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Auteur (up) Brehmer, P.; Sarre, A.; Guennegan, Y.; Guillard, J. doi  openurl
  Titre Vessel Avoidance Response: A Complex Tradeoff Between Fish Multisensory Integration and Environmental Variables Type Article scientifique
  Année 2019 Publication Revue Abrégée Rev. Fish. Sci. Aquac..  
  Volume 27 Numéro 3 Pages 380-391  
  Mots-Clés acoustic backscatter; always encounter; behavior; boat noise; cod; fish behavior; fish school; fisheries acoustics; gadus-morhua; multibeam sonar; pelagic fish; school structure; silent ships sometimes; small pelagic assessment; target strength; Vessel avoidance  
  Résumé The avoidance reaction by fish in front of an approaching vessel is a major source of bias in direct biomass assessment and ecological studies based on fisheries acoustics data. An experiment was carried out to compare echosounder data obtained using a small speedboat and a research fisheries vessel generating significant higher noise above conventional reduced-noise standard. The results show that there was no significant difference between the individual fish target strength distributions, and the numbers of schools recorded by both boats, these schools having similar areas and perimeters. However, the schools detected by the noisier vessel were significantly deeper, and unexpectedly had a significantly higher energy level. These findings suggest that noise-reduced vessels trigger a different vessel avoidance reaction. The noise-reduction standard is not sufficient to reduce avoidance behavior. It is also to take into consideration the ambient noise, which could impair perception of the platform by the fish, and the probability that the acoustic stimuli could be less important than visual perception under some local conditions. The paper introduces the concept of partial avoidance and presents a conceptual diagram of the strength of the avoidance reaction. Last, it is not recommended, because of noise reasons, that vessels routinely used for pelagic stock assessment surveys be changed. Indeed standardized time series, which could be disrupted when switching to a new vessel, are more important than the hypothetical gain from change to quieter vessels. Obviously, all long-term surveys must change vessels; best practice will be to estimate the vessel effect before any change to avoid disrupting the time series and/or perform vessel intercalibration surveys.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 2330-8249 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2603  
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Auteur (up) Handegard, N.O.; du Buisson, L.; Brehmer, P.; Chalmers, S.J.; De Robertis, A.; Huse, G.; Kloser, R.; Macaulay, G.; Maury, O.; Ressler, P.H.; Stenseth, N.C.; Godo, O.R. url  doi
openurl 
  Titre Towards an acoustic-based coupled observation and modelling system for monitoring and predicting ecosystem dynamics of the open ocean Type Article scientifique
  Année 2013 Publication Revue Abrégée Fish and Fisheries  
  Volume 14 Numéro Pages 605-615  
  Mots-Clés ecosystem models; fisheries acoustics; micronekton; mid-trophic level; observatories; platforms of opportunity  
  Résumé Assessment of open-ocean ecosystems relies on understanding ecosystem dynamics, and development of end-to-end ecosystem models represents an approach that addresses these challenges. These models incorporate the population structure and dynamics of marine organisms at all trophic levels. Satellite remote sensing of ocean colour and direct at-sea measurements provide information on the lower trophic levels of the models, and fisheries studies provide information on top predator species. However, these models suffer from a lack of observations for the so-called mid-trophic levels, which are poorly sampled by conventional methods. This restricts further development, and we argue that acoustic observations from a range of platforms (e.g. buoys, moorings) can be linked to the ecosystem models to provide much-needed information on these trophic levels. To achieve this, the models need to be tailored to incorporate the available acoustic data, and the link from acoustic backscatter to biologically relevant variables (biomass, carbon, etc.) needs attention. Methods to progress this issue are proposed, including the development of observation models and focal areas for ground truthing. To ensure full use of the potential of acoustic techniques, we argue that a systematic and long-term strategy incorporating the following elements is required: development of metadata standards and automated data analysis, inclusion of acoustic sensors in large-scale observatory programmes, improvement of observation-model links, and efficient sampling strategies. Finally, these elements should be tied together in an observation-modelling framework, coordinated by international organizations, to improve our understanding and quantification of open-ocean ecosystem dynamics.  
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  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1467-2960 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 281  
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