Tuesday, 14 April 2009 11:39


Financial supports for this project are: JIMAR Pelagic Fisheries Research Program of the University of Hawaii School of Ocean and Earth Science and Technology under Cooperative Agreement number NA17RJ12301 from the National Oceanic and Atmospheric Administration (NOAA) and Pacific Islands Oceanic Fisheries Management Project (OFM project) funded by the Global Environment Facility (GEF).

Biodynamic trophic modeling approach Ecopath with Ecosim (EwE - is an analysis package based on a static flow model. Ecopath provides a framework for the construction of mass-balance models of ecosystems. Modelling is based on estimates of how abundant the resources are (biomasses), the productivity or mortality rates of the resources, how they interact (diet compositions and food consumption rates), and how efficiently the resources are utilized in the ecosystem. Data on the different components of the ecosystem is required and information central to the process of balancing the model is the diet matrix which informs on the links beween the species. Ecopath allows visualizing the ecosystem and it is a very useful learning tool to better apprehend the ecosystem and its functionning.

Ecopath model of the eastern Pacific pelagic ecosystem. (Olson & Watters 2003. IATTC Bulletin.22(3)).


Given the description of the ecosystem in Ecopath, Ecosim provides a tool with the capacity of testing different fishing policies and environmental change scenarios. By means of dynamic simulations it will assist managers with identifying the most robust and reliable management options that will achieve their objectives.

Ecosim simulation testing the effect of closing definitely the FAD fisheries in the western Pacific Warm pool pelagic ecosystem (Allain et al 2007. WCPFC-SC3-EB-IP8).


Several Ecopath models were developed since 2002 for the warm pool; particularly in 2007 as part of an international collaborative work with Ecopath experts and scientists of the region. Data are based on biomass estimates from MULTIFAN-CL and SEAPODYM and diet matrix is based on the trophic studies conducted by SPC.

More work is needed to further develop this Ecopath – Ecosim model and to try and validate its outcome before being able to use it as a testing tool on which decisions can be taken.

Average position and spatial extent of the warm pool and cold tongue ecosystemsAverage position and spatial extent of the warm pool and cold tongue ecosystems


Preliminary results of Ecopath with Ecosim model have been presented during various conferences and publications:

PFRP annual reports (2003 – 2008) of the project “Trophic structure and tuna movements in the cold tongue-warm pool pelagic ecosystem of the Equatorial Pacific”:

Allain V., Nicol S., Essington T., Okey T. Olson R.J. & Kirby D. 2007. An Ecopath with Ecosim model of the Western and Central Pacific Ocean warm pool pelagic ecosystem. Third regular session of the Scientific Committee of the Western and Central Pacific Fisheries Commission. 13-24 Aug. 2007. Honolulu, USA. WCPFC-SC3 – EB SWG/IP-8: 1-42.

Graham B., Olson R., Fry B. Popp B. Allain V. & Galván-Magaña F. 2006. The new PFRP Tag: using stable isotope techniques to better understand the trophic ecology and migration patterns of tropical tunas. PFRP Newsletter. 11 (2): 1-12.

Allain V. 2005. Ecopath model of the pelagic ecosystem of the western and central Pacific Ocean. First regular session of the Scientific Committee of the Western and Central Pacific Fisheries Commission. 8-19 Aug. 2005. Noumea, New Caledonia. WCPFC-SC1 – EB WP-10: 1-19.

Godinot O. & Allain V. 2003. A preliminary Ecopath model of the warm pool pelagic ecosystem. 16th Meeting of the Standing Committee on Tuna and Billfish, SCTB16, Mooloolaba, Queensland, Australia, 9-16 July 2003. SCTB16 – BBRG5: 1:27.

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