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In situ target strength measurement of the black triggerfish Melichthys niger and the ocean triggerfish Canthidermis sufflamen


Salvetat, J and Lebourges-Dhaussy, A and Travassos, P and Gastauer, S and Roudaut, G and Vargas, G and Bertrand, A, In situ target strength measurement of the black triggerfish Melichthys niger and the ocean triggerfish Canthidermis sufflamen, Marine and Freshwater Research, 71, (9) pp. 1118-1127. ISSN 1323-1650 (2020) [Refereed Article]

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Copyright 2020 CSIRO

DOI: doi:10.1071/MF19153


Triggerfish are widely distributed in tropical waters where they play an important ecological role. The black triggerfish Melichthys niger may be the dominant species around oceanic tropical islands, whereas pelagic triggerfish, such as the ocean triggerfish Canthidermis sufflamen, can assemble around fish aggregating devices (FADs) where they are a common bycatch of tuna fisheries. In this study we combined acoustic and optical recordings to provide the first in situ target strength (TS) measurement of black and ocean triggerfish. Data were collected in the Archipelago of Fernando de Noronha off north-east Brazil. The mean TS of a 27.8-cm-long black triggerfish at 70 and 200kHz was 39.3dB re 1m2 (CV=14.0%) and 38.9dB re 1m2 (CV=14.4%) respectively. The mean TS values of ocean triggerfish (with a size range of 3944cm) at 70 and 200kHz were 36.0dB re 1m2 (CV=15.7%) and 33.3dB re 1m2 (CV=14.0%) respectively. This work opens up the field for acoustic biomass estimates. In addition, we have shown that TS values for ocean triggerfish are within the same range as those of small tunas. Therefore, acoustic data transmitted from FADs equipped with echosounders can introduce a bias in tuna acoustic biomass estimation and lead to increased rates of bycatch.

Item Details

Item Type:Refereed Article
Keywords:biomass estimation, north-east Brazil, small tuna, target strengthlength relationships, tropical ecosystem, underwater acoustics, underwater video
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish physiology and genetics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biological sciences
UTAS Author:Gastauer, S (Mr Sven Gastauer)
ID Code:143081
Year Published:2020
Web of Science® Times Cited:2
Deposited By:Ecology and Biodiversity
Deposited On:2021-02-25
Last Modified:2021-03-31

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