Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2021-10 Spanish survey (October 2021).

• Main Authors: Ramos, F. (Fernando), Córdoba-Sellés, M.P. (María del Pilar), Tornero, J. (Jorge), Sánchez-Barba, M.J. (María José), Navarro, M.R. (María Rosario)
• Format: Report
• Language: English
• Published: Centro Oceanográfico de Cádiz 2022
• Subjects: Gulf of Cadiz; Acoustic-trawl surveys; Pelagic fish resources; Spatial distribution; Recruitment; pelagic fish; distribution; species; Acoustic data; North Atlantic
• Online Access: http://hdl.handle.net/10508/16184

The present working document summarises the main results obtained from the ECOCADIZ-RECLUTAS 2021-10 Spanish (pelagic ecosystem-) acoustic-trawl survey conducted by IEO between 21st October and 07th November 2021 in the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz (GoC) onboard the R/V Ramón Margalef. The survey suffered a ten-day delay in relation to the usual starting dates. The survey’s main objective is the acoustic assessment of anchovy and sardine juveniles (age 0 fish) in the GoC recruitment areas. The 21 foreseen acoustic transects were sampled. A total of 18 valid fishing hauls were carried out for echo-trace ground-truthing purposes. Chub mackerel, anchovy and sardine were the most frequent captured species in the fishing hauls, followed by horse mackerel, bogue, Atlantic mackerel, Mediterranean horse mackerel and blue jack mackerel. Boarfish, longspine snipefish and pearlside showed an incidental occurrence in the hauls performed in the surveyed area. Sardine and chub mackerel showed the highest yields in these hauls, followed by anchovy and Mediterranean horse mackerel. Total and Spanish estimates of total NASC allocated to the “pelagic fish species assemblage” in this survey showed lower values than those recorded last year, whereas the Portuguese estimates showed an increasing trend. GoC anchovy was widely distributed in the surveyed area, although avoided the easternmost waters. Higher densities were recorded between Alfanzina and west of Cape Santa Maria, in the Algarve, and between Isla Cristina and Bay of Cadiz. Anchovy acoustic estimates in autumn 2021, 17 512 t and 1973 million fish, experienced 38% and 51% decreases in abundance and biomass, respectively, in relation to the last year’s autumn estimates and they were lower than their time-series averages. The population was composed by fishes not older than 2 years. As usual, the bulk of the population, including juveniles, was located in Spanish waters. Age-0 anchovies accounted for 83% (1629 million) and 69% ...