17450

2002-031-00 PI SPRING CHINOOK GROWTH RATE MODULATION

6/1/2004

5/31/2006

157. Collect/Generate/Validate Field and Lab Data

Work Element Usage Report

D: 157 - Estimate precocious maturation rate of Yakima hatchery spring Chinook salmon

D. The purpose of this WE (objective) is to accurately assess the incidence of1+ precocious male maturation for brood year 2002 Yakima hatchery spring chinook released from the Easton, Jack Creek, and Clark Flat acclimation sites. In cooperation with Ray Brunson (USFWS pathologist) we will sacrifice 60 fish/raceway for length, weight, visual assessment of gonadal development, and plasma 11-ketotestosterone levels (a reproductive steroid that indicates initiation of the maturation process). Samples will be collected in March of 2004 during the routine pathogen screening prior to the opening of the gates for volitional release.
Fish #'s
60 fish/raceway X 6 raceways X 50% males = approximately 180 males screened/site
Total # fish = 1080 fish/year or approximately 540 male fish analyzed/year
Expectations: The expectation from this objective is that the hatchery fish reared in the programs conventional manner will differ from the wild fish. The incidence of age 1+ precocious male maturation will be approximately 30-50% at each acclimation site. Half of the fish currently being reared for this program are being grown according to a modified regime in response to our previous research findings (see Objective 4). The expectation from these fish is that the maturation rate may be reduced by 30-40% compared with those reared under the standard regime.

Provide resource managers with annual estimate of precocious male maturation rate and size of Yakima hatchery spring Chinook salmon grown on low and high growth regimes to monitor efficacy of growth modulation treatments for reducing high rates of precocious male maturation in hatchery stock.

$33,000

17.80%

03/07/2006

05/31/2006

06/18/2006

Concluded

n/a

n/a

Recurring