From the Dublin Penny Journal, Volume 1, Number 30, January 19, 1833
THE wonderful instinct implanted in migratory animals, by which they are able to return to their native haunts, is well known to naturalists, and unfolds a wonderful instance of the design and wisdom of the great Creator. Sir Humphrey Davy in his instructive little book, Salmonia, says "that it is scarcely possible to doubt, that the varieties of the salmon, which haunt the sea, come to the same river to breed in which they were born, or where they have spawned before." A remarkable experiment, proving this singular fact, was made some years ago in the little river Ballinahinch, in Connemara, by Thomas Martin, Esq. Eighteen salmon which were taken on their passage to the sea, were marked and thrown back into the river, and of these, seventeen were taken in the year following.
The characteristic peculiarities by which the salmon of one river are distinguished from those of every other, seem attributable to this instinctive principle. The instincts of fishes however, appear to be no more infallible than the reasoning powers of man—each may be led into error by fortuitous circumstances. The philosophical angler above quoted, remarked that "in great floods, often connected with storms, or violent motion near the shores, salmon sometimes mistake their river." I remember (he adds) `in this' way, owing to a tremendous flood, catching with a fly a large salmon that had mistaken his river, having come into the Bush, near the Giant's Causeway, instead of the Bann. No fish can be more distinct in the same species than the fish of these two rivers, their length to their girth being nearly a ratio of 20 : 6, and 20 : 13."