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Auteur Carvalho, P.G.; Jupiter, S.D.; Januchowski-Hartley, F.A.; Goetze, J.; Claudet, J.; Weeks, R.; Humphries, A.; White, C. doi  openurl
  Titre Optimized fishing through periodically harvested closures Type Article scientifique
  Année 2019 Publication Revue Abrégée J. Appl. Ecol.  
  Volume 56 Numéro 8 Pages 1927-1936  
  Mots-Clés bioeconomic model; conservation; coral-reef fishes; fish behaviour; fisheries management; management; marine protected areas; marine reserves; new-zealand; outcomes; periodically harvested closures; population dynamics; vulnerability; yield  
  Résumé Periodically harvested closures are a widespread, centuries-old form of fisheries management that protects fish between pulse harvests and can generate high harvest efficiency by reducing fish wariness of fishing gear. However, the ability for periodic closures to also support high fisheries yields and healthy marine ecosystems is uncertain, despite increased promotion of periodic closures for managing fisheries and conserving ecosystems in the Indo-Pacific. We developed a bioeconomic fisheries model that considers changes in fish wariness, based on empirical field research, and quantified the extent to which periodic closures can simultaneously maximize harvest efficiency, fisheries yield and conservation of fish stocks. We found that periodic closures with a harvest schedule represented by closure for one to a few years between a single pulse harvest event can generate equivalent fisheries yield and stock abundance levels and greater harvest efficiency than achievable under conventional fisheries management with or without a permanent closure. Optimality of periodic closures at maximizing the triple objective of high harvest efficiency, high fisheries yield, and high stock abundance was robust to fish life history traits and to all but extreme levels of overfishing. With moderate overfishing, there emerged a trade-off between periodic closures that maximized harvest efficiency and no-take permanent closures that maximized yield; however, the gain in harvest efficiency outweighed the loss in yield for periodic closures when compared with permanent closures. Only with extreme overfishing, where fishing under nonspatial management would reduce the stock to <= 18% of its unfished level, was the harvest efficiency benefit too small for periodic closures to best meet the triple objective compared with permanent closures. Synthesis and applications. We show that periodically harvested closures can, in most cases, simultaneously maximize harvest efficiency, fisheries yield, and fish stock conservation beyond that achievable by no-take permanent closures or nonspatial management. Our results also provide design guidance, indicating that short closure periods between pulse harvest events are most appropriate for well-managed fisheries or areas with large periodic closures, whereas longer closure periods are more appropriate for small periodic closure areas and overfished systems.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  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 0021-8901 ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000478601300007 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2619  
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Auteur Teixido, N.; Gambi, M.C.; Parravacini, V.; Kroeker, K.; Micheli, F.; Villeger, S.; Ballesteros, E. doi  openurl
  Titre Functional biodiversity loss along natural CO2 gradients Type Article scientifique
  Année 2018 Publication Revue Abrégée Nat. Commun.  
  Volume 9 Numéro Pages 5149  
  Mots-Clés carbon; community; consequences; diversity; fish; impact; ocean acidification; redundancy; reveals; vulnerability  
  Résumé The effects of environmental change on biodiversity are still poorly understood. In particular, the consequences of shifts in species composition for marine ecosystem function are largely unknown. Here we assess the loss of functional diversity, i.e. the range of species biological traits, in benthic marine communities exposed to ocean acidification (OA) by using natural CO2 vent systems. We found that functional richness is greatly reduced with acidification, and that functional loss is more pronounced than the corresponding decrease in taxonomic diversity. In acidified conditions, most organisms accounted for a few functional entities (i.e. unique combination of functional traits), resulting in low functional redundancy. These results suggest that functional richness is not buffered by functional redundancy under OA, even in highly diverse assemblages, such as rocky benthic communities.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  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 2041-1723 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2477  
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Auteur Villon, S.; Mouillot, D.; Chaumont, M.; Darling, E.S.; Subsol, G.; Claverie, T.; Villeger, S. doi  openurl
  Titre A Deep learning method for accurate and fast identification of coral reef fishes in underwater images Type Article scientifique
  Année 2018 Publication Revue Abrégée Ecol. Inform.  
