1. Effect of a Transducer Horizontality Default on Lake Fish Stock Assessment
- Author
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Arthur Blanluet, Chloé Goulon, Anne Lebourges-Dhaussy, Jean Guillard, Pauline Eymar-Dauphin, Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), and This work was supported by OFB (Office Francais de la Biodiversite, previously named Agence Francaise pour la Biodiversite) and had support from AnaEE France and SOERE OLA (boat and technical facilities). The hydroacoustic and limnological data are issued from OLA, Observatory of LAkes (http://www6.inra.fr/soere-ola (c) SOERE OLA-IS, AnaEE-France, INRAE Thonon-lesBains, SILA, developed by Eco-Informatics ORE INRAE Team). The authors want to thank Jean-Christophe Hustache and Dr. Helge Balk for their precious help during the survey, as well as Michael Girard for previous analyses. We want to thank Laurent Berger and the anonymous reviewer for their pertinent comments and remarks about the manuscript. The authors Arthur Blanluet, Jean Guillard and Chloe Goulon are associate members of the Cogitamus Laboratory.
- Subjects
0106 biological sciences ,Fisheries acoustics ,biomass ,Acoustics and Ultrasonics ,ACL ,010604 marine biology & hydrobiology ,Attenuation ,aspect target strength ,Sampling (statistics) ,alpine lake ,Principle of original horizontality ,Geodesy ,Fish stock ,010603 evolutionary biology ,01 natural sciences ,Freshwater ,Transducer ,Quality (physics) ,Orientation (geometry) ,Hydroacoustics ,Transducer miss-alignment ,14. Life underwater ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Geology - Abstract
Freshwater hydroacoustic surveys are frequently performed with small research boats. Thus, the transducer, usually fixed on a pole on the side of the boat, could be misaligned with the horizontal axis (i.e., the lake surface). Given that fish acoustic responses are strongly directional, the transducer angle could induce attenuation of their backscattering strengths. To test the influence of a small shift of the transducer orientation, we compared hydroacoustics estimates from two sampling nights on the Lake Annecy: the first one being a transducer angle of $$1.5^{\circ }$$ with the horizontal and the second one being strictly horizontal. We showed that the effect of such an angle is negligible over the sampling variability on the TS distribution of the fish population and the biomass assessment. We conclude that a small shift in the transducer horizontality ( $$\le 1.5^{\circ }$$ ) will not degrade the quality of the acoustic data.
- Published
- 2020
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