Recovering otter populations yield more benefits than costs

The benefits of sea otter recovery along the Pacific coast will outweigh the commercial losses to local crab, urchin, and shellfish fisheries by as much as 46 million Canadian dollars per year, according to a new study. Critically, the analysis "provides a method for looking beyond depredation in assessing the costs and benefits of living with predators," write James Estes and Lilian Carswell in a related Perspective. This has long been a challenge for those working at the intersection of ecology and natural resource management. After otters were hunted to near extinction during the 18th and 19th centuries, populations of crabs, clams and urchins - no longer otter fodder - thrived, opening up new fisheries along the eastern North Pacific coast.

The now decades-old reintroduction of otters, an apex predator, has led to transformational changes. Even as the changes have largely revitalized iconic Pacific kelp forests, they also threaten the now well-established commercial fisheries. While such social-ecological conflicts arising from the return of keystone predators are common, they are rarely evaluated, making the equitable management of natural resources difficult. Leveraging the natural experiment occurring in the waters off Vancouver Island, Canada, where sea otters have re-occupied a large portion of their historical habitat, Edward Gregr and colleagues developed a modeling framework to evaluate several key economic costs and benefits of otters' return and its effects. The authors' model, calibrated with local data, also accounts for uncertainties in the future value and potential interactions among the species in the coastal ecosystem.

According to Gregr et al., the overall monetary value of sea otter-induced increases in tourism, finfish fisheries and carbon capture will far exceed the losses to impacted commercial fisheries. However, the costs and benefits of sea otter recovery will be distributed inequitably among economic sectors and local communities, the authors say, especially for Indigenous Peoples, who are experiencing the losses more acutely. But, they emphasize, quantifying the impacts of such ecological transformations will help mitigate conflicts, promote public acceptance of ecosystem change, and identify alternate opportunities for local communities. "The analysis by Gregr et al. should spark a new era of ecological-economic research that can be used by natural resource policymakers and managers to make and defend more rational, equitable, and far-sighted decisions affecting predators," write Estes and Carswell.