Protecting the ocean twilight zone: Building from Science to Action

The twilight or mesopelagic zone is host to a wealth of ocean biodiversity. A critical component of the ocean food web,these species are important prey species. Due to daily mass migrations, mesopelagic species transfer 2-6 gigatons of carbon per year to the deep sea, an amount equivalent to twice the emissions produced by cars worldwide annually. Recognizing the significant abundance of biomass in the twilight zone, efforts have been made over time to commercially extract these resources. While none of those past fisheries have resulted in fishing at scale, interest remains and pressure to find new sources of protein is rising as current stocks of small pelagic species, critical inputs to fishmeal and fish oil production, are declining or shifting their distributions due to climate change. Other potential activities associated with deep-sea mining and marine carbon dioxide reduction may impact the natural carbon sequestration pathways facilitated by the mesopelagic. Given what we know about the importance of the twilight zone, it is imperative that these critical ecological and climate services are protected. A number of published papers have identified pathways for large-scale protections. They include actions within country EEZs based on existing governance frameworks, expert guidance from the UN Food and Agriculture Organization, the IPCC, and the wider scientific community, actions by regional fishery management organizations, expansion of the role of the London Protocol on regulating marine carbon dioxide reduction research; and the pending ratification of the BBNJ agreement. This talk will present the work of a group of actors spanning academia, NGOs, and government entities to leverage the existing base of science and knowledge about the ocean twilight zone in support of sound policy to protect these critical resources.