Identifying social thresholds and measuring social achievement in social-ecological systems: A cross-regional comparison of fisheries in the United States

In marine social-ecological systems (SESs), environmental and human-induced stressors can push ecosystems from a high-functioning state into a new, often undesirable state (i.e., regime shift) with limited delivery of ecological goods and services (e.g., high to low fisheries production). While ecological regime shifts are well studied, social regime shifts within SESs are underexplored. Socioeconomic indicators were used to identify thresholds and trends in fisheries and coastal employment for six marine SESs around the U.S. These study sites represent coastal regions delineated by the National Oceanic and Atmospheric Administration for which periodic monitoring and data collection occur. We first used Generalized Additive Modeling to identify periods of change, then linked them to potential regional and national drivers. Social outcomes were ranked using composite social and environmental indices for each region, constructed using Data Envelopment Analysis. Technological innovation and national regulatory changes (e.g., Magnuson Stevens Act) co-occurred with detected nationwide shifts in fisheries productivity, while engagement in specific fisheries determined local regional shifts. Our study demonstrates the effectiveness of the complementary threshold analysis and outcome ranking methods in identifying regimes and assessing performance. Together, they provide management information and insight into possibilities for preventing unfavorable shifts and to assess society's ability to adapt to those shifts.