190 VISIT OF THE SMOLTS TO THE SEA. [CHAP. v. 



fish, who dart with inconceivable rapidity upon the defenceless 

 shoal and play havoc with the numbers. 



Many naturalists dispute most lustily the assertion that the 

 smolt returns to the parental waters as a grilse the same year 

 that it visits the sea ; and some writers have maintained that 

 the young fish makes a grand tour to the North Pole before it 

 makes up its mind to " hark back." It has been pretty well 

 proved, however, that the grilse may have been the young smolt 

 of the same year. A most remarkable fact in the history of 

 grilse is, that we kill them in thousands before they have an 

 opportunity of perpetuating their kind ; indeed on some rivers 

 the annual slaughter of grilse is so enormous as palpably to 

 affect the " takes" of the big fish. It has been asserted, like- 

 wise, that the grilse is a distinct fish, and not the young of the 

 salmon in its early stage. There has been a controversy as to 

 the rate at which the salmon increases in weight ; and there 

 have been numerous disputes about what its instinct had 

 taught it to " eat, drink, and avoid." 



It has been authoritatively settled, however, that grilse be- 

 come salmon ; and, notwithstanding a recent opening up of this 

 old sore, I hold the experiments conducted by his Grace the 

 Duke of Athole and the late Mr. Young of Invershin to be 

 quite conclusive. The latter gentleman, in his little work on 

 the salmon, after alluding to various points in the growth of 

 the fish, says : " My next attempt was to ascertain the rate of 

 their growth during their short stay in salt water, and for this 

 purpose we marked spawned grilses, as near as we could get 

 to four pounds weight ; these we had no trouble in getting 

 with a net in the pools below the spawning-beds, where they 

 had congregated together to rest, after the fatigues of deposit- 

 ing their seed. All the fish above four pounds weight, as well 

 as any under that size, were returned to the river unmarked, 

 and the others marked by inserting copper wire rings into 

 certain parts of their fins : this was done in a manner so as 



