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THE BIOLOGY OF LLYN TEGID TROUT 1960
Author(s) -
GRAHAM T. R.,
JONES J. W.
Publication year - 1962
Publication title -
proceedings of the zoological society of london
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0370-2774
DOI - 10.1111/j.1469-7998.1962.tb01598.x
Subject(s) - salmo , brown trout , trout , fish <actinopterygii> , productivity , biology , fishery , interim , range (aeronautics) , ecology , environmental science , geography , archaeology , engineering , macroeconomics , aerospace engineering , economics
This paper reports the results of an interim investigation into the biology of the brown trout ( Salmo trutta L.) of Llyn Tegid (Bala Lake), North Wales. Earlier investigations on the biology of the trout were completed before the controlled‐outflow scheme came into operation in 1955. This scheme has lowered the mean and range of the lake level. A comparison is made between the fish sampled in 1953/4 and those sampled in 1959/60. The latter fish showed a decrease in growth, condition, food intake and calorific value of the diet. It is concluded that the scheme is responsible for this by decreasing the productivity of the lake and by changing the quantitative composition of the bottom organisms consumed by the fish. It is suggested that these changes may be temporary.