Characterize and Quantify Residual Steelhead in the Clearwater River, Idaho, 1999-2000 Progress Report PDF Download

Author: Jody K. Brostrom
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Languages : en
Pages : 75

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Book Description
During 1999-2002 we determined whether size at release and release site influenced emigration success and survival of hatchery steelhead smolts raised at Dworshak National Fish Hatchery and released into the Clearwater River drainage. We marked 4,500 smolts each year with Passive Integrated Transponder Tags (PIT-tags) which enabled us to track emigration and estimate survival through mainstem Snake and Columbia river dams. Hatchery steelhead raised in System I freshwater were significantly smaller than those raised in warmer System II re-use water (196 mm, 206 mm, 198 mm and 201 mm System I; 215 mm, 213 mm, 206 mm and 209 mm System II). However, there was no significant difference in detection rates to mainstem observation sites between the two groups (65%, 58%, 78% and 55% System I; 69%, 59%, 74% and 53% System II). Survival estimates to Lower Granite Dam were also not significant between the two groups (72%, 81%, 80% and 77% System I; 77%, 79%, 77%, and 72% System II). Smolts less than 180 mm FL were less likely to be detected than larger smolts. Hatchery steelhead smolts released into Clear Creek, the South Fork Clearwater River and the Clearwater River at Dworshak National Fish Hatchery had significantly different lengths each year, but there was no discernible pattern due to random egg takes and rearing systems. Detection rates to mainstem observation sites for smolts released into Clear Creek were significantly less than the other two groups in all years except 2002 (62%, 57%, 71%, and 57% Clear Creek; 68%, 63%, 73% and 61% South Fork Clearwater River; 70%, 59%, 78% and 55% Clearwater River). However, survival rates to Lower Granite Dam were not significantly different (73%, 65%, 78%, and 77% Clear Creek; 79%, 72%, 79% and 76% South Fork Clearwater River; 81%, 76%, 80% and 83% Clearwater River). Similar to the size at release group, smolts less than 180 mm FL were less likely to get detected than larger smolts. Smolts from both size at release and release site groups that were mature at tagging rarely migrated downstream. If smolts migrated they did it in the same year they were released, as less than 0.02% were observed migrating the second year. We sampled the Clearwater River, North Fork Clearwater River, Bedrock Creek, Big Canyon Creek, Cottonwood Creek, Jacks Creek and the Dworshak National Fish Hatchery adult ladder to collect residual hatchery steelhead. We PIT-tagged and released 3,651 hatchery steelhead and collected 645 hatchery steelhead for coded wire tags. Most residual hatchery steelhead were caught within 4 rkm of Dworshak National Fish Hatchery. Hatchery steelhead sampled in the North Fork Clearwater River and the Dworshak Hatchery adult ladder were significantly larger than those sampled in the Clearwater River and lower tributaries in all years except 2001 (205 mm, 205 mm, 223 mm and 238 mm North Fork Clearwater River; 190 mm, 182 mm, 226 mm and 189 mm Clearwater River). Of the hatchery steelhead we PIT-tagged, only 12% were observed at downstream observation sites. Most migrants were tagged in the Clearwater River (91%) and were smaller than hatchery steelhead that were tagged but were not detected. Most migrants were detected in the same year they were tagged, but 14% held over and migrated in the second year after tagging. We documented migration outside of the normal window, as one detection occurred on October 31 at Lower Granite Dam. We recaptured 130 individual hatchery steelhead that we had tagged during sampling. Over 77% of the recaptures were within one km of where they were tagged, and 67% of the recaptures were tagged in the North Fork Clearwater River and the Dworshak Hatchery adult ladder. We calculated a mean growth rate of 0.27 mm/day for fish we recaptured. For those hatchery steelhead we PIT-tagged, the proportion of males was 13%, the rest we could not ascertain gender. All the males were precocious. Over 97% of the coded-wire tag recoveries came from hatchery steelhead released at Dworshak National Fish Hatchery. The Contribution group (random egg take and rearing system) comprised 44% of the recoveries, followed by 32% System I and 24% System II. The mean length of the Contribution group was significantly smaller than the other two groups in all years except 2001 (173 mm, 191 mm, 209 mm and 197 mm Contribution; 210 mm, 206 mm, 205 mm and 228 mm System I; 226 mm, 216 mm, 213 mm and 225 mm System II). Males made up 81% of the recoveries, and their maturity ranged from 0% to 100%. The Contribution group had significantly more males than the other two groups in 1999 and 2001.