Marine Fish and Benthos Studies - Knik Arm Bridge and Toll Authority

3.3.2.5 Longfin Smelt
2004. Two-hundred-twelve longfin smelt (Spirinchus thaleichthys) were captured
during the July to November sampling period (Table 4) making this the second
most abundant species captured in 2004. Over 77 of these individuals
(38 percent) were captured at Station KA 13, Point Woronzof, at the entrance to
the Arm. Age groups represented in nearshore samples include transparent
young-of-the-year larvae or post-larvae less than 40 mm, and sub-adult or adult
fish over 100 mm in length (Figure 16). The majority of fish in September were
in the 101- to 140-mm size range and may represent another age class of
immature adults. Longfin smelt were relatively well distributed over the summer
sampling period with CPUE ranging from about 0.5 to 1.4 fish per set though
September (Figure 14, Table 3). A sharp peak in abundance in October (to over
6 fish per set) was largely the result of increased numbers of 41 to 60 mm fish
but included a few larger fish up to 140 mm (Figure 16). In November, only the
larger fish were taken but sampling conditions (high content of silty ice shards in
the net) made finding small transparent organisms such as larval smelt in the haul
very unlikely.
Few longfin smelt were observed during the spring 1983 sampling period
(Dames & Moore 1983).
2005. In 2005, longfin smelt were third in abundance behind threespine
stickleback and saffron cod in beach seine catches (Tables 3 and 6). As in 2004,
this species was notably more abundant at Station KA 13 (Point Woronzof) near
the entrance to the Arm (62 percent of all longfin captured). Substantially, but
not significantly, fewer longfin smelt were captured at middle Arm stations and
very few fish appeared at stations within the inner Arm. Longfin smelt began
appearing within the outer Arm in May, peaking in June with a CPUE of over
6 fish/set. CPUE in July declined significantly to 3.1 fish/set (Figure 14, Table 3),
but it is not known whether this represents a true decline in abundance since
over 60 percent of fish observed in June were taken at the station at the
southern edge of the study area near Point Woronzof (KA 13). Most longfin
smelt were sub adults or adults between 81 and 140 mm with a small, but
significant number of transparent young-of-the-year observed in April through
June (Figure 16).
3.3.2.6 Eulachon
In 2005, 199 eulachon were captured in beach seine sets at stations within the
middle and outer Arm. Several individual gravid adults were captured in April,
but the bulk of fish appeared in May as post-spawn fish, indicating a relatively
short spawning period within Arm streams in May (Table 3). Most fish were
Pentec Environmental Page 23
12214-12 November 30, 2005