Large Whale Entanglements off the U.S. West Coast, From 1982–2017

February 20, 2020

Large whale interaction and entanglement with gear in the ocean poses a major threat to animals worldwide.

Entanglement can cause mortality, minor to significant injuries that may compromise the health of the individual animal which may impact their ability to feed or reproduce. There are also economic impacts associated with large whale entanglements. Commercial and recreational fishing industries may incur expenses due to lost gear or potential gear modifications, and increased regulations to reduce future whale entanglements. A significant investment is also needed when a response is undertaken to remove gear from an animal or to remove gear from the water.

Reports from California, Oregon, and Washington were standardized and combined to form a single database. This standard database was then analyzed for spatial and temporal trends in whale species, fishing gear types and associated fisheries, known outcomes of whale entanglements, and entanglement response.

Off the coast of California, Oregon, and Washington, there were 521 whale entanglements reported and 434 confirmed entanglements between January 1, 1982 and December 31, 2017. Whale entanglement reports were confirmed using criteria that include reviewing photos or videos or through direct observation by the National Oceanic and Atmospheric (NOAA) staff or another expert. Data analyses document a recent spike in entanglements, jumping from an annual average of 9 confirmed entangled large whales between 1982 and 2013, to an average of 41 confirmed entangled large whale reports between 2014 and 2017. Multiple factors may contribute to this increase in the number of reported entanglements, including, but not limited to, an increase in public awareness and reporting, changes in the spatial distribution and abundance of whales, fishing effort, and ocean conditions.

NOAA Technical Memorandum NMFS-OPR-63

Last updated by West Coast Regional Office on 06/15/2020