FRESH-WATER TROUT-LOCITLEVENS, LIFE HISTORY, ETC. 220 



Rurface as if they wove vcny uneasy. Should they l)c much fed at this period it 

 has boon thouglit that distension of tlio abdomen from food sometimes causes them 

 to prematurely extrude their eggs. Sometimes the old lish will even si)ring on to 

 the banks of the ponds, and so meet with their deaths. The kelts at Howietouu 

 commence feeding about a month after breeding. 



Life history.— It Avill bo very important to follow this out in the Lochlcvcn 

 trout, showing hoAV it may vary with changing circumstances, and consequently 

 supply an excellent example of how very variable arc these unstable forms, not 

 only in their external appearance, but also in their internal structure. The alevms 

 at Howietoun do not show a trace of orange on the adipose or dead fin of the back, 

 nor is it seen on either edge of the caudal : at Delaford, in April, 1887, I 

 similarly observed that this orange colour was absent. But at Mr. Andrews' at 

 Guildford, among those hatched from Howietoun eggs it was present in all (April, 

 1887), similarly to what existed in the brook trout raised from eggs obtained from 

 local forms. This must conclusively show that certain causes will occasion the 

 adipose dorsal fin* and the upper and lower margins of the caudal to take on an 

 orange colour similar to the common brook trout. Passing on to the fry, or those 

 which have absorbed the yelk-sac, we find that at about two months of age, or 

 even less, the finger marks shoAV themselves on the sides, and that prior to the 

 appearance of the scales. 



Lochleven Fishery.— At Lochleven the drainage works do not appear to have 

 proved beneficial to 'the trout in the loch, where from 1846 to 1855 the captures 

 principally taken by net averaged annually 13,200, subsequent to which figures 

 have not been obtained until 1872, when 18,000 were taken by anglers and 2000 

 by net : and in 1873, when 13,394 were taken by the rod. Latterly this loch has 

 been much frequented by anglers, and as the fish (probably due to the excessive 

 lowness of the burns) appear now to be less favourable for breeding, artificial 

 stocking has been resorted to.f 



Sir J. G. Maitland (Field, September 23rd, 1882) showed the results of 

 stocking this loch from his establishment at Howietoun : — 



: captures 5093 : average weight each 1-113 lb. 

 3227: „ „ 1-080 lb. 



6286: „ „ -901 lb. 



13,519: „ „ •685 1b. 



„ 21,491: „ „ -777 lb. 



„ 19,642: „ „ -900 lb. 



16,811: „ „ 1-050 lb. 



9415: „ „ 1011 lb. 



14,227: „ „ -913 Ih. 



15,940: „ „ -874 lb. 



, 16,775: „ „ •873 1b. 



12,157: „ ., -956 lb. 



Mv. Francis (Field, October 1st, 1881) observed that he was shown small 

 ponds at Sir James Maitland's at Howietoun, proving most conclusively that: — 



* Although I am unable to satisfy myself of the existence of rays in the adipose fin of young 

 trout, still they have been asserted to be present. Mr. Gorelwer observed, m the Transactions of 

 the Ea^t Kent Natural History Society, that this fin is " small and rudimentary, not unlike a fatty 

 layer in a thin skin-film, it is quite destitute of fat, and is kept extended by a thickly crowded set 

 of parallel and very delicate rays, extending from the back of the fish upwards to the free margin 

 of the fin, and often projecting a little beyond it, as one may witness by the help of an achromatic 

 object glass of half an inch focal length. These rays are indeed composed of a peculiar glassy 

 and homogeneous matter, like the intercellular part of true cartilage, quite structureless, and devoid 

 of cells ; nor have these rays any muscular provision for their motion which we know to belong to 

 true fins, neither have the rays of the adipose fin any resemblance in structure to the bony rays ot 

 other fins." . , i . i • 



t It was pointed out that it takes two seasons for the fry to attain to a useful size,_a conclusion 

 which agrees with the figures, also that with the increased takes at first there is a diminution m 

 the weight of the individual fish. ,,..•,, i t- t i 



+ Also in 1882, 3000 two-year-old fish from Howietoun were placed in the loch. Knox found 

 that Lochleven trout were filled with entomostraca in the month of January, but that during the 

 remainder of the year they lived on Buccinum : at Howietoun they thrive on clams, or horsellesn. 



