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Relationship Retween Food Supply and Condition of Wild Brown Trout, Salmo trutta Linnaeus, in a Michigan Stream
Author(s) -
ELLIS ROBERT J.,
GOWING HOWARD
Publication year - 1957
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.1957.2.4.0299
Subject(s) - brown trout , salmo , trout , fauna , productivity , fishery , fish <actinopterygii> , biology , environmental science , abundance (ecology) , ecology , invertebrate , zoology , macroeconomics , economics
Field study revealed great differences in the biological productivity of two adjacent areas of a Michigan trout stream resulting from the entrance of domestic sewage into the stream between the two areas. Monthly samples were collected from the two areas to determine the seasonal cycles in abundance of bottom fauna, feeding habits of the trout, and coefficient of condition of the brown trout. In the less productive area upstream, a paucity of food of aquatic origin caused a sharp decline in condition of the fish, a reduction in the quantity of food per stomach, and a shift to a diet containing a considerable portion of terrestrial organisms. In the more productive area downstream (which, throughout the year, had a greater volume of bottom fauna than the unproductive area) trout maintained a significantly higher and much less variable coefficient of condition, their stomachs contained more food in midsummer and did not show the increase in terrestrial foods.