262 



Appendices to Thirty -third Anmial Ueport 



It is certainly convenient that this definition should hold, since salmon, 

 grilse, and sea trout are all caught together by the same methods of 

 fishing, either in the sea or in the tidal waters of rivers ; since they are 

 somewhat similar in habit, and belong to the same genus. None the less 

 the curious anomaly remains that from the point of view of the systematic 

 ichthyologist, the sea trout is indistinguishable from the brown trout 

 which lives in fresh water. To separate them is simply a convenient 

 economic arrangement. 



The sea trout is a silvery migrating fish as it comes from the sea 

 to the river, and at such times it is sharply distinguished from the fresh- 

 water trout. Even after it has spent a considerable time in fresh water 

 and has spaAvned, it is still easily recognised, and so long as its habit of life is 

 similar to that of the salmon, no difficulty should arise. The brown trout 

 has a way, however, of descending to estuaries, of feeding upon marine 

 or estuarial food, and of gaining certain qualities which are associated 

 with salt water. When large trout with slightly silvery sides and slightly 

 yellow bellies are found in an estuary, the difficulty arises, — Are they 

 sea trout, i.e. salmon, or are they fresh- water trout ? The late Dr. 

 Giinther of the British Museum described several of these trout from 

 different localities, and regarded them as separate species. Thus the 

 well-known slob trout of Ireland he called Salmo estuarius, while the fish 

 of Orkney, which naturally passes to an.d fro in brackish water, he called 

 S. orcadensis. Any number of similar creatures are to be found in the 

 Outer Hebrides, wliile, as every trout angler knows, marked differences 

 are to be found in the general appearance of trout caughtjin a great 

 variety of lochs and streams in otir country. Even in onejsmall loch 

 trout of very different appearance may be obtained. I might mention 

 as an example, a small loch, inaccessible to migratory fish, high up in the 

 island of Raasay, between Skye and the mainland. Here ordinary little 

 red-speckled trout may be caught, and here also trout as clear and bright 

 as new silver. 



Similarly, in the case of Loch Leven trout, it was found many years 

 ago, when the late Sir James Gibson Maitland was a member of the 

 Fishery Board, and when the late Francis Day was experimenting at 

 Howietoun, that certain changes of feeding produced silvery red-fleshed 

 fish, or brown white-fleshed fish. Again, small red-speckled Dorsetshire 

 trout transported to New Zealand and put in a river where no salmonidse 

 previously existed, grew amazingly, went down to the sea, became per- 

 fectly silvery, and finally were described as pure sea trout. This New 

 Zealand experience is only a well-defined example of what our own British 

 trout have always been doing in a rather more obscure manner. 



There is only one species of British trout, whether fario or ferox, 

 levenensis or trutta, estuarius or orcadensis. If the fish of different 

 appearance, caught in different localities, be preserved, and if they be 

 compared after the external colouration and skin markings have faded, 

 they will all be found alike, so far as features of any specific value are 

 concerned. 



It need not follow, however, that names for local varieties may be given 

 up, any more than that the name sea trout or brown trout should be 

 given up. There is considerable interest in the features of a Loch Leven 

 trout or a Gillaroo. 



It is customary to distinguish two British races of sea trout, Salmo 

 trutta, the form we are most familiar with in Scotland, and S. cambricus, 

 the sewin of Wales and the south of England, and the white trout of 

 Ireland. In my view the so-called bull trout of the Tweed and Coquet 

 has an equal right to be regarded as a local race. I have elsewhere * 

 ♦ Proc. Roy. Sue. Edin. xxv., Part i. p. 27. 



