Temperature - European Investment Bank

WEST AFRICAN POWER POOL (WAPP) PÖYRY ENERGY LTD.
Mount Coffee HPP ESIA and RAP 2012-09-18
ESIA Report Page 74
19 families have been identified, with Cichlidae, Cyprinidae, Clariidae, Mormyridae
and Alestidae being the most represented. Only 2 species, Labeo curriei and Doumea
chappuisi, are listed as vulnerable in the IUCN list; Labeo curriei, was observed having
significant contribution to fish production in the project area. Studies should focus on its
acclimatation for aquaculture, as contribution to its preservation. At least 4
families/species, namely Heterotis niloticus, Gymnarchus niloticus, Clarias gariepinus
and Lates niloticus are introduced from foreign river basins.
6 species have been selected as key species for the Mt. Coffee Project area either due to
their natural value or economic value. A short description on their life cycle is given
below:
Labeo curriei (rock fish) is vulnerable and has an economic value. The reproduction
cycle starts in the rainy season and last 9 to 11 months. Consequent ovulation is related
to rain and rises in water level; laying is total, spread over a relatively long period.
Female outnumbered males (1/1.42 sex ratio) and precocious sexual maturity of males
is observed in Labeo barbus batesi. Labeo sp. dwell in rocky or sandy substrate, and in
rapid flowing waters. They exploit all water strata, and show omnivorous feeding,
including microorganisms (diatoms), plant detritus, crustaceans and rotifers; some
preference for plants material. The growth is isometric (similar dual growth in length
and weight), with maximum size recorded attaining 50 cm in total length. Reproductive
patterns may justify the vulnerability of the species compared to spontaneous and multispawning
species such as tilapias.
Doumea chappuisi (Amphilidae) is vulnerable: Usually naked body, small size
species (11.4 cm maximum size observed), benthic. Given the fusiform body, pointed
head and small mouth, the fish is adapted to quick running water, making it a vulnerable
species in case of impoundment. Few observations reported on the life cycle of the
species.
Barbus sp (horse fish) has an economic value: Large Barbus (big size) show normal
well developed lips sometimes forming a mental lobe (differently to Labeo sp whose
mouth opening is bottom oriented). 65 cm specimen were observed in Barbus bynni
occidentalis. Barbus sp. are usually bottom strata feeders of insect larva, mollusks,
aquatic weeds, but also copepods, ostracods, filamentous algae, crayfish and crabs,
terrestrial insects and small fish. As the Labeo, Barbus sp perform reproductive
migration upstream of the junction of small quick running water course during specific
seasons of the year. Building of impoundment without developing corrective measures
may threaten the sustainability of the species.
Tilapia (Ph or Ngoukna) has an economic value: Tilapia gonads are differentiated a
few weeks after hatching, and sexual maturity is attained rapidly (within 6 months in
natural water bodies, less than 3 months in captivity). Successive breeding occurs, with
the same female spawning several times successively with few weeks interval,
continuously. Social contact (e.g. ponds conditions) increases spawning frequency. This
excessive spawning capability has led in culture conditions to adopt polyculture with a
predator fish to control tilapia offspring, and generally for Oreochromis sp, to adopt
sex-reversed fry. Young thrive on zooplanktons, and become omnivorous with
preference to filamentous algae and macrophytes. In culture environment, tilapia has
ability to valorize different feeding niches of the earthen pond environment. Although
growth parameters remain among average, the above cited features made tilapia among
the first ranking bony fish cultivated.