Species identification of fish shoals combining multibeam and split-beam echo-sounders with visual observations from diving [résumé]

2022

Colloque

David V., Minart C., Mouget A., Perrot Yannick, Thiriet P., Feunten E., Cheminée A., Le Goff L., Acou A., Brehmer Patrice

Jech M. (ed.), Working group of fisheries acoustics, science and technology (WGFAST)

ICES Scientifics Reports, 2022, 4 (54), 45-46 ISSN 2618-1371

ICES. Working Group of Fisheries Acoustics, Science and Technology (WGFAST), Somone (SEN), 2022/04/25-28

One challenge of acoustic observations of marine organisms is the identification of species, par-ticularly in shallow waters where high diversity occurs. We deployed combining split-beam EK80 (70, 120 and 200 kHz) and M3 multibeam (500 kHz) echosounders to detect monospecific fish shoals in coastal shallow waters (5-60 m). Innovative protocols for the specific allocation were tested, using (i) scuba divers census on fish shoals and (ii) towed scuba diver. Stereoscopic video system was also used to assess fish length and abundance and compare with the visual estimations of divers. Several independent replicates of monospecific shoals from 5 fish species were obtained. The combined used of the echosounders allows to have complementary morpho-logic, acoustic and spatial descriptors to correctly discriminate the shoals. In addition, as the stereoscopic system has shown to provide precise measurements of individuals and could over-come the visual diver observations, our results suggest that a system equipped with cameras like a remotely controlled towed instrumentation platform could be used in a near future for ground trust in shallow and clear waters.

Limnologie physique / Océanographie physique [032] ; Ressources halieutiques [040]

Fonds IRD [F B010089464]

fdi:010089467