Browsing by Author "Chapman, Lauren"

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    Feeding ecology of the intensively fished Nile Perch, Lates niloticus, in Lake Victoria, Uganda
    (Aquatic Ecosystem Health & Management, 2014) Nkalubo, Winnie; Chapman, Lauren; Muyodi, Fredrick
    The diet of Nile Perch (8.0–121.0 cm total length [TL]) from the Ugandan waters of Lake Victoria was quantified through stomach content analysis of specimens collected from experimental catches and fish factory samples. A total of 7824 stomachs (5602 from experimental fishing and 2222 from factory samples) were examined, of which 34.8% contained food. Fish from the experimental catches were smaller (8.0–41.6 cm TL) and had a higher diversity of prey dominated by unidentifiable fish prey, haplochromine cichlids, Rastrineobola argentea, Odonata and Caridina nilotica, while larger fish (30.0–121.0 cm TL) from the factory samples had a predominance of fish remains and haplochromine cichlids. Nile Perch that had a high proportion of fish prey (versus invertebrates) in their stomachs showed a larger size for a given age, and were in a better condition (K = 1.24) than those that had primarily invertebrates (K = 1.10) in their stomachs. Nile Perch exhibited a much smaller size (15 cm versus 30 cm TL) at shift to piscivory in comparison to Nile Perch examined in earlier studies, when haplochromines were rare in Lake Victoria. The recovery of haplochromine cichlids coincident with declining Nile Perch densities illustrates the importance of developing sustainable management options that can define a proper balance between fishing mortality and Nile Perch predation.
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    Identification of migratory and spawning habitats of Clarias gariepinus (Burchell, 1822) in Lake Edward - Ishasha River watershed, Albertine Rift Valley, East Africa
    (International Journal of Fisheries and Aquatic Studies, 2015) Mbalassa, Mulongaibalu; Nshombo, Muderhwa; Eliezer Kateyo, Mujugu; Chapman, Lauren; Efitre, Jackson; Bwanika, Gladys
    Catfish (1103) were sampled twice monthly with beach-seines, tagged with external T-bar Anchor tags and released at four estuarine sites, in July – August; September - October 2011; February-March and; April - May 2012. The study aimed to identify catfish migratory and spawning habitats around Lake Edward watershed. The relocations for 115 C. gariepinus recaptured within the lake watershed were determined and spawning condition examined. About 73% of catfish were recaptured from the littoral, 11.3% from marginal wetlands, 8.7% from the pelagic, 3.5% from river mouths and river channel, respectively. Among the ripe females, about 46% were recaptured from the marginal wetlands, 23% from river channel, and about 15.5% from the littoral and river mouths, respectively. The selected habitats were identified as migratory and spawning grounds for C. gariepinus. These should be conserved and protected from human activities and development programs and their connectivity ensured.