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West African croakers - Guinea-Bissau and Guinea
Marine Resource  Fact Sheet
CECAF Scientific advice 2016
West African croakers - Guinea-Bissau and Guinea
Fact Sheet Citation  
Otoliths (Pseudotolithus spp) - Guinée-Bissau et Guinée
Owned byFood and Agriculture Organization (FAO) – More
Monitoring periodPreviously monitored as: West African croakers - Guinea
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Related observationsLocate in inventorydisplay tree map
 
Species:
Geographic extent of West African croakers - Guinea-Bissau and Guinea
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Regional
Management unit: Yes        Reference year: 2009
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateFcur/F0.1 = 105% ; Fcur/FMSY = 95%Not applicable
Abundance levelBcur/B0.1 = 65% ; Bcur/BMSY = 72%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/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 the current biomass level.
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: Estuarine; Neritic.   Vertical distribution: Demersal/Benthic.  

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 has considered a single stock of Pseudotolithus spp. for the assessment of Guinea- Bissau and Guinea.
Exploitation
 
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionCatch 6255tonnes1994
Catch 11100tonnes1995
Catch 12224tonnes1996
Catch 11467tonnes1997
Catch 10768tonnes1998
Catch 9972tonnes1999
Catch 12505tonnes2000
Catch 12666tonnes2001
Catch 11221tonnes2002
Catch 13491tonnes2003
Catch 15147tonnes2004
Catch 19312tonnes2005
Catch 11735tonnes2006
Catch 12246tonnes2007
Catch 7954tonnes2008
Catch 7005tonnes2009
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 total catches of Pseudotolithus spp. for Guinea-Bissau and Guinea for the period 1995-2009 were used. The catches of Guinea-Bissau were estimated6 for the periods 1998-1999 and 2002-2004. Those of Guinea for the year 2009 were estimated assuming the exploitation was the same as in 2008. The abundance indices used were those from scientific surveys carried out in Guinea. The Working Group considered that these data better reflected the abundance of this group of species than the CPUE of other types of fleets of the two countries. The initial input parameters were r (intrinsic growth rate) = 2.30; K (initial biomass) = 20 000 and BI/K (biomass of the stock at the beginning of the data series, compared with the initial biomass) = 74 percent.
Overall Assessment Results

The model provides a satisfactory fit to the data. The overall result is that the stock is overexploited. However, the other information on the fishery shows that the Pseudotolithus spp. stock is fully exploited.
Scientific Advice

Reduction in the fishing effort compared with the 2009 level. The total catch should not exceed the 2009 catch (7 000 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
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