Noëlle BRU Laboratoire de Mathématiques et ses Applications UMR CNRS 5132 Université de Pau et des Pays de l’Adour : [email protected]Patrick PROUZET IFREMER LRHA Michel LEJEUNE Université Grenoble 2 As an example the Adour Estuary (Southwestern part of France)
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Noëlle BRU Laboratoire de Mathématiques et ses Applications UMR CNRS 5132
Daily and seasonal biomasses estimates of glass eels runs ( Anguilla anguilla L.) in an opened estuary. As an example the Adour Estuary (Southwestern part of France). Noëlle BRU Laboratoire de Mathématiques et ses Applications UMR CNRS 5132 Université de Pau et des Pays de l’Adour. - PowerPoint PPT Presentation
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Noëlle BRU Laboratoire de Mathématiques et ses Applications
UMR CNRS 5132 Université de Pau et des Pays de l’Adour
As an example the Adour Estuary (Southwestern part of France)
About management groups : ICES (International Council for the Exploration of the sea): “the stock of
European eel (Anguilla Anguilla L.) is outside safe biological limit and that current fisheries are not sustainable”.
18 September 2007: the Council of the European Union adopted a council regulation (EC 1100/2007) establishing measures for the recovery of stock of European eel.
November 2007 : the IUCN (International Union for Conservation of Nature) listed the European eel on its Appendix II and considered the eel as an endangered species.
Glass eel = young eel... Passive migration… During flood tide… Mainly by night…
Colloque ASP - Boulogne sur Mer 2008 2
General context…General context…
(source : IFREMER)
Colloque ASP - Boulogne sur Mer 2008 3
In European estuaries: constant decrease is observed for several years.
Over-exploitation at the different phases of the biological cycle ?
Inland habitat loss ?Climate and ocean current changes ?
Diseases ? Degradation of continental environment and pollution ?…
General context…General context…
??
Colloque ASP - Boulogne sur Mer 2008 4
• Most methods : » Designed for a fixed stock within a given area » Geostatistical approaches» Hydroacoustics campaigns…
• A specific method : in a particular environment : from the mouth of a estuary + an area of migration ... a species with a specific migratory behavior... a method to compute an efficient estimate of glass eels abundance...
Problems…Problems…
Colloque ASP - Boulogne sur Mer 2008 5
Used to propose biomass estimates…
How and why to put together these datasets ??
About the talk...About the talk...
What are the data available to do so ?
Historical time series of professional catches
(by day, into the maritime area)
Data from scientific in situ surveys
Step 1
Step 2
Are they really good indicators of abundance ?
Step 1 of the method :
Using data from scientific in situ surveys…
Step 1 : In situ scientific surveys…
• Sampling protocol and data
• Statistical method for estimation of « observed » glass eels biomass
• Results and discussion
Step 2 : Using professional catches…• Estimate of seasonal glass eels
biomass migrating by night • Estimate of glass eels recruitment