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The role of diel inshore movements by Clarias gariepinus (Pisces: Clariidae) for the capture of fish prey
Author(s) -
Bruton M. N.
Publication year - 1979
Publication title -
the transactions of the zoological society of london
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0084-5620
DOI - 10.1111/j.1096-3642.1979.tb00058.x
Subject(s) - diel vertical migration , predation , clarias gariepinus , biology , predator , fishery , fish <actinopterygii> , ecology , catfish
The diel movements of predator and prey populations of freshwater fish in a natural lake in south‐east Africa are described. The predator, Clarias gariepinus (Burchell) feeds in inshore areas at night although its main fish prey Sarotherodon mossambicus (Peters) mainly inhabits these areas during the day. Field and laboratory observations revealed that C. gariepinus has difficulty catching S. mossambicus during the day whereas this prey is more readily caught during the nocturnal inshore movement. Three factors were identified and shown to increase the predation efficiency of C. gariepinus on S. mossambicus (i) decreased water depth, (ii) decreased light intensity, (iii) increased predator numbers. By feeding in shallow areas as a group at night, C. gariepinus is able to catch fish prey which is normally too elusive. As fish prey contribute more energy than do invertebrate prey, C. gariepinus can afford to expend a considerable amount of energy on their capture, including that used during the diel inshore movements.