the second half of July, and that these are caught together with 

 other ones of the sanie spawning period and having a length of 

 58 ra. ra. already. 1 think it quite clear that on August 31 little 

 fishes are taken of 40 to 50 m.ra. and also other ones of 60 to 

 70 m.m. November 20 a single straggler is 73 m.m., most of the 

 young herrings, however, have then a length of 85 — 90 m.m.; De- 

 cember 14 their length is 80 — 100 m.m. Probably in winter they 

 grow longer at a very slow rate only and this explains that the 

 majority on February 20 had a length of 88 — 95 m.m, only. 



How are we to explain, however, that there occur in July young 

 herrings of 98 m.m , in August of 80, in September of 90 , in 

 November of 110 m.ra.; how to understand those young herrings 

 which have on March 26 a length of 49 m.m. only? The only 

 explanation I can give rests on the supposition that all the young 

 herrings which are caught in the Zuiderzee are not boru in that 

 sea: there may occur also other young fishes, which have entered 

 the Helsdeur or any other way and which are — like the white- 

 bait caught on the HoUandsch Diep and Haringvliet — the off- 

 spring of an in winter spawning Northsea-herring. Occasionally 

 immense quantities of young herrings and young sprats are caught 

 near the Dutch Northsea-coast, in the strait between Helder and 

 Texel, and even in the harbour of Nieuwediep. At the latter 

 place I collected a few of them in the month of August. Whe- 

 reas the young herrings boru in the Zuiderzee in that month 

 will have a length of about 60 m.ra., the young herrings I 

 then collected in the Nieuwediep-harbour measured 80 a 85 m.m.: 

 probably they were the offspring of herrings which spawned in 

 winter in the Northsea not f ar from the coast. Why should not 

 such little fishes enter the Zuiderzee as well, since this is done 

 by fuU-grown herrings, so-called half-herrings and sprats? 



I adrait thus that from time to time »zeebliekjes" from the North- 

 sea may enter the Zuiderzee; but I think too that, in some 

 raonths of the year, their number must be of no consequence 

 at all. I remeuiber for example that I have investigated in March 

 '89 several hundreds of young herrings, which had all about the 



