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Distribution, Growth, and Feeding of Postemergent Grayling Thymallus thymallus in an English River
Author(s) -
Scott Alasdair
Publication year - 1985
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1985)114<525:dgafop>2.0.co;2
Subject(s) - grayling , predation , biology , fish measurement , fishery , larva , benthic zone , juvenile fish , invertebrate , fish <actinopterygii> , zoology , ecology
Postemergent larval grayling (15–28 mm fork length) were sampled from the River Frome, Dorset, between 19 April and 9 May 1983. They occupied surface waters close to river banks until they reached lengths greater than 25 mm, when they migrated to near‐benthic habitats. The fish were distributed in areas where water velocity was between 3 and 9 body lengths˙s −1 . While in the surface waters, the grayling fed exclusively on invertebrates drifting on or near the surface; larval, pupal, and adult chironomids accounted numerically for 80–90% of the diet. The fish ceased feeding at night and elected prey larger than 2 mm during the day. Food passed through the gut in 6.5 h when fish fed ad libitum, but took 9 h following a single meal. Comparisons of the amount of food available in the river with that consumed by the fish indicated that prey abundance was not a limiting factor to the growth of larval grayling in the River Frome during the early post‐emergence period.