Éditeur(s) : Edp Sciences S A
Résumé : 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.
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 fréquences 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.
Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2009-10 , Vol. 22 , N. 4 , P. 433-445

Droits : EDP Sciences, IFREMER, IRD 2009
http://archimer.ifremer.fr/doc/00000/11165/7517.pdf
DOI:10.1051/alr/2009027
http://archimer.ifremer.fr/doc/00000/11165/

Éditeur(s) : Inter-research
Résumé : Ecosystem-based management (EBM) requires more extensive information than single-species management. Active underwater acoustic methods provide a means of collecting a wealth of ecosystem information with high space-time resolution. Worldwide fisheries institutes and agencies are carrying out regular acoustic surveys covering many marine shelf ecosystems, but these data are underutilized. In addition, more and more acoustic data collected by vessels of opportunity are becoming available. To encourage their use for EBM, we provide a brief introduction to acoustic and complementary data collection methods in the water column, and review current and potential contributions to monitoring population abundance and biomass, spatial distributions, and predator-prey relationships. Further development of acoustics-derived indicators is needed. We review and propose indicators for assessing and monitoring zooplankton, population dynamics of fish and other nekton, and changes in diversity and food-web functioning. Acoustic methods have the potential to make a strong contribution to EBM. Evaluation of new indicators and suitable reference points in different ecosystems are the current challenges.
Marine Ecology-progress Series (0171-8630) (Inter-research), 2011 , Vol. 442 , P. 285-301

Droits : 2011 Inter-research
http://archimer.ifremer.fr/doc/00073/18445/15972.pdf
DOI:10.3354/meps09425
http://archimer.ifremer.fr/doc/00073/18445/

Éditeur(s) : Elsevier
Résumé : This paper presents a survey of French Eastern English Channel fishers' observations of the past and current state of the marine ecosystem and their wishes for the future, as a first step towards formulating management objectives. Twenty-nine semi-directive interviews were carried out in June 2006 among fishers and shellfish farmers. Cognitive maps proved useful to formalise their experience and knowledge. Most interviewees mentioned a decrease of the resource in recent years and pointed out the presence of several problems, such as pollution, degradation of the ocean floor and harmful impacts of human activities, including fishing. The indicators used by the fishers as the basis to form their opinion were similar to those generally used by scientists for assessing the state of exploited marine populations and communities (average fish length, CPUE, fished biomass...); additional indicators were the timing and duration of fishing seasons. (c) 2008 Elsevier Ltd. All rights reserved.
Ocean & Coastal Management (0964-5691) (Elsevier), 2008-06 , Vol. 51 , N. 6 , P. 450-462

Droits : 2008 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2008/publication-6134.pdf
DOI:10.1016/j.ocecoaman.2008.04.005
http://archimer.ifremer.fr/doc/00000/6134/

Éditeur(s) : Elsevier
Résumé : Choice of sampling method and survey period can have an important impact on the perception of the structure and dynamics of an ecological community. For the Celtic Sea fish assemblage we compared data obtained by three different trawl surveys: an autumn groundfish survey with a GOV trawl, and a spring and an autumn groundfish survey, both carried out with a Portuguese high-headline trawl. Time-series of abundance estimates were not consistent among surveys for all species and were generally very noisy. An analysis of variance components showed that the sampling method contributed more to the variance in abundance estimates compared to survey period, interannual variability, or even sampling variance. Overall community assessments based on indicators such as proportions of non-commercial and piscivorous species, and the proportion of benthic species showed similar trends for all data series. The shape of the size spectrum based on abundances per length class summed over all fish species, although stable over time, was highly sensitive to the sampling method. With the exception of size spectra, community indicators for marine fish assemblages monitored by surveys seem to be robust to survey period and trawling gear, but species abundance trends are method dependent.
ICES Journal of Marine Science (1054-3139) (Elsevier), 2004-05 , Vol. 61 , N. 3 , P. 351-362

Droits : 2004 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd
http://archimer.ifremer.fr/doc/2004/publication-899.pdf
DOI:10.1016/j.icesjms.2004.01.004
http://archimer.ifremer.fr/doc/00000/899/

