Benchmarking ecosystem performance using index numbers: A case study of the northeast large marine ecosystem Marine Policy

Ecosystem indicators provide important information to managers about the results of their efforts to provide goods and services from marine ecosystems, along with the environmental condition of the ecosystem. Often, multiple indicators are of interest, which represent a cross-section of goods and services provided through ecosystem based management (EBM). This can make evaluation of whether ecosystem managers are improving their stewardship of marine ecosystems challenging because multiple indicators may give conflicting signals about management success. In order to overcome this problem, we develop an environmental output and input quantity index that collapses multiple ecosystem indicators into two composite indices. Our indices are based on distance functions constructed using Data Envelopment Analysis (DEA), a linear programming technique. We construct an output quantity index with data on fishery revenue, right whale populations and recreational trips from the northwest Atlantic Large Marine Ecosystem (LME) for the years 1998–2019. This is combined with an environmental quantity index using data on zooplankton abundance, chlorophyll-A, and aggregate fishery biomass. Both indices use 1998 as a benchmark year. Results from the combined output quantity-environmental quantity index show that relative to 1998, ecosystem performance generally improved before declining after 2016. Environmental conditions substantially improved, but outputs from the system declined in recent years. Although outputs are greater than in 1998, the system should be able to produce more given the environmental quality. Reasons for lower outputs could be due to exogenous factors beyond the control of managers.