New trophic indicators and target values for an ecosystem-based management of fisheries

Type Article
Date 2016-02
Language English
Author(s) Bourdaud PierreORCID1, Gascuel Didier2, Bentorcha Abdelkrim3, Brind'Amour AnikORCID4
Affiliation(s) 1 : IFREMER, Ctr Manche Mer Nord, RH, F-62200 Boulogne Sur Mer, France.
2 : Univ Europeenne Bretagne, Agrocampus Ouest, UMR Ecol & Sante Ecosyst 985, F-35042 Rennes, France.
3 : Ifremer Brest, F-29280 Plouzane, France.
4 : IFREMER, EMH, F-44311 Nantes 03, France.
Source Ecological Indicators (1470-160X) (Elsevier Science Bv), 2016-02 , Vol. 61 , P. 588-601
DOI 10.1016/j.ecolind.2015.10.010
WOS© Times Cited 33
Keyword(s) Environmental status, Trophic indicators, Ecosystem-based management, Ecopath with Ecosim, EcoTroph
Abstract In the present study, we tested five trophic indicators and we demonstrated their usefulness to assess the environmental status of marine ecosystems and to implement an ecosystem approach to fisheries management (EAFM). The tested indicators include the slope of the biomass spectrum, the mean trophic level (MTL), the marine trophic index (MTI) and two newly developed indicators, the high trophic level indicator (HTI) and the apex predator indicator (API). Indicators are compared between current state and potential reference situations, using as case studies: the Celtic Sea/Bay of Biscay, North Sea and English Channel ecosystems. Trophic spectra are obtained from Ecopath models while reference situations are estimated, simulating with EcoTroph and Ecosim different fishing pressures including three candidate scenarios for an EAFM. Inter-ecosystems assessments are done using Ecopath models, simulations outputs and scientific surveys data to assess the current states of the studied ecosystems, contrast the reference situations and analyze the responses of all indicators. Sensitivity analyses are also conducted on the main simulation parameters to test the robustness of the chosen indicators. Ecosystems specific targets for EAFM are proposed for the five trophic indicators estimated from whole-ecosystem models, while in the Celtic Sea/Bay of Biscay ecosystem targets are proposed for the MTL (=3.85) and HTI (48%) estimated from standard bottom-trawl surveys. The HTI is proposed to be relevant for survey data and the API is recommended using whole-ecosystem models. We conclude that HTI and API show trends in ecosystems health better than MTI.
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