BULLETIN OF THE UNITED STATES FISII COMMISSION. 187 



57 NOTES UPON TBBE BNCKEASE AI>» DECREAi^E OE FISH.* 



By A. IfitJBi\ER. 



The Werbellin Lake, which is about 28 fathoms deep and has very 

 clear water, contained among other fisli up to ISoO many marenas 

 {maranCj a kind of Coregonns) and sticklebacks. During tlie next ten 

 years the marenas gradually decreased and nearly disappeared, so that 

 during the twenty years from 1860 to 1880 only a few, at most fifteen, 

 were caught per year. From the year 1880 they again increased, with- 

 out an J' known human agency, so that in the autumn of 1882 several 

 luindredueights were taken, and in 1885 about 10,000 pounds. The 

 fisheries are carried on in nearly the same way as forty years ago, 

 only tranrsportation to Berlin has become easier and more rapid. As 

 this lake has a season of prohibition in spring, the fisheries were con- 

 tinued (also since 1880) during the autumn, when the marena spawns. 

 It is suificiently proved that these fisheries have not done any injury, 

 and that the marenas having begun to disai)i)ear gradually thirty years 

 ago, without any indication of disease, may possibly have been the 

 work of the sticklebacks. These fish, which in former years were 

 caught in enormous masses, to be used and dried as fish-food, i^robably 

 aie the spawn of the marenas, so that there was not enough left for re- 

 production. In favor of this supposition we ma^' cite the fact that when 

 (during the ten years from 1860 to 1870) the sticklebacks also began to 

 decrease the marenas again made their appearance. Kevertheless they 

 again appeared in enormous numbers, when five years previously there 

 was hardly any trace left of them. On the other hand, it is very strange 

 that of the artificially raised marenas which were planted in this lake 

 about eight years ago not one has been seen again. While there were 

 no marenas in Lake Werbellin the public forgot this fish, so that at pres- 

 ent no one wants to buy them. Hence they do not bring a high price. 

 The same is true at the large fish-market in Berlin. When alive these 

 fish will not sell at all, and when dead they at most fetch 20 pfennige [5 

 cents] per pound in the Berlin market. If the sticklebacks have caused 

 the disappearance of the marenas, what has caused the disappearance of 

 the sticklebacks? Is it because they no longer found as food any spawn 

 of the marenas? But, then, the marenas had long since disappeared, 

 when the sticklebacks were still flourishing. Owing to their sharp fins, 

 sticklebacks are not attacked by other fish,, and the meshes of the nets 

 used in this lake are too wide to permit of the supposition that most of 

 the sticklebacks had been caught. The fishermen do not know what 

 cause to assign, and ajre only glad that they have got rid of them. 



* ^'' lUUselhaftcs Vermchren oder Feischivinden einzelncr Fischfjaitnnf/en." From thci 

 Deulsrhe Fisr.hcrci-Zcitnnr/j'Vo]. IX, Nos. 1 and 2. Stctlin, Jiuiiiary 5 and 12, 188G. 

 Translated from tlie German by Herman Jacobson. 



