Underwater time-lapse video technology has been used to monitor adult spring and summer chinook salmon (Oncorhynchus tshawytscha) escapement into the Secesh River and Lake Creek, Idaho, since 1998. Underwater time-lapse videography is a passive methodology that does not trap or handle this Endangered Species Act listed species. Secesh River chinook salmon represent a wild spawning aggregate that has not been directly supplemented with hatchery fish. The Secesh River is also a control population under the Idaho Salmon Supplementation study. This project has demonstrated the successful application of underwater video adult salmon abundance monitoring technology in Lake Creek in 1998 and 1999. Emphasis of the project in 2000 was to determine if the temporary fish counting station could be installed early enough to successfully estimate adult spring and summer chinook salmon abundance in the Secesh River (a larger stream). Snow pack in the drainage was 93% of the average during the winter of 1999/2000, providing an opportunity to test the temporary count station structure. The temporary fish counting station was not the appropriate technology to determine adult salmon spawner abundance in the Secesh River. Due to its temporary nature it could not be installed early enough, due to high stream discharge, to capture the first upstream migrating salmon. A more permanent structure used with underwater video, or other technology needs to be utilized for accurate salmon escapement monitoring in the Secesh River. A minimum of 813 adult chinook salmon spawners migrated upstream past the Secesh River fish counting station to spawning areas in the Secesh River drainage. Of these fish, more than 324 migrated upstream into Lake Creek. The first upstream migrating adult chinook salmon passed the Secesh River and Lake Creek sites prior to operation of the fish counting stations on June 22. This was 17 and 19 days earlier than the first fish arrival at Lake Creek in 1998 and 1999 respectively. Peak net upstream adult movement at the Secesh River site occurred June 28 and at the Lake Creek site on June 27. Peak of total movement was August 16 at Secesh River and August 7 at Lake Creek. The last fish passed through the Lake Creek fish counting station on August 31 and on September 8 at the Secesh River site. Migrating salmon in the Secesh River and Lake Creek exhibited two behaviorally distinct segments of fish movement. The first segment of movement was characterized, mainly, by upstream movement only. The second segment consisted of upstream and downstream movement with very little net upstream movement. The fish counting stations did not impede salmon movements, nor was spawning displaced downstream. Fish moved freely upstream and downstream through the fish counting structures. Fish movement was greatest between the period of 5:00 p.m. and 4:00 a.m. There appeared to be a segment of ''nomadic'' males that moved into and out of the spawning area, apparently seeking other mates to spawn with. The downstream movement of salmon allowed by this fish counting station design may be an important factor affecting reproductive success as male salmon seek other females to spawn with. Traditional weirs operated for broodstock collection do not allow for downstream movement of adults. This methodology has the potential to provide more consistent and accurate salmon spawner abundance information than single-pass and multiple-pass spawning ground surveys. Accurate adult abundance would allow managers to determine if recovery actions were benefiting these salmon spawning aggregates and if recovery goals were being met.

Zeitungsausschnitte.

