Habitat and Biology
Climatic zone: Temperate. Bottom type: Unspecified. Depth zone: Coastal (0 m - 50 m); Shelf - Uppershelf (up to 100 m). Horizontal distribution: Littoral. Vertical distribution: Pelagic.
Jurisdictional distribution: Shared between nations
Considered a single stock: No
Sardine stocks distinguished by the
Working Group were the same as those used during the previous Working Groups (Figure 2.1.1):
- Sardine - Morocco (northern stock 35°45''-32°N)
- Sardine - Morocco (central A+B stock 32°N-26°N)
- Sardine - Southern stock C (26°N to southern limit of species distribution)
|Figure 2.1.1: Stock units and sardine fisheries/Unités de stock et pêcheries de sardine |
Sardine catches by fleet and by country are given in Table 2.2.1a. Total catches for the whole region are shown in Figure 2.2.1a.
The sardine catch in 2011 declined considerably compared with that of 2010 going from around 931 000 tonnes in 2010 to about 783 000 tonnes in 2011, a reduction of 16 percent (Figure 2.2.1a). About 73 percent of the catches are taken from the Moroccan zone and 26 percent from the Mauritanian zone. The catch from the Senegalese zone is small with around 0.4 percent of the total in the subregion.
Sardine production in the Moroccan Atlantic zone decreased significantly in 2011 compared with the previous year, from a sardine catch of about 805 000 tonnes in 2010 to around 575 000 tonnes in 2011, representing a reduction of 29 percent. The sardine catch recorded in Zone B constitutes 59 percent of the total sardine catch in Morocco. Catches of this species recorded in Zone C, Zone A and Zone North represent 37 percent, 3 percent and 2 percent respectively of the total catch landed in Moroccan ports.
In Zone B, the catch in 2011 decreased by 29 percent compared with 2010, from about 590 000 tonnes in 2009 to below 340 000 tonnes in 2011. In Zone C, the total sardine catch also declined by 28 percent in 2011 compared with 2010, going from a catch of around 294 000 tonnes to a catch of about 210 000 tonnes. The Moroccan fleet and the vessels chartered by Moroccan companies took 83 percent of this catch, the Russian fleet 12 percent and the European Union (EU) fleet 4 percent.
In the Mauritanian zone, the total catch of sardine increased sharply by 64 percent, from a catch of 125 000 tonnes in 2010 to around 205 000 tonnes in 2011.
In Senegal, landings of sardine by the artisanal fleet decreased from around 18 tonnes in 2010 to about 3 390 tonnes in 2011. No catch was reported for the industrial fleetFishing effort
Effort by fleet and by country is given in Table 2.2.1b.
Sardine is fished in the northwest African region by national fleets and foreign fleets which operate under fishing agreements or under charter arrangements.
In Morocco, the sardine fishery in 2011 was carried out by a heterogeneous fleet consisting of traditional coastal purse seiners, modern vessels equipped with refrigerated seawater (RSW) tanks and pelagic freezer trawlers. In the north zone, the sardine is fished by a Moroccan coastal fleet whose effort is yet to be determined. In Zones A+B, the sardine is fished exclusively by traditional coastal purse seiners. In terms of positive fishing trips (trips with catches of sardine), fishing effort increased in Zone A, from nearly 4 100 trips in 2010 to more than 7 700 trips in 2011. In Zone B, effort in terms of positive fishing trips decreased to around 14 700 trips in 2011.
In Zone C, the effort by the Moroccan purse seiners decreased in 2011 compared with 2010, from around 5 300 trips to 4 300 trips. The effort recorded for Moroccan RSW vessels show a slight increase of around 7 percent compared with 2010. The effort by Russian pelagic trawlers also decreased to 510 fishing days in 2011. No effort was reported for the EU fleet which operated in the Zone C before fishing was stopped from November 2011.
In the Mauritanian zone, the sardine was fished in 2011 by a fleet consisting of pelagic freezer trawlers operating under Mauritania˗EU, Mauritania˗Russia fishery agreements and under charter arrangements. The fishing effort reported for the series shows the effort in 2011 was the highest, with about 17 400 fishing days.
In Senegal, the sardine is fished only occasionally by both the industrial fleet and the artisanal fleet. It is noted that the fishing effort of the artisanal fishery declined to around 10 percent compared with 2010.
Schaefer dynamic production model
The Schaefer dynamic production model was run to assess the exploitation level of the sardine stock A+B (Cap Cantin–Cap Boujdor) and the sardine stock C (Cap Boujdor to Senegal. Due to the lack of the abundance indices of both stocks in 2011, the same indices of 2010 were used for that year. The model was implemented on an Excel spreadsheet (Appendix II). For the estimation of biological reference points (BRPs) adopted during previous meetings, the indices Bcur
have been used as limit reference points, whereas the indices Bcur
have been chosen as target reference points for management recommendations.
The Working Group used the total catches in Zones A+B and Zone C for the years 1995 to 2011. The Nansen series (Chapter 1.7) was used as abundance index to fit the model for the two zones (Chapter 2.3.2). However, as no estimation for the last year was available, the same abundance index of 2010 was used for 2011 in the two assessments.
Length Cohort Analysis
Essays were also performed for both stocks by applying the yield-per-recruit model of Thomson and Bell and the LCA model for the stock A+B. Both models are described in Sparre and Venema (1996).
