An Evaluation of Steelhead Habitat and Population in the Gabilan Creek Watershed Julie Hager...
-
Upload
edmund-clark -
Category
Documents
-
view
214 -
download
1
Transcript of An Evaluation of Steelhead Habitat and Population in the Gabilan Creek Watershed Julie Hager...
An Evaluation of Steelhead Habitat and Population in
the Gabilan Creek Watershed
Julie HagerCapstone Project
5/24/01
State Water Resource Control Board
Primary Objectives
Is there suitable habitat for steelhead in the Gabilan Creek watershed?
Have populations existed there in the
past?
Do populations currently exist, and if not, why?
Overview
Steelhead life cycle and characteristics
Reconnaissance survey
Spawning and rearing habitat
Population survey
Limiting Factors
• Temperature (Preferred 7.3 -14.6 ° C)
• Dissolved Oxygen (Criterion >7.8 mg/L)
• Suspended Sediment (Criterion <25 mg/L)
• Cover (overhead and escape)
• Food (aquatic insects)
• Lack of Pools and Sufficient Flow
• Migration Barriers
• Substrate for Spawning (diameter .6-10.2 cm)
• Pollution
• Overfishing
Phase 1: Reconnaissance Survey
perennial water
obstructions
creek pattern, profile, and roughness
important features:• pool/riffle sequences• dominant substrate• bank condition• riparian vegetation• pollution sources• adjacent land use• fish and frog sightings• estimates of bankfull width and depth
Reach 1Location Perennial
WaterPools LWD Overhead
CoverErosion Bank
VegetationSubstrate Fish & Amphibian
SightingsAdjacent Land Use
Section 1 Yes - - - + - sand, silt Common Carp row crop agriculture
Section 2 Yes - - - +
sand, silt California Roach row crop agriculture
Section 3 Yes - - - + - silt, clay Common Carp row crop agriculture
Section 4 Yes - - - +
silt, clay California Roach row crop agriculture,industrial
(-) very little to none ( ) moderate (+) abundant
Reach 2Location Perennial
WaterPools LWD Overhead
CoverErosion Bank
VegetationSubstrate Fish & Amphibian
SightingsAdjacent Land Use
Section 1 Yes - - + sand Pacific Treefrog residential
Section 2 No - +
sand Western Toad row crop agriculture,
grazing, residentialSection 3 No - - - + - sand none row crop agriculture
residential
(-) very little to none ( ) moderate (+) abundant
Reach 3
Location PerennialWater
Pools LWD OverheadCover
Erosion BankVegetation
Substrate Fish & AmphibianSightings
Adjacent Land Use
Section 1 Yes + + + - + cobbleboulder
Rainbow Trout grazing
Section 2 Yes + + + - + bedrockboulder
none grazing
Section 3 Yes + + + - + cobbleboulder
Bullfrog grazing
(-) very little to none ( ) moderate (+) abundant
Phase 2: Detailed Habitat Assessment
Section Length(m)
Avg. CobbleAbundance
Avg. CobbleEmbeddedness
Average PoolDepth (m)
RearingIndex
Density(fish per meter)
Habitat 1 44.00 18% 21% .24 4182 1.58
Habitat 2 14.00 14% 30% .16 1767 2.02
Habitat 3 12.85 23% 35% .34 1121 1.47
Habitat 4 21.90 33% 26% .22 1300 1.08
Habitat 5 24.60 24% 18% .31 2525 1.72
•Rearing Index for Young-of-
Year
•length, width,& depth
• velocity & embeddedness
•rate cover and roughness
• # fish per meter
•suspended sediment, DO, &
temperature
Monitoring
Location Mean SummerTemp (C)
Reach 1 20.75
Reach 2 21.0
Reach 3 12.93
Above Preferred Range
RainEvent
Range of Suspended SedimentConcentration (mg/L)
Reach 1 Reach 2
Jan 7-13 29 - 913 0-1904
Jan 23-26 47 -1928 7.8-6714
Feb 9-12 No Data 302-5884
Feb 18-19 33-1321 2.5-6812
Can Prevent Migration
Phase 3: Population Assessment
Electrofishing was not conducted due to lengthy ‘take’ permit process
During ~400 visits, zero steelhead were observed
Local residents reported 20 inch steelhead catch ~10 years ago
Is there suitable habitat for steelhead in the Gabilan Creek
Watershed?
Suitable rearing and spawning habitat exists in the headwaters
Watershed has potential to support 30,000 young-of-the-year
Reclamation Ditch and lower reaches are problematic for migration:• lack sufficient cover
• lack woody debris
• uniform flow structure lacking pools and riffles
• high summer temperatures
• high suspended sediment concentrations
YES
Have populations existed there in the past? Maybe
One interview reported a catch 10 years ago
zero positive steelhead observations (lack of rainfall and flow)
16 Rainbow Trout were observed in headwaters
potential exists due to polymorphic life-history allowing resident trout to assume anadromy
Do populations of steelhead currently exist? No
Outcomes Prior to this study, there was no information on
steelhead habitat or population in Gabilan Creek
Increase awareness within management, local agencies, & community about the potential for a steelhead run in Gabilan Creek
Address problematic areas in the lower reaches (restoration, education, sustainable land use practices)
RDIPAC
Continue studies on steelhead habitat and population in the Gabilan Creek watershed