Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 355236
Title Spatial and seasonal patterns in the feeding habits of juvenile Lates niloticus (L.) in the Mwanza Gulf of Lake Victoria
Author(s) Katunzi, E.F.B.; Densen, W.L.T. van; Wanink, J.H.; White, F.
Source Hydrobiologia 568 (2006)1. - ISSN 0018-8158 - p. 121 - 133.
Department(s) Wageningen Marine Research
Publication type Refereed Article in a scientific journal
Publication year 2006
Keyword(s) ontogenic niche shifts - nile perch - east-africa - nyanza-gulf - rastrineobola-argentea - haplochromine cichlids - largemouth bass - life-history - fish - predation
Abstract Flexibility in the feeding habits of juvenile Nile perch (1¿30 cm total length) was studied from September 1988 to September 1989 at four sites (depth range: 1¿25 m) in the Mwanza Gulf of Lake Victoria. During this period haplochromine cichlids were virtually absent in the area. We looked at the combined effects of predator size, season and habitat. Stomach content analysis showed that with increase in size, the diet of Nile perch shifted from zooplankton and midge larvae, to macro-invertebrates (shrimps and dragonfly nymphs) and fish. At a size of 3¿4 cm Nile perch shifted from size-selective predation on the largest cyclopoids to predation on the largest, less abundant, calanoids. Zooplanktivory ended at a size of ca. 5 cm. Although an ontogenetic shift in the diet of juvenile Nile perch was obvious at all sampling stations, the contribution of prey types appeared to be habitat related. With increasing water depth the frequency of occurrence in the diet of most prey types decreased, but that of shrimps increased. At the entrance of the gulf (20¿25 m deep) shrimps were the main food source throughout the year. Halfway the gulf (12¿16 m), Nile perch showed seasonality in their feeding behaviour. Shrimps were taken there especially during the rainy season (January to May) when their densities at this station were high, whereas cannibalism prevailed during the rest of the year. In an environment with Nile perch and dagaa as alternative prey, shrimps were taken almost exclusively. They could be regarded as a key prey for Nile perch between 5 and 30 cm
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