American bullfrogs (Lithobates catesbeianus) are a prolific invasive species worldwide, and one of increasing regulatory and management interest in California. Valley Water, as part of the Upper Llagas Creek Flood Protection Project, was required to perform bullfrog control in accordance with permit conditions following wetland restoration at Lake Silveira in southern Santa Clara County. As part of the comprehensive habitat mitigation and monitoring plan Valley Water implemented, Sequoia conducted bullfrog control at Lake Silveira in 2022 and 2023. Field efforts consisted of a reconnaissance survey to identify life stages present and appropriate methods of control. Control efforts consisted of three nights of removal in September, in both 2022 and 2023. In 2022, a total of 203 post-metamorphic bullfrogs were culled during shoreline-based surveys using gig and air rifle techniques. In 2023, a total of 210 post- metamorphic bullfrogs were culled during a mix of shoreline- and boat-based surveys, using air rifle techniques almost exclusively. Between 2022 and 2023, strong regrowth of shoreline riparian vegetation necessitated the introduction of boat-based surveys to effectively approach bullfrogs. This poster presents preliminary results in demographics, catch-per-unit-effort (CPUE; frogs/person-minute) data by year and encounter type, field method efficacy, and recommendations for future work.

Brett Hanshew is a Principal Biologist and Senior Technical Specialist at Sequoia Ecological Consulting, Inc. He studied Environmental Biology and Management at the University of California, Davis (BS) and Fisheries Science at Oregon State University (MS), and focuses on applied freshwater ecology, herpetology, ecosystem-based management, and scientific-regulatory interface in his professional practice. Mr. Hanshew more than twenty years' experience in academic and professional experience, and holds USFWS and CDFW authorizations for threatened & endangered species including California red-legged frog, California tiger salamander, listed vernal pool branchiopods, San Franciso garter snake, and foothill yellow-legged frog.