Habitat and Biology
Bottom type: Unspecified. Depth zone: Coastal (0 m - 50 m); Shelf (50 m - 200 m); Slope (200 m - 1000 m). Horizontal distribution: Neritic; Oceanic. Vertical distribution: Pelagic.
Jurisdictional distribution: Shared between nations
Considered a single stock: Yes
In the absence of studies on the stock identity of this species, the Working Group considers all anchovy in the whole subregion to belong to a single stock.
In the northwest region of Africa, anchovies are fished mainly in Morocco and Mauritania. In Morocco they are fished by a fleet of Moroccan sardine boats in Zone North, A+B, and in Zone North by a fleet of Spanish purse seiners. This species is not targeted by the industrial pelagic fishery in Mauritania, which takes it only as bycatch. Total catches
Catches of anchovy are shown in Table 6.2.1 and Figure 6.2.1. In 2011, catches of anchovy in the subregion increased slightly by 1 percent compared with 2010, from 149 000 tonnes to 150 000 tonnes respectively. This increase was recorded in Morocco, with around 3 000 tonnes while in Mauritania, catches decreased by 2 000 tonnes (Figure 6.2.1).
In 2011, around 74 percent of the total anchovy catch in the subregion was recorded in Mauritania. It has increased from 8 percent of the total catch in 1995 to more than 95 percent in 2003. In 2004 and
2005, catches decreased by 47 percent in Mauritania. In 2006 and 2007, catches increased again, before showing another decline in 2008 and 2009 followed by another increase in 2010 and 2011. Catches by the Russian and Ukrainian fleets represent 51 percent of the total declared catch in Mauritania. However, several indications exist that the bulk of the catches declared in Mauritania as anchovy could be juvenile horse mackerel or other species which have been processed into fishmeal and thus are impossible to identify.
In Morocco, catches of anchovy in 2011 increased compared with 2010 despite the fact that there was no change in the fleet operating in the zone. The largest part of this catch was taken in the northern zone with more than 10 000 tonnes and in Zone A with over 22 000 tonnes, representing an increase of 22 percent compared with 2010 in the two zones (Table 6.2.1). Fishing effort
Fishing effort for anchovy is defined as the total effort of the trawlers and coastal purse seiners directed at all pelagic species in Mauritania and Morocco. The Spanish fleet is composed of 20 purse seiners that operate in the northern zone of Morocco. They spent 312 days at sea (Table and Figure 6.2.2). Recent developments
The year 2011 marked the end of the fisheries agreement between Morocco and Spain allowing 20 Spanish purse seiners to fish for anchovy in the northern zone.
For the application of the LCA model, the Group used the sampling data of landings in the northern zone, and Zones A+B in Morocco in 2009, 2010 and 2011. An average of the length distributions of the total catch for the areas concerned has been used for these three years. The final distribution contains individuals with lengths between 7 cm and 19 cm.
The growth parameters used were obtained from a study carried out in Zone A by INRH in 2008 and 2010 (Table 6.6.1). The value of natural mortality of 1.5 per year was obtained from the thesis of Ba Ibrahima in Mauritania in 1988 (Ba Ibrahima, 1988).
In 2011, the data available on the anchovy fishery in the subregion were insufficient for the application of a production model. The Group therefore applied the yield-per-recruit model of Thomson and Bell and the LCA model. The two models used are described in Sparre and Venema (1996).
Overall Assessment Results
After the necessary model fits, the results indicate that current fishing mortality (Fcur) is close to the value corresponding to F0.1 (Figures 6.7.1 and 6.7.2). This means that the stock is fully exploited.Discussion
As in previous sessions, the discussions of the Group dealt with the quality and availability of data on this species in the different fishing areas, in particular Mauritania where catches of anchovy constitute a large part of the total catch in the subregion. No biological data or effort data are available for this area for the entire period. The Working Group does not have new biological data for the northern area and Zones A+B. Furthermore, there is uncertainty about the stock identity of the anchovy in the subregion. Because of the short lifespan of anchovy (two years at the most), abundance is dependent upon variations in recruitment. Moreover, acoustic abundance indices (Figure 6.3.1) showing rather large fluctuations are not reflected in the model. For the reasons mentioned above, the diagnosis of full exploitation resulting from the model should be considered with prudence.
The Working Group was unable to make short- or medium-term projections for the anchovy stock in the subregion because of the strong interannual variation in abundance and the short lifespan of this species.
Scientific AdviceFuture research Follow-up on last year’s recommendations
As the 2011 Working Group’s recommendations were not fully implemented, the 2012 Group makes the following recommendations:
for Management consideration
- Intensify sampling in the different segments of the fishery to identify and distinguish anchovy in reported or processed catches in Mauritania.
- Start genetic studies to identify the stock.
While waiting for more information on the stock identity of anchovy in the subregion and more reliable catch statistics particularly in Mauritania, the Working Group takes a precautionary approach and recommends not to increase effort and catches above the current level.
Biological State and Trend
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