Climate change, distribution shifts, and choke species: A threat assessment to advance fishery ecosystem planning

Oceans are warmer and contain less oxygen than any time in recent history. Because oxygen levels are thought to pose a key constraint on where marine animals can and cannot sustain life, scientists and managers expect organisms to move out of areas with insufficient oxygen and into areas that allow them to meet their oxygen demands. These shifts are an important response that allows animals to survive, but they also may challenge fisheries if key target species shift out of usual fishing areas, or if they move into areas where local fisheries lack permits that would enable them to fish. This project is providing the first assessment of the risk posed by changing oxygen and temperatures on the U.S. Pacific fisheries, which will foster adaptation planning by affected regions, communities, and governance systems.

Project background

The coastal ecosystems that support fisheries are undergoing rapid change. Temperatures are increasing and oxygen levels are decreasing; in theory, these two trends simultaneously constrain marine life because increased temperatures increase oxygen demand while declining oxygen levels decrease supply. In response, fish are moving to avoid inhospitable areas. These shifts can cause fisheries management problems — for example, fish may shift into areas that are under a different management jurisdiction.

Results and findings

Washington Sea Grant-funded researchers are compiling and analyzing existing trawl surveys to investigate the sensitivity of various groundfish species to temperature and oxygen levels. They will use this information to infer future short- and long-term patterns of groundfish distributions given climate change. The researchers are evaluating these patterns at broad scales, from California to the Bering Sea, and are also looking at localized patterns such as the usual and accustomed fishing area of coastal Tribes.

The team has developed two tools now available for public use: a database of groundfish survey and oceanographic data integrated from multiple sources, and an R code package that provides estimates of how existing fish distributions respond to the joint effects of oxygen and temperature. The team also made several advances in improving the information available to assess how changing oxygen conditions in coastal oceans is likely to affect when and where species are present. The team collated lab data from over 140 marine animal species on their critical oxygen requirement to sustain metabolism, and used that to fit a taxonomy-based model to predict this quantity when lab data are absent. Preliminary findings suggest that oxygen sensitivity is more similar among closely-related taxa than distantly-related taxa, though there remains considerable uncertainty in predicted threshold values. Finally, the project tested methods to determine oxygen measurements at the time of collection of biological samples (e.g. trawl surveys), finding that in data rich areas like the U.S. West Coast integrated model predictions can be very accurate.

Contact information

Tim Essington
Professor
School of Aquatic and Fishery Sciences, University of Washington
206.616.3698
essing@uw.edu