F. DAY: PERIODS OF MIGRATION. 



117 



these marked fish were caught in or near their own pool, to do which 

 they must have come back a circuit of at least forty miles, and passed 

 by six or seven tributaries. 



Were the homeing instinct in these fishes very strongly marked, 

 such as were hatched from eggs brought from a certain river might 

 (like the Blue-rock Pigeons reared from eggs obtained from another 

 dovecote) return to the locality where the ova were originally deposited. 

 But if such were an invariable rule, the re-stocking of salmonless 

 rivers from distant sources would be useless, while experiments have 

 demonstrated the procedure to be almost invariably satisfactory. 



Still a very strong opinion exists, and which observations have 

 proved to be to a certain extent correct, that salmon return to the 

 river they were originally reared in. Some have imagined that they 

 select the purest waters, or recognise the taste or smell of their native 

 stream • but, on the other hand, it has been asked, how could the 

 purity of the water induce salmon to enter certain rivers, for they 

 generally ascend during a flood, when they are most full of mud, but 

 at which times the fish are keenest to pass up. 



Mr. D. Milne Home, when writing about the Tweed, observed 

 that marked fish from that river had been taken in the Frith of Forth, 

 the Don, and Dee, while to the south at Holy Island, the Tyne, 

 Shields, and even Yarmouth. This last was a so-called ' Bull Trout,' 

 caught in the Whitadder, a tributary of the Tweed, on March 29th, 

 1852 ; it was netted at Winteston, near Yarmouth, April 2nd, 1852, 

 or nearly 300 miles distant, within four days. A second, marked in 

 the Whitadder, March 10th, i860, was taken at Yarmouth, May 5th, 

 i860. He considered it certain that salmon, after having frequented 

 particular rivers from time immemorial, have abandoned them ; and 

 the inference is that they betake themselves to other rivers which they 

 deem preferable. As an example of this, the Whitadder may be 

 referred to : it has a course of about forty miles from the Lammer- 

 muir Hills. This river joins the Tweed at a distance from its mouth 

 of about three miles, so that all the salmon caught in the higher waters 

 of the Tweed must have passed the Whitadder. The tide flows into 

 it as well as into the Tweed, going up the latter for six or seven miles. 

 Formerly the true Salmo salar frequented the Whitadder, but during 

 the last thirty years none of that species has been seen in it. It is 

 now only frequented by ' Bull Trout.' In the Midlothian Esk, he 

 also remarked, that about fifty years ago he had seen hundreds of true 

 salmon wriggling up over the mill weirs ; but for the last twenty years 

 there has been no such fish in that river. 



In the Coquet the salmon were similarly observed to have become 

 scarce, a nd it was suggested by H.M. Inspectors of Fisheries that 



April 1886. 



