Quantifying uncertainty in the wild‐caught fisheries goal of the Ocean Health Index

Abstract

Sustainability indices are proliferating, both to help synthesize scientific understanding and inform policy. However, it remains poorly understood how such indices are affected by underlying assumptions of the data and modelling approaches used to compute indicator values. Here, we focus on one such indicator, the fisheries goal within the Ocean Health Index (OHI), which evaluates the sustainable provision of food from wild fisheries. We quantify uncertainty in the fisheries goal status arising from the (a) approach for estimating missing data (i.e., fish stocks with no status) and (b) reliance on a data‐limited method (catch‐MSY) to estimate stock status (i.e., B/BMSY). We also compare several other models to estimate B/BMSY, including an ensemble approach, to determine whether alternative models might reduce uncertainty and bias. We find that the current OHI fisheries goal model results in overly optimistic fisheries goal statuses. Uncertainty and bias can be reduced by (a) using a mean (vs. median) gap‐filling approach to estimate missing stock scores and (b) estimating fisheries status using the central tendency from a simulated distribution of status scores generated by a bootstrap approach that incorporates error in B/BMSY. This multitiered approach to measure and describe uncertainty improves the transparency and interpretation of the indicator and allows us to better understand uncertainty around our OHI fisheries model and outputs for country‐level interpretation and use.

Co-creating coastal sustainability goals and indicators

“…The Coastal Barometer uses the OHI (Halpern et al 2012) as a framework, which can be used to assess ocean health and sustainable coastal development from global to local scales using quantitative indicators. It has, for instance, been used to track progress towards Aichi target 10 and UN Sustainable Development Goal 14 "Life below Water" at global scales (Sachs et al 2018;Afflerbach et al 2019) and to assess how changes in management and human use of oceans have affected overall ocean health at regional scales (O'Hara et al 2020;Montgomery et al 2021). The OHI defines a healthy ocean as one that "sustainably delivers a range of benefits to people now and in the future", which is measured against 10 overarching goals (Halpern et al 2012).…”