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Working Group 3: Trophic pathways in the open ocean ecosystems

Key Scientific Questions

  • What are the main trophic pathways and how do they differ among and within oceans?
  • Is there evidence of change in trophic pathways over time and space consistent with climate variability. Can seasonal and spatial variability be used to explore the impacts of climate variability?
  • What is the relative impoartance of mesopelagic versus epipelagic prey resources in oceanic top predators, and how does this vary within and among oceans. How does climate variability affect the distribution and availability of mesopelagic and epipelagic prey?
  • Is it possible to identify indicators, such as prey species or size spectra, that would highlight significant changes in trophic pathways?

Working Group activities

  • Cephalopod International Advisory Council Symposium (27 Oct - 2 Nov 2012, Florianópolis, Brazil). More info...
  • Comparative world-wide studies on the stomach contents and stable isotopes of top fish predators. Recent focus has been on the development of appropriate statistical analyses.
  • Contribution to joint working group 1 and 3 at Shimizu Japan, September 2011. More info...
  • Bob Olson and Jock Young: editing a volume for Deep Sea Research II resulting from the CLIOTOP-supported meeting in Hawaii in 2006 on the "The role of squid in open ocean ecosystems" due for completion in 2012.
  • Contributing a chapter on trophic pathways to: Tunas and Their Fisheries: safeguarding sustainability in the 21st century (eds, Brill, Hobday, Dagorn)
  • Methods workshop on using classification trees to examine diet data of top predator fishes in the Pacific Ocean: 
    • Meeting  1 (January 2011, Hobart, Tasmania, Australia). Conveners: Petra Kuhnert, Leanne Duffy and Jock Young. More info;
    • Meeting  2 (April 2011, La Jolla, California, USA). Conveners: Petra Kuhnert, Leanne Duffy and Robert Olson. More info
  • CLIOTOP mid-term Workshop (8-11 February 2010, Paris, France). Conveners: Olivier Maury et al. More info
  • Workshop on 'Inter-ocean comparisons of oceanic food webs' (28 September - 2 October 2009, Sète, France). More info
  • "Can latitude be used as a proxy for climate change in the analysis of top predator food webs?". Conveners: Frederic Menard, Robert Olson and Jock Young. Meeting as part of the Workshop on 'Inter-ocean comparisons of oceanic food webs' (28 September - 2 October 2009, Sète, France). More info
  • "The role of squid in open ocean ecosystems" (16 November 2006, University of Hawaii, Hawaii, USA). Conveners: Robert Olson and Jock Young. More info
  • "Workshop on the Application of Stable Isotopes in Pelagic Ecosystems" (31 May–1 June 2004, La Paz, Mexico). Conveners: Robert Olson, Young JW, Valérie Allain and Felipe Galván-Magaña. More info


  • Popp et al. (2007)  Insight into the trophic ecology of yellowfin tuna, Thunnus albacares, from compound-specific nitrogen isotope analysis of proteinaceous amino acids. In Dawson, T.E., and R.T.W. Siegwolf (eds.), Stable Isotopes as Indicators of Ecological Change. Elsevier-Academic Press, Terrestrial Ecology Series, San Diego: 173-190. More info...
  • Progress in Oceanography (2010) Volume 86, Issues 1-2, Pages 1-316, Editors: Patrick Lehodey, Olivier Maury and Mélanie Rathburn. Relative to the CLIOTOP International Symposium La Paz, Mexico, 3-7 December 2007 (More info...):
    • Olson et al. Food web inferences of stable isotope spatial patterns in copepods and yellowfin tuna in the pelagic eastern Pacific Ocean. pp 124-138.
    • Young et al. Discrimination of prey species of juvenile swordfish Xiphias gladius (Linnaeus 1758) using signature fatty acid analyses. pp 139 - 151.
    • Dambacher et al. Analyzing pelagic food webs leading to top predators in the Pacific Ocean: a graph-theoretic approach. pp 152 - 165.

 Technical reports

  • Graham B., R. Ollson, B. Fry, B. Popp, V. Allain and F. Galván-Magaña (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): 1-3, 12. More info...
  • Olson R. and J.W. Young (2007) The role of squid in open ocean ecosystems. GLOBEC Report 24, VI, 94 pp. Report of the GLOBEC-CLIOTOP/PFRP workshop (16-17 November 2006, Honolulu, Hawaii, USA - More info).   
  • Young J.W. and R. Olson (2007) The ecological role of squid in pelagic ecosystems. GLOBEC International Newsletter (April 2007) on GLOBEC-CLIOTOP/PFRP workshop (16-17 November 2006, Honolulu, Hawaii, USA - More info).
  • Olson R. and J.W. Young (2007) CLIOTOP/PFRP Workshop: The Role of Squid in Pelagic Marine Ecosystems. Pelagic Fisheries Research Program Newsletter 12, 2-4 (GLOBEC-CLIOTOP/PFRP workshop (16-17 November 2006, Honolulu, Hawaii, USA - More info).
  • Phleger C.F., J.W. Young, M. Lansdell and P. D. Nichols (2007) Signature fatty acids: A robust method for evaluating trophic relationships in open ocean ecosystems. In: Robert J. Olson and Jock W. Young (Eds.) 2007.  More info... 
  • Maury O., P. Lehodey, A. Garcia, F. Marsac, R. Olson, J.W. Young, R. Murtugudde and K. Miller (2008) The first CLIOTOP Symposium: An overview. GLOBEC INTERNATIONAL NEWSLETTER APRIL. Vol. 14 (1): 59-63. More info... 
  • Phleger, C. F., J.W. Young, M. Lansdell, P. D. Nichols (2009) Signature lipids - A Tool to Monitor Climate and Environmental Change in Top Level Predators, Int. Soc. Fats, September 27-30, Sydney, Australia.
  • Dambacher, J.M., J.W. Young, R. Olson and V. Allain (2009) A Graph-Theoretic Approach to Analyzing Food Webs Leading to Top Predators in Three Regions of the Pacific Ocean. PFRP Newsletter. Vol. 14, No. 1, 4-12.
  • Kuhnert P., L. Duffy, J.W. Young (2011) Methods workshop on using classification trees to examine diet data of top predator fishes in the Pacific Ocean (a contribution from CLIOTOP Working Group 3 (Trophic interactions of top ocean predators). IMBER Newsletter, Issue 17. 

See also all CLIOTOP publications and reports




CSIRO, Tasmania, Australia


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Frédéric MENARD


IRD/IFREMER, Sète, France


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Robert OLSON


Inter-American Tropical Tuna Commission,  La Jolla, CA, USA


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Brian HUNT


Department of Earth, Ocean and Atmospheric Sciences, UBC

Vancouver, Canada

Mediterranean Institute of Oceanography



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