Applying a New Ensemble Approach to Estimating Stock Status of Marine Fisheries around the World

Abstract

The exploitation status of marine fisheries stocks worldwide is of critical importance for food security, ecosystem conservation, and fishery sustainability. Applying a suite of data-limited methods to global catch data, combined through an ensemble modeling approach, we provide quantitative estimates of exploitation status for 785 fish stocks. Fifty-three percent (414 stocks) are below B MSY and of these, 265 are estimated to be below 80% of the B MSY level. While the 149 stocks above 80% of B MSY are conventionally considered "fully exploited," stocks staying at this level for many years, forego substantial yield. Our results enable managers to consider more detailed information than simply a categorization of stocks as "fully" or "over" exploited. Our approach is reproducible, allows consistent application to a broad range of stocks, and can be easily updated as new data become available. Applied on an ongoing basis, this approach can provide critical, more detailed information for resource management for more exploited fish stocks than currently available.

Status and rebuilding of European fisheries

“…Looking at the 12 ecoregions supporting the 397 stocks analyzed in this study (Table 1), including nine large marine ecosystems also analyzed in Worm et al [59], no region had an average exploitation rate at or below the rate predicted to achieve maximum sustainable yields (Table 1). Similarly, Rosenberg et al [64] apply a combination of four data-limited methods with strong known biases [24,65] and no corrections for reduced recruitment to global catch data and conclude that, e.g., half of the stocks in the Northeast Atlantic and the Mediterranean and Black Sea have a biomass near or above B msy in 2013, whereas our more detailed study shows that this applies to only 28% and 5% of these stocks, respectively.…”

Generic solutions for data‐limited fishery assessments are not so simple

“…Generically applied DLMs may be appropriate (and thus, the value of individually tailored DLMs diminished) if their purpose is not to examine individual stock status, but rather, to undertake a broader (regional or global) “health check” of overall sustainability (examples include Rosenberg et al. (), Costello et al. (, ), Kleisner, Zeller, Froese, and Pauly () and Thorson et al.…”

“…Generically applied DLMs may be appropriate (and thus, the value of individually tailored DLMs diminished) if their purpose is not to examine individual stock status, but rather, to undertake a broader (regional or global) "health check" of overall sustainability (examples include Rosenberg et al (2017), Costello et al (2012, 2016, Kleisner, Zeller, Froese, and Pauly (2013) and Thorson et al (2012)-see Table 2 for details). Despite the concern of compounding sources of uncertainty, at such scales, it could be argued that the inaccuracy of DLMs due to lack of data/information may be absorbed, rather than compounded by, the lack of accuracy caused by generic parameterization of DLMs.…”

“…The first is to try to understand and report on the global or regional status of fisheries across many stocks. This typically involves application of a single DLM to a large number of stocks (e.g., Costello et al, 2012;FAO 1995;Froese, Zeller, Kleisner, & Pauly, 2012;Rosenberg et al, 2017;Thorson, Branch, & Jensen, 2012;Zeller et al, 2016), to gain an understanding of the general health of fisheries for the purpose of motivating funding, research and reform. The second is to assess the status of individual data-limited stocks, for status reporting or guiding management decisions, the latter typically within a harvest, or management, strategy (e.g., Sainsbury, Punt, & Smith, 2000;Butterworth & Punt, 2003;and Dowling et al (2008a,b) (Figure 1).…”

The assessment of fishery status depends on fish habitats

“…Many fisheries support the livelihoods of people with few other sources of protein (Hall, Hilborn, Andrew, & Allison, ), and income from fisheries can be a major contributor to social well‐being in coastal and inland communities (FAO, ). In some parts of the world, management regulations have successfully reduced the capacity of fishing fleets and reduced fishing pressure to levels that should enable stock recovery (Bell, Watson, & Ye, ; Rosenberg et al., ; Worm et al., ). To date, the debate over the global status of fish stocks has focussed on overfishing as the primary cause of declines in fish stock production (e.g., Branch, Jensen, Ricard, Ye, & Hilborn, ; Pauly, Hilborn, & Branch, ; Worm et al., ).…”