Lower Trinity Tributary Egg Survival Hoopa Valley Reservation

Project Objectives:

1. Estimate egg to fry (emergence) survival in 14 artificial redds.

2. Measure abiotic conditions in artificial redds, including sediment composition, water temperature, and surface flow velocity.

3. Compare estimated survival rates from artificial redds to estimates from other studies being conducted in the upper Trinity.



Project Description: The number of spawning adult Chinook salmon returning to reservation streams has steadily declined in recent decades. While a number of restoration projects have been completed in reservation streams, these project target returning adults and out migrating juveniles by providing spawning areas and increased floodplain for juvenile occupancy, it is unknown how successful individual redds are across reservation streams. This project would use artificial redds placed in restored and non-restored areas of reservation creeks to determine redd success by estimating the egg-to-alevin survival rate of eggs placed in those artificial redds.



The project aims to estimate Chinook salmon egg survival in tributaries within the Hoopa Reservation by deploying artificial salmon redds mimicking fall-run Chinook salmon nests. Each redd will contain approx. 300 artificially fertilized fall Chinook eggs from Trinity River hatchery, situated adjacent to real salmon redds. Survival estimation will hinge on successful fry hatching to glean insights into the conditions of the Hoopa Reservations tributaries. Site selection will occur in areas with documented current and historical redds, while construction details will ensure minimal disturbance any existing redds. Monitoring will include temperature and velocity data to predict hatching dates. Artificial redds will be excavated one week after eggs have reached the required degree days for hatching. A thorough assessment of redds, substrate, and comparison between locations will follow. Adjustments to project timelines will be contingent upon the availability of fall Chinook salmon eggs from Trinity River hatchery, considering potential substitutions or delays.

Project Benefit: The project carries several significant benefits. By estimating a baseline of Chinook salmon survival from egg to alevin in tributaries within the Hoopa Reservation, it contributes valuable empirical data essential for the restoration of salmonid populations to pre-dam levels. Understanding survival rates at various life stages is crucial for formulating effective conservation strategies and management interventions. Additionally, the projects comparison of survival rates from artificial redds to those from other systems provides essential insights into the adaptability of survival estimates across different river basins. This comparative analysis not only enhances our comprehension of tributaries within the Hoopa Reservation but also facilitates the identification of broader patterns and trends in salmonid survival dynamics, thereby informing more comprehensive conservation approaches. Moreover, the projects meticulous recording of emergence timing data and comprehensive redd assessments not only aids in refining existing models but also provides a robust foundation for future research endeavors and management decisions. Ultimately, the projects outcomes serve as a cornerstone for evidence-based policy formulation and implementation, fostering sustainable salmonid populations and ecosystem health in the tributaries within the Hoopa Reservation and the larger Trinity River watershed.