DOI: 10.6073/pasta/4d2e8b496adafb8b5bb0903c9cdc6f78
title: Juvenile salmonid rotary screw trap data from Battle and Clear Creeks, Shasta and Tehama Counties, California.

description: Clear Creek
 
 The U.S. Fish and Wildlife Service continued its juvenile salmonid
 monitoring project in Clear Creek, Shasta County, California, that
 began in December 1998 using a rotary screw trap (RST) located at
 river mile (RM) 1.7. This monitoring project has three primary
 objectives: (1) calculate annual juvenile passage indices for
 Chinook Salmon Oncorhynchus tshawytscha and Rainbow
 Trout/steelhead O. mykiss (we use the term O. mykiss to refer to
 both the stream resident (Rainbow Trout) and anadromous
 (steelhead) life histories because of the difficulties in
 differentiating the anadromous and resident forms in the field)
 for inter-year comparisons and analyses of the effectiveness of
 stream restoration activities; (2) obtain juvenile salmonid life
 history information including size, timing, and potential factors
 limiting survival; and (3) collect biological samples from
 juvenile salmonids. Chinook Salmon run classifications show that
 all Chinook Salmon runs known to the Sacramento River were
 captured; however, due to overlapping spawning times of spring-run
 and fall-run Chinook Salmon it was problematic to index the
 juvenile passage using only the RST at RM 1.7. Since 2003 a
 separation weir has been used to isolate adult spring-run Chinook
 Salmon from adult fall-run Chinook Salmon; therefore, a second RST
 was added above the weir at RM 8.4.
 
 
 
 Battle Creek
 
 The U.S. Fish and Wildlife Service continued its juvenile salmonid
 monitoring project in Battle Creek, Shasta and Tehama Counties,
 California, that began in December 1998 using a RST located at
 river mile (RM) 6.2. The upper Battle Creek RST objectives are to
 (1) calculate annual juvenile passage indices for spring-run,
 late-fall run, and winter-run Chinook Salmon; Rainbow
 Trout/steelhead O. mykiss (we use the term O. mykiss to refer to
 both the stream resident (Rainbow Trout) and anadromous
 (steelhead) life histories because of the difficulties in
 differentiating the anadromous and resident forms in the field);
 (2) obtain juvenile salmonid life history information including
 size, timing, and potential factors limiting survival; and (3)
 collect biological samples from juvenile salmonids. Chinook Salmon
 run designations in the Sacramento River watershed were developed
 using length-at-date criteria for Sacramento River fall-run
 Chinook Salmon. These designations may not be accurate when used
 for salmon captured in tributaries of the Sacramento River; these
 streams have variable and overlapping run timing of spring-run and
 fall-run Chinook Salmon. After 2008 all fall-run designated
 Chinook Salmon were reassigned as spring-run in the spring-run
 Chinook Salmon passage indices as preventative measures were taken
 to reduce the potential for fall-run Chinook Salmon to enter the
 upper watershed (above the Coleman National Fish Hatchery barrier
 weir).
 
 
 
 Mark–recapture trials
 
 Since the RST only captures fish from a small portion of the creek
 cross section, it is necessary to implement a method to project
 the RST catch numbers to portions of the creek outside of the RST
 capture zone. Mark–recapture trials were attempted, when creek
 conditions were conducive for such studies and when fish numbers
 allowed, to determine the efficiency of the RSTs to catch juvenile
 salmonids moving downstream during a given time period. If one or
 no mark–recaptures trials were conducted, then the historic
 monthly and global averages were used to calculate that passage
 indices. Mark-recapture–trials on Battle Creek are conducted using
 hatchery-origin fish (from Coleman National Fish Hatchery), while
 on Clear Creek natural-origin fish are used. Fish used for the
 trials were either single or dual marked. For the single mark
 trials the fish were stained with Bismarck brown-Y. Dual marked
 fish clipped with surgical scalpels, removing an area of
 approximately 1–2 mm^2 from the tip of either the upper or lower
 lobe of the caudal fin and then the fish were stained as above.
 
 
 Note: data within the current year’s monitoring season are
 considered provisional. The monitoring season typically concludes
 at the end of September.