In recent decades many of the distinct salmon populations in the Columbia River have experienced a steady decline due to habitat loss, dams, and over fishing (NRC 1996, NMFS 2000a).  In response to these declines, a number of captive propagation and conservation hatchery programs have been initiated to preserve the genetic resources associated with these populations, and to re-introduce and restore these populations as environmental conditions associated with the original declines are mitigated (NWPPC 1999).  Several Columbia River salmon populations and ESUs have reached critically low levels, and NOAA Fisheries (NMFS 2000b), the NWPPC (2000), and several state and tribal agencies, have endorsed and implemented captive broodstock programs as a safety net for threatened and endangered populations.

The goal of Project #199305600, ‘Assessment of Captive Broodstock Technologies', is to conduct scientific research to quantify risks and benefits of captive broodstock strategies and guide improvements in captive broodstock technology for Pacific salmon.

Captive broodstocks appear vital to salmonid population recovery in the Pacific Northwest, and research has led to improvements in captive broodstock technology.  Nevertheless, captive broodstocks grown under current technologies suffer from less than optimal culture environments that can affect health, reproduction, behavior and survival.  Project 199305600 is currently focused on knowing whether performance can be improved by modifying rearing protocols, and identifying the underlying mechanisms responsible for deficiencies.  Continued development and refinement of captive broodstock technology is necessary to provide optimal mechanisms to stabilize populations until recovery actions succeed in addressing factors for their decline.

The project pursues research under five broad objectives, viz:

1: Improve reintroduction success.  This will be accomplished by conducting studies of the reproductive behavior and reproductive success of captively reared Chinook salmon reared under experimental temperature regimes at rearing different densities.

2: Improve olfactory imprinting and homing.  This will be accomplished to determine the timing and duration of home-stream odor exposure that
is critical for successful imprinting in captively-reared sockeye salmon.

3: Improve physiological development and maturation.  This will be accomplished by evaluating the effects of several different growth regimes on age of maturity, adult body size, fecundity, and egg size in spring Chinook salmon.  This information will be used to develop rearing regimes to reduce early age of male maturation yet minimize impacts to female reproduction.  The goal is to produce spring Chinook salmon with a life history pattern and phenotype more similar to wild fish.

4: Improve in-culture survival through prevention and treatment of disease.  This will be accomplished by assessing the levels and disposition of bacteria as a result of antibiotic treatment in captively reared Chinook salmon affected by bacterial kidney disease.  In a separate experiment, the risk of antibiotic-resistant bacteria among ESA stocks will be evaluated.

5: Evaluate effects of inbreeding and inbreeding depression. This will be accomplished by evaluating variation in survival and growth of marked, experimentally inbred and control (outbred) Chinook salmon in hatchery culture; ultimately, the comparison will entail evaluation of variation in survival, growth, and life history to adulthood in hatchery-cultured Chinook salmon released to sea.