Auke Creek Weir Studies
Operations at the Auke Creek Weir through September 2003 completed 214
consecutive days of weir activity. Most fish counts, except for coho salmon
and cutthroat trout, decreased after August, which is typical for Auke
Creek. Water levels were moderate throughout the month but did not interrupt
weir activities; water temperatures were below average during September.
For 2003, a total of 3,239 sockeye salmon migrated upstream at Auke Creek
through September. This is greater than the average annual return (2,500
fish) of wild sockeye over the last two decades at Auke Creek but still
well below the 1963-1981 average (7,000 fish). The preliminary estimate
of marine survival, based on smolt counts from the year 2000, is 25%. Scales
were collected from several hundred adult sockeye as well as from late-run
pink salmon but have not been processed.
Figure 4. Pink salmon escapements by brood year at Auke Creek, 1967-68 and 1971-2003.
A total of 10,580 pink salmon were counted at the weir in 2003 (Fig. 4 above).
There were no hatchery fish for the year. The average run of wild fish
from 1967 to 2002 was 7,460; the average run of wild fish plus hatchery
fish was 10,266. Most of the pink salmon (6,098) entered Auke Creek during
August; 4,198 were counted in September (Fig. 5 below). The estimated year 2003
return of wild pink salmon, based on the number of fry counted at Auke
Creek weir in 2002, is 7%.
Figure 5. Proportion of the total pink salmon run returning in September at Auke Creek.
The lines in each group of markers represent the average of each group.
A total of 1,578 chums passed through the weir in 2003. Based on run timing
and numbers, most of these fish were probably strays from DIPAC remote
site releases. Three chum salmon migrated into Auke Creek in September,
including one on 29 September, the latest a chum has ever been observed there.
A total of 518 adult and 216 jack coho salmon were counted at the weir
in September. This is below average for the total return of coho salmon
to the creek, and one of the lowest counts of coho adults on record for
Auke Creek; average adult return to Auke Creek is 732. However, the marine
survival for returning jacks and adults combined is above average. Despite
a 44% incidence of the nematode parasite Philonema in year 2002 smolts,
the estimate of survival for coho smolts that left Auke Creek in 2002 is
25%; the average marine survival of Auke Creek coho salmon smolts is 23.9%.
The coho run at Auke Creek can continue into October, and the total weir
and fishery counts will not be known until the end of that month.
A total of 164 adult chinook salmon (larger than 250 mm) were counted at
the weir in 2003. No minijacks were captured this year because there was
no release of juveniles in Auke Bay. This was the one of the lowest counts
of adult chinook at Auke Creek, and because chinook salmon stray into the
creek and are not allowed to spawn in Auke Lake, was a welcome reduction
from the 2002 return of 668; only 4 years have had lower numbers of chinook
salmon at Auke Creek.
A total of 91 cutthroat trout were captured in the weir through September.
These fish usually continue to migrate upstream through October. From 1997
to 2002, the average count of upstream migrant cutthroat trout was 268.
Dolly Varden were also captured going upstream in 2003. Through the end
of September, 3,770 fish were caught and released upstream of the weir.
These fish usually continue to migrate upstream through October. The average
number of upstream migrant Dolly Varden from 1997 to 2002 was 4,610.
By Jerry Taylor.
quarterly July-Sept 2003 sidebar
Auke Bay Lab