26 / 74
26
5.4. Tuna and Billfish
The tuna species, which include
Thunnus albacares
(yellowfin tuna),
Katsuwonus pelamis
(skipjack) and
Euthynnus alletterates
(little tuna) are associated with
upwelling zones. Tuna stocks are in good condition and
improving according to results of the present assessment.
5.5. Inner shelf (0–50m) demersal fish
assemblages
The shelf demersal stocks include mainly the sciaenial
fauna. Members of the sciaenial assemblage live above
the thermocline on shallow muddy bottoms. Some 60–80
species have been identified with the dominant ones being
Pseudotolithus elongatus
,
Drepane africana
,
Cynoglossus
goreensis
,
Arius lasticutus
and
Dasyatis margarita
.
These stocks are under pressure from artisanal fishermen
and from commercial trawlers (Fig. 5.2). They are in poor
condition and in a state of decline according to results of
stock assessments and the present assessment.
5.6. Outer shelf (50–200) demersal and
benthopelagic fish assemblages
According to the assessment and results of stock assessment
surveys (2005, 2010) these assemblages are in good
condition and stable.
5.7. Slope-demersal fish assemblages (>200m)
According to the results of stock assessment surveys; (2005,
2010) these assemblages are in good condition.
5.8. Meso-pelagic fish assemblages
These assemblages are in good and stable condition.
5.9. Small pelagics – inner shelf (0–50)
These fisheries are in a poor and declining condition.
5.10. Small pelagics – outer shelf (50–200)
Stocks of small pelagics are in good but declining
condition.
5.11. Inner shelf Shell Fish (Invertebrates,
Squid, Crustaceans etc.)
The two species of Cuttle fish,
Sepia officinalis
and
Sepia
berthelotii
are found in the north and south of the EEZ on
coarse ground at depths of 17–18m. There are four squid
species;
Thysanoteuthis rhombus
and
Toderopsis eblanae
are demersal below 1000 meter depth.
Molluscs such as bivalves are commercially important
shell fish resources for the coastal communities.
Mangrove oyster (
Crassostrea tulipa
) can be found on the
roots of mangrove trees in coastal swamps and estuaries
where they are harvested for subsistence as well as for
commercial purposes. Other bivalves exploited include
clams such as
Senilia senilis
,
Anadara senegalensis
, cockles
and periwinkles (
Tympanotonus
spp.).
The Inner shelf shell fish populations are assessed to be
in good condition.
5.12. Outer shelf and inner slope
invertebrate species
The invertebrate species of the outer shelf and inner
slope also consist of the shrimps, cuttlefish and squid.
These stocks are being exploited by commercial
trawlers. They are in good condition according to
results of the present assessment.
Figure 5.2:
Fish landings Sierra Leone
(Sea Around Us project 2011)