dc.description.abstract | Habitat suitability indices indicate how
fish species respond to different habitat types. We
assessed effects of habitat characteristics on fish
distribution in an equatorial lake, Lake Naivasha,
Kenya, where habitats vary according to substrate,
depth and turbidity. Using monthly data between 2008
and 2010 using multi-mesh gill nets, catch per unit
effort was used as a relative abundance measure to
identify how habitat variables drive fish distribution.
The focus was on commercial fishes: two introduced
species (Cyprinus carpio and Micropterus salmoides)
and two naturalised species (Oreochromis leucostictus
and Tilapia zillii). Analyses revealed distinct preferences
for different habitat variables by all commercial
species except for C. carpio. For example, O. leucostictus
preferred shallow waters with silt–clay
substrates whilst M. salmoides preferred deeper waters
with sandy/rocky substrates. Conversely, C. carpio
showed no specialised habitat requirements. Niche
overlaps were significantly lower between O. leucostictus
and its respective sympatric species than
between other species, a likely result of its territorial
behaviour. The continued environmental degradation
of Lake Naivasha may imperil the preferred habitats of
the niche restricted M. salmoides, O. leucostictus and
T. zillii. By contrast, the ubiquity of C. carpio may
facilitate their invasion, and consequently sustain their
dominance in the lake’s commercial fishery. | en_US |