824 BULI^ETIN OF THE BUREAU OF FISHERIES. 



I do not wish to enter into detail upon the physiological part of this subject, 

 however; it has been studied with great care by Professor Miescher-Ruesch, of 

 Basel, who on the same occasion published an excellent description of the histo- 

 logical changes of the milt of the salmon, which changes occur during that devel- 

 opment of the sexual organs. Later investigations (of Noel Paton and others) 

 have in the main confirmed the results arrived at by the Swiss physiologist. 



These are the headlines of the natural history of the Rhine salmon ; the same 

 fish as occuring in other European rivers has perhaps not been studied quite so 

 carefully as the Rhine salmon, but from what we know about the other rivers, 

 which after all is not so little, we may safely conclude that the salmon behave 

 about the same all over Europe. 



PROPAGATION. 



About the propagation of the Rhine salmon few words need be added. We 

 saw that the natural propagation takes place in the upper parts of the tributaries, 

 the spawning places being well known to the inhabitants and being easily dis- 

 tinguished from the shore, especially when the water is clear and the depth 

 unimportant. Some of the fish, however, spawn in the main river itself, spawn- 

 ing beds (Laichgruben) having been observed in the Rhine between Strasburg 

 and Basel, as also between Basel and Schaffhausen. Whether spawning in the 

 main river takes place regularly or only accidentally has never been investigated 

 thoroughly; in fact, even fot a fish so much studied as the Rhine salmon, in some 

 regards information is wanting which after all might perhaps not be so difficult to 

 obtain. 



The real spawning places of the Rhine salmon, it is easily understood from 

 the foregoing, spread over a wide area situated for the greater part in Germany 

 and for a smaller one in Switzerland. The relative richness in salmon which 

 the Rhine even at present possesses is unquestionably to a very large extent 

 due to the wide reaches of its tributaries, the spawning places of our fish. That 

 richness would undoubtedly be much greater if more salmon were permitted 

 to reach these spawning places, if these places were better protected, that the 

 salmon might propagate undisturbed, and if all the young salmon hatched in 

 the upper regions of the river could safely arrive in the ocean. 



There can be no question that on the Rhine relatively few salmon nowadays 

 come to spawning in the natural way. Of some of the tributaries (of the 

 Moselle especially, but of some of the affluents in the Grand Duchy of Baden 

 also) I studied the upper regions in this regard, and the result has not been 

 very edifying. The fish reaching the upper region, the number of which is limited 

 by the fishing in the lower and middle regions of the river,- are sought with 

 great eagerness. Though their value as food, especially in the very last days 

 and weeks before the spawning, is, comparatively speaking, a small one, they 



