 200 millimeters in length. 



The Schlei herring which is caught in spring is therefore not a differ- 

 ent race from the Kiel herring, but simply a fully-matured herring of 

 the kind found along the whole eastern coast of Schleswig-Holstein. 

 In this Schleswig-Holstein race of coast herring the following stages of 

 age and size may be distinguished : 



1. The larval form, measuring at most 40 millimeters in length (Fig. 

 XIV). It is much more slender than the juvenile form of the herring. 

 A larva measuring 33 millimeters in length is only 2 millimeters high, 

 whilst the height of a herring which has already assumed its juvenile 



