122 



F. day: periods of migration. 



Salmonidse, or, in fact, render a fish temporarily sterile. At Howie- 

 toun it wasobserved in 1884, that the American Char (Salmo fontinalis) 

 suffered a good deal from fungus, owing, it was believed, to their 

 over-feeding. Consequently, in 1885 their diet was reduced, and 

 that with the best results as regards fungus ; but when the breeding 

 season came round it was found that large numbers were sterile. 

 That this is solely a question of food a most interesting instance in 

 pond No. 5 may be quoted. Here the hybrids were kept and fully 

 fed, and one female fontinalis was placed along with them. She 

 attained to a large size, and in November 1885 was found to be full 

 of eggs. Deficiency of food may, therefore, occasion sterility by an 

 arrest of development in the ova, or, should the eggs be formed in 

 the ovaries, it may arrest (possibly not entirely) their further augmenta- 

 tion in size, as cold will retard the development of the embryo in eggs 

 that have been deposited, as has been abundantly proved by trans- 

 mitting them to distant countries by the assistance of ice. Possibly 

 in some few instances these early-ascending fish may find a locality 

 where food from some cause is unusually abundant, allowing the ova 

 to augment in size, and that this is the explanation of occasionally a 

 female salmon with large eggs being captured at the end of the 

 summer ; but normally these fish will be sterile during the year of 

 their ascent in the condition described, at least until after they have 

 revisited the sea. 



But it may be advanced, if this is so, how do land-locked 

 salmon breed ? Here we have an entirely different set of circum- 

 stances to deal with. The fish have never been to the sea-feeding 

 grounds, but have been compelled to adapt themselves to local 

 conditions. Thus, in large lakes, as Wenern and other suitable 

 places, where food abounds, they breed, or else they may become 

 ' demoralised salmon,' as Agassiz remarked ; or, finally, they may 

 die out, due to sterility, the nourishment which they are able to 

 obtain being insufficient or unsuited to allow them to perpetuate 

 their race. 



The foregoing makes me think that Mr. George was in error when 

 he reported to the Severn Fishery Board in 1885, that, due to a long 

 series of dry weather, no run of spawning salmon occurred until the 

 beginning of December. The first salmon spawned in the Barrow, 

 November 12th, 1884, and in the Verniew on the 15th. These were 

 fish that had been in the fresh water all the summer. Without being 

 marked, it is difficult to be sure on such a subject, and I would rather 

 hold to the opinion that these were fish lately ascended from the 

 sea. 



Naturalist, 



