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Lesser African threadfin - Côte d'Ivoire, Ghana, Togo and Benin
Marine Resource  Fact Sheet
CECAF Scientific advice 2016
Lesser African threadfin - Côte d'Ivoire, Ghana, Togo and Benin
Fact Sheet Citation  
Petit capitaine (Galeoides decadactylus) - Côte d'Ivoire, Ghana, Togo et Bénin
Owned byFood and Agriculture Organization (FAO) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Lesser African threadfin, fr - Petit capitaine, es - Barbudo enano africano

Fishery Indicators
Production: Catch
Geographic extent of Lesser African threadfin - Côte d'Ivoire, Ghana, Togo and Benin
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Regional
Management unit: Yes        Reference year: 2010
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateFcur/F0.1 = 158%; Fcur/FMSY = 142%Not applicable
Abundance levelBcur/B0.1 = 50% ; Bcur/BMSY = 55%Not applicable
FAO Categories
Exploitation stateOverexploited

Fcur/F0.1: Ratio between the observed fishing mortality coefficient during the last year of the series and F0.1.
Fcur/FMSY: Ratio between the observed fishing mortality coefficient during the last year of the series and the coefficient that would give a maximum sustainable yield over the long term.
Bcur/B0.1: Ratio between the estimated biomass for the last year and the biomass corresponding to F0.1.
Bcur/BMSY: Ratio between the estimated biomass for the last year and the biomass corresponding to FMSY.
Unless otherwise indicated, the indicators were based on the Schaefer dynamic production stock assessment model.
Habitat and Biology
Climatic zone: Tropical.   Bottom type: Soft bottom clean sand; Soft bottom muddy or muddy-sand.   Depth zone: Coastal (0 m - 50 m).   Horizontal distribution: Littoral.   Vertical distribution: Demersal.  

Geographical Distribution
Jurisdictional distribution: Shared between nations

Water Area Overview
Spatial Scale: Regional

Geo References
Resource Structure
Considered a single stock: Yes


The Working Group considered a single stock of Galeoides decadactylus for this study zone.
Exploitation
 
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionCatch 2212tonnes1990
Catch 2924tonnes1991
Catch 2254tonnes1992
Catch 2437tonnes1993
Catch 2472tonnes1994
Catch 2412tonnes1995
Catch 3601tonnes1996
Catch 1718tonnes1997
Catch 1466tonnes1998
Catch 1502tonnes1999
Catch 2537tonnes2000
Catch 3622tonnes2001
Catch 2922tonnes2002
Catch 2645tonnes2003
Catch 3568tonnes2004
Catch 2774tonnes2005
Catch 3980tonnes2006
Catch 2859tonnes2007
Catch 2826tonnes2008
Catch 1954tonnes2009
Catch 2088tonnes2010
Assessment
 

Assessment year: 2011
The CECAF Working Groups have adopted the following Biological Reference Points (BRPs):
- Limit Reference points: BMSY and FMSY
- Target Reference Points: B0.1 and F0.1
Stock status is assigned based on current estimates of fishing mortality (Fcur) and biomass (Bcur) relative to these target and limit reference points (Bcur/BMSY, Fcur/FMSY, Bcur/B0.1, Fcur/F0.1). The results from the stock assessment of this stock are found under the “Biological state and trend section”.
Assessment Model
Type:  Biomass-aggregated
Schaefer dynamic production model

The input prepared to assess Galeoides decadactylus by the FAO/CECAF Working Group on the Assessment of Demersal Resources Subgroup South were the series of total catch from 1990 to 2010. As an abundance index, the CPUEs of the Côte d’Ivoire industrial fleet were adopted. The input parameters in the spreadsheet were estimated as follows: r (intrinsic growth rate)=0.55; K (initial biomass)= 5000 tonnes and BI/K (biomass of the stock at the beginning of the data series, compared with the initial biomass) = 40 percent.
Assessment Model
Type:  Size-structured
Length Cohort Analysis (LCA)

To apply the LCA model, the Working Group used the length frequency data of species/group of species of Côte d’Ivoire from 2006 to 2010. Figure 3.4.4a (FAO, 2015) shows the distribution of the length frequencies of Galeoides decadactylus in Côte d´Ivoire. The results show that the majority of the fish catch have a length between 12 and 19 cm. An extrapolation coefficient (total quantity of catches/total quantity of the sample) was applied to bring the length frequencies to the total catch of the zone. The FiSAT software was then used to determine the growth parameters (L∞, K, and M) for all the species. The parameters of the weightlength ratio (a and b) were obtained from the FishBase database. The final matrix involves the individuals of lengths between 9 and 55 cm (Figure 3.3.4a of FAO 2015).
Yield per Recruit Analysis (Y/R)
Overall Assessment Results

The fit of the model with the CPUE of the Côte d’Ivoire industrial fleet is satisfactory (Figure 3.4.4 of FAO, 2015). The results of the model in terms of biomass and fishing mortality indicate that the Galeoides decadactylus stock is overexploited. The current biomass is about half of the biomass of the target reference point B0.1 (Bcur/B0.1). Fishing mortality is 58 percent higher than that corresponding to B0.1. Fcur is 2 percent lower than the mortality which would keep biomass at a sustainable level (Fcur/FsYcur) (Table 3.4.4 of FAO, 2015) [see also "Biological state and trend"]. The results of the LCA show that the majority of the fish catch have a length between 12 and 19cm. 
Scientific Advice

Given the results obtained from the assessment and the trends in CPUEs, the Working Group recommends a reduction in fishing effort. The total catch in the zone should not exceed the 2010 level (2500 tonnes).
Management
Management unit: Yes
Source of information
 
FAO. 2016. Fishery Committee for the Eastern Central Atlantic, Report of the seventh session of the Scientific Sub-Committee, Tenerife, Spain, 14–16 October 2015 / Comité des pêches pour l’Atlantique Centre-Est Rapport de la septième session du Sous-Comité scientifique. Tenerife, Espagne 14-16 octobre 2015. FAO Fisheries and Aquaculture Report / FAO Rapport sur les pêches et l’aquaculture No. 1128. Rome, Italy.  Click to openhttp://www.fao.org/3/a-i5301b.pdf
FAO. 2015. Report of the FAO/CECAF Working Group on the Assessment of Demersal Resources – Subgroup South. Accra, Ghana, 15–24 November 2011 / Rapport du Groupe de travail FAO/COPACE sur l’évaluation des ressources démersales – Sous-groupe Sud. Accra, Ghana, 15-24 novembre 2011. CECAF/ECAF Series/COPACE/PACE Séries. No. 15/76. Rome, Italy/Italie.  Click to openhttp://www.fao.org/3/a-i5138b.pdf
Bibliography
 
All references to figures, tables and bibliography in the text are found within the source of information.
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