64 



froni the diraeiisions of the larvae, to foretell , that the larvae 

 collected in the Zuiderzee belonged to a herring which spawns in 

 spring in brackish water. Exactly in the same way I was able 

 to pronounee a decided opiniou over the herrings caught in 1886 

 and 87 in the Hollandsch Diep and Haringvliet, where the water 

 is brackish as in the Zuiderzee. No spawning-places of the her- 

 ring are known in these waters; a good raany young herrings 

 (like whitebaits in the Thames) are met with , a few fullgrown 

 ones also , and I was auxious to ascertain where they came 

 from. The larvae enabled me to pass judgment as to their origin : 

 in the first place, because I collected them in great quantities in 

 jMarch ; and in the second place, because they measured 46 — 48 m.m. 

 — a single one even having a length of nearly 50 m.ra. No doubt 

 they are not born in the water where they were taken: they 

 belong to a race of herrings, which spawns in winter in the open 

 Northsea in water of great salinity. 



But let us return to the herring of the Zuiderzee : we know now 

 that it is a herring spawning in brackish water during spring-time, 

 and the larvae of which are coraparatively small. The next chapter 

 of its life-history deals with its youth. As soon as they have 

 reached the size of 40 a 50 m.m. they are called »zeebliek" by the 

 Dutch fishermen , and the same name is stil) given them when 

 their size is more than twice as long. During this period of their 

 existence they stay in the Zuiderzee and only change it for 

 the open Northsea after their length has become about 110 a 

 120 m.m. Their rate of growth seems to be rather different in 

 different individuals; as a rule they will stay in the Zuiderzee 

 until they are about one year old and have got a length of 

 about 115 m.m. A good many irregularities, however, occur no 

 doubt in this respect. Before entering in a discussion thereupon I 

 give a list of the measures of the young herrings which I have 

 collected in the Zuiderzee throughout nearly all the months of 

 the year. 



