80 PHYSOSTOMI. 



spring and summer fishing was fairly favourable, while in August there was 

 a large increase both in grilse and salmon : the effects of the mortality seemed to 

 show itself in the decreased weight of the individual salmon and the paucity of 

 exceptionally heavy fish, none attaining 40 lb. until the commencement of June. 

 This would go towards favouring the contention that kelts when mended do 

 return to the river, but that a great destruction of them does not necessarily 

 involve a greatly diminished take of salmon the ensuing year. 



An experiment of permitting kelts to be destroyed in one river for a single 

 year, and ascertaining the effect on the stock of salmon and grilse the succeeding 

 season, appears well worthy of a fair trial. 



The question here arises what is an " unclean " and "unseasonable" salmon ? 

 these terms being employed in Parliamentary language. Certainly a " kelt " 

 would come under this designation as would also one that is about to spawn or 

 " red fish " if a male, " black fish " if a female. But the latter could hardly be 

 termed a foul fish being in its way as good food as is a laying hen or many an 

 animal. By a clean salmon, on the contrary, is meant one in good health, and 

 not on the point of spawning. 



Siebold has shown that certain individuals are not sexually developed, and he 

 believed this sterility extended throughout their existence, a view opposed by 

 Widegren and others, who contend such to be temporary and merely affecting 

 a few individuals. 



Hybridism in a natural state appears to be rare as regards the salmon, but that 

 such may take place has been proved by Rasch who fertilized their ova with the 

 milt of the trout and of the charr (see p. 59). It might be worth a trial whether 

 such hybrids could not be raised for the purpose of populating waters in rivers 

 wherein pollutions in its lower portions or other causes precludes the ascent of 

 of the fish. Probably most hybrids would be sterile, and possibly they would not 

 attempt to migrate, if so the angler could supply his district with fish which 

 would be good for sport and likewise for the table. 



Whether salmon could be permanently retained and breed in fresh waters is a 

 subject upon which various opinions have been given. The difficulty of offering 

 an opinion upon this question is that it seems occasionally questionable whether 

 the recorded instances of such having been successfully accomplished, the observer 

 refers to Salmo salar, or a sea-trout. Lloyd (Field Sports North of Europe, i, p. 301) 

 remarks that near Katrineberg there is a valuable fishery for salmon, eleven or 

 twelve thousand of these fish being taken annually. They are bred in the lake, 

 and in consequence of cataracts cannot have access to the sea. They are small in 

 size and inferior in flavour. The year 1820 furnished 21,817. Bertram observing 

 upon having been present at Stormontfield at the yearly exodus of smolts in 1861, 

 when they were found to be large and in fine condition continues, " one fish, 

 which has been detained for three years for the purpose of discovering whether 

 the species will grow in fresh water without being permitted to visit the sea, was 

 found to be fully twice the size of the largest smolt " (Harvest of the Sea, p. 110). 

 It must not be overlooked in experiments of this nature that the extent of the 

 fresh water in which these fish are confined must exercise a considerable influence 

 upon the result, and also on the amount of food which is available for their 

 consumption. 



Professor Rasch, of the Christiania University, remarked, " some years ago 

 Hetting hatched out a number of salmon ova, which he subsequently turned loose 

 in the Tyri-fiord, and during the last two years fish have been caught in that lake 

 resembling in every respect ' salmon proper.' It is impossible for them to return 

 thither, even should they succeed in reaching the sea " (Land and Water, 1866, 

 pp. 221, 245). 



Kipper is a term sometimes used for males after breeding, but which has also 

 become employed for members of the salmon family that have been detained in 

 fresh water, and as a consequence become sick, lean and unseasonable (see 

 S. argenteus, pi. cxi). This term is also employed to old males, and means bony 

 gristle, which grows from their lower jaw resembling a "hawk's bill," and unless 

 absorbed, may hinder them from feeding, causing them to pine away and die. 



