Biological State and Trend
Habitat and Biology
Climatic zone: Tropical. 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 zone 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 northern (Guinea-Bissau, Guinea, Sierra Leone and Liberia), western (Côte d’Ivoire, Togo, Ghana, Togo and Benin), central (Nigeria and Cameroon) and southern (Gabon, DR Congo, Congo and Angola) (Figure 2.1.1).
Since no participants were present from Congo, the data from this country are not included in the analysis. Artisanal fleets form the main fishing fleet for the sardinellas in this region. Surface gillnets operated from canoes are employed in the artisanal fishery while the industrial fleet uses pelagic trawl. The dominant species off DR Congo is S. maderensis
. While this species occurs all year round, S. aurita
is most abundant between May and September. Off DR Congo, the species are exploited by both artisanal and industrial fleets. Surface gillnets operated from canoes are employed in the artisanal fishery while the industrial fleet use pelagic trawl.
In Angola the two species were proportional, S. maderensis
occurs inshore and S. aurita
occurs offshore. The abundance of sardinellas is linked to the upwelling periods. They are exploited by both the artisanal and semi-industrial fleets. The industrial pelagic trawling was closed in 2004. The purse seiners and artisanal gears mainly exploit the sardinellas. Sardinella maderensis
is also the dominant of the two species off Angola and occurs in coastal waters, whereas S. aurita
occurs offshore. The abundance of sardinellas is linked to the upwelling periods.Catch
The catches of sardinella are shown in Tables 2.2.1a,b,c. Effort is shown in Table 2.2.2 and Figures 2.2.2a,b.
The catch data series from DR Congo are very low compared to the entire region to explain clear variations. However, S. aurita dominates the catch in this country.The dominant catch in this region is Sardinella aurita
which is mainly caught by Angola. The catches and effort of Sardinella aurita
and Sardinella maderensis
of DR Congo are very low. The main fishery for sardinella in the south is the artisanal fishery.
The dynamic production model implemented on an Excel spreadsheet was used (Appendix II).
A summary of the results of the assessments is presented in Table 2.6.3. The results of the assessment show that the current biomass is 49 percent above B0.1
showing that the stock is moderately exploited. The current fishing mortality is below F0.1
and below the fishing mortality that will provide sustainable yield in the long term. Table 2.6.3
: Summary of the results for the Sardinella
Southern stock (Angola, Gabon, DR Congo and Congo)
|Stock/abundance index ||Bcur/B0.1 ||Fcur/FSYcur ||Fcur/FMSY ||Fcur/F0.1 |
|Sardinella spp. (South/CPUE Angola Nansen) ||149% ||149% ||55% ||61% |
: Relationship between the estimated biomass for the last year and the corresponding biomass at F0.1
: Relationship between the fishing mortality coefficient observed over the last year of the series and the coefficient that would provide a sustainable yield at the current biomass level.
: Relationship between the fishing mortality coefficient observed over the last year of the series and the coefficient that would provide a sustainable yield over the long term.
: Relationship between the fishing mortality coefficient observed over the last year of the series F0.1
The model shows that Sardinella
spp. in the south is moderately exploited. This result was confirmed by LCA analysis. However the result should be interpreted with caution because of uncertainties in the data due to data declaration bottlenecks. No data were available for Congo for the last three years series. The same catch data in 2005 were used for the series of 2006 to 2008. This is a major limitation of the assessment.
Scientific AdviceFuture research
for Management consideration
- Fisheries research should be emphasized for all the regions. Data collection schemes should be improved and effort should be made to collect data on species basis in the artisanal and industrial fisheries.
- Intensify biological sampling for better estimates of growth, mortality and abundance indices.
- Identification of species especially the Carangidae and Sardinella.
- Continue with Nansen surveys to obtain fisheries independent data.
- To obtain better abundance indices of the sardinellas below the 30 metres depth contour.
- To better understand interactions between the resource and the environment.
- Adoption of a systematic sampling programme for the collection of catch and effort data for all fleet.
No catch value limit is recommended for this stock. However, data collection and declaration consistencies are recommended. As a precautionary measure, it is suggested not to increase catches of these species.
Source of information
Report of the FAO/CECAF Working Group on the Assessment of Small Pelagic Fish – Subgroup South Accra, Ghana, 19–28 October 2009./Rapport du Groupe de travail FAO/COPACE sur l'évaluation des petits poissons pélagiques – Sous-groupe Sud Accra, Ghana, 19-28 octobre 2009. http://www.fao.org/docrep/018/i2909b/i2909b.pdf