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Madeiran sardinella and Round sardinella - Benin, Côte d'Ivoire, Ghana and Togo
Marine Resource  Fact Sheet
Status of stocks and resources 2009
Madeiran sardinella and Round sardinella - Benin, Côte d'Ivoire, Ghana and Togo
Fact Sheet Citation  
Sardinella maderensis and Sardinella aurita - Western Stocks
Owned byFood and Agriculture Organization (FAO) – More
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Species:
Geographic extent of Madeiran sardinella and Round sardinella - Benin, Côte d'Ivoire, Ghana and Togo
Main Descriptors
Considered a single stock: No        Spatial Scale: Sub-Regional
Reference Year: 2008
 
 
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.  

Geographical Distribution
Jurisdictional distribution: Shared between nations

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
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).
Exploitation
 

The catches are dominated by S. aurita off Ghana and Togo while S. maderensis is the dominant species off Benin. The two sardinellas are exploited mainly by the artisanal fleets in Ghana, Togo and Benin and to a lesser extent by the semi-industrial (inshore) fleet and the industrial fish trawlers in Ghana and Côte d’Ivoire. In the three countries, the artisanal fleet uses either artisanal purse seine gear (locally called Poli/Watsa) or beach seine to exploit the two species.

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.
Peak catches of the two species occur in June–September which coincides with the major upwelling period in the area. Fishing effort on sardinella in this region is mainly from the artisanal sector. Ghana has the largest series of effort for sardinella in the region, from 1990 to 2008 for inshore fishery. The catch appears to be stable between 1992 and 2000 followed by fluctuations around 80 000 tonnes. In general, catches of the western stock for Sardinella aurita has shown a declining state since 2004.
Assessment
 
Assessment Model
Type:  Others

The dynamic production model implemented on an Excel spreadsheet was used (Appendix II).
Standardised CPUE
Results

The model fitted reasonably well for all the above stocks selected (Figures 2.6.2a,b). A summary of the results of the assessments is presented in Table 2.6.2. For Sardinella aurita the current biomass level Bcur of the stock is less than the biomass at B0.1, although the current fishing mortality for the S. aurita is less than FMSY (Fcur/FMSY= 58%) that will bring the stock to sustainable levels. The model fits reasonably well the data for S. maderensis (Table 2.6.3). The current biomass is 10 percent less than B0.1 and the current fishing mortality is 10 percent higher than the fishing mortality that will bring the stock to a sustainable level.

Table 2.6.2: Summary of the results for the Sardinella aurita and S. maderensis in the western stock
Stock/abundance index Bcur/B0.1 Fcur/FSYcur Fcur/FMSY Fcur/F0.1
S. aurita (West/CPUE Ghana inshore) 58% 43% 58% 65%
S. maderensis (West/CPUE Ghana artisanal) 90% 110% 112% 124%

Bcur/B0.1: Relationship between the estimated biomass for the last year and the corresponding biomass at F0.1.

Fcur/FSYcur: 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.

Fcur/FMSY: 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.

Fcur/F0.1: Relationship between the fishing mortality coefficient observed over the last year of the series F0.1.
Scientific Advice

Future research

  • 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.


for Management consideration

The stock of S. aurita is overexploited in biomass, hence, as a precautionary measure, catches should not exceed 40 000 tonnes annually. The stock of S. maderensis is fully exploited. Any further increase in effort in the fishery could lead to higher fishing mortality thus reducing the biomass. Though S. maderensis is fully exploited, catches should not exceed the average of the last five years (20 000 tonnes).
Biological State and Trend
 
Sardinella aurita
 Exploitation state: OverexploitedExploitation rate: Fcur/F0.1: 65%
Sardinella maderensis
 Exploitation state: Fully exploitedExploitation rate: Fcur/F0.1: 124%
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. Click to openhttp://www.fao.org/docrep/018/i2909b/i2909b.pdf
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