Sawtooth Fish Hatchery Research Articles

A Fish Out of Basin: Increased Stress Physiology and Reduced Performance of Salmon River Hatchery Chinook Salmon

AbstractVariation in rearing conditions across hatcheries and basins can affect the performance of hatchery salmonids in the wild. In 2008, the Shoshone‐Bannock Tribes began planning an out‐of‐basin hatchery facility on the eastern Snake River Plain for rearing threatened Chinook Salmon Oncorhynchus tshawytscha for release in tributaries of the upper Salmon River, Idaho, USA. To help determine the viability of the planned out‐of‐basin hatchery, we reared 100,000 juvenile Chinook Salmon from the same genetic stock at one in‐basin (Sawtooth Fish Hatchery on the Salmon River) and one out‐of‐basin (Springfield Fish Hatchery on the Snake River Plain) site in Idaho that are characterized by significant differences in water hardness and temperature regime. In October 2018 and April 2019, we tested whether fish condition, stress physiology, acute mortality, and downstream survival differed between the two groups at the parr and smolt life stages upon release in the Yankee Fork Salmon River, which is characterized by low water hardness. For both release groups, parr experienced low acute mortality during the 48 h after release; however, the out‐of‐basin group had a downstream survival rate through an unimpounded portion of the migration corridor that was an order of magnitude lower than that for the in‐basin group. During the smolt release, the out‐of‐basin group showed signs of extreme physiological stress, acute mortality rates of 40–80%, and low survival in the unimpounded portion of the migratory corridor. The in‐basin group recovered from the stress of transport and release, had no acute mortality, and survived through the unimpounded migratory corridor at a rate comparable to that of previous years’ releases. Based on the results of this comparative study, comanagers are evaluating alternatives to the proposed out‐of‐basin hatchery program. This case study highlights the effects of differences between rearing and release conditions on salmon physiology and survival as well as the value of conducting preliminary evaluations prior to implementing large‐scale hatchery supplementation programs.

Evaluating Artificial Propagation Release Strategies for Recovering Endangered Snake River Sockeye Salmon

AbstractAs a growing number of aquatic organisms become imperiled due to anthropogenic and environmental threats, there is an increasing need to implement captive propagation programs to conserve some species. These captive propagation programs can aid in the recovery of species, such as for Sockeye Salmon Oncorhynchus nerka, by providing individuals that can be used to supplement wild populations. The Snake River Sockeye Salmon Captive Broodstock Program implemented a comprehensive monitoring and evaluation plan to evaluate adult recruitment using three juvenile release strategies from excess eggs of captive females. Hatchery‐produced eyed eggs, presmolts, and smolts were released into the upper Salmon River basin to increase the abundance of individuals expressing an anadromous life history as a way to support population augmentation. A mixed‐effects logistic regression model used to evaluate egg‐to‐adult returns between release strategies indicated that release strategies differed from one another. Full‐term smolt production was observed to produce the highest recruitment among the release strategies and has become the focus of recovery efforts involving juvenile releases. The estimated odds of a fish (egg) returning as an adult were 9.7 times greater for smolts reared at the Oxbow Fish Hatchery and 3.6 times greater for smolts reared at the Sawtooth Fish Hatchery relative to eggs that were hatchery reared and released as presmolts or placed into in‐lake incubator boxes. The variation observed in productivity and in expression of life history traits among release strategies indicates that juvenile releases are not one size fits all, and we recommend undertaking a similar assessment to match observed outcomes with desired objectives when initiating supplementation programs.