  Volume 48 Numéro Pages 238-244  
  Mots-Clés Automated identification; Convolutional neural network; density; Machine learning; Marine fishes; neural-networks; system; temperate; Underwater pictures; video stations; visual census; vulnerability  
  Résumé Identifying and counting fish individuals on photos and videos is a crucial task to cost-effectively monitor marine biodiversity, yet it remains difficult and time-consuming. In this paper, we present a method to assist the identification of fish species on underwater images, and we compare our model performances to human ability in terms of speed and accuracy. We first tested the performance of a convolutional neural network (CNN) trained with different photographic databases while accounting for different post-processing decision rules to identify 20 fish species. Finally, we compared the performance of species identification of our best CNN model with that of humans on a test database of 1197 fish images representing nine species. The best CNN was the one trained with 900,000 images including (i) whole fish bodies, (ii) partial fish bodies and (iii) the environment (e.g. reef bottom or water). The rate of correct identification was 94.9%, greater than the rate of correct identification by humans (89.3%). The CNN was also able to identify fish individuals partially hidden behind corals or behind other fish and was more effective than humans to identify fish on smallest or blurry images while humans were better to identify fish individuals in unusual positions (e.g. twisted body). On average, each identification by our best CNN using a common hardware took 0.06 s. Deep Learning methods can thus perform efficient fish identification on underwater images and offer promises to build-up new video-based protocols for monitoring fish biodiversity cheaply and effectively.  
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  Editeur Lieu de Publication Éditeur  
  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 1574-9541 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2475  
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Auteur Legras, G.; Loiseau, N.; Gaertner, J.-C.; Poggiale, J.-C.; Gaertner-Mazouni, N. doi  openurl
  Titre Assessing functional diversity: the influence of the number of the functional traits Type Article scientifique
  Année 2020 Publication Revue Abrégée Theor. Ecol.  
  Volume 13 Numéro 1 Pages 117-126  
  Mots-Clés biodiversity; Dissimilarity metric; framework; Functional diversity; Functional traits; global hotspots; Index sensitivity; indexes; mismatch; redundancy; reveals; species richness; Trend analysis; vulnerability  
  Résumé The impact of the variation of the number of functional traits on functional diversity assessment is still poorly known. Although the covariation between these two parameters may be desirable in some situations (e.g. if adding functional traits provides relevant new functional information), it may also result from mathematical artefacts and lead to misinterpretation of the results obtained. Here, we have tested the behaviour of a set of nine indices widely used for assessing the three main components of functional diversity (i.e. functional richness, evenness and divergence), according to the variation in the number of functional traits. We found that the number of functional traits may strongly impact the values of most of the indices considered, whatever the functional information they contain. The FRic, TOP and n-hypervolume indices that have been developed to characterize the functional richness component appeared to be highly sensitive to the variation in the number of traits considered. Regarding functional divergence, most of the indices considered (i.e. Q, FDis and FSpe) also showed a high degree of sensitivity to the number of traits considered. In contrast, we found that indices used to compute functional evenness (FEve and Ru), as well as one of the indices related to functional divergence (FDiv), are weakly influenced by the variation in the number of traits. All these results suggest that interpretation of most of the functional diversity indices considered cannot only be based on their values as they are, but requires taking into account the way in which they have been computed.  
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  Auteur institutionnel Thèse  
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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 1874-1738 ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000515172600009 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2750  
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Auteur Bonnin, L.; Lett, C.; Dagorn, L.; Filmalter, J.D.; Forget, F.; Verley, P.; Capello, M. doi  openurl
  Titre Can drifting objects drive the movements of a vulnerable pelagic shark? Type Article scientifique
  Année 2020 Publication Revue Abrégée Aquat. Conserv.-Mar. Freshw. Ecosyst.  
  Volume Numéro Pages  
  Mots-Clés aggregating devices fads; behavior; bycatch; carcharhinus-falciformis; fish aggregating devices; Lagrangian drift model; near-surface currents; ocean; pop-up satellite archival telemetry; postrelease survival; purse seine fishery; silky shark; tropical tuna; vulnerability; yellowfin thunnus-albacares  
  Résumé Juvenile silky sharks (Carcharhinus falciformis)regularly associate with floating objects yet the reasons driving this behaviour remain uncertain. Understanding the proportion of time that silky sharks spend associated with floating objects is essential for assessing the impacts of the extensive use of fish aggregating devices (FADs) in the tropical tuna purse-seine fisheries, including increased probability of incidental capture and the potential of an ecological trap. Previous studies provided insight into the amount of time that silky sharks spent at an individual FAD but were unable to assess neither the time spent between two associations nor the proportion of time spent associated/unassociated. The percentage of time that juvenile silky sharks spend unassociated with floating objects was estimated through the analysis of horizontal movements of 26 silky sharks monitored with pop-up archival tags. Under the assumption that a high association rate with drifting FADs would align the trajectories of tracked sharks with ocean surface currents, a novel methodology is proposed, based on the comparison of shark trajectories with simulated trajectories of passively drifting particles derived using a Lagrangian model. Results revealed that silky shark trajectories were divergent from surface currents, and thus unassociated with FADs, for at least 30% of their time. The potential of the methodology and the results are discussed in the context of increasing FAD densities in the Indian Ocean.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  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 1052-7613 ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000560611000001 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2864  
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