Habitat and Biology
Climatic zone: Unspecified. Bottom type: Unspecified. Depth zone: Coastal (0 m - 50 m); Shelf (50 m - 200 m); Slope (200 m - 1000 m). Horizontal distribution: Unspecified. Vertical distribution: Pelagic.
Jurisdictional distribution: Shared between nations
Considered a single stock: No
Sardinellas caught in the southern CECAF Area from Guinea to Angola are composed of two species, the round sardinella (Sardinella aurita
) and the flat sardinella (Sardinella maderensis
). The surveys carried out in the CECAF area show that the two species are found in a vast area stretching from the southern Moroccan stock to south of Angola. The FAO/CECAF Working Group for the moment has agreed on the existence of four stocks for these two species in the Southern CECAF area. These are the northern (Guinea and Sierra Leone), western (Côte d’Ivoire, Togo, Ghana and Benin), central (Nigeria and Cameroon) and southern (Gabon, Congo and Angola).Northern stock (Guinea and Sierra Leone)
The Sardinella aurita
occur offshore and are exploited by the industrial pelagic trawlers of Guinea and shrimp trawlers of Sierra Leone. The pelagic trawlers in Guinea are about 70 m in length overall (LOA) with an engine power of over 2 000 hp. S. aurita
is the second most abundant fish after Decapterus
spp. in their catches. The shrimp trawlers of Sierra Leone fish the S. aurita as bycatch. The shrimpers are about 50 m in LOA with engine power of 600 hp. The S. maderensis
occur in coastal waters and are exploited by the artisanal canoes of both Guinea and Sierra Leone. In both countries, the artisanal canoes use ring nets to catch these species.
Catch and effort
The two species are caught all year round with peak periods in January–May and September–December. The peak catches coincide with the upwelling periods in the area.
The Schaefer logistic production model was used on an Excel worksheet.
Assessments were made for S. maderensis (north).
The input data was catch and effort data on S. maderensis
from the artisanal and industrial fisheries for the period 1995–2004 for Guinea and Sierra Leone data for 2002–2004. The CPUE of the Guinean artisanal fishery was used in the assessment.
Overall Assessment Results
The model fitted reasonably well for all the northern stock. A summary of the results of the assessments is presented in Table 1.
Table 1: Summary of the state of the stock
|S. maderensis north/CPUE_GuiArt/
Bcur/B0.1: Ratio between the estimated biomass for the last year and the biomass corresponding to F0.1.
Fcur/FSYcur: Ratio between the observed fishing mortality coefficient during the last year of the series and the coefficient that would give a sustainable yield at current biomass levels.
Fcur/FMSY: Ratio between the observed fishing mortality coefficient during the last year of the series and the coefficient giving maximum long term sustainable yield.
Fcur/F0.1: Ratio between the observed fishing mortality coefficient during the last year of the series and F0.
The main limitation to the assessment is non-availability of data for some countries in the region. In the north, Sierra Leone has a very short data time, while data for Côte d’Ivoire was not available for the western stock. With the exception of S. maderensis (west), the current biomass of the different stocks is less than the biomass at B0.1. The current fishing effort is greater than fishing effort at MSY and if effort is not reduced the stock level will decrease further in the future.
Scientific AdviceFuture research
for Management considerations
- Biological sampling intensification.
- Continue with Nansen surveys to obtain fisheries independent data.
- Adoption of a sampling programme for the commercial fleet.
Reduction in catch is recommended and there should be no licensing of new vessels. The canoe fleet numbers should be controlled.
S. aurita: As a precautionary measure, catch level should not exceed the average of the 5 last years (4 000 tonnes).
S. maderensis: As a precautionary measure, do not increase catches of this species until further analysis with more complete data on the stock is available.
Biological State and Trend
Sardinella maderensis (Northern stock)
Exploitation state: OverexploitedExploitation rate: Fcur/F0.1: 167%
Abundance level: Bcur/B0.1: 20 %
No reliable results for S. aurita. The CPUE series available shows an increasing trend until 2002.
Source of information
FAO Fishery Committee for the Eastern Central Atlantic/Comité des pêches pour l’Atlantique Centre-Est. “Report of the FAO/CECAF Working Group on the Assessment of Small Pelagic Fish – Subgroup South” Limbe, Cameroon, 25 September–1 October 2006
“Rapport du Groupe de travail FAO/COPACE sur l’évaluation des petits poissons pélagiques – Sous-Groupe Sud” Limbé, Cameroun, 25 septembre-1er octobre 2006
Rome, FAO . 2009
The bibliographic references are available in the report included in "Source of Information".