9J, SALMONID^ OF BRITAIN. 



eggs have been obtained, and young in the form of salmon par have since been 

 raised. It has also been advanced that grilse cannot be young salmon,* ignoring 

 the fact that only in salmon-rivers are there true grilse, and wherever they exist 

 there also are salmon. Now, although it has been shown that grilse may be 

 reared from salmon eggs, still, it has been pointed out that salmon and grilse of 

 the same size can readily be distinguished one from another. In the evidence 

 taken before a Committee of the House of Commons, in 1824, Mr, Johnstone 

 stated the difference between a grilse and a salmouf to be as follows: — " The grilse 

 is a much less fish in general, it is much smaller at the tail in proportion, and it 

 has a much more swallow tail, much more forked ; it is smaller at the head, sharper 

 at the point of the nose, and generally the grilse is more bright in the scale than 

 the salmon." 



Doubtless there is a difference in the appearance of a small salmon and a grilse 

 of the same size, but such is probably due to the former from some cause not 

 having got into condition and so lost a season. That grilse frequently re-ascend 

 rivers at irregular periods has been constantly observed, J while they have also 

 been entirely absent for a whole season, as in 1867, as has been already remarked 

 (see page 72). 



At p. 71 I have recorded the captures made by anglers in the Shin, which tend 

 to show that grilse commence running up the river at the end of May or commence- 

 ment of June, while the greatest number ascend in July, after which there is a 

 decrease. The p.verage weight of each fish captured in the various months in 

 1886 were as follows : — February, salmon, 9 lb. : March, II lb. : April, 13 lb. : 

 May, I2i lb. ; June, 14 lb. : July, 12| lb. : August, 10 lb. : while September was 

 not fished. Of grilse the average weights of fish were in May, 3 lb. : June,',4| lb. : 

 July, 5| lb. : August, 6 lb. : September not fished. These figures agree to a con- 

 in 1859, deposited 18,000 salmon ova at DoohuUa, they hatched in February, 1860, only a few 

 were ready for sea when about thirteen months old, the great majority migrating at twenty-seven 

 months old, they stayed from thirteen to fifteen months at sea, when they returned as grilse at 

 two years and four months old (Fish Culture, by Francis Francis, 1865, Appendix, page 311). 



* In 1860, Mr. Mackenzie, when publishing his father's treatise on the Salmon Fishery of 

 Scotland, did not accept the view therein held that the grilse was a young salmon, but gave his 

 reasons in an appendix under the title " do grilse grow to be salmon ? " And he asserted that they 

 did not, that " its instincts in some respects are different, though its habits are precisely the same." 

 His arguments being that the salmon's instinct impel them to ascend rivers in winter and spring, 

 but the grilse do not leave the sea for the fresh waters until the summer, one in short being a 

 spring, and the other a summer fish. That salmon and grilse do not spawn promiscuously ; and 

 when the grilse appear in May or June, their roe is in precisely the same stage of growth as in the 

 salmon when they appear in rivers in January, but as they spawn about the same time, it shows 

 that the roe of the grilse requires only half the time which that of the salmon requires to bring it 

 to maturity. Also, that grilse in May weigh from 3 lb. to to 5 lb. ; in July, from 10 lb. to 12 lb. ; 

 and instead of finding them in August and September 16 lb. or 20 lb., which would be natural if 

 they continued to grow in order to become salmon, they apparently begin to grow backwards, 

 as in October they are as small as in May. The river Shin produces salmon, but very 

 few grilse ; the Oykell few salmon, but shoals of grilse. The tail-fin of a grilse tapers off to a finer 

 edge than in the salmon. A Committee of the Commissioners of the river Tweed, ignoring some 

 of the experiments previously conducted in that river, reported in 1863, as follows: — " Our 

 opinion from the experience of the last twenty years, is, that grilse never become salmon at any 

 stage whatsoever." 



t Fraser (/. c, p. 37) observed, " A large grilse is a breeder the first season. A small salmon 

 may be of the same age with the large grilse, but it has never spawned, owing to its not getting in 

 its season to the proper feeding-ground, and before the young fish it feeds upon have grown 

 strong and left the ground. These (salmon) fry not only lost the season, but lost their ordered 

 food, and are only in condition to return to rivers, some early and some from first to last of every 

 season." Professor Brown-Goode (Natural History of Aquatic Animals, p. 474) observed of the 

 grilse and adolescent salmon, that the two may be easily distinguished, even though both should 

 be of the same size as not infrequently happens. " The male grilse is sexually mature, but not so 

 the female in America ; in Europe the same is claimed for the male par and the female grilse " 

 (smolt). 



+ Mr. J. Miller, Land and Water, May 10th, 1879, reported on having caught in 1879, four 

 grilse weighing 20^ lb., all in the scale together, the largest 5.^ lb., the smallest 4 lb. These 

 Galway grilse were ascending at the latter end of April, and such an early run, it was supposed, 

 had not happened for twenty-five years, the main run generally occurring in May and June. 

 In 1881, the first grilse in the Forth was recorded on June 28th, but in 1882 they were a week 

 later. 



