BULLETIN OF THE UNITED STATES FISH COMMISSION. 399 



ence on the quantity of the young herring which are hatched in that 

 water.' Whether the value of the fisheries in the whole of the Schlei 

 would be decreased thereby, is a question which cannot be answered at 

 present. 



The sprat, salmon, sea-trout, eel, sturgeon, and lamprey resemble the 

 herring in this, that at different periods of their life they change their 

 location. Just as the Baltic herring, in spring, seek the brackish coast- 

 waters, for the purpose of spawning, thus the salmon, sea-trout, and 

 lampreys ascend the rivers to the neighborhood of their sources for the 

 purpose of depositing their eggs, and, reversing this, the mature eels 

 migrate from fresh waters into the sea in order to spawn there. 



The young herring, salmon, sturgeon, and lamprey live on organic 

 matter which is developed in the localities where they are hatched, and 

 after having reached a certain age they go into salt water. Young eels 

 find their first suitable food in the sea, and afterwards develop in fresh 

 water, whilst the salmon, sea-trout, sturgeon, and lampreys transform 

 numberless marine animals into delicious fish-flesh. 



The feeding territory of the migratory fish is larger than that of the 

 stationary fish. The migratory fish are, therefore, more of flesh-form- 

 ing fish than the stationary fish. Their marine pastures and spawning- 

 places located in the sea cannot be changed by man ; but it is within 

 pur power to change their pastures and spawning-places in fresh and 

 brackish water, or to prevent them from reaching these places. In 

 former times the Windeby Noor, an inlet near Eckernforde, was a good 

 spawning-place for our herrings ; but by the construction of a dike they 

 have been deprived of it. We should be careful not to deprive the fish 

 on our coast of any more spawning-places, if we desire that their num- 

 ber shall remain at its average height. For the young eels and sea-trout 

 and the mature salmon, ways should be constructed near mill-dams so 

 they may be able to ascend the streams. The descending salmon, sea- 

 trout, and eels should be protected against turbines and other hurtful 

 contrivances, if we desire that, both in fresh and salt water, all that 

 matter which may serve as fish food shall be transformed into food for 

 man. 



Of the shell-fish found in our coast- waters, only oysters and common 

 mussels [Mytilus edulis) are eaten in Germany, whilst in France and 

 England the heart-mussel [cockle], and in North America the sand- 

 mussel (Mya armaria) [soft clam] also form articles of food. 



For the proper management of our Schleswig oyster-beds we have, 

 by scientific and technical investigations, and by a rational system of 

 renting, gained a safe basis, and they will soon again produce their 

 former quantities of oysters. 



With us the number of marketable oysters cannot, by artificial oys- 

 ter-culture, be raised to such a height as on some parts of the French 

 and Dutch coasts, because we have to contend with vast quantities of 

 ice and heavy floods; but by scattering oyster-shells in parts of the 



