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Marine Ecology Progress Series

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MEPS 512:155-166 (2014)  -  DOI:

A century of fish biomass decline in the ocean

Villy Christensen1,*, Marta Coll2,3, Chiara Piroddi4, Jeroen Steenbeek3, Joe Buszowski3, Daniel Pauly1

1Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
2Institut de Recherche pour le Développement, UMR EME 212, Centre de Recherche Halieutique Méditerranéenne et Tropicale, Avenue Jean Monnet, BP 171, 34203 Sète Cedex, France, and Institute of Marine Science, ICM-CSIC, Passeig Marótim de la Barceloneta, 37-49, Barcelona 08003, Spain
3Ecopath International Initiative Research Association, Barcelona, Spain
4European Commission - DG JRC, Institute for Environment and Sustainability, Water Resources Unit, Via E. Fermi,
2749 - TP 272, 21027 Ispra, VA, Italy
*Corresponding author:

ABSTRACT: We performed a global assessment of how fish biomass has changed over the last 100 yr, applying a previously developed methodology using ecological modeling. Our assessment built on more than 200 food web models representing marine ecosystems throughout the world covering the period from 1880 to 2007. All models were constructed based on the same approach, and have been previously documented. We spatially and temporally distributed fish biomasses delivered by these models based on fish habitat preferences, ecology, and feeding conditions. From these distributions, we extracted over 68000 estimates of biomass (for predatory and prey fishes separately, including trophic level of 3.5 or higher, and trophic level between 2.0 and 3.0, respectively), and predicted spatial-temporal trends in fish biomass using multiple regression. Our results predicted that the biomass of predatory fish in the world oceans has declined by two-thirds over the last 100 yr. This decline is accelerating, with 54% occurring in the last 40 yr. Results also showed that the biomass of prey fish has increased over the last 100 yr, likely as a consequence of predation release. These findings allowed us to predict that there will be fish in the future ocean, but the composition of fish assemblages will be very different from current ones, with small prey fish dominating. Our results show that the trophic structure of marine ecosystems has changed at a global scale, in a manner consistent with fishing down marine food webs.

KEY WORDS: Fish biomass · Global distribution · Trends · Ecosystem models · Fishing down marine food webs

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Cite this article as: Christensen V, Coll M, Piroddi C, Steenbeek J, Buszowski J, Pauly D (2014) A century of fish biomass decline in the ocean. Mar Ecol Prog Ser 512:155-166.

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