Cascading social-ecological costs and benefits triggered by a recovering keystone predator

Abstract

Predator recovery often leads to ecosystem change that can trigger conflicts with more recently established human activities. In the eastern North Pacific, recovering sea otters are transforming coastal systems by reducing populations of benthic invertebrates and releasing kelp forests from grazing pressure. These changes threaten established shellfish fisheries and modify a variety of other ecosystem services. The diverse social and economic consequences of this trophic cascade are unknown, particularly across large regions. We developed and applied a trophic model to predict these impacts on four ecosystem services. Results suggest that sea otter presence yields 37% more total ecosystem biomass annually, increasing the value of finfish [+9.4 million Canadian dollars (CA$)], carbon sequestration (+2.2 million CA$), and ecotourism (+42.0 million CA$). To the extent that these benefits are realized, they will exceed the annual loss to invertebrate fisheries (−$7.3 million CA$). Recovery of keystone predators thus not only restores ecosystems but can also affect a range of social, economic, and ecological benefits for associated communities.

The maturation of ecosystem services: Social and policy research expands, but whither biophysically informed valuation?

“…The rise of non‐monetary valuation, qualitative social assessment, social studies of access, demand and equity reveals that economics is clearly no longer the only social science deeply engaged with ES. And yet the rarity of integrative studies—for example, that both characterize relevant biophysical changes underpinning services and the implications of those changes via valuation (Gregr et al., 2020)—suggests that the interdisciplinary integration that excited so many remains only partly fulfilled.…”

Diffusion modeling reveals effects of multiple release sites and human activity on a recolonizing apex predator

“…Sea otters in the region also face growing conflicts with human interests and activities due to their effects on commercially-valuable and subsistence species (Carswell et al, 2015). However, the return of the historical state of the nearshore marine ecosystem is gaining support among many stakeholders because there is great value in the ecosystem services that the predator-dominated system can render, such as improved carbon sequestration, nursery habitat for fish, and greater fish biomass (Wilmers et al, 2012;Gregr et al, 2020).…”

“…When an apex predator is reintroduced, however, such a perturbation followed by continued growth and expansion of the population can change ecological communities and revert an ecosystem to a previous state (Ripple and Beschta, 2012). Although often controversial, such shifts in ecosystem state can achieve conservation goals and afford ecological and economic benefits (Gregr et al, 2020).…”

“…Predator reintroductions are sometimes proposed to recover ecosystem services or remedy human-caused declines, such as those due to overharvest (Ritchie et al, 2012;Gregr et al, 2020). One of the most successful and celebrated efforts has been the reintroduction of wolves (Canis lupus) and subsequent recovery in the Greater Yellowstone Ecosystem.…”

“…Legislation, beginning with the Fur Seal Treaty (1911), followed by the Marine Mammal Protection Act (MMPA;1972) and the Endangered Species Act (1977), protected sea otters from harvest, with the exception of harvest by Alaska Natives for subsistence and handicraft, per the MMPA (Bodkin, 2015). This protection facilitated sea otter population growth and expansion across parts of their range, which has been reverting the nearshore ecosystem in some of these areas to the historical predator-dominated state (Estes and Palmisano, 1974;Estes and Duggins, 1995;Estes et al, 2010;Gregr et al, 2020).…”