Assessing Potential Entanglement Risk for Large Whales on the West Coast

West Coast

Large whale entanglement in commercial fishing gear off the U.S. West Coast has been identified as an issue of concern by NOAA Fisheries because of the potential impacts to both large whales (individually and at a stock/population level) and the commercial fishing industry. Large whales entangled in gear may be injured and/or impaired, which could affect the ability of individuals to survive and a population's ability to recover.

Along the U.S. West Coast, an average of 10 large whales have been reported entangled per year between 2000-2012. At that time, little information had been confirmed from entanglement reports about the origin of the entangling gear. Therefore, NOAA Fisheries developed two analytical tools to assess the potential entanglement risk associated with various fixed gear fisheries relative to their occurrence with large whale species.

A model to represent the spatial and temporal distributions of commercial fishing effort. This model focuses on fixed gear fisheries with gear that has been (a) confirmed as entangling whales through sightings and strandings of entangled animals, or (b) has the potential for causing entanglement based on similarities in the general configuration of gear across the fisheries.
A co-occurrence model that identifies where and when large whales are more likely to encounter fishing gear, and thus have a greater risk of entanglement. The model identifies species-specific areas and times of year when entanglement risk may be greater.

Confirmed entanglement reports were compared with the model results. Alignment of known entanglement locations with areas of higher co-occurrence scores supported the use of the co-occurrence model for assessment of whale entanglement risk off the U.S. West Coast.

Beginning in 2015, there has been an increase in the number of entanglements per year above the previous average of 10. There were over 50 confirmed entanglements in 2015 and 2016, over 30 in 2017, and over 40 in 2018. NOAA Fisheries has initiated multiple strategies to increase our understanding of these events and how we can prevent future entanglements.

Strategies that NOAA Fisheries has initiated and continues to use to improve our ability to minimize or mitigate the risk of large whale entanglements include:

continued research on the identified elevated risk areas for entanglements,
increasing the ability to trace gear,
continuing to research gear types that cause entanglements,
strengthening collaboration with the fishing community and other stakeholders, and
increasing outreach initiatives to improve reporting.