3.0 Affected Environment - Knik Arm Bridge and Toll Authority

Knik Arm Crossing DraftFinal EIS
Affected Environment
Table 3-29. Essential fish habitat designations and presence in the Knik Arm
portion of the Study Area
Groundfish and
forage fish
species
Egg
Larvae
Late
juvenile a, b Adulta, b Spawning
Pacific cod • c • c
Sculpin spp. • c •
Walleye pollock • • c
Eulachon • •
Pacific Salmon
species
Egg and
larvae
(fresh
water d )
Juvenile
(fresh
water d )
Juvenile
estuarine b )
Adult
(marine
waters b )
Spawning
(freshwater
only d )
Chinook salmon • •
Chum salmon • •
Coho salmon • • •
Pink salmon • • •
Sockeye salmon • • •
a
NOAA Fisheries, 2005
b
KABATA, 2005
c
Designated as EFH, but not captured in any studies in Knik Arm
d
ADF&G, 2005
Juveniles and adults of all five Pacific salmon species are present in Knik Arm as well as in
more than a dozen streams and rivers that discharge into Upper Cook Inlet. Analysis of
length, frequency, and timing patterns suggests that juvenile pink and chum salmon move
through Knik Arm relatively quickly and do not grow much in this environment. On the other
hand Knik Arm may be important rearing habitat for the juvenile coho, chinook, and sockeye
salmon emerging from streams and rivers that discharge into Knik Arm. Juveniles of these
species appear to be feeding and growing actively in Knik Arm into August (FHWA and
ADOT&PF 1983a; Moulton 1997; KABATA 2005b; Pentec 2005).
Juvenile salmon use of both shoreline and mid-channel habitats in Knik Arm differs from
that of juvenile salmon use of clearwater estuaries (KABATA 2005b), where early
out-migrants are found primarily residing in nearshore habitats (see reviews by Salo 1991;
Sandercock 1991; Healey 1991). A comparison of beach seining and tow net data as catch
per unit effort (CPUE), which accounts for bias in relative effort for differences in sampling
efficiency associated with various sampling gear types, suggests a shoreline or intertidal
preference by juvenile chinook and coho salmon. Juveniles of chum and sockeye salmon
appear to use both nearshore and mid-channel habitats, with a markedly higher occurrence in
mid-channel habitat. Juvenile pink salmon were primarily found in mid-channel habitat
(KABATA 2005b).
3-198 12/18/07