JCJC - Jeunes chercheuses et jeunes chercheurs

Les prédateurs supérieurs comme indicateurs des dynamiques de l'écosystème marin exploité – TOPINEME

Submission summary

Human activities in marine ecosystems are facing three major challenges: implementing an ecosystem-based approach to fisheries, achieving conservation objectives, and anticipating the effects of climatic change. Addressing each of those three issues requires specific scientific frameworks. Nevertheless they all call for a set of ecosystem indicators and sentinels metrics that enable real time assessment of the general state of the ecosystem and provide warning signals about changes and risks for the ecosystem. Being downstream in terms of energy flow, top predator foraging behaviour and ecology are likely to reflect ecosystem dynamics. For that reason, using top predators to monitor marine ecosystem health is an attractive concept that has motivated a series of specific integrated studies, especially in temperate and high latitude regions. Fewer efforts have been made in low latitude upwelling ecosystems even when those ecosystems usually host both diverse and numerous top predator populations and economically important forage fish fisheries. In the Humboldt Current system off Peru, only two contributions give an ecosystem view of top predator population ecology (1) for seabirds, the carbon flux modelling approach developed by Jahncke et al. (2004) and (2) for fishers, the relationship between their spatial behaviour and anchovy distribution (Bertrand S. et al., 2004, 2005, 2008b); and the statistical description of scenarios of spatial re-organisations from physics to fishers developed by Bertrand S. et al. (2008a). The question is not any more if top predators can be used to inform management, but how, i.e. how to define this framework for diverse ecosystems and predators populations. Using top predators as ecosystem indicators requires before all integrated multi-disciplinary projects for elucidating the functional links between marine predators, their prey and the marine climate. That is what we propose to develop in this project, with case study the Peruvian Humboldt Current System (PHCS), a highly productive coastal upwelling, which provides an excellent natural laboratory for conducting such an approach. One innovation of the project will be to consider fishers not only as an external source of forage fish removals for birds and mammals, but as a fully interacting top predator in the system that has comparable foraging strategies to natural predators and may have local competition or enhancement effects on natural predators. Relying on both historical time series analysis and specific small scale at sea experiments, we aim at quantifying to what extent top predators (marine birds, pinnipeds and fishers), their abundance, forage fish removals and foraging behaviour, reflect the properties of the main components of the ecosystem, from physical habitat to plankton communities and forage fish populations. The project will be organised into five work packages. The first work package aims at producing high resolution physical and primary production 'landscape' characterization at meso and sub-meso scales. The second work package aims at producing high resolution plankton and forage fish spatial distribution characterization at meso and sub-meso scales. The third work package will document and model top predator spatial behaviour (telemetry and vessel monitoring system) at the foraging trip scale. The fourth work package aims at increasing the documentation on seabirds and pinnipeds diet and population abundances. And finally the fifth work package aims at testing to what extent top predator abundance, diet and spatial behaviour integrate and reflect ecosystem conditions in terms of oceanography, plankton and forage fish. This project aims to (1) explicit the functional links between marine predators, their prey and the oceanography; (2) provide operational ecosystem indicators and sentinel metrics for supporting fishery management and monitoring forthcoming climate change effects; (3) enable collection of critical information on top predator populations which is still unavailable (e.g. movements and foraging strategies of birds and pinnipeds in the PHCS); (4) provide an opportunity to re-compile and examine existing historical databases; (5) provide critical advances for bird and mammal conservation objectives; (6) give a solid basis for comparison with other ecosystems (e.g. Benguela system); (7) provide realistic inputs for ecosystem models already in phase of development in the PHCS(e.g. Ecopath, Osmose, Seapodym); (8) provide insights for defining fish over-exploitation from an ecosystem perspective; (9) provide insights for evaluating the further use of pinnipeds for oceanographic profilers.

Project coordinator

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


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Beginning and duration of the scientific project: - 0 Months

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