Chenik Lake - Cook Inlet Aquaculture Association, Kenai, Alaska

allowed migrating smolt the ability to move out of the trap and travel back to the lake. Third,
field personnel spent an insufficient amount of time managing the trap site. The crew inspected
the trap 2 to 5 times per night for up to 20 minute intervals. The combination of late trap
construction, poor trap location, and insufficient time managing the trap may have resulted in
some late-migrating smolt holding over in Shell Lake for another year. Based on the age
structure of the 2009 smolt migration, the number of fish holding over in Shell Lake was not
believed to be large.
In Spring 2009, an ash plume emitted from Mt. Redoubt was carried north by winds and settled
in the Skwenta and Talkeetna areas. Shell Lake accumulated a heavy fall of ash which resulted
in an earlier than usual ice-out. Based on Shell Lake residents’ reports, ice-out occurred on 14
May and field crew began monitoring on 16 May. The 2009 Shell Lake smolt migration was
enumerated from 16 May and continued daily until 24 June. During this time, an estimated
68,700 (±8,700) sockeye (O. nerka) and 7 coho (O. kisutch) smolts migrated from the lake.
Personnel conducted the 10% sub-sampling procedure to estimate 64%, or 44,120 (±8,700), of
the sockeye smolts were sub-sampled. Based on the sockeye smolt samples collected, an
estimated 94% (±0.01%) were age 1 and 6% (±0.4%) were age 2. The average length and
weight of age 1 sockeye smolt were 101 mm (±0.6 mm) and 10.6 g (±0.3 g). The average length
and weight of age 2 sockeye smolt were 149 mm (±4 mm) and 28.9 g (±2.2 g). Based on the
reported ice-out on 14 May, the smolt migration monitoring was considered to be complete.
During the 2007, 2008, and 2009 smolt migrations, field personnel have seen northern pike in
Shell Creek but were unable to conduct a statistically valid enumeration.
Table 3 – Summary of Shell Lake sockeye salmon smolt characteristics
Migration
Age Class (%) Mean length (mm) Mean weight (g)
Smolt Age 95% Age 95% Age 95% Age 95% Age 95% Age 95%
Year Number 1.0 C.I. 2.0 C.I. 1.0 C.I. 2.0 C.I. 1.0 C.I. 2.0 C.I.
2007 80,600 95% (±0.02%) 5% (±1.08%) 110 (±0.6) 143 (±10.6) 12.7 (±0.3) 27.7 (±5.7)
2008 3,200 84% (±0.1%) 16% (±0.8%) 100 (±0.8) 137 (±3.8) 9.0 (±0.9) 20.2 (±1.9)
2009 68,700 94% (±0.01%) 6% (±0.4%) 101 (±0.6) 149 (±4) 10.6 (±0.3) 28.9 (±2.2)
Mean 50,833 91% 9% 104 143 10.8 25.6
Min 3,200 84% 5% 100 137 9.0 20.2
Max 80,600 95% 16% 110 149 12.7 28.9
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