U.S. Dept Commerce/NOAA/NMFS/NWFSC/Publications

NOAA-NWFSC Tech Memo-27: Status Review of West Coast Steelhead
Table 5. Ocean age frequency for selected steelhead populations (modal values are presented in bold). Data are from adult steelhead and indicate age at the first spawning migration. Populations are generally arranged from north to south. Stream-maturing (summer) steelhead spend up to a year in fresh water prior to spawning; this period has generally been excluded from the ages shown on this table. Therefore, an age-2-ocean stream-maturing steelhead is actually up to one year older at spawning than an age-2-ocean ocean-maturing steelhead.
Ocean age at first spawning migration Sample
Population Run typea 0 1 2 3 4 5 size Reference
Alaska
Karluk River S -- 0.18 0.79 0.03 -- -- 62 Sanders 1985
Anchor River S -- 0.26 0.74 -- -- -- 80 Sanders 1985
Upper Copper River S -- 0.17 0.77 0.06 -- -- 30 Sanders 1985
Situk River S/O -- -- 0.57 0.43 -- -- 211 Sanders 1985
Sitkoh Creek O -- -- 0.59 0.41 -- -- 497 Sanders 1985
Karta River O -- <0.01 0.72 0.27 -- -- 542 Sanders 1985
British Columbia (mainland)
Babine River S -- 0.10 0.72 0.18 -- -- 100 Narver 1969
Cheakamus River O -- -- 0.52 0.40 0.08 -- 64 Withler 1966
Capilano River O -- -- 0.67 0.33 -- -- 70 Withler 1966
Capilano River S -- 0.01 0.56 0.42 0.01 -- 86 Withler 1966
Seymour River O -- 0.07 0.57 0.34 0.02 -- 58 Withler 1966
Seymour River S -- -- 0.64 0.36 -- -- 25 Withler 1966
British Columbia (Fraser River Basin)
Coquitlam River O -- 0.01 0.73 0.23 0.03 -- 146 Withler 1966
Alouette River O -- -- 0.50 0.46 0.04 -- 131 Withler 1966
Chilliwack River O -- <0.01 0.50 0.49 <0.01 -- 770 Maher and Larkin 1955
Chehalis River O -- -- 0.50 0.50 <0.01 -- 111 Withler 1966
Coquihalla River O -- 0.05 0.64 0.31 -- -- 39 Withler 1966
Coquihalla River S -- 0.12 0.83 0.05 -- -- 150 Withler 1966
British Columbia (Vancouver Island)
Keough River O? -- 0.01 0.65 0.34 <0.01 -- 1391 Ward and Slaney 1988
Nanaimo River ? 0.01 0.68 0.31 -- -- -- 228 Narver and Withler 1974
Nahmint River S -- 0.05 0.91 0.03 -- -- 58 Narver 1974
Washington
Skagit River O -- -- 0.57 0.42 0.01 -- n/ab WDFW 1994b
Deer Creek S -- 1.00 -- -- -- -- n/a WDF et al. 1993
Snohomish River O -- -- 0.57 0.42 0.01 -- n/a WDF et al. 1993
Green River O 0.02 0.07 0.66 0.25 -- -- 100 Pautzke and Meigs 1941
Puyallup River O -- -- 0.70 0.30 -- -- n/a WDFW 1994b
Nisqually River O -- -- 0.63 0.36 0.01 -- n/a WDFW 1994b
Hoh River O -- 0.02 0.81 0.17 -- -- n/a Larson and Ward 1954
Quillayute River O -- -- 0.53 0.45 0.02 -- n/a WDFW 1994b
Chehalis River O -- 0.07 0.72 0.20 0.01 -- n/a Larson and Ward 1954
Columbia River Basin
Toutle River O -- 0.08 0.81 0.11 -- -- 37 Howell et al. 1985
Cowlitz River O -- -- 0.64 0.34 0.02 -- 56 Howell et al. 1985
Kalama River O -- 0.04 0.76 0.20 -- -- 1363 Howell et al. 1985
Kalama River S -- 0.20 0.74 0.06 -- -- 909 Howell et al. 1985
Willamette River O -- -- 1.00 -- -- -- 141 Howell et al. 1985
Washougal River S -- 0.14 0.71 0.14 -- -- 7 Howell et al. 1985
Wind River S -- 0.05 0.68 0.26 -- -- 19 Howell et al. 1985
Klickitat River S -- 0.16 0.79 0.05 -- -- 148 Howell et al. 1985
Deschutes River S -- 0.53 0.47 -- -- -- 100 Howell et al. 1985
John Day River S -- 0.51 0.44 0.04 -- -- 115 Howell et al. 1985
Yakima River S -- 0.51 0.47 0.02 -- -- 64 BPA 1992
Wenatchee River S -- 0.76 0.18 0.06 -- -- 17 Howell et al. 1985
Entiat River S -- 0.88 0.12 -- -- -- 8 Howell et al. 1985
above Wells Dam S -- 0.30 0.70 -- -- -- 349 Mullan et al. 1992
Snake River Basin
Lower Granite Dam S -- 0.29 0.55 0.16 -- -- 100 Hassemer 1992
Clearwater River S -- 0.61 0.38 0.01 -- -- 510 Whitt 1954
S.F. Salmon River S -- -- 0.20 0.80 -- -- 65 BPA 1992
Lemhi River S -- 0.09 0.86 0.05 -- -- 353 BPA 1992
Oregon
Nehalem River O -- 0.07 0.84 0.08 -- -- 310 Weber and Knispel 1977
Alsea River O -- 0.05 0.66 0.26 0.03 -- 978 Chapman 1958
Siuslaw River O -- -- 0.82 0.17 0.01 -- 125 Lindsay et al. 1991
Rogue Riverc O -- 0.14 0.86 -- -- -- 547 ODFW 1990
California
Klamath River S -- 0.78 0.22 <0.01 -- -- 391 Kesner and Barnhart 1972
Mad River O -- 0.28 0.69 0.03 -- -- 35 Forsgren 1979
Jacoby Creek O -- 0.35 0.63 0.02 -- -- 109 Harper 1980
Van Duzen River S -- 0.09 0.62 0.29 -- -- 58 Puckett 1975
M. F. Eel River S -- 0.56 0.42 0.02 -- -- 82 Puckett 1975
Sacramento River O? -- 0.57 0.43 -- -- -- 83 Hallock 1989
Waddell Creek O -- 0.60 0.40 <0.01 -- -- 3,888 Shapovalov and Taft 1954

aO = Ocean maturing; S = Stream maturing.
bSample size not indicated in reference.
cAdults with half-pounder life history (spawning migrants, ODFW 1990) are included as age-2-ocean; these comprise 26% of the sample size.