Auke Bay Laboratory  (cont.)

Auke Creek 2001 Pink Salmon Return

The 2001 return of wild pink salmon was close to the long-term average for Auke Creek.  Annual counts of pink salmon adult runs at Auke Creek over three decades show the interannual variability common in this fish.  Runs of wild fish at Auke Creek ranged from 300 to 28,000 fish over the last 30 years, and it was not unusual to see a 5- to 10-fold increase or decrease in consecutive even- and odd-year brood lines.  Pink salmon spawn throughout the Auke Lake system in the tributaries to Auke Lake, Auke Creek, and in the intertidal area. In even- and odd-numbered years there are distinct runs of pink salmon in August and September, referred to as the early and late runs.  Pink salmon adults were counted at Auke Creek in 1967 and 1968, and annually since 1971.  The average run of wild fish for all years is 7,536 (Figure 1 below).  In some years, hatchery-produced fish contributed heavily to the runs; however, the average return of hatchery adults during the last two decades is 979 fish.  The production of hatchery fish was reduced after the early 1980s because of redirection of research priorities at Auke Creek.

 
Figure 1.  Wild and hatchery pink salmon at Auke Creek, 1967-68 and 1971-2001.

 Figure 2.  Upstream migration of wild pink salmon at Auke Creek, 2001.

In 2001, 8,323 pink salmon, 7,828 wild fish, and 465 hatchery fish returned to Auke Creek.  Wild fish were released to spawn in the creek, and all hatchery fish were killed for spawning and collection of  tissue samples.  Pink salmon were captured at the weir daily from the third week of July through mid-September.  For the wild fish, based on the increase in the proportion of bright, silver females with loose scales, 28 August was considered the start of the late run (Figure 2 above).  At that time, early-run females were ready to spawn, late-run females were not and could be easily distinguished when handled during counting.  The early and late wild runs were 3,943 and 3,909 fish, respectively. Over the last two decades, the median dates of upstream migration for all wild fish shifted about 10 days earlier than the median dates before 1982, and the median date for the 2001 run was no exception (Figure 3 below).

 
Figure 3.  Median migration dates of pink salmon adults at Auke Creek.

By Jerry Taylor.

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AFSC Quarterly
Research Reports
July-Sept 2001