Identifying highly used Dungeness crab fleet fishing areas off central and northern California to inform entanglement risks of large whales
- Foraging
- Entanglement
Abstract
Large whales seasonally aggregate into highly productive areas to feed, which often overlap with regions popular for various fishing activities. This spatial and temporal overlap can lead to whale entanglements in fishing gear. Along the California coast, such impacts have been amplified by intense marine heat waves and climate-driven shifts in whale migration and habitat use, resulting in unprecedented reports of entangled whales and substantial disruptions to the region’s valuable Dungeness crab fishery. In response, the Risk Assessment and Mitigation Program (RAMP) was established to reduce entanglement risk through collaboration and adaptive management. As part of this program, we sought to quantify the spatial footprint of crabbing effort in California waters. To achieve this, we analyzed solar logger positional data collected from a sample of commercial crabbing vessels in Central and Northern California, applying movement models adapted from animal behavior studies to identify where crabbing occurred. We then fitted resource selection functions using environmental and operational variables predicted to influence crab fishing behavior, producing a spatial surface of crabbing probability. This information on the timing and location of crabbing activity enhances our understanding of fishing effort distribution and enables managers to implement targeted strategies that, when combined with whale distribution data, may reduce entanglement risk while maintaining optimal crabbing opportunities.
Johns, M., George, K., Lane, R., & Jahncke, J. (2026). Identifying highly used Dungeness crab fleet fishing areas off central and northern California to inform entanglement risks of large whales. California Fish and Wildlife Journal, (112), e5. https://doi.org/10.51492/cfwj.112.5
Meet The Experts
{"image":"\/People\/Portrait\/kathi-george.jpg","alt":"Kathi George","title":"Kathi George","text":"Director of Cetacean Conservation Biology","link_url":"https:\/\/www.marinemammalcenter.org\/person\/kathi-george","link_text":"Read Bio"}
Related Publications
{"image":"\/Animals\/Patients\/Harbor seals\/hs-by-bill-hunnewell-c-the-marine-mammal-center.jpg","alt":"harbor seal in a life preserver enrichment item","title":"Enrichment as a Tool for Rehabilitating Harbor Seals","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/enrichment-as-a-tool-for-rehabilitating-harbor-seals","label":"Research Paper"}
{"image":"\/Animals\/Wild\/Harbor porpoise\/cropped-images\/harbor-porpoises-foraging-by-marc-webber-c-the-marine-mammal-center-4-0-1276-996-1618438446.jpg","alt":"harbor porpoises eating a large fish","title":"Prey-Related Suffocation in Harbor Porpoises","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/prey-related-suffocation-in-harbor-porpoises","label":"Research Paper"}
{"image":"\/Animals\/Wild\/Humpback whale\/cropped-images\/humpback-whale-breach-golden-gate-by-pilar-rodriguez-c-the-marine-mammal-center-noaa-permit-26532-647-0-1710-1336-1702426697.jpg","alt":"humpback whale breaches with Golden Gate Bridge in the background","title":"New Urban Habitat for Endangered Humpback Whales: San Francisco Bay","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/new-urban-habitat-for-endangered-humpback-whales-san-francisco-bay","label":"Research Paper"}
{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/gray-whale-baleen-shutterstock-526-1-3317-2591-1604510915.jpg","alt":"gray whale with mouth open above water","title":"Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales (Eschrichtius robustus) in California","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/fish-feeding-and-rapid-foraging-behavior-switching-by-gray-whales-eschrichtius-robustus-in-california","label":"Research Paper"}
Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales (Eschrichtius robustus) in California
Read MoreRecent News
{"image":"\/Animals\/Wild\/Humpback whale\/humpback-whale-spout-by-bill-hunnewell-c-the-marine-mammal-center.jpg","alt":"Humpback whale spout","title":"A Collaboration to Protect Whales and Support California\u2019s Dungeness Crab Fishery","link_url":"https:\/\/www.marinemammalcenter.org\/news\/collaboration-to-protect-whales-and-support-californias-dungeness-crab-fishery","label":"Press Release","date":"2026-10-22 02:00:00"}
A Collaboration to Protect Whales and Support California’s Dungeness Crab Fishery
October 22, 2026
Read More{"image":"\/People\/Action\/Response\/cropped-images\/c-common-dolphin93026cuesta-inlet-in-morro-bayphoto-c-the-marine-mammal-center-noaa-mmhsrp-24359-0-399-1270-992-1790883642.jpg","alt":"Stranded dolphin response","title":"Three Common Dolphins Freed from Mudflats in Morro Bay","link_url":"https:\/\/www.marinemammalcenter.org\/news\/three-common-dolphins-freed-from-mudflats-in-morro-bay","label":"News Update","date":"2026-10-02 02:00:00"}
{"image":"\/Animals\/Wild\/Humpback whale\/cropped-images\/a-humpback-whalesf-bay91526photo-by-norely-faz-c-the-marine-mammal-center-noaa-permit-26532-772-1-1270-992-1789760973.png","alt":"Humpback whale Rio","title":"Humpback Whale \"Rio\" Spotted in the Sacramento-San Joaquin Delta","link_url":"https:\/\/www.marinemammalcenter.org\/news\/humpback-whale-rio-spotted-in-the-sacramento-san-joaquin-delta","label":"News Update","date":"2026-09-18 12:10:00"}
Humpback Whale "Rio" Spotted in the Sacramento-San Joaquin Delta
September 18, 2026
Read More{"image":"\/Animals\/Patients\/California sea lions\/2024\/d-california-sea-lionsin-treatment-for-domoic-acidsausalito72624photo-by-giancarlo-rulli-c-the-marine-mammal-center.jpg","alt":"California sea lions","title":"SF GATE: Sick, disoriented sea lions are washing up on California beaches","link_url":"https:\/\/www.marinemammalcenter.org\/news\/sf-gate-sick-disoriented-sea-lions-are-washing-up-on-california-beaches","label":"In the News","date":"2026-09-01 10:39:22"}
SF GATE: Sick, disoriented sea lions are washing up on California beaches
September 1, 2026
Read More