Ingredient 7

The Spatial Expansion of Fisheries (1950 - 2005)

The Chagos MPA was "Protected" before April 1, 2010 when it was officially designated by the UK.
 

Reported landing records show that the 200 nautical mile limit around the Chagos (the "EEZ") had significantly lower fisheries activity than the surrounding Indian Ocean long before the MPA existed. The UK heralded "Protection" for an already protected area. By far, a greater benefit would have been achieved in spending political and real capital toward reforming UK and EU fishery policy in the surround Indian Ocean region, where it was needed.

ABOVE: The Chagos EEZ (2005 above) was protected before the MPA of 1 April 2010.

The figure shows fishery extraction as a percent of primary productivity.

The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present)

Wilf Swartz,    Enric Sala,    Sean Tracey,    Reg Watson,    Daniel Pauly; 2010. PLOS One

(got to PLOS1 journal article)

• Abstract

  Using estimates of the primary production required (PPR) to support fisheries catches (a measure of the footprint of fishing), we analyzed the geographical expansion of the global marine fisheries from 1950 to 2005. We used multiple threshold levels of PPR as percentage of local primary production to define ‘fisheries exploitation’ and applied them to the global dataset of spatially-explicit marine fisheries catches. This approach enabled us to assign exploitation status across a 0.5° latitude/longitude 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. 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 exceed 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.
  Citation: Swartz W, Sala E, Tracey S, Watson R, Pauly D (2010) The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present). PLoS ONE 5(12): e15143. doi:10.1371/journal.pone.0015143

  Introduction

  There is a wide realization that fisheries, similar to agriculture on land [1], has a tremendous impact on marine ecosystems and on the biodiversity embedded therein [2], [3]. This applies particularly to modern industrial fisheries, here defined as fisheries using craft powered by fossil fuel, which began in about 1880, when the first British steam trawlers were deployed. These quickly depleted the coastal population of flatfish and other bottom fish they were targeting, and they had to move offshore, gradually expanding into the entire northeastern Atlantic [4], [5]. A similar development was mirrored off New England, and along the coast of Japan, where local fish populations, already much reduced by operation conducted off sail-powered vessels (e.g.,[6]), were strongly depleted.

   In the late 1980s, global catches ceased to increase and peaked at 90 million t [9]. The slow decrease of about half million t per year which then ensued has not been reversed since[7], and is not likely to ever be [10].

  
  

  This decrease occurred, essentially, because the rate at which new fish stocks (for example of deep sea fish; [11]) were accessed, from the late 1980s on, failed to compensate for the rate at which ‘traditional’ stocks were depleted. Moreover, the number of new stocks has been decreasing linearly over time [12].

  However, the global impact of fishing on the ecosystem, which includes species across the food chain from herbivores to top predators, cannot be fully assessed by the study of single-species catches. A more appropriate way of quantifying the expansion of and limits to fisheries is using the primary production required (PPR) to sustain catches – a metric of the ecological footprint of fishing. As defined by Pauly and Christensen [15], PPR allows direct comparison of the primary production required to generate a catch of a given (group of) species in a given time period (here: 1 year), and hence it allows for (indirect) comparisons between the catches of very different species of fish and invertebrates. Further, when the PPR of a given catch taken at a given locale is expressed as a fraction or percent of the primary production observed at that locale, we can use arbitrary thresholds of this fraction to define this locale as ‘exploited’, i.e., drawn into the scope of fisheries. Here we used different levels of “% PPR” (i.e., percentage of the primary production of the cells of a map of the global ocean) to quantify the expansion of fisheries since 1950 and extract the dominant patterns of this expansion.

  
  

  Results and Discussion

  
  

  Most of the ecological footprint of fishing concentrated on the waters off the industrialized countries of North America and Europe, and off Japan in 1950, and have expanded to cover most of the world's productive waters by 2005. Figure 1 presents the spatial patterns of the proportion of the local primary production required to sustain the catch, for 1950 and 2005. These figures clearly demonstrate the expansion of fisheries, particularly of areas where the proportion of primary production exploited equal or exceed 30% (in red). The expansion is accompanied by the nearly five-fold increase in catch, from 19 million tonnes in 1950 (equivalent to 9 billion tonnes [wet weight] of primary production) to 87 million tonnes in 2005 (equivalent to 45 billion tonnes [wet weight] of primary production). In 2005, the footprint of one tonne of catch was, on average, 556 tonnes of PP (wet weight).

  Some patterns in Figure 1 should be noted. First, the exploitation levels off the coast of East Africa in 2005 are likely to be underestimated due to underrepresentation of unreported catches in the region [16], [17]. Moreover, waters off the Pacific Island countries are known fishing grounds for tuna fisheries and reported to have a relatively high level of illegal and unreported catch [18].

  
  

  

  Figure 1. Primary production required (PPR) to sustain global marine fisheries landings expressed as percentage of local primary production (PP).

  
  

  Estimates of PPR, PP and PPR/PP computed per 0.5° latitude/longitude ocean cells. PPR estimates based on the Sea Around Us catch database (www.seaaroundus.org) and PP estimates derived from SeaWiFS's global ocean colour satellite data. The maps represent total annual landings for 1950 (top) and 2005 (bottom). Note that PP estimates are static and derived from the synoptic observation for 1998.

  doi:10.1371/journal.pone.0015143.g001