Juvenile salmonid rotary screw trap data from Battle and Clear Creeks, Shasta and Tehama Counties, California.

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.