10.04.2013 Views

Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

epresenting about 10% of the total adult count, to 2,200 (1997-2001), representing about<br />

17% of the adult count during this period of time (ICBTRT 2003). Table 24 identifies<br />

populations within the UCR Steelhead salmon DPS, their abundances, <strong>and</strong> hatchery<br />

input.<br />

Table 24. UCR Steelhead salmon populations, abundances, <strong>and</strong> hatchery contributions<br />

(Good, Waples et al. 2005).<br />

Population<br />

Historical<br />

Abundance<br />

Most Recent<br />

Spawner<br />

Abundance<br />

Hatchery<br />

Abundance<br />

Contributions<br />

Wenatchee/Entiat rivers Unknown 1,899-8,036 71%<br />

Methow/Okanogan rivers Unknown 1,879-12,801 91%<br />

Total Unknown 3,778-20,837<br />

Life History<br />

The life history patterns of UCR steelhead are complex. Adults return to the Columbia<br />

River in the late summer <strong>and</strong> early fall. Most migrate relatively quickly up the mainstem<br />

to their natal tributaries. A portion of the returning run overwinters in the mainstem<br />

reservoirs, passing over the upper-mid-Columbia dams in April <strong>and</strong> May of the following<br />

year. Spawning occurs in the late spring of the calendar year following entry into the<br />

river. Juvenile steelhead spend one to seven years rearing in freshwater before migrating<br />

to sea. Smolt outmigrations are predominantly age-two <strong>and</strong> age-three juveniles. Most<br />

adult steelhead return after one or two years at sea, starting the cycle again.<br />

178

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!