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A total of 29 species or species groups have been assessed
(Fig. 5.1). On average biodiversity seems to be in good
condition. Several groups show a declining trend over
the past 5 years (e.g. inner shelf demersal and pelagic
fish species, terns). Condition of other species or species
groups seems to be stable. A discussion on the results is
provided below.
5.1. Dolphins
Little is known about the status of populations in Sierra
Leone with the exception of sporadic sightings. The
Atlantic Humpback dolphins (
Sousa teuszii
) frequently
occur in the artisanal bycatch. Other cetaceans include the
Clymene and common dolphins which are often sighted in
deep waters beyond the 50 m isobar.
According to results of the assessment, dolphin populations
are in a very good condition. This is because they are not
harvested.
5.2. West African Manatee (
Trichechus
senegalensis
)
A single representative of the Sirenean, the Africanmanatee
(
Trichechus senegalensis
) occurs in river estuaries of Sierra
5. Species
Leone. They frequently occur in the vicinity of the Ribbi
River, Bonthe, Gbondapi etc. The assessment revealed that
manatees are still in good condition.
5.3. Sharks and rays
Sharks andrays areexploitedusingbottomsetnets respectively
and their fishing efficiencies are subject to environmental
variability. The artisanal fish landings for sharks appear to
be at a peak in the dry season (March–April) and generally
lower in rainy season (June–August). The reason for the
apparent differences in seasonal shark landings has been
attributed to the turbulence in the water column as a result
of the ensuing tidal current caused by the rains. The situation
would normally create difficulty in setting the net and hence
undermine catchability and landings of shark species.
The dominant ray species in shrimp trawl fisheries are
Dasyatis pastinaca
(44%) and
D. margarita
(23%). The
shark species are dominated by
Sphyrna lewini
(72%)
and
Carcharhinus obscurus
(15%). In the case of finfish
demersal trawl fisheries, the dominant shark species are
Carcharadon carcharias
(44%),
Carcharhinus brevipina
(15%) and
Sphyrna lewini
(15%).
These stocks are under pressure from commercial trawlers.