Estimation by acoustical methods stock biomass of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) Spanish Mediterranean.

Estimation by acoustical methods stock biomass of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) Spanish Mediterranean.

Benthopelagic ecosystem structure in the western Mediterranean: a multidisciplinary approach and different time scales in the Balearic Islands.

Benthopelagic ecosystem structure in the western Mediterranean: a multidisciplinary approach and different time scales in the Balearic Islands.

Background and Aims MEDWAVES The Strait of Gibraltar (SG) and the surrounding areas, Gulf of Cadiz (GoC) in the Atlantic, and Alboran sea (AS) in the Mediterranean, are key areas to understand the distribution and connectivity of marine communities (Patarnello et al. 2007), as the SG and the encounter of water masses at the Almeria Oran front represent an oceanographic transition area, connecting the Atlantic Ocean and the Mediterranean Sea (Lacombe & Richez 1982). The Mediterranean water flows out from Gibraltar (MOW), extends towards the East of the Atlantic, building a warm and salty water mass which propagates in North West direction from Portugal originating the “Mediterranean Water“ (MW) in the Atlantic. This warm and salty water mass becomes characteristic of the North Atlantic in mid waters (around 1100 m) (Candela 2001). The occurrence of cold-water coral (CWC) communities in the NE Atlantic has been related to the pathway of the MOW, whereby this current system would have an historical influence on the migration of coral larvae and (re)colonization of the Atlantic in the post-glacial era (De Mol et al. 2005, Henry et al. 2014). The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) cruise target areas under the potential influence of the MOW within the Mediterranean and Atlantic realms. These include seamounts where CWC have been reported but that are still poorly known, and which may act as essential “stepping stones” connecting fauna of seamounts in the Mediterranean with those of the continental shelf of Portugal, the Azores and the Mid-Atlantic Ridge. During MEDWAVES sampling will be conducted through two of the case studies of ATLAS: Case study 7 (Gulf of Cadiz-Strait of Gibraltar-Alboran Sea) and Case study 8 (Azores). The main goals of the cruise are: (1) to characterize physically and biogeochemically the MOW Path and understand its interaction with the general Atlantic Meridional Overturning Circulation (AMOC) stream, from the Alboran Sea to the Azores, through the Gulf of Cadiz, and the Ormonde Seamount (see map), exploring the relationship between the oceanographic settings of these target areas and the ecosystems therein (ATLAS WP1 and WP3) and (2) to characterize communities associated to the transition area, and sample for population genetic analysis aiming at understanding the way the populations located in the target areas contribute or have contributed to connectivity between the Mediterranean Sea and the Atlantic Ocean (ATLAS WP3 and WP4). Results gathered during the cruise will also contribute later to feed other ATLAS WPs. The activities planned to achieve these aims are presented in the brief description of the work program of the different research teams participating in ATLAS (Work program of the research teams).

Sampling at Ithioplacton stations, CTD stations and pelagic fishing, acoustic sampling with EK60 echo sounder. The general method is to quantify the freshly spawned eggs in the water column on the spawning grounds. Report egg species identification and staging. To be able to establish a relationship between eggs and biomass of the spawning stock, the fecundity of the females must also be determined.

This campaign to evaluate deep demersal resources on the coasts of Algeria responds to the need to update and expand the studies and evaluations carried out in the 1980s. During this fishing prospecting campaign, 55 catches were made between 200 and 800 meters deep, using bottom trawls. To determine the abundance and properties of the main fishing resources of Algeria, it was necessary to obtain prior knowledge of the characteristics of the seabed on the sampled fishing beaches. Likewise, the precise knowledge of the bathymetry and morphology of the bottom optimized the trawl work and, in short, the achievement of the fishing campaign. GOALS Image of ship's personnel releasing trawl - Bathymetric and morphological recognition of the seabed in the upper slope and the Algerian coast. - Know the biological structure of demersal communities subjected to exploitation in the upper and middle slope of the study area. - Obtain indices of abundance and biomass of the main deep demersal species (hake, monkfish, white prawn, Norway lobster and red shrimp). - Characterize the demographic structure of the main demersal species exploited on the slope, as well as its geographical and bathymetric distribution. - Collect data and collect samples (otoliths) from deep demersal species for growth and reproduction studies. WORK AREA The bathymetric surveys were carried out at night, in such a way that sufficient time was available to elaborate the bathymetric maps and digital terrain models. This allowed the selection of the haul zones and served as an electronic cartography for navigation.

CR Tunibal

The Algerian continental shelf, very narrow and rocky, is not conducive to bottom trawling. Its average length is 6 km, even in certain areas, the 500-meter isobath is 3 miles from the coast. Only in some gulfs in the west of the country (such as Oran), near the Alboran Sea, the platform reaches an extension above average. According to the Algerian Geographic Unit, it is estimated that only 1/3 of the surface is optimal for bottom trawling: 3,500 km2 up to 200 m depth and 7,000 km2 between 200 and 350 m. This limits the availability of demersal species and thus, rg / 1999 / xhtml "> of the total catches of these species (~ 25,000 Tm), about 4,000 (~ 20%) correspond to crustaceans, mainly prawns, which are caught between 200 and 400 m GOALS Determine the abundance and characteristics of the main demersal resources of Algeria. For this, the following partial objectives are proposed: - Know the biological structure of the communities exploited by the trawl fishery on the platform and the upper slope. - Obtain indices of abundance and biomass of the main species, such as mullet, sparids, hake, monkfish, white shrimp, Norway lobster, pink prawn, Moorish prawns, octopus and cuttlefish. - To determine the characteristics of the demographic structure of these species, as well as to know their geographical and bathymetric distribution. - Collect data on the state of maturity, size and weight, and collect biological samples of demersal species for growth and reproduction studies.

CR Tunibal