1903-4.] Mr Calclerwood on Bull Trout of Tay and Tweed. 27' 
The Bull Trout of the Tay and of Tweed. 
By W. L. Calderwood. (With a Plate.) 
The particular bull trout with which I desire to deal in this paper 
are the important migratory fishes which are commonly referred to 
by this name in Scotland. I make no mention of more or less- 
monstrous examples of the common brown trout, or even of those 
examples of S. fario which have assumed a semi-migratory habit, 
and have become much modified by reason of their life in the 
estuaries of our larger rivers. 
Amongst the true migratory salmonidae are two fishes which I 
hope to show are distinct from one another, but concerning which 
considerable confusion seems at present to exist, because they are 
both called bull trout. This somewhat ambiguous term ‘ bull trout r 
is a familiar one throughout Scotland, but the two forms to which 
I here refer are well represented, the one in the Tay and the other 
in the Tweed, and it is convenient, therefore, to mention these two 
rivers specially, since they are, as it were, the homes of the separate 
forms. Parnell, in his essay on the Fishes of the Firth of Forth, 
describes and figures eight bull trout, to some of which he gives- 
the name of ‘salmon bull trout.’ These fishes are placed as 
varieties of the species S. eriox, and are, curiously enough, included 
in part by Gunther under his species S. trutta (Brit. Mus. Cat.,. 
vol. vi. p. 26). 
During last summer I had the opportunity of examining many 
Tay bull trout, and I am satisfied that this fish is the same as the 
‘ salmon bull trout ’ of Parnell ; and further, that it cannot be 
referred either to S. eriox or to S. trutta. 
The bull trout of the Tay grows to a size beyond that ever- 
attained by any variety of sea trout. Examples occur from 5 lbs. 
to 60 lbs. I have not myself seen any example approaching 60 lbs.,, 
and such are naturally extremely rare, but records in the possession 
of the Secretary of the Tay Salmon Fisheries Co. are sufficient to^ 
show that the fish attains as great weights as the salmon. During 
the past season two or three occurred well over 40 lbs., the heaviest- 
