Nearshore Habitat Use by Juvenile Chinook Salmon in Lentic ...

Martha Washington Park, 2003.—In 2003, a total of 40 juvenile Chinook salmon
were observed along the 80-m-long transect during four night snorkeling surveys. In
contrast, only two Chinook salmon were observed during three surveys of the same
transect in 2002. This transect was surveyed from March to early May in both years.
Rainier Beach Lake Park and Marina, 2003. —Four night snorkeling surveys
were conducted at the Rainier Beach site from March to May 2003. On all survey dates,
the abundance of juvenile Chinook salmon at the undeveloped transect exceeded that of
the developed marina transect (Figure 21). On average, their abundance was four times
higher on the undeveloped transect than on the marina transect. The mean number
observed was 85 Chinook salmon (65 fish/100 m shoreline) on the undeveloped transect
and 20 Chinook salmon (20 fish/100 m shoreline) on the marina transect.
Rainier Beach Lake Park and Marina, 2004.—Five night snorkeling surveys were
conducted at the Rainier Beach site from February to June 2004. Substantially fewer
Chinook salmon were observed at the Rainier Beach Lake Park and Marina site in 2004
(Figure 22). In 2003, a total of 420 Chinook salmon were observed; whereas in 2004,
only 57 were observed. In 2003, the number of early migrants from the Cedar River was
195,000 (Seiler et al 2005a), whereas in 2004 it was 67,000 (Seiler et al 2005b). In both
years, the highest number of Chinook salmon at the Rainier Beach Lake Park and Marina
site was observed in March; in 2003, 146 Chinook salmon were observed along the
undeveloped shoreline and in 2004, 32 were observed. Similar to 2003, most Chinook
salmon in 2004 were along the undeveloped shoreline transect.
Shuffleton Power Plant Outflow, 2003.—Two night snorkeling surveys were
conducted at the Shuffleton Power Plant Outflow in 2003. On both surveys, the
abundance of juvenile Chinook salmon was substantially higher at the sandy beach
transect than along the steel wall (Figure 23). Because of the gradual slope of the sandy
beach area, we only surveyed a part of the nearshore habitat while we were able to survey
the entire nearshore area of the steel wall because of its 90 o slope and depth. Therefore,
the difference in abundance between the two transects is probably greater than shown in
Figure 23.
30