452 ME. F. DAT ON THE BREEDING OF SALMON FROM PARENTS 



1200 or 1300 . . . "Within two months of the date of their liberation, viz. between the 29th 

 of May and 31st of July, twenty-two of the young fish so marked when in the state of 

 smolts, on their way to the sea, have been, in their returning migration up the river, 

 recaptured, and carefully examined. This fact may be considered as still further 

 established, by observing the increased weight, according to date, of the grilse caught 

 and examined : those taken first weighing 5 to ( .H lbs., then increasing progressively to 

 7 and 8 lbs., whilst the one captured 31st July weighed no less than 9| pounds. In all 

 these fish the wound caused by marking was covered with skin, and in some a coating of 

 scales had formed over I lie part " *. This question of smolts returning or not the same, 

 year as they migrated to the sea, I do not propose entering on here. 



llespecting one half of the purrs migrating seaward one season, and the remainder not 

 doing so until the next year, ltu>sel observes, ".V new hypothesis was brought out, to 

 the effect that the females descend the first year and the males the second " (op. cit. p. 17). 

 But on investigation it appeared "thai the fish remaining during the second year 

 consisted of both males and females, the milt of the males being fully developed, while 

 the roe of the females was discernible only by a microscope " (/. c. p. 18). 



Mr. Dunbar, who annually hatches about 500,000 Salmon ova in the Thurso river in the 

 county of Caithness, informed -Mr. Young that about 8 per cent, became smolts at the 

 end of the first yearf, and about GO per cent, al the end of the second year, and the 

 remainder, or 32 per cent., at the end of the third year. The fish which were hatched 

 in the spring of 1837 at Drumlanrig did not assume the migratory livery and seek to 

 depart in May 1838 as Mr. Shaw expected, but did so in May 1839 %. It has been 

 argued that young Salmon may have their growth stunted and their instinct overruled by 

 being kept in a state of comparative confinement. 



" Until the parr takes on the smolt scales it shows no inclination to leave the fresh 

 water. They cannot live in salt water. This fact was put to the test at the ponds, by 

 placing some parrs into salt water — the water being brought fresh from the sea at 

 Carnoustie — and immediately on being immersed in it, the fish appeared distressed, the 

 tins standing stiff out, the parr marks becoming a brilliant ultramarine colour and the 

 belly and sides of a bright orange. The water was often renewed, hut they all died — the 

 last that died lived nearly five hours. After being an hour in the salt water, they 

 appeared very weak and unable to rise from the bottom of the vessel which contained 

 them, the body of the fish swelling to a considerable extent. This change of colour in 



* Report of Committee on Storraontfield Ponds to British Association, 1S50, p. 4-V>. 



t I conclude he meant to say at the termination of the first year after being hatched, for they do not descend 

 seawards in their first year. 



t " It was said of Mr. Shaw's experiments that the two-years' freshwater residence of the fry was ascribable to the 

 •difference of temperature between the waters of the Nith from which the ova were taken, and the waters of the 

 ponds in which they were hatched and reared.' Put where is the evidence as to what was the difference in temper- 

 ature, or whether there was any at all? On inspecting Mr, Shaw's Observations, for information on this point, we 

 can only find that the temperature of the ponds, as compared with that of the river, was on one occasion three 

 degrees below and on another six degrees above. So whatever difference there was, seems to have been in favour 

 of the ponds stimulating, not retarding, as compared with the river or natural habitat. Put suppose it were other- 

 wise, what then '? Wo know that a lower temperature might retard the hatching of the fry by a week or two, or 

 their growth by half an inch or half an ounce ; but we have no ground for supposing that it would retard for a 

 whole year such a change as that of assuming the migratory dress." (Pussel, I.e. p. -t s .) 



