Responses of ecological indicators to fishing pressure under environmental change: Exploring non-linearity and thresholds

Contribution to the Themed Section Science in support of a nonlinear non-equilibrium worl.-- This is a contribution to the IndiSeas Working Group, co-funded by IOC-UNESCO (www.ioc-unesco.org) and EuroMarine (http://www.euromarinenetwork.eu), to the project EMIBIOS (FRB, contract no. APP-SCEN-2010-II) and to the IOC-UNESCO GOOS Programme and GOOS Biology and Ecosystems Panel.-- 16 pages, 9 figures, 2 tables, supplementary material https://doi.org/10.1093/icesjms/fsz182

Marine ecosystems are influenced by multiple stressors in both linear and non-linear ways. Using generalized additive models (GAMs) fitted to outputs from a multi-ecosystem, multi-model simulation experiment, we investigated 14 major ecological indicators across ten marine ecosystems about their responses to fishing pressure under: (i) three different fishing strategies (focusing on low-, high-, or all-trophic-level taxa); and (ii) four different scenarios of directional or random primary productivity change, a proxy for environmental change. From this work, we draw four major conclusions: (i) responses of indicators to fishing mortality in shapes, directions, and thresholds depend on the fishing strategies considered; (ii) most of the indicators demonstrate decreasing trends with increasing fishing mortality, with a few exceptions depending on the type of fishing strategy; (iii) most of the indicators respond to fishing mortality in a linear way, particularly for community and biomass-based indicators; and (iv) occurrence of threshold for non-linear-mixed type (i.e. non-linear with inflection points) is not prevalent within the fishing mortality rates explored. The conclusions drawn from the present study provide a knowledge base in indicators’ dynamics under different fishing and primary productivity levels, thereby facilitating the application of ecosystem-based fisheries management worldwide

The work on Canada West Coast ecosystem was sponsored by Fisheries & Oceans Canada under the Aquatic Climate Change and Adaptation Services Programme. YJS and LV were supported by the project EMIBIOS (FRB, contract no. APP-SCEN-2010-II). AG was supported by NOAA’s Integrated Ecosystem Assessment (IEA) programme (http://www.noaa.gov/iea/). MC was supported by the Marie Curie Career Integration Grant Fellowships—PCIG10-GA-2011-303534—to the BIOWEB project and the Spanish National Project PELWEB (CTM2017-88939-R). All other authors were supported by their respective affiliations

With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)