Habitat and Biology
Bottom type: Soft bottom muddy or muddy-sand. Depth zone: Coastal (0 m - 50 m); Shelf (50 m - 200 m); Shelf - Edgeshelf. Horizontal distribution: Neritic. Vertical distribution: Demersal/Benthic. Sparus auriga
is a benthopelagic species which lives at average depths of 170 metres. In the east Atlantic, the species is distributed from Portugal to Angola. It is found on rocky bottoms. The young migrate towards the coast. The species feeds on crustaceans and molluscs.Sparus aurata
is a demersal species living in depths up to 150 metres. In the east Atlantic the species is distributed from the Straits of Gibraltar to the Canary Islands. It is found on rocky and sandy bottoms in less deep waters up to 30 metres. The adults migrate to 150 metres depth. It is a sedentary species, living alone or in small groups. In spring, the species migrates towards the coastal zones close to the lagoons and estuaries. It is a carnivorous and occasionally herbivorous species that feeds on molluscs. It lives in both salty and hyper-salty waters.
Jurisdictional distribution: Shared between nations
Considered a single stock: No
The species is composed mostly of redbanded seabream, bluespotted seabream and common seabream. They are caught by the ocean-going, coastal and artisanal fleets.
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 series of total seabream (Sparus
spp.) landings estimated by the Working Group was used as the series of total catch of the stock.
Two abundance indices series were tried, the CPUE series of the Moroccan ocean-going cephalopod trawlers and the abundance indices from the surveys.
The dynamic Schaefer production model implemented on an Excel spreadsheet was used to assess the state of the white hake (Sparus
spp) stock (Appendix 2).
Overall Assessment Results
The available data did not permit conclusive results to be obtained for the assessment of Sparus
The poor fit of the model could be explained by the fact that the CPUEs do not reflect the real stock abundance. Sparus spp. seem to become a target when more in demand species, such as cephalopods, are not available.
Scientific Advicefor Management considerations
Considering the large catches recorded over the last few years, any increase in effort should be avoided until more detailed assessments are available.
Source of information
FAO Fishery Committee for the Eastern Central Atlantic/Comité des pêches pour l’Atlantique Centre-Est. “Report of the 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 ressources démersales dans la zone Nord” Banjul, Gambie, du 6 au novembre 2007. Rome, FAO . 2010. .
The bibliographic references are available in the report included in "Source of Information".