3.0 Affected Environment - Knik Arm Bridge and Toll Authority

Knik Arm Crossing DraftFinal EIS
Affected Environment
3.8.8.2.2 Anadromous fish
The Mat-Su
There are no anadromous fish streams crossed or adjacent to the Mat-Su portion of the
proposed KAC project; therefore, no anadromous fish are expected within this portion of the
Study Area.
Knik Arm
The 2004 and 2005 shoreline and mid-channel sampling collected both juveniles and adults
of all five Pacific salmon species. Juvenile salmon numbers peak within Knik Arm from May
into August, depending on species, and juvenile salmon use both nearshore and mid-channel
habitats in Knik Arm during out-migration to marine feeding areas in lower Cook Inlet and
the Gulf of Alaska (Moulton 1997; KABATA 2005b, Pentec 2005). Adult salmon migrate
through Knik Arm between May and September to reach spawning grounds in more than a
dozen anadromous streams that empty into Knik Arm (KABATA 2005b). The Essential Fish
Habitat Assessment (Appendix F) provides additional information on the life history and
habitat requirements of anadromous salmonids in Knik Arm as well as their distribution in
the vicinity of the Study Area.
Longfin smelt (Spirinchus thaleichthys) and eulachon are seasonally common in Knik Arm.
Longfin smelt were the second and third most abundant species caught during the 2004
and 2005 Knik Arm fish and benthos study (KABATA 2005b). Longfin smelt were observed
throughout the summer in the lower and middle portions of Knik Arm, with peak abundances
in October 2004 and June 2005. Eulachon move through Knik Arm in early spring (April and
May) to spawn in area streams. No eulachon were observed from July through
November 2004 or 2005. More discussion of eulachon can be found in The Essential Fish
Habitat Assessment (Appendix F).
Two species of anadromous sticklebacks (threespine and ninespine; Gasterosteus aculeatus
and Pungitius pungitius, respectively) are seasonally common in Knik Arm. Threespine
stickleback has been the most abundant species overall in all systematic sampling programs
conducted north of the Foreland Islands in Lower Cook Inlet (FHWA and ADOT&PF 1983;
Moulton 1997; KABATA 2005b; Pentec 2005). In Knik Arm, densities peaked in June and
July with recruitment of large numbers of very small (0.5 to 1.0 inch) young-of-the-year fish
(KABATA 2005b; Pentec 2005). Presence of these small fish in offshore as well as
nearshore sampling suggests that they, like smaller juvenile salmonids, are being passively
transported by strong currents.
Subadult Bering cisco (Coregonus laurettae), rainbow trout (Oncorhynchus mykiss), and
Dolly Varden char (Salvelinus malma) were also occasionally taken in beach seine sampling
in and near the Study Area (KABATA 2005b).
Anchorage
Anadromous fish within the Anchorage portion of the Study Area include Dolly Varden char
and four Pacific salmon species discussed in the EFH section, above.
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