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Red mullet - Northern Tunisia, Gulf of Hammamet, Gulf of Gabes
Fact Sheet Title  Fact Sheet
Stock status report 2021
Red mullet - Northern Tunisia, Gulf of Hammamet, Gulf of Gabes
Fact Sheet Citation  
Mullus barbatus - Northern Tunisia, Gulf of Hammamet, Gulf of Gabes (GSAs 12-14)
Owned byGeneral Fisheries Commission for the Mediterranean (GFCM) – ownership
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Species List:
Species Ref: en - Red mullet, fr - Rouget de vase, es - Salmonete de fango, ru - Султанка обыкновенная (=барабулька)

Fishery Indicators
Production: Landed Volume
ident Block Red mullet - Northern Tunisia, Gulf of Hammamet, Gulf of Gabes
Aq Res
Biological Stock: No         Value: Sub-Regional
Reference year: 2019
 
 
Aq Res State Trend
Aq Res State Trend
Aq Res State Trend Aq Res State Trend
Aq Res State TrendIn overexploitation (F/Fref = 2.84)Not applicable
Aq Res State TrendNot applicable
Aq Res State Trend
Aq Res State TrendOverfished

In overexploitation.
[The GFCM methodology to provide stock status and management advice is described in the Appendix F of the Sixteenth Session of the Scientific Advisory Committee Report. See the Bibliography section.]
Habitat Bio
Climatic Zone: Temperate.   Bottom Type: Soft bottom.   Depth Zone: Shelf (50 m - 200 m).   Horizontal Dist: Neritic; Littoral.   Vertical Dist: Demersal/Benthic.  

Water Area Overview
Spatial Scale: Sub-Regional

Water Area Overview
Aq Res Struct
Biological Stock: No


Stock assessment in the GFCM area of application is often conducted by management units, based on GSAs. This method does not ensure that the whole stock is assessed, since stocks may cover several different management units. In some cases, when there is scientific evidence of a stock spreading through different GSAs, as well as information on species from different GSAs, existing information is combined across GSAs. This is then defined as a “joint stock assessment of a shared stock”. The GFCM recommends that when scientific evidence of shared stocks exists, joint stock assessments should be attempted. A number of activities aimed at achieving a better definition of stock boundaries are currently being conducted at the GFCM level. [The State of Mediterranean and Black Sea Fisheries, 2016]
Exploit
 

The red mullet is an important demersal species for commercial fisheries in GSAs 12-14. It is exploited by the trawl and small-scale fleet. Small gear (trammel nets and gillnets) account for 5 percent of the total landings of red mullet (average for the 2010-2019 period). Trawl fleet accounts for 2 707 tonnes (average for the 2010-2019 period). Trawl fishery exploits a highly diversified species assemblage, the main commercial species being the caramote prawn (Penaeus kerathurus), striped red mullet, European hake, sparid fish, common pandora (Pagellus erythrinus), annular sea bream (Diplodus annularis), gilthead sea bream (Sparus auratus). Catch lengths of red mullet range between 8 cm and 26 cm total length, with an average size of 14 cm total length.
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionLanded Volume 3 420.58tonnes2010
Landed Volume 2 700.43tonnes2011
Landed Volume 2 644.94tonnes2012
Landed Volume 2 357.54tonnes2013
Landed Volume 2 909.71tonnes2014
Landed Volume 2 929.49tonnes2015
Landed Volume 2 169.91tonnes2016
Landed Volume 2 347.82tonnes2017
Landed Volume 3 036.55tonnes2018
Landed Volume 2 551.6tonnes2019
Bio Assess
 
Data

Stock assessment of red mullet was carried out using the official Tunisian catch data of bottom trawling in GSAs 12-14. Number-at-age data from experimental trawl surveys carried out in the considered GSAs were used as tuning data. The vector of natural mortality by age was calculated using the Gislason model. The biological parameters used were: L∞ = 25.96, k = 0.309, t0 = 0.824, a =0.0044, b = 3.29 for combined sexes. Maturity by age data was estimated using the maturity ogive parameters of red mullet female.
Assess Models
Type:  Age-structured
XSA

The assessment was performed using XSA as implemented in the FLR. Model settings in terms of shrinkages and catchability of the best benchmark model (2018 GFCM benchmark session for the assessment of red mullet in GSAs 12-16 and 19) were assumed. According to the recommendations of the WG, current F was obtained as the average of three previous years (2017-2019).
Results

According to the recommendations of the WG, F(current) was estimated as the average of the last three years of the time series considered (2017-2019) and equal to 1.32; F0.1 was estimated using FLR routine.
Sci Advice

Reduce fishing mortality; STF available.
Sources
 
FAO. 2021. General Fisheries Commission for the Mediterranean (GFCM). Report of the twenty-second session of the Scientific Advisory Committee on Fisheries, online, 22–25 June 2021. FAO Fisheries and Aquaculture Report No. 1347. Rome. Click to openhttps://www.fao.org/3/cb7622en/cb7622en.pdf
Report of the Working Group on Stock Assessment of Demersal Species (WGSAD). Online, 18–23 January 2021. Click to openhttps://www.fao.org/gfcm/technical-meetings/detail/en/c/1412431/
GFCM Stock Assessment Results (STAR) for red mullet in GSAs 12-14 (reporting year: 2021). Click to openhttps://gfcm.sharepoint.com/EG/_layouts/15/download.aspx?share=EQtYLm0iFyNHtJ1-N-jfOH4BpiXmUyw07Uq71lnSwoS3Sw
Bibliography
 
FAO. 2020. The State of Mediterranean and Black Sea Fisheries 2020. General Fisheries Commission for the Mediterranean. Rome. Click to openhttps://www.fao.org/3/cb2427en/cb2427en.pdf
FAO. 2016. The State of Mediterranean and Black Sea Fisheries. General Fisheries Commission for the Mediterranean. Rome, Italy. Click to openhttps://www.fao.org/3/i5496e/i5496e.pdf
FAO General Fisheries Commission for the Mediterranean/Commission générale des pêches pour la Méditerranée. Report of the sixteenth session of the Scientific Advisory Committee. St. Julian’s, Malta, 17–20 March 2014/Rapport de la seizième session du Comité scientifique consultatif. Saint Julien, Malte, Malte, 17-20 mars 2014. FAO Fisheries and Aquaculture Report/FAO Rapport sur les pêches et l’aquaculture. No. R1102. Rome. 2015. 250 pp. Click to openhttps://www.fao.org/3/i4381b/i4381b.pdf
General Fisheries Commission for the Mediterranean (GFCM) Stock Assessment Results (STAR). Click to openhttps://www.fao.org/gfcm/data/star/en/
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