Éditeur(s) : Blackwell science
Résumé : The trophic level mean and variance, and the degree of omnivory for five Celtic Sea fish predators were estimated using a database of stomach content records characterized by a high level of taxonomic resolution. The predators occupied a high position in the food web, i.e. 4.75 for Atlantic cod Gadus morhua, 444 for haddock Melanogrammus aeglefinus, 4.88 for European hake Merluccius merluccius, 5.00 for megrim Lepidorhombus whiffiagonis and 5.27 for whiting Merlangius merlangus. The level of taxonomic resolution of the prey did not greatly affect mean T-L predator values; an effect on variance was evident, low resolution masking intra-population variability in T-L. Generalized additive models (GAM) were used to explain the variability of predator T-L caused by environmental variables (international Council for the Exploration of the Sea, ICES, division and season) and predator characteristics (total length, L-T). Significant year, location season and interaction effects were found for some species and with L-T, at the scale of ICES subdivision. The species-specific variability of T-L could be due to spatio-temporal variations in prey availability and in predator selectivity following ontogenetic changes. Omnivorous fish T-L. was less affected by spatio-temporal variations. In addition, results showed that the omnivory index and T-L variability provide dissimilar information on predator feeding strategy. Combining information on T-L. variability and omnivory allowed between within individual and between-individual components contributing to trophic niche width to be separated and the type of generalization of fish predators to be identified. (c) 2008 The Authors Journal compilation (c) 2008 The Fisheries Society of the British Isles.
Journal of Fish Biology (0022-1112) (Blackwell science), 2008-09 , Vol. 73 , N. 4 , P. 763-781

Droits : 2008 Wiley Blackwell Publishing, Inc. The Fisheries Society of the British Isles
http://archimer.ifremer.fr/doc/2008/publication-4699.pdf
DOI:10.1111/j.1095-8649.2008.01938.x
http://archimer.ifremer.fr/doc/00000/4699/

Éditeur(s) : Oxford university press
Résumé : The results of a survey on fishers' perceptions of recent changes in the eastern English Channel ecosystem carried out in 2006 were compared with fishery and bottom-trawl survey data. A hypothesis-testing framework was used, testing the null hypothesis that fishers' statements were true, which permitted evaluation of both agreement and disagreement. Overall good agreement between fishers' statements and scientific data was found, and both sources suggested that the fish community in the Channel is undergoing large changes, among which are decreases in some commercially important species; in addition, a number of human pressures impact the ecosystem. Fishers had an accurate perception of changes and their time-frames, but not necessarily of their causes. They had a greater power than survey data to detect recent changes, showing that fishers' perceptions have great potential as early warning signals.
ICES Journal of Marine Science (1054-3139) (Oxford university press), 2008-09 , Vol. 65 , N. 6 , P. 1057-1068

Droits : 2008 International Council for the Exploration of the Sea. Published by Oxford Journals.
http://archimer.ifremer.fr/doc/2008/publication-4474.pdf
DOI:10.1093/icesjms/fsn062
http://archimer.ifremer.fr/doc/00000/4474/

Éditeur(s) : Wiley-blackwell
Résumé : An ecomorphological method was developed, with a focus on predation functions, to define functional groups in the Celtic Sea fish community. Eleven functional traits, measured for 930 individuals from 33 species, led to 11 functional groups. Membership of functional groups was linked to body size and taxonomy. For seven species, there were ontogenetic changes in group membership. When diet composition, expressed as the proportions of different prey types recorded in stomachs, was compared among functional groups, morphology-based predictions accounted for 28-56% of the interindividual variance in prey type. This was larger than the 12-24% of variance that could be explained solely on the basis of body size. (C) 2013 The Fisheries Society of the British Isles
Journal Of Fish Biology (0022-1112) (Wiley-blackwell), 2013-08 , Vol. 83 , N. 2 , P. 355-377

Droits : 2013 The Fisheries Society of the British Isles
http://archimer.ifremer.fr/doc/00152/26294/24831.pdf
DOI:10.1111/jfb.12177
http://archimer.ifremer.fr/doc/00152/26294/