Acoustic correction factor estimate for compensating vertical diel migration of small pelagics

Bonanno; A.; Barra; M.; De Felice; A.; Giannoulaki; M.; Iglesias; M.; Leonori; I.; Ventero; A.; Aronica; S.; Biagiotti; I.; Ti?ina; V.; Canduci; G.; Genovese; S.;

Differences in acoustic estimates of small pelagic fish biomass, due to data acquisition during daytime and nighttime surveys, have been recognized for many years as a problem in acoustic surveys. In the absence of a single rule for all species and for all locations, some expert groups identified specific time intervals for acoustic data acquisition in relation to the schooling behavior of the target species. In the Mediterranean Sea, the research groups working in the MEDIAS (Mediterranean International Acoustic Survey) agreed on the importance that acoustic sampling are conducted only during day-time. Only when available time does not permit to complete the survey during daytime, data collection might be extended. In this case, working on data collected during both daytime and nighttime, a bias may occur in the biomass estimates. In order to evaluate and correct such bias, specific experiments were performed in some geographical sub-areas of the Mediterranean Sea. The data analysis allowed the estimation of a mean correction factor for the Strait of Sicily, where five surveys were carried out in different years. The correction factor was estimated also for the Adriatic Sea, Tyrrhenian Sea and Northern Spain; the observed variability among areas highlighted the importance of the spatial and temporal coverage of the survey area in order to obtain reliable estimates of the correction factor. Further studies are necessary to improve the interpretation of the obtained estimates in relation to area-related peculiarities such as zooplankton composition and abundance along with small pelagic fish community structure.

2021 - Journal article

Mediterranean Marine Science (Online) 22 (2021): 784–799. doi:10.12681/mms.25120

Keywords: MEDIAS, Mediterranean Sea, small pelagics, Day-night acoustic comparison

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The research activities of the Institute are carried out in the context of research, development and innovation projects, both national and international, based on regional funding programs (POR FEAMPA - Regional Operational Program of the European Maritime Affairs Fisheries Fund and Aquaculture and POR FESR - Regional Operational Program of the European Regional Development Fund) or ministerial (PRIN - Projects of relevant national interest, PNRA - National Research Program in Antarctica, PO FEAMPA - National Operational Program European Maritime Affairs Fisheries and Aquaculture Fund) , programs for European Territorial Cooperation (Interreg), direct funding programs of the European Commission (Horizon2020 and Horizon Europe, Life, JPI - Joint Programming Initiatives, ERA-NET Cofund) and thematic collaboration initiatives managed by international organizations such as, for example , the FAO - GFCM (General Fisheries Commission for the Mediterranean). The Institute also develops funded projects in the context of collaborations with private companies in the sectors of the blue economy as well as technology transfer and research results. Research projects, mainly of a collaborative nature, are developed through a wide network of partners that include major Italian and foreign research institutions and universities.

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