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As part of our collaboration with National Geographic on the
Seafoodprint
of fisheries, we illustrated and quantified the pace of spatial expansion of fisheries
globally since 1950 (see
W. Swartz, E. Sala, S. Tracey, R. Watson
and D. Pauly, 2010 PLoS one 5(12):e15143). Essentially, the seafoodprint is the oceanic
Primary Production Required (PPR) to generate the catch of fisheries, similar to
the grass that would be required per year to generate a certain production of milk
or meat (see
D. Pauly and V. Christensen, 1995, Nature, Vol. 374 Pages 255-257). Here,
we used estimates of the Primary Production Required (PPR) to support fisheries
catches, to analyze the geographical expansion of the global marine fisheries from
1950 to 2005 (see figure 1). We used multiple threshold levels of PPR as percentage
of local primary production to define ‘fisheries exploitation’ and applied them
to the global Sea Around Us dataset of spatially-explicit marine fisheries
catches. This approach enabled us to assign exploitation status across the 0.5o
latitude/longitude Sea Around Us ocean grid system and trace the change
in their status over the 56-year time period. This result highlights the global
scale expansion in marine fisheries, from the coastal waters off North Atlantic
and West Pacific to the waters in the Southern Hemisphere and into the high seas
. The southward expansion of fisheries occurred at a rate of almost one degree latitude
per year, with the greatest period of expansion occurring in the 1980s and early
1990s (see figure 2). By the mid 1990s, a third of the world’s ocean, and two-thirds
of continental shelves, were exploited at a level where PPR of fisheries exceeded
10% of PP, leaving only unproductive waters of high seas, and relatively inaccessible
waters in the Arctic and Antarctic as the last remaining ‘frontiers.’ The growth
in marine fisheries catches for more than half a century was only made possible
through exploitation of new fishing grounds. Their rapidly diminishing number indicates
a global limit to growth and highlights the urgent need for a transition to sustainable
fishing through reduction of PPR.
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Figure 1. Primary Production Required (PPR) to sustain global marine fisheries landings,
expressed as percentage of local primary primary production [ High resolution].
Figure 2. Time series of areas exploited by marine fisheries by latitude, expressed
as a percentage of the total ocean area. ‘Area exploited’ is defined as regions
where primary production required (PPR) to sustain reported fisheries landings is
greater than 10% of local primary production (PP) [ High resolution].
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