Long‐term, spatial marine harvest intensity as an indicator of human impact on shallow rocky reef ecosystems

Abstract

AbstractAs human activities continue to expand globally, there will be increased need to incorporate the impacts of these activities into ecological studies for a holistic understanding of ecosystems. Within the Southern California Bight, as in other highly productive marine ecosystems, fishing has long contributed to the ecology and evolution of marine fish and invertebrate communities. As fishing varies across space and over time, there is a need for a reliable metric that quantifies the spatiotemporal variation in the impact of fishing. Here, we quantify an index of harvest intensity on the highly productive and heavily fished, shallow rocky reefs of Southern California. To this end, we take advantage of two long‐term, spatially explicit, multi‐species datasets collected by the California Department of Fish and Wildlife on commercial and recreational marine harvest, combined with reef‐species survey data and a geospatial reef data layer. Using this approach, we recover predictable patterns for harvest intensity across the Southern California Bight, with harvest intensity decreasing in fishing blocks located at greater distances from the nearest port. Further, our results indicate an important interaction effect between distance to nearest port and year on harvest intensity, suggesting there are important shifts in spatiotemporal patterns over the 30‐year time period. As fishing can have numerous impacts on ecological and evolutionary processes, the observed spatiotemporal variation in harvest intensity illustrates the need for incorporating the contribution of human impacts into marine ecosystem studies.