Redefining risk in data‐poor fisheries

Abstract

The productivity susceptibility analysis (PSA) is a widely used method to rapidly assess species risk to fishing activities in data‐poor fisheries. A step in ecological risk assessments and used in data‐poor assessment for sustainable fisheries certification programmes (e.g. MSC) and recommendation lists (e.g. Seafood Watch), the PSA is semi‐quantitative, yet little attention has been given to the theoretical basis of this analysis. Current thresholds designating low‐, medium‐ and high‐risk categories divide the PSA plot by equal area, assuming area corresponds to likelihood. We show that plot area does not correspond to likelihood, however, and existing thresholds need revision due to the non‐uniform distribution of vulnerability scores on the PSA plot. The probability of medium risk assignment increases with the number of attributes used to characterize productivity and susceptibility. Here, we present a novel and statistically robust method to derive vulnerability, where threshold values between the risk categories are adjusted with the number of attributes used in the assessment. Our comprehensive framework accounts for all variations in the method, including logarithmic scaling of axes, weighting of attributes and scoring procedures. Simulated results across a range of conditions and comparative evaluation of 302 species in five studies show that one‐third of species may be re‐categorized with the new PSA approach. Importantly, the existing PSA approach underestimates risk by up to 35% when compared with the new method. These findings have strong implications for management of data‐poor fisheries. We recommend adoption of this approach to the PSA to better resolve species’ risk.

Spatially explicit risk assessment of marine megafauna vulnerability to Indian Ocean tuna fisheries

“…Instead, the value of the PSA is that it can provide a baseline comparison of relative risk across species and threats in data‐poor contexts and help identify priorities for additional monitoring or more robust assessment tools (Gallagher, Kyne, & Hammerschlag, 2012; Hobday et al, 2011; Lucena‐Frédou et al, 2017). Recently, there have been several proposed improvements to the PSA that could better resolve risk estimates, focusing primarily on how attributes are selected and scored and how the overall vulnerability score is derived (Grewelle et al, 2021; Hordyk & Carruthers, 2018).…”

“…The overall susceptibility score is the geometric mean of the attributes:Many studies have adjusted this formula to suit different contexts, such as incorporating additional attributes, weighting attributes deemed to be more important, or using an additive (arithmetic) mean instead of a geometric mean (Brown, Reid, & Rogan, 2015; Grewelle, Mansfield, Micheli, & De Leo, 2021; Micheli et al, 2014). We made two key adjustments to the calculation of susceptibility outlined in Hobday et al, 2011.…”

“…Recently, there have been several proposed improvements to the PSA that could better resolve risk estimates, focusing primarily on how attributes are selected and scored and how the overall vulnerability score is derived (Grewelle et al, 2021;Hordyk & Carruthers, 2018).…”

“…The method implies that the susceptibility and productivity components are equally important drivers of vulnerability, where a unit of susceptibility is equivalent to a unit of productivity (Hordyk & Carruthers, 2018). There is no biological or empirical evidence for this assumption, but this framing provides a reasonable way to incorporate both elements into the calculation of risk and interpret the results (Grewelle et al, 2021). Depending on the context, practitioners may be more concerned about the vulnerable species with higher susceptibility scores (e.g.…”

IUU Fishing dalam Pengelolaan Perikanan Lobster Skala Kecil di Pantai Selatan Jawa

“…Di Indonesia masalah tersebut juga terjadi untuk perikanan lain, seperti perikanan pelagis kecil (Mous et al, 2005;Pet-Soede et al, 1999). Oleh karena itu, analisis perikanan sulit dilakukan dan solusi untuk masalah di perikanan lobster menjadi sukar ditemukan (Grewelle et al, 2021;Pilling et al, 2008).…”