Temperature - European Investment Bank

WEST AFRICAN POWER POOL (WAPP) PÖYRY ENERGY LTD.
Mount Coffee HPP ESIA and RAP 2012-09-18
ESIA Report Page 69
environments. This explains the population decrease/disappearance of running water
species within the reservoirs.
Most often, man-made lakes attract new fishermen, with the outbreak of new diseases of
which bilharziosis. To fight against this, it is recommended to reinforce stocks of
species capable of contributing to a biological fight against the intermediate host of the
disease, e.g. Heterotis niloticus. This species thrives best in shallow and calm water
bodies, where it can easily build nests for reproduction. It feeds on vegetation under
decomposition, insects, molluscs, worms and leeches. The arrival of new fishermen,
specifically those with better equipment and more experienced in fishing than the local
population can also generate conflicts; in this respect, measures for community
management involving all stakeholders should be anticipated in this modified fishing
site deriving from the dam project, initially designed for the only electricity supply
purpose.
To sum up, benthic rocky species including Mormyriids usually disappear in reservoirs
with their habitats and feeding niches being covered with mud; intermediary species
including cyprinids (Labeo, Chrisichthys, Alestes, Brycionus) accommodate themselves,
although with diminishing population, while tilapias, as well as most of their natural
predators, proliferate. To secure biodiversity it may be necessary to facilitate the
upstream movement of some potamodromous species using punctual devices as stairs
and elevators predesigned while building the barrage.
Valorising reservoirs through stock enhancement:
China is the country where extensive aquaculture in man-made lakes is mastered.
Millions of Chinese carps are stocked in reservoirs and fishponds alike, with massive
maturing systems where night soil passing in specialised stations is treated and recycled
as water fertilization. More than 1.2 million tons of fish is yearly produced through this
system. Species composition (8 species occupying different habitats), densities and
stocking sizes (>14.7 cm) are scientifically established for optimum production (Li and
Xu, 1995). The productivity of stocked reservoirs averages 300 kg*ha -1 *y -1 (Welcomme
and Bartley, 1998; Lorenzen et al., 2001).
11.2 Methodology
11.2.1 Survey of Fishermen and Side Activities
Interviews were conducted using the Participatory Rural Appraisal method (PRA) to
appraise fishing activities in the project site. Given the limited time length of the
assignment, this method developed by social scientists focuses on local people's
knowledge to gather in a joint-learning process the most reliable data available on the
subject. The interview guide dealt with different aspects of fishing such as fishing gears
and methods, seasons, species, transformation, organization of the profession (presence
of common initiative groups, support from GOs/NGOs), and wishes in case the dam
may be rehabilitated. Information on fish farming activities in the area was also
collected while visiting some fish stations in the area.
Interviews were conducted on a distance of 8 km upstream and 6 km downstream of the
dam site, given logical observations on spot, e.g., scheduled water extension limit of the
future reservoir, and miscellaneous infrastructures linked to the proximity of Monrovia
and the sea, respectively. Individual interviews and group meetings were organized in