Habitat and Biology
Climatic zone: Tropical. Bottom type: Hard rocky bottom; Soft bottom. Depth zone: Coastal (0 m - 50 m); Shelf - Uppershelf (up to 100 m). Horizontal distribution: Littoral. Vertical distribution: Demersal/Benthic.
This is a benthopelagic species found in depths of up to 500 metres. Axillary seabream are found on hard and sandy bottoms. It lives at depths of 100 metres, the young are coastal. It is an hermaphrodite, omnivorous species, eating molluscs and crustaceans.
Jurisdictional distribution: Shared between nations
Considered a single stock: Yes
The axillary seabream population (Pagellus acarne
) was considered as a single stock. In the eastern Atlantic the species is distributed from the Bay of Biscay to Senegal and includes Cap Vert, the Azores, Madeira and the Canary Islands.
Due to their generally elevated market value, coastal demersal resources are very sought after in all four of the northern CECAF zone countries (Morocco, Mauritania, Senegal and The Gambia). They are exploited by artisanal and industrial fleets (national and foreign). The fisheries are multi-purpose and demersal fish species often represent bycatch of other specialized fisheries such as the cephalopod, hake or shrimp fisheries.
The demersal fish to be assessed this year are the Pagellus bellottii
, Pagellus acarne
spp., Dentex macrophthalmus
, Pagrus caeruleostictus
spp. and Epinephelus aeneus
. Overall catch for these species fluctuates between around 20 000 and 37 000 tonnes.
Demersal fish resources in Morocco are exploited by a heterogeneous fleet of Moroccan cephalopod freezer trawlers (Ceph. N), coastal fishing vessels: trawlers and longliners (coastal), artisanal boats (artisanal), leased boats and Russian vessels operating under the Morocco-Russia fishing agreement. Only the longliner and some of the artisanal boats target demersal fish, other vessels catch them as bycatch.
In Mauritania exploitation of demersal resources is carried out by various types of trawler: foreign cephalopod (Ceph. E), national cephalopod (Ceph. N), foreign and national hake (Hake), foreign and national shrimp (Shrimp), foreign pelagic trawlers (Pelagic) and foreign and national demersal fish trawlers (Fish).
In Senegal demersal resources are mainly caught by artisanal boats using fishing lines. Two categories exist: motorized line canoes (MLC) carrying out daily trips and ice canoes (IC) equipped with ice that do trips lasting several days. These resources are also caught by Senegalese and foreign trawlers fishing under fishing agreements. Each of these fleets is made up of freezer and ice trawlers. The artisanal fleet is currently composed of 12 619 canoes and the number of Senegalese trawlers was 100 in 2005.
In the Gambia, it is foreign freezer trawlers (PI) and artisanal canoes that exploit demersal resources.
The total landings’ series (coastal + ocean-going cephalopod trawlers) of axillary seabream (Pagellus acarne
) estimated by the Working Group was used as the series of total stock catch. It should be noted that the weak catches over the last few years of the ocean-going fishery could be due to the biological closed season which has become ever longer.
As an abundance indices series, the Working Group used three different series, the CPUEs (tonnes/fishing day) of the Moroccan ocean-going cephalopod trawlers, the abundance indices (kg/h) of the trawl surveys carried out between Bojador and Lagouira and an average of the survey indices.
The Schaefer dynamic production model implemented on an Excel spreadsheet was used to evaluate the state of the stock of the Pagellus acarne
fisheries (FAO, 2007).
Overall Assessment Results
The model provided a good fit to the average abundance indices series for each year of the surveys.
The axillary seabream stock is overexploited (Table 1) as the current biomass is less than the target biomass, B0.1. Actual fishing effort is above the F0.1 effort.
Table 1: Indicators on the state of the stock and fishery of Pagellus acarne in the northern CECAF zone
|| F cur /F SYcur
|| B cur /B 0.1
|| F cur /F 0.1
|| B cur /B MSY
|| F cur /F MSY
|Pagellus acarne/Moroccan surveys
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 current biomass levels.
Bcur/B0.1: Ratio between the estimated biomass for the last year and the biomass corresponding to F0.1.
Fcur/F0.1: Ratio between the observed fishing mortality coefficient during the last year of the series and F0.
Bcur/BMSY: Ratio between the estimated biomass for the last year and the biomass coefficient corresponding to FMSY.
Fcur/FMSY: Ratio between the observed fishing mortality coefficient during the last year of the series and the coefficient giving maximum long term sustainable yield.
The assessments show that the stock is overexploited. The stock situation has been aggravated due to the increase in fishing effort.
Scientific Advicefor Management considerations
Taking note of the results of the assessments, the Working Group decided to recommend the following management measures:
Reduce the effort carried out on the axillary seabream stock to allow the stock to build itself up.
- Ensure a follow-up of the application of current regulations.
Biological State and Trend
Source of information
FAO Fishery Committee for the Eastern Central Atlantic/Comité des pêches pour l’Atlantique Centre-Est. “Report of the FAO/CECAF Working Group on the Assessment of Demersal Resources, Sub-Group North” Banjul, The Gambia, from 6 to 14 November 2007
“Rapport du Groupe de travail FAO/COPACE sur l’évaluation des poissons demersaux – Sous-Groupe Nord” Banjul, Gambie, 6 - 14 Novembre 2007
Rome, FAO . 2010
The bibliographic references are available in the report included in "Source of Information".