Advancing abalone conservation by revealing change in predator-prey interactions and social-ecological resilience through time

Species conservation remains challenged by paucity of long-term data on how human use and environmental factors have shaped species abundance and trends. Further, as humanity pushes against limits of the biosphere, sustainable environmental governance could benefit from understanding factors that conferred resilience to enduring coupled social-ecological systems (SESs). Along Canada’s west coast, northern abalone (Haliotis kamtschatkana) and coastal indigenous peoples (First Nations) have co-evolved for millennia. Yet within a half-century, commercial overfishing under centralized fisheries management caused closure of all abalone fisheries and subsequent listing of abalone as endangered. While loss of this cultural keystone species profoundly affected coastal First Nations and recent abalone recovery fuels interest in restoring traditional fisheries, concurrent recovery of a key predator, sea otters (Enhydra lutris), poses a conservation conundrum. I aim to advance abalone conservation by illuminating key changes in components and interactions within this SES through time. To understand ecological effects of sea otter recovery on abalone, I conducted field surveys in three regions of coastal British Columbia, representing four decades of sea otter occupation and varying environmental conditions. While sea otters caused abalone density decline, indirect effects improved habitat conditions and altered abalone behaviour and distribution, thereby mediating predation effects. Next, I synthesized multiple knowledge sources to demonstrate how ecological extirpation of sea otters caused social-ecological regime shifts allowing abalone to obtain higher historical abundances than were likely prior to European contact. This shifted baseline and continuing declines amplified perceptions of abalone extinction risk. However, if abalone are not truly endangered, society is morally obligated to conserve abalone and restore sustainable traditional fisheries for reasons of social justice. Finally, I explored how fisheries sustainability might be achieved using traditional knowledge of past governance and management protocols. Although polycentric institutions for abalone recovery today might support future co-management, key issues of power asymmetries, trust and funding remain barriers to address. By broadening our understanding of the abalone SES in western Canada, my thesis provides insights into how weaving indigenous knowledge of past resource management with contemporary western science can inform ecologically sustainable and socially just approaches to coastal fisheries today.