112-30 CRAB CREEK Ks Glel sii 
N55°07.1 W131° 22.5 Previous No. 110 
KETCHIKAN, REVILLAGIGEDO CHANNEL, CRAB BAY, Head 
MAJOR SPECIES Pink OTHER SPECIES Chum, coho 
ESCAPEMENT TIMING Late. Sep. -Oct. ESCAPEMENT MAGNITUDE 25-50, 000 
SPAWNING FACILITIES Extensive upper intertidal zone stream sections offer very good facilities. However, 
past observations have found spawning to be equally divided between the intertidal and upstream areas. The 
upstream has some excellent spawning facilities in the lower part. Though more coarse upstream, there are 
also good facilities at intervals. 
STREAM TEMPERATURES Warm range. Observed temperatures: 53°F., 9/12/52, 52°F., 10/7/52; 54°F. 
9/11/53, 52°F. 9/24/53. 
VALLEY DESCRIPTION Low valley with head at divide above Purple Lake. Bare granite areas are extensive. 
Glacial origin. 
DRAINAGE 7 square miles (Polar Planimeter). Main discharge from precipitation fed chain of small lakes E. of 
head of Purple Lake. Small lake feeds small stream entering main stream . 2 mile above high tide. 
STREAM MOUTH IDENTIFICATION Entrance to extensive intertidal grassflats through constriction. 
ANCHORAGE Well protected anchorage in bay S. of stream mouth. 
TRAILS AND SURVEY ROUTES Extensive intertidal zone requires that stream be reached at high tide by 
skiff and the upstream section surveyed quickly in order that return to the skiff be before the tide drops and 
strands it- During higher than normal water levels, skiff can be floated out in the stream. Upstream route in 
the stream bed. 
AERIAL SURVEY NOTES Very good aerial observation conditions in intertidal zone on most water levels. 
Upstream section is relatively straight and easily followed by plane. Very rough air during westerly winds of 
moderate or stronger force. 
INTERTIDAL ZONE 
LENGTH _ 1.5 miles AVERAGE WIDTH/DEPTH § 100'/12-24" 
GRADIENT AND VELOCITIES <.5° at 1-2' per second 
BOTTOM _ Sand and gravel, some bedrock in lower intertidal zone. 
LOW TIDE LOCATION Below constriction near anchorage. 
HIGH TIDE LOCATION Head of the grassflats at stream emergence from woods. 
SCHOOLING AREAS Schooling has been observed throughout intertidal zone. Large concentrations usually 
found in the upper third of the zone. 
SPAWNING AREAS _ Upper -5 mile of intertidal zone has good spawning facilities. Largest spawning concen- 
trations observed near high tide mark. 
GENERAL NOTES Small stream enters from N. side at the high tide mark. Negligible spawning populations 
compared to main stream. 
UPSTREAM 
LENGTH ACCESSIBLE .4 mile AVERAGE WIDTH/DEPTH _  50-60!/12-24" 
GRADIENT AND VELOCITIES 1-2 at 2-3' per second 
BOTTOM Sand, gravel, boulders, some bedrock 
MARKER DISTANCE .-3 mile. 
MARKER IDENTIFICATION At confluence with small stream entering from the W. where main stream 
turns 90° toward the N. 
BARRIERS Falls .4 mile upstream is barrier to salmon migration. 
TRIBUTARIES Small tributary enters . 3 mile upstream from W. at terminal mark. Not accessible to salmon. 
SCHOOLING AREAS Most schooling is found in the intertidal zone. Most salmon observed upstream have been 
spawning. 
SPAWNING AREAS The greatest spawning concentrations have been observed in the first . 3 mile, densest near 
high tide. 
GENERAL NOTES 
