SALMON— ASCENDING RIVEES— DEVELOPING EGjGS. 69 



prevented the parent salmon ascentling the river as usual (Livingston-Stone : 

 IStdl. U.S. Fish. Comm., 1885). But the remarks of Sir W. Jai-dine and others 

 must not be overlooked, that temperature in estuaries is occasionally, at least, a 

 cause as to the side they select when migrating, for they have been observed to 

 choose the sunny side during the cold months, and the shady during the warmer 

 portions of the year. 



But the period arrives when these fish consider it necessary to migrate from 

 the tidal portions of a river and ascend into the fresh waters, where, instead of 

 going with the tide, they have to pass on against the stream ; and fishermen, at 

 least in the Wye, appear to consider that it is a rule, excepting during a fresh, 

 that these migrations take place chiefly during the night-time — in fact, so strong 

 on this point is the opinion of some, that they do not hesitate to say that, were 

 night-fishing in this river to be put an end to, their occupation would be gone. 

 It may be worthy of investigation, whether the constant netting to which these 

 fishes arc subjected is not one cause of their selecting to ascend during the 

 night-time. 



During this period they require shelter, and even if they are found near ledges 

 of rock or large stones there is almost certainly some gravelly spot in the vicinity 

 where they can rest. 



The salmon having while in the ocean stored up fat, which is most readily 

 seen on and around its pyloric appendages, and possibly, especially if in the 

 autumn, being in such a condition that within a definite period its roe or mUt 

 must be deposited, commences its migration towards its breeding-grounds in the 

 fresh waters. One reason why the fish maturing its eggs has an excess of fat over 

 one not so engaged, is supposed to be the great amount of nourishment which 

 is required by the females while the eggs are rapidly maturing. 



In November, 1885, being with Sir James Maitland searching for salmon eggs 

 in theTeith, near Stirling, we took a female, 15 lb. weight, so injured by seals that 

 it succumbed. It was a clean silvery fish,* with ovaries 4'7 inches in length, the 

 two weiffhiuj; 2^ ounces, and each ess being' 0"1 inch in diameter. It is clear that 

 a salmon having eggs one-tenth of an inch in diameter at the end of Novembt r 

 could not have its ova sufliciently ripe to spawn within the next two month?, 

 while experience tells us that no other period for depositing eggs will normally 

 come round before this time the succeeding year. November 26th, 1886, out of 

 nine salmon netted in the same place three were clean newly-run fish. It has 

 long been accepted as a physiological necessity that a female smolt must descend 

 to the sea before it can develop eggs, the reason advanced being, as stated by 

 Rasch, in 1866, that the development of ova requires far more nourishment than 

 that of milt ; that in the ovary of the female the eggs are formed nearly simul- 

 taneou.sly, and their development is uniform, one being enveloped in as large an 

 amount of albamen as another. But in order to produce this albumen, a far greater 

 quantity of food is needed than the fish can normally procure in fresh-water rivers. 

 On the other hand, grilse at Howietoun, both last year and during the present 

 season (1884-85 and 1885-86) have given eggs without going to sea ; and the land- 

 locked salmon breeds in fresh water without descending to the ocean. 



I think that the explanation of these apparently contradictory facts is possible. 

 Thus, it is generally admitted that salmon, while residing in rivers, do not increase 

 in weight, but rather fall off the longer they are absent from the sea, existing as 

 they mainly do ujion the fat which they have accumulated while feeding in the 

 salt water, and such food as they can procure is sufficient for nutrition of the body 

 but insufiicient in females for breeding purposes. If this is so (and of it I think 

 there can be no reasonable doubt), they would be unable to obtain enough nourish- 

 ment wherewith to develop eggs so long as they continued in the river, that, in 



* Three similar ones were likewise captured that day, but being uninjured were at once 

 returned to the Teith. On December 23rd, 1881, five clean fish were taken when obtaining 

 salmon eggs in tlie same river. These must not be considered exceptional occurrences, as clean fish 

 at this time are invariably netted when seeking for gravid salmon. In the Ehine, Barturth 

 observed in 1874, that spawners ascend from September to Novemljer, while there is likewise a 

 barren winter variety coming sporadically and for a brief season from September until May. 



