Fishery biomass trends of exploited fish populations in marine ecoregions, climatic zones and ocean basins
Prof. Jessica Meeuwig | September 30, 2020
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CITATION
Palomares MLD, Froese R, Derrick B, Meeuwig J, Nöel S-L, Tsui G, Woroniak J, Zeller, D, Pauly D, Fishery biomass trends of exploited fish populations in marine ecoregions, climatic zones and ocean basins, Estuarine, Coastal and Shelf Science (2020), doi: https:// doi.org/10.1016/j.ecss.2020.106896
HIGHLIGHTS
First long-term global study of widely consumed fish and invertebrates reveals strong population decline based on assessment of over 1300 stocks
82% of fish and invertebrate stocks were in various states of depletion with few exceptions to the general declining trend
The size of exploited marine fish and invertebrates’ populations for all coastal areas on the planet was analysed by climate zones
The declining trend is consistent with systematic widespread global overfishing observed over the last 60 years
Effective and enforced fishing effort-reducing management is needed to halt and reverse the decline of fish populations, along with the implementation of large, no-take marine protected areas to empower stock rebuilding and resilience
Management strategies must be science-based and strongly enforced to limit annual catches and allow fish stock recovery
ABSTRACT
This contribution presents time series of the ‘fishery biomass’ of fish populations, defined as the weight (whole-body, wet weight) of the in-water part of a fishable population, i.e., that part of a population (also called ‘stock’) that is exposed to a certain fishing gear. Detailed data of this type are only available for a limited number of species that are targets of the fisheries in the waters of economically developed regions, such as Europe, the USA, Canada or Australia.
However, similar fishery biomass assessments are generally lacking for developing countries, even for many of their most heavily fished species. Here, an estimation of the long-term fishery biomass trends of 1320 fish and invertebrate populations for 483 species exploited by fisheries in the 232 coastal Marine Ecoregions (MEs) around the world was undertaken. Fishery biomass trends were derived using the Bayesian CMSY stock assessment method applied to the global fisheries catch database for 1950-2014 as reconstructed by the Sea Around Us for every maritime fishing country in the world.
Overall, the results suggest a consistent decline in the fishery biomass of exploited populations, in virtually all climatic zones and ocean basins in the world. The only zone with currently higher fishery biomass than in 1950 is the northern Pacific polar-boreal zone, likely due to environmental changes that occurred in the region positively affecting fish populations, combined with prudent management of the fisheries. For populations in MEs that are known to have highly questionable catch statistics, the results suggested smaller declines in fishery biomass than likely occurred in reality, implying that these results do not exaggerate declining trends in fishery biomass. This study used informative Bayesian priors to improve the trend analyses in areas where systematic stock assessments were conducted. The use of these independent assessments reduced the uncertainty associated with the findings of this study.
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GLOBAL MARINE ECOREGIONS
The global system of Marine Ecoregions (ME in dark blue, Spalding et al., 2007) overlaid over climatic zones of the world (Anonymous, 1991). Centroid colour in each ME indicates the climatic zone to
which each ME was assigned.
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CLIMATIC ZONES
Summary by climatic zone of the number of populations analyzed and the number of populations excluded from this analysis due to uncertainties in the underlying catch data or because more than 20% of the catch consisted of poorly monitored discards.
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BIOMASS STATUS
Frequency distribution of the average fishery exploited population biomass status (B) over the most recent five-year period (2010-2014) relative to the optimal biomass level for Maximum Sustainable Yield (BMSY) for the 1320 populations analyzed in this study.
FUNDING & ACKNOWLEDGEMENTS
Acknowledgments: We would like to thank F. Le Manach for the preliminary catch data reconstruction for the Seychelles’ EEZ on which the present contribution builds.
Funding: This was a contribution of the Marine Futures Lab and the Sea Around Us—Indian Ocean, both are research initiatives at the University of Western Australia. The Marine Futures Lab was supported by the Ian Potter Foundation, the Pangaea Initiative, Parks Australia, and private philanthropy. The research of the Sea Around Us initiatives were supported by the Oak Foundation, the Paul M. Angell Family Foundation, the Marisla Foundation, the David and Lucile Packard Foundation, the MAVA Foundation, Bloomberg Philanthropies, Oceana and the Minderoo Foundation.