This project aims to test the feasibility of using novel acoustic transmitters to track Delta smelt in the San Francisco Bay-Delta. Successful utilization of acoustic telemetry to track Delta smelt can provide researchers and resource managers with information about the species’ habitat preferences, the effects of water-management practices on Delta smelt movement and distribution, and the success of ongoing supplemental release efforts. The assessment of feasibility will include a comprehensive analysis of both the lethal and sublethal effects of surgical tag implantation on Delta smelt, as well as the development of a species-specific tagging protocol.
The Sacramento-San Joaquin Delta is a highly altered and impaired ecosystem that is critical to the freshwater infrastructure of the State of California. Salt intrusion from San Francisco Bay into the Delta, however, threatens freshwater delivery to the southern portions of the state and so management and restoration actions within the Bay-Delta must continuously balance both ecosystem and operational needs. While previous numerical modeling studies have sought to examine changes in the estuarine physics of the system, these tools are costly to develop and run. Thus there is a need to develop alternate methods for monitoring the movement of water through the Bay-Delta, as proposed here. The proposed research project approaches tracking the mixing between the Bay and Delta waters through the novel use of daily satellite color imagery. These findings will be linked to in situ measurements throughout the system and used to inform relevant agencies of flow characteristics within the waterways. This work is motivated by a need for high frequency monitoring of finescale features within the dynamic Bay-Delta ecosystem and to take advantage of new advanced remote sensing technology to inform on long-term trends within the Delta.
The primary objectives of this research are to: 1. Enhance monitoring programs to inform management in the presence of climate change and additional stressors, 2. Inform on ecosystem resilience to interannual hydrologic variations and climate change impacts, and 3. Evaluate how climate change and flow regime changes will impact water quality in the Delta.
The San Francisco Estuary (SFE) supports the southernmost reproductive population of longfin smelt (LFS) along the Pacific Coast. Long term monitoring studies have observed a precipitous decline of LFS in the SFE over the past several decades, and the San Francisco Bay-Delta Distinct Population Segment was listed as endangered under the Endangered Species Act in July of 2024. There are important gaps in our understanding of LFS ecology and movement within the highly urbanized SFE, posing challenges to the development of effective recovery strategies. More complete information about the movement and migration of LFS in the wild can lead to improved life-cycle modeling and provide insight into the species’ relationship with temperature, salinity and other habitat features of the SFE. An effective tool to learn about fish migration and movement is through a tracking method known as acoustic telemetry. Until recently this practice has been impossible on small fish such as LFS due to their body size relative to existing acoustic transmitters, or ‘tags’. With recent advances in telemetry technology, we now have an opportunity to implant newly miniaturized acoustic transmitters into adult LFS. However, before the results of telemetry studies utilizing these newly developed transmitters can be used to make inferences about wild populations, it is imperative to determine whether the tagged individuals are surviving and behaving in the same way as their un-tagged counterparts. The study aims to establish post-tagging survival and transmitter retention rates of wild and captive-reared LFS surgically implanted with newly miniaturizes acoustic transmitters, as well as the sublethal effects of transmitter implantation on LFS swimming performance. The results of this study will directly inform the implementation of acoustic telemetry on LFS, aiding in the conservation and recovery of an imperiled native species.
