The ultimate goal of the Idaho Department of Fish and Game (IDFG) Captive Rearing Program of Salmon River Spring Chinook Salmon is to maintain a minimum number of adults spawning in specific target streams annually.  To achieve this goal, the program is testing the efficacy of the captive rearing conservation approach.  Project activities are divided into two parts:  1) hatchery propagation and 2) spawning performance monitoring and evaluation.  The success of the project depends on developing culture techniques to produce fish with proper behavioral, morphological, physiological characteristics to successfully interact with and breed with wild individuals.  Field monitoring is used to document behavioral interactions, spawn timing, success of redds spawned by captive-reared individuals, and to determine if changes in culture technique result in desired changes in reproductive behavior or performance.  In addition, an important component of this program is to document successful production (juveniles and adults) from captive adult spawning events.

1) Hatchery Propagation:
a) Early Rearing (eyed-egg through smolt).  Approximately 300 eyed-eggs collected from wild/natural redds on the East Fork Salmon River and the West Fork Yankee Fork.  Eyed-eggs are collected from five to six wild/natural redds and the eggs are transported to Eagle Fish Hatchery for incubation and rearing.  Eagle Fish Hatchery will culture these Chinook salmon through the smolt stage at which time they are transported to NOAA Fisheries Manchester Research Station for seawater rearing through maturation.  While in culture at Eagle Fish Hatchery; water temperature and growth rates are monitored closely to produce smolts similar in size as to their natural counterparts.  During early rearing (first 15 months), juveniles are maintained in family groups based on the redd the eyed-eggs are collected from, at this point juveniles are PIT tagged and groups are mixed, while maintaining segregation between stocks.  Before transfer to seawater, the juveniles are vaccinated with Renogen and Vibrogen, and marked with an Elastomer tag.

b) Adult Holding:  Maturing adult Chinook salmon are transported back to Eagle Fish Hatchery for temporary holding in freshwater before release to natal streams (July/August).

2) Spawning Performance Monitoring and Evaluation:
a) Eyed-egg collections.  Idaho Department of Fish and Game (IDFG) research biologists monitor wild/natural Chinook salmon spawning activities, documenting redd development (location) and stream temperatures.  Based on this information, naturally spawned eyed-eggs are collected from approximately 15 redds in each drainage by hydraulically sampling (redd pumping) individual redds.   All eyed eggs collected are used as research subjects for the emergence survival study and ongoing parent-progeny genetic analyses.  Eggs are no longer collected for captive culture broodstock.  Upon sampling, dead eggs, egg-shells, and live eggs are enumerated to estimate survival to the eyed-egg stage of development.  Next, Approximately 80 eyed-eggs are collected per redd.  Collected eggs are used in two ways. First, approximately 40 eyed-eggs are carefully placed into an egg capsule filled with gravel collected from the redd (treatment group) and inserted back into the natal redd from where it came . Second, another 40 eggs are taken to the Eagle FH for incubation and rearing (see #1 above).

Surviving fry from both control (hatchery) and treatment (egg capsule) study groups are sampled after depletion of yolk reserves, determined by tracking accumulated Celsius temperature units (CTU’s) and using historic emergence timing estimates for similar stocks of Chinook salmon. After enumeration and survival estimation, fry hatched from BY08 egg collections from both treatment (egg capsule) and control (hatchery incubation) groups will be lethally sampled, after yolk-absorption in early-2009, and fin clips taken for later genetic analyses.

b) Adult Observations:  After maturing Captive Reared Chinook salmon adults are transported back to Eagle Fish Hatchery, adults are marked for visual identification in the field after release.  Petersen Disc, jaw, spaghetti, or floy tags are used to mark individual fish.  A blocking weir is installed on the East Fork Salmon River to contain the captive reared salmon in the observation area (wild/natural salmon and other species are allowed to move up or down stream freely.  Radio transmitters are also inserted in six to eight adults to assist with tracking adult movements within the West Fork Yankee Fork after release, since no blocking weir is installed.  Spawning observations include: habitat selection (pool, rifle/run, cut bank, overhead vegetation) and behavioral observations (holding, aggression, courting, moving, milling). spawn timing, and spawning behavior.

c) Reproductive Success:  Genetic samples are collected from all released captive reared adult salmon and from about 500 juveniles.  This information is used to determine if spawning events from captive reared Chinook salmon produced offspring the following summer using parental exclusion genetic analyses.