A STUDY ON TROUT AND YOUNG SALMON. 333 



If we now examine the curve in fig.s 4 and 7 representing 

 the annual numbers of bag nets, there is not the slightest doubt 

 that the constant increase in the number of fishing implements, 

 is the only clear and obvious source of the progress of our 

 salmon-fisheries. 



Accordingly it seems to me perfectly evident, that if all 

 fishing, in the sea were prohibited, this would not result 

 in a proportionally large yield in the rivers. I have no doubt 

 that the total yield of our salmon-fisheries would then be much 

 smaller. 



The scientific explanation of this fact is another matter. 

 Personally I am inclined to believe that the phenomenon is to 

 be attributed to the circumstance that a large proportion of the 

 catch in the sea consists of grilse which are not yet sexually 

 mature and consequently do not ascend the rivers. Possibly 

 also, numbers of the large salmon caught in the sea are resting 

 fish, which would not have spawned in the year when caught. 

 Such investigations as would solve these questions (this could 

 easily have been done by opening large numbers of salmon in the 

 market) I have not been able to effect, on account of the large 

 expense thus entailed. 



Supposing, however, for the sake of argument, that we 

 stopped all fishing in the rivers, and thus could spare the 250 000 

 kilos of sexually mature salmon which are annually caught in 

 the rivers, spare it exclusively for the purpose of spawning, 

 clearly we would possess an immense power of increasing the 

 yield of the fisheries in the sea, supposing always the fundamen- 

 tal theories of the propagation of salmon to be correct. 



The general opinion on this point at the present time is 

 fairly unanimous, namely that an increase in the numbers of 

 spawning fish and consequently that of fry would result in a 

 corresponding increase in the numbers of individuals of the 

 species. In other words a direct relation exists between spaw- 

 ning and the increase in the stock of fish. Whether this, generally 



