Aerial Surveys for Large Whale Monitoring in the Santa Barbara Channel

Since 2014, the California Marine Sanctuary Foundation, in collaboration with the Channel Islands National Marine Sanctuary and the Volgenau Foundation, has conducted monthly aerial surveys over the Santa Barbara Channel to systematically document the presence and distribution of large whale species. These include the endangered blue (Balaenoptera musculus), fin (Balaenoptera physalus), and humpback whales (Megaptera novaeangliae). The data collected through these surveys is essential for understanding regional population dynamics and informing targeted conservation strategies.

Aspen Helicopters pilot Jacob Fuerst flying a Partenavia aircraft circling to identify species and number of individuals present on survey flight in the Santa Barbara Channel. Credit: Claire Fackler (NOAA).

Trained observers conduct these surveys from a Partenavia twin-engine aircraft, owned and operated by Aspen Helicopters, flying a standardized route out of Oxnard Airport at an altitude of 1,000 feet and at a speed of 100 knots. The 200-mile flight path follows the Ship Traffic Separation Scheme, extending past Point Arguello along the northbound traffic lane before returning along the southbound lane. During each flight, observers systematically record whale sightings while also noting environmental conditions that may affect visibility and detection probabilities. This long-term dataset enables researchers to track seasonal trends, monitor shifts in whale distribution, and assess changes in the timing of species’ arrivals and departures in the region.

Map of 2024 survey details which recorded 108 whales across 8 flights. Credit: Anastasia Kunz (CMSF)

In 2024, the survey documented over 108 whales across eight flights; four surveys were canceled due to weather. A particularly notable survey in June recorded 34 blue whales and three humpbacks near Santa Cruz and Santa Rosa Islands, in areas adjacent to the shipping lanes. Such observations highlight the importance of continued monitoring in this ecologically significant region.

Picture of 3 blue whales from the June 2024 survey flight. Credit: Claire Fackler (NOAA)

A key application of this dataset is mitigating the risk of ship strikes, one of the leading threats to large whales in the Santa Barbara Channel and around the world. As a heavily trafficked shipping corridor, the region presents a significant challenge for conservationists working to reduce vessel-whale collisions. Each year, from May through December, NOAA, the U.S. Coast Guard, and the Environmental Protection Agency request that large vessels over 300 gross tons reduce their speed to 10 knots or less in designated Vessel Speed Reduction (VSR) zones, including the Santa Barbara Channel, to minimize the risk of ship strikes. Data from these aerial surveys support the placement and timing of these zones and help assess whether whale presence justifies temporal adjustments to the VSR season. In 2024, the persistent high number of humpback whales in the region led to an extension of the VSR season through January 15, 2025. By confirming extended presence and identifying whale aggregation zones, CMSF’s surveys provide critical information to refine and strengthen these programs.

In addition to informing policy decisions on reducing the risk of ship strikes, these data are also used to help inform California Department of Fish and Wildlife’s (CDFW) Dungeness Crab Fishing Gear Working Group’s (Working Group) Risk Assessment and Mitigation Program (RAMP), to reduce the risk of entanglements, another known major contributor of mortality to endangered whales. When the data show that whale presence is high and entanglement risk is elevated, CDFW consults with the Working Group to determine a policy action and response, like fishery closures and gear reductions.

MSC container ship transiting through the Southern California Vessel Speed Reduction Zone by Anacapa and Santa Cruz Islands. Credit: Anastasia Kunz (CMSF)

Beyond informing these policy actions, these aerial surveys contribute to broader ecological research. Long-term monitoring provides insights into regional population trends, potential impacts of climate change on whale distribution, and the effectiveness of existing conservation measures. As climate and oceanographic conditions continue to shift, this dataset will be even more critical in adapting conservation efforts to ensure the protection of these endangered species in an increasingly dynamic marine environment.