TROUT— VARIATIONS IN COLOUR. 145 



from Carlisle passing from the salmon-trout grilse or wbiLling into that of the 

 frcsli-wator tront. 



The next form I propose adverting to is the Lochleven trout, Avhich miglit 

 possibly be traced in its external ajipearance to the sea trout. In it there is normally 

 a smolt stage in whieh the iish, subsequent to its par condition and for the third or 

 fourth sea.sons of its life,* is somewhat silvery, but without any orange edging to 

 the adipose dorsal fin usually present in young trout, and all the spots are generally 

 black. 



But subsequently, as already observed, it assumes most of the brook trout 

 colours, but without the wliite black-based margin to the front edge of the dorsal, 

 ventral, and anal fins. If the eggs, however, are sent to other and distant 

 localities, as Guildford, or even to Gloucestershire, the young reared from them 

 do not usually assume the colours seen in Lochleven or Howietoun, but 

 take on morfe or less those of the indigenous brook trout of the locality v.-hero 

 they are hatched and brought up {see plates v and vi). But this is not a 

 deteriorating race, because consequent on certain circumstances which Avill be 

 subsequently detailed {see Lochleven trout) when one of these lishcs in Glouces- 

 tershire obtained a large amount of food, owing to the removal of many of the others 

 from the pond, it grew more rapidly than its former fellows, and even had the 

 Lochleven colours, previously denied to the rest. Also, deteriorated examples 

 at Howietoun assume the brook trout livery, and even the orange edging to the 

 adipose dorsal fin, apparently owing to want of sufficient food or mal-assimilation 

 of it. A Lochleven trout having been crossed at Howietoun by a salmon-par, the 

 offspring possessed the orange-tipped adipose dorsal fin which is seen in the young 

 of .the sea and brook trout ; and it may be asked from whence could such have been 

 obtained, unless the Lochleven possessed blood of one of these races ? While the 

 male parent, being only a par, probably occasioned weakness in the constitution 

 of the offspring. In colours, then, we have a distinct chain connecting the sea 

 trout with the Lochleven, and so on into the brook trout forms. 



But silvery trout are not unknown in fresh waters ; thus at Loch Crasspuil 

 {see plate vi, fig. 3) exists a race of this colour, and in a locality where they are 

 unable to migrate seawards, still it has been surmised that originally they might 

 have been sprung from an introduced anadromous stock. While every year silvery 

 trout are captured in inland pieces of water unfrequented by sea trout,t and would 

 seem in some cases to be sterile forms, but in others to be examples reverting to 

 their ancestral colours. But we have some evidence to show that such a change 

 of colour might occur owing to local conditions as in the following instance. In 

 Land and Water, August I5th, 1885, Mr. Edon, of the Buckland Museum, 

 remarked upon the appearance of some ti'out in a loch in Ross-shire, 2200 feet 

 above the level of the sea and entirely fed by springs. Up to seventeen years 

 previously it had been troutless, and then Mr. Fowler turned in some small black 

 trout. In 1 885 it held a number of fine fish—'' those under 2 lb. were beautifully- 

 fed deep fish, silvery with a few faint red spots, more like sea trout {Salino 

 trntta) than /ar/o." Lastly, the late Mr. Arthur, of Otago, observed that some of 

 the descendants of our common brook trout sent to Australasia apparently have 

 commenced reverting to anadromous habits and colours, thus the largest trout 

 disappeared from the waters of the Lcith, except during the spawning season. 

 They evidently went to the salt water of Otago Harbour in search oi more water 

 and more food than could be got in the river. Common trout arc being constantly 

 caught in the fishermen's nets in the bay, and these show a tendency to acquire a 

 sea-lrout appearance, as they are usually very silvery, and the black spots are 

 often, but not always, X-shaped. 



I think in the few examples w^hich have been adduced (and they might be 

 largely increased) reasons have been shown for admitting that sea trout might 



* Dr. Giinther has raised the question that Loch Leven some twenty years since was partially 

 restocked with brook trout, but for this there does not appear to be the slightest foundation, as 

 will be more fully entered upon when describing the Lochleven variety. 



t See paper on The silvery trout from Loch Lomond, by l''raucis Day, Field, September 2Gth, 



10 



