Precocious Wild and Hatchery Spring Chinook on the Spawning Grounds

Abundance: Artificially high or low numbers of precocious males may harm wild populations through either competitive or genetic mechanisms.
Distribution: the impact hatchery precocious males have upon the wild population is influenced by proximity to spawning females, affecting reproductive success.
Size and Behavior: differences in size and behavior (dominance) between hatchery and wild precocious males may also influence proximity to female spawners, and reproductive success.

Determine if the Cle Elum Supplementation and Research Facility alters the abundance, distribution, age/size, or behavior of precociously maturing males in the natural environment.

Age 0+ spring Chinook continue to make up the largest proportion of precocious males on the spawning grounds.
Environmental conditions appear to play a large role in determining the abundance of hatchery precocious males on the spawning grounds
No detectable difference between natural production and hatchery precocious males per female on the spawning grounds
Hatchery precocious males continued to be most abundant in areas downstream of spawning locations.