Overview of recent progress in fisheries acoustics made by Ifremer with examples from the Bay of Biscay

Abstract

-This paper provides an overview of the progress Ifremer has made recently in fisheries acoustics and the study of small pelagic fish by: i) pushing observation frontiers using a range of platforms including an autonomous underwater vehicle, AUV, ii) developing measuring instruments and methods and iii) studying fish distributions. Presently, information from several frequencies of single-beam echosounders is routinely collected together with data from the ME70 multibeam echosounder. For onboard data acquisition control the HERMES software was developed. The new MOVIES 3D software includes modules for simultaneous realistic 3D visualisation and post-processing such as bottom detection, school extraction and calculation of descriptors and integration of all acoustic data. Several data analysis methods are being developed and some initial results are presented. Finally, results on the spatial distribution of small pelagic fish schools in the Bay of Biscay illustrate the role that acoustics can play, and are already playing, in the implementation of an ecosystem approach to fisheries. Key words:Multibeam echosounder / Oceanographic AUV / Pelagic fish / Fisheries acoustics Résumé -Cet article présente une vue d'ensemble des avancées récentes de l'Ifremer en acoustique halieutique et une étude des petits poissons pélagiques tenant compte : i) de l'extension des limites de l'observation, en utilisant une gamme diverse de plates-formes dont un engin sous-marin autonome (AUV), ii) des développements méthodologiques et d'instruments de mesures, iii) de l'étude de la répartition des poissons. Désormais, les données de plusieurs fré-quences des sondeurs mono-faisceaux sont collectées en routine en parallèle à celles du sondeur multifaisceau ME70. Le logiciel HERMES a été développé pour le contrôle de l'acquisition des données à bord. Le nouveau logiciel MOVIES 3D comprend des modules de visualisation réaliste en 3D et de post-traitement (dont la détection du fond, l'extraction de bancs et le calcul de leurs descripteurs ainsi que l'intégration de toutes les données acoustiques). Plusieurs méthodes d'analyse de données sont en cours de développement et quelques premiers résultats sont présentés. Enfin, les résultats relatifs à la répartition spatiale des bancs de petits poissons pélagiques dans le golfe de Gascogne illustrent le rôle actuel et potentiel de l'acoustique dans la mise en place d'une approche écosystémique des pêches.

Convergence and divergence between two multibeam sonars (SIMRAD SM20 and RESON SeaBat 6012) used to extract the spatial, morphologic and energy parameters of fish schools

“…using the new Ifremer software Movies3D (Trenkel et al, 2009), which will eliminate contributions from second-order echoes. With the exception of the school length parameter, the observed outliers for all class-2 parameters were a consequence of the extraction by IMA of a high proportion of the fish school second-order echoes, and to some overestimations of the width, height, surface and volume of the fish schools observed by SM20.…”

A Review of the Tools Used for Marine Monitoring in the UK: Combining Historic and Contemporary Methods with Modeling and Socioeconomics to Fulfill Legislative Needs and Scientific Ambitions

“…Recent technological developments in fisheries acoustic methods have included the use of omni-directional (including MBES) sonars with benefits in fisheries research include improved sampling of fish close to the seabed (in the acoustic dead-zone), and to resolve multiple targets at the same range simultaneously, by reducing the transducer beamwidth and combining multiple split-beams (Trenkel et al, 2009). The omni-directional multibeam sonar were specifically developed to make observations in the acoustic blind zone between the sea surface and the position of the downward facing transducers, either on the hull or a drop keel (Andersen et al, 2006) and to image the entire shape of a school instantaneously using multiple (100s) directional beams.…”

Towards the implementation of an integrated approach to fisheries resources management in Ifremer, France

“…The programme has contributed to increasing the Ifremer scientists' capacity to work on pelagic biodiversity ( [29] Trenkel et al, p. 433) through: (i) the development of improved acoustic methods using autonomous underwater vehicles (AUVs); (ii) combined use of multi-frequency single-beam and multibeam echosounders; (iii) sophisticated onboard processing software and 3-D visualisation and (iv) automated or semi-automated classification of species or group of species. The technique was successfully applied in the Bay of Biscay, discovering new aggregation structures of pelagic fish and improving the estimates of biomasses.…”