Underwater time- lapse video technology has been used to monitor adult spring and summer chinook salmon (Oncorhynchus tshawytscha) escapement into the Secesh River and Lake Creek, Idaho, since 1998. Underwater time-lapse videography is a passive methodology that does not trap or handle this Endangered Species Act listed species. Secesh River chinook salmon represent a wild spawning aggregate that has not been directly supplemented with hatchery fish. The Secesh River is also a control stream under the Idaho Salmon Supplementation study. This project has successfully demonstrated the application of underwater video monitoring to accurately quantify chinook salmon abundance in Lake Creek in 1998, 1999, 2001 and 2002. The adult salmon spawner escapement into Lake Creek in 2002 was 410 fish. Jack salmon comprised 7.1 percent of the run. Estimated hatchery composition was 6.1 percent of the spawning run. The first fish passage on Lake Creek was recorded on June 26, 15 days after installation of the fish counting station. Peak net upstream movement of 41 adults occurred on July 8. Peak of total movement activity was August 18. The last fish passed through the Lake Creek fish counting station on September 2. Snow pack in the drainage was 91% of the average during the winter of 2001/2002. Video determined salmon spawner abundance was compared to redd count expansion method point estimates in Lake Creek in 2002. Expanded index area redd count and extensive area redd count point estimates in 2002, estimated from one percent fewer to 56 percent greater number of spawners than underwater video determined spawner abundance. Redd count expansion methods varied from two percent fewer to 55 percent greater in 2001, 11 to 46 percent fewer in 1999 and 104 to 214 percent greater in 1998. Redd count expansion values had unknown variation associated with the point estimates. Fish per redd numbers determined by video abundance and multiple pass redd counts of the larger extensive survey areas in Lake Creek have varied widely. In 2002 there were 2.05 fish per redd. There were 2.07 fish per redd in 2001, 3.58 in 1999 and in 1998, with no jacks returning to spawn, there were 1.02 fish per redd. Migrating salmon in Lake Creek exhibited two behaviorally distinct segments of fish movement in 2002. Mainly upstream only movement of both sexes characterized the first segment. The second segment consisted of upstream and downstream movement with less net upstream movement and appeared to correspond with the time of active spawning. The fish counting stations did not impede salmon movements, nor was spawning displaced downstream. Fish moved freely upstream and downstream through the fish counting structures. The downstream movement of salmon afforded by this fish counting station design may be an important factor in the reproductive success of listed salmon. This methodology provides more accurate salmon spawner abundance information than expansion of single-pass and multiple-pass redd counts. Accurate adult escapement information would allow managers to determine if recovery actions benefited listed chinook salmon in tributary streams.

Underwater time-lapse video technology was used to monitor adult spring and summer chinook salmon abundance in spawning areas in Lake Creek and the Secesh River, Idaho, in 1999. This technique is a passive methodology that does not trap or handle this Endangered Species Act listed species. This was the third year of testing the remote application of this methodology in the Secesh River drainage. Secesh River chinook salmon represent a wild salmon spawning aggregate that has not been directly supplemented with hatchery fish. Adult chinook salmon spawner abundance was estimated in Lake Creek with the remote time-lapse video application. Adult spawner escapement into Lake Creek in 1999 was 67 salmon. Significant upstream and downstream spawner movement affected the ability to determine the number of fish that contributed to the spawning population. The first passage on Lake Creek was recorded on July 11, two days after installation of the fish counting station. Peak net upstream adult movement occurred at the Lake Creek site on July 20, peak of total movement activity was August 19 with the last fish observed on August 26. A minimum of 133 adult chinook salmon migrated upstream past the Secesh River fish counting station to spawning areas in the Secesh River drainage. The first upstream migrating adult chinook salmon passed the Secesh River site prior to the July 15 installation of the fish counting station. Peak net upstream adult movement at the Secesh River site occurred July 19, peak of total movement was August 15, 17 and 18 and the last fish passed on September 10. Migrating salmon in the Secesh River and Lake Creek exhibited two behaviorally distinct segments of fish movement. Mainly upstream only, movement characterized the first segment. The second segment consisted of upstream and downstream movement with very little net upstream movement. Estimated abundance was compared to single and multiple-pass redd count surveys within the drainage. There were differences between the two methodologies. The fish counting stations did not impede salmon movements, nor was spawning displaced downstream. Fish moved freely upstream and downstream through the fish counting structures. Fish movement was greatest between the period of 10:00 p. m. and 4:00 a. m. There appeared to be a segment of ''nomadic'' males that moved into and out of the spawning area, apparently seeking other mates to spawn with. This methodology has the potential to provide more consistent and accurate salmon spawner abundance information than single-pass and multiple-pass spawning ground surveys. Accurate adult escapement information would allow managers to determine if recovery actions benefited listed chinook salmon in tributary streams.