This study focuses on understanding how restored tidal wetlands with different physical configurations function as refuge and rearing habitat for fishes, including native and imperiled species such as delta smelt and juvenile Chinook salmon. This research will assess the spatial distribution of predation risk as it varies within and across tidal wetlands. The proposed research will generate a statistical model that helps predict predation outcomes from various restored tidal wetland designs and channel configurations. This will be a powerful tool for managers to forecast how proposed habitat restoration or water management actions may impact native fish populations.
This study will investigate fish swim performance in response to temperature, using salmon and two of its known predators: largemouth bass and Sacramento pikeminnow. The researcher will assess swim performance metrics and predation risk inside and outside the ideal thermal range of each species to determine if a temperature advantage predicts salmon survival in predation scenarios. This project's results will provide a mechanistic understanding of how temperature stress may influence mortality risk of juvenile Chinook salmon through predation, which will offer a more holistic perspective on the management of this species
The California Recreational Fisheries Survey (CRFS) mission is to collect fishery-dependent data on California's marine recreational fisheries, and to accurately estimate catch and effort in a time frame and on a scale that meets management needs. CRFS collects the data necessary to estimate catch and effort for California's diverse recreational finfish fisheries which range from the California-Mexico border to the California-Oregon border extending over 1,100 miles of coast and is surveyed at over 400 sampling sites. Annually, CRFS conducts over 7,000 sampling assignments and contacts over 68,000 fishing parties. High sampling rates produce confidence in estimates with a 20 percent sample rate of private boat anglers during salmon or groundfish seasons. CRFS collects the data to produce the estimates for all sport-caught finfish.
Observations of individual and population dispersal of delta smelt are essential for improving models that can inform management strategies potentially improving movement into favorable areas or reducing movement into areas of poor habitat quality and risk of pumping loss. However, delta smelt movement patterns are largely unknown. Pacific Northwest National Labs has developed a much smaller Juvenile Salmon Acoustic Telemetry System (JSATS) tag, called the "Shad tag." Recent experiments suggest these tags can be successfully implanted in delta smelt without having significant, negative effects on individual condition and swimming behavior. The next step to determine if the newest technology may provide a tool for acoustic observation of fish dispersal over small spatial scales. Filling this data gap is important because changes in delta smelt spatial distribution (i.e., movement or dispersal) play a significant role in the management and recovery of the species.
This project includes two years of field-based experiments necessary to move this technology into the field. The existing San Francisco Estuary's JSATS array was designed to detect larger, more powerful tags and may not be as effective at detecting the smaller, less powerful tags. Therefore, first, we will test the detectability of the Shad tag by the existing JSATS array and explore detectability at potential locations for new receivers at delta smelt-relevant locations. Secondly, we will design and deploy a 3D positioning array to test performance of such an array in upper San Francisco Estuary habitats. Finally, we will conduct several small releases of delta smelt implanted with the new Shad tag to assess the capacity of the JSATS receiver arrays to detect and position live fish. This feasibility study will lay the groundwork for the development of a receiver array and post detection signal processing algorithm to detect delta smelt tagged with Shad tags in later phases of the project.
