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

# of marked Chinook
40
30
20
10
0
Away from river
Towards river
March 25 April 1 April 9 April 15
Survey dates
FIGURE 13.—Number of marked Chinook salmon in Gene Coulon Park (south Lake Washington) that
moved away from and towards the mouth of the Cedar River, March-April 2003. Fish were released on
March 24. Data were combined from two release groups.
Discussion
Results of the residence time investigation indicated many Chinook salmon
remain in a small, localized area; however, it is possible other Chinook salmon moved
outside our study area. Some of the marked Chinook salmon had moved over 80 m after
1 day and therefore, may have left the study area by the next survey, which was 6 days
later. Because the median distance moved remained the same from day 1 to day 21 and
the number of recaptures was greatly reduced, it would seem reasonable that some of the
marked Chinook salmon remained close to the release site and another substantial portion
of the marked fish moved a relatively long distance by moving outside the survey area.
Results of index site surveys in February 2003 also indicate that some Chinook salmon
are capable of moving a long distance in a relatively short period of time. For example,
we observed Chinook salmon on Mercer Island as early as February 3 in 2004 and they
were first captured in the Cedar River fry trap on January 18 and large numbers of fry
were not observed at the trap until January 29 (Seiler at al. 2005b). Therefore, Chinook
salmon fry appear capable of moving approximately 8.5 km (Cedar River trap to Mercer
Island) in two weeks or less.
In general, the movement patterns of Chinook salmon in Lake Washington may
be similar to patterns observed in other salmonids and other fishes. Fausch and Young
(1995) reviewed several studies of fish movements in streams and concluded that often a
large percentage of the fish population is resident but a substantial percentage move a
considerable distance. The authors suggested that often these long distance movements
are not known unless some type of radio telemetry project is undertaken. In Lake
Washington, detecting long distance movements of juvenile Chinook salmon in February
through April would be difficult because the fish are too small for radio tags.
Use of marked fish and snorkel surveys appeared to be an effective method to
determine residence time, but to accurately determine the overall movement and
residence time of juvenile Chinook salmon, a larger, more involved study is needed.
Marking more fish would increase the probability of observing marked fish at locations
20