For the application of the LCA model to the sardine stock of Zones A+B, the Group used the sampling data of landings in Zones A+B in Morocco (INRH). An average of the length composition of the total catch for the period 2007–2011 was used. The final length composition contains individuals with lengths between 6 cm and 28 cm (Table 2.5.1a). For the assessment of stock C by the same method, the 2011 length composition of landings was estimated with samplings of Morocco landed by the Moroccan fleet (INRH) and the Russian fleet (AtlanNIRO) and of Mauritania catch by the Russian fleets (AtlantNIRO) and by the EU fleet landed in Las Palmas (IEO). An average final composition of the total catch for 2007–2011 was used, with lengths between 9 and 29.5 cm (Table 2.5.1 b).
Overall Assessment ResultsStock A+B
The fit of the dynamic production model was not satisfactory for stock A+B. In addition, the results obtained for the assessments of stock A+B by LCA and yield-per-recruit analysis were not good and could not be accepted by the Working Group. Therefore, taking into account the decrease of abundance indicator (CPUE) of the sardine during 2011, the Working Group decided to keep the diagnostic of overexploitation from the last year. Stock C
The results of the production model for the stock C of sardine show that although the current level of exploitation remains below F0.1
(Figure 2.6.1c; 2.6.3b), the biomass in 2011 was also below the target biomass B0.1.
These results indicate that the stock is not fully exploited. Table 2.6.1c:
Summary of the results of fitting the Schaefer dynamic production model for the stock C of Sardina pilchardus
|Stock/abundance index ||Bcur/BMSY ||Bcur/B0.1 ||Fcur/FSycur ||Fcur/FMSY ||Fcur/F0.1 |
Sardine, Zone C/
Ratio between the estimated biomass for the last year of the series and the biomass corresponding to F0.1
: Ratio between the estimated biomass for the last year of the series and the biomass corresponding to F0.1
: Ratio between the observed fishing mortality coefficient for the last year of the series and that which would produce a sustainable catch at the current biomass level Fcur/FMSY
: Ratio between the observed fishing mortality coefficient for the last year of the series and that which would extract a maximum sustainable yield over the long term.Fcur/F0.1
:Ratio between the fishing mortality coefficients observed for the last year of the series and F0.1
Although unfortunately there is not an assessment of the sardine Zones A+B, the CPUE trend of the Moroccan fishery in this area shows a progressive decline of this resource since 2009. Furthermore, a progressive decrease of the sardine sizes has been detected from catches during these last three years. The trimodal length composition of 2011 catches was mainly composed of small individuals (16 cm mode), showing a length reduction from the year before of 2 cm.
This CPUE decrease of the sardine abundance in Zones A+B is coincidental with a CPUE increase in Zone C in the same period 2009–2011. These could be attributed to certain environmental conditions that favoured good recruitments of the sardine in the southern area. However, the acoustic estimations of the R/V ATLANTIDA show an important decrease of the sardine biomass in the area between Cap Juby and Cap Blanc in 2011.
The Working Group proceeded to make projections of catch and abundance for the next five years for stock C. The Status quo scenario was examined for Zone C. Maintaining effort at its current level would lead to a catch increase in 2012 and in subsequent years with stabilization below FMSY
. In the same way, the abundance would increase and subsequently stabilize at a level above the target biomass B0.1
The projections presented should be treated with a great deal of caution taking into account the effects of the environment on the abundance and dynamics of the stocks, which could be subject to strong variations that are not related to the fishery. Furthermore, it should be kept in mind that the abundance index of the last year used as an input data of the production model is not a real estimation but the same data that the previous year.
Scientific AdviceFuture research
The recommendations made in 2011 could not be put into effect during the period of intersession. Some progress was made in Mauritania and Senegal in measuring the sardine length to ½ cm. Yet, it is essential to follow up on these recommendations in order to improve the assessment of the sardine stocks.
The following recommendations have therefore been retained:
for Management consideration Stock A+B
- Continue estimating the stock abundance for the whole region through coordinated regional surveys between the national research vessels of the region, and carry out acoustic surveys throughout the subregion.
- Sardine length should be measured to ½ cm below the sampling level of catches obtained in Mauritania and Senegal.
- Maintain the age-reading exchange programme between the countries in the region.
- Undertake age reading in Zone C.
- Analysis of length frequency distribution with the purpose of using these in structural models.
- Compilation of fishing effort series of all fleets operating in the subregion.
The Working Group is concerned about the current state of the central stock. It notes that the stock is highly dependent on recruitment which fluctuates with changes in the environment.
The Working Group recommends that the 2012 total catches should not exceed the 2011 level. Stock C
The total catch level should be adjusted to natural changes in the stock. The stock structure and abundance should be closely monitored by fishery independent methods.
Biological State and Trend
Sardine - Morocco (northern stock 35°45'-32°N)
Sardine - Morocco (central A+B stock 32°N-26°N)
Sardina pilchardus - Southern stock C (26°N to southern limit of species distribution)
Sardine in zone C is not fully exploited
Source of information
Report of the FAO Working Group on the Assessment of Small Pelagic Fish off Northwest Africa./Rapport du groupe de travail de la fao sur l’évaluation des petits pélagiques au large de l’afrique nord-occidentale. Dakar, Senegal, 21–25 May 2012. http://www.fao.org/docrep/019/i3346b/i3346b.pdf