Steve Cramer Casey Justice
Ian Courter
Environmental drivers of steelhead abundance in partially anadromous Oncorhynchus mykiss populations
Key Characters in the Plot
Project Objectives
• Determine how environmental factors drive productivity of resident and anadromous O. mykiss ecotypes
Test this understanding:• Can the functional relationships of O. mykiss
productivity to environmental factors predict the observed distribution of the two ecotypes in the Yakima Basin?
Examples of Resident Rainbow Streams
within the Anadromous Fish ZonesAugust
Basin Flow (cfs)
Temperature
McKenzie 2,600 54o F
Metolius 1,400 46o F
Upper Yakima 3,600 60o F
Upper Sacramento
10,000 55o F
Mainstem Teanaway
Teanaway and Yakima River confluence
Yakima River Temperatures
30
40
50
60
70
80
Average T
em
peratu
re (
F)
JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC
Month
Yakima R @ Umtanum (Rb)Yakima R @ Prosser (Sthd)
Yakima Basin
Rainbow And Steelhead Intermix And Produce Both Types
• Interbreeding of Rb x St is observed
• Genetics show similarity by basin, not by ecotype
• Breeding studies show each type produces some of the other
• Sr/Ca ratio in otoliths of spawners confirms cross parentage
Focal Point Depth and Velocity. From Everest and Chapman 1972
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7
Depth (ft)
Pro
bab
le S
uit
abil
ity
fry
juvenile
adult
Depth Suitability for O. mykiss
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5Velocity (fps)
Pro
ba
ble
Su
ita
bil
ity
fry
juvenile
adult
Velocity Suitability for O. mykiss
From Grant and Kramer (1990)
Fork Length (mm)
0 50 100 150 200 250 300 350 400
Ter
rito
ry S
ize
(m²)
0
2
4
6
8
10
12
14
16 Fry Juvenile Adult
Flow (cfs)
0 500 1000 1500 2000
Fry
cap
acit
y
0
10000
20000
30000
40000
50000
60000
Juve
nil
e an
d a
du
lt c
apac
ity
0
1000
2000
3000
4000
FryJuvenileAdult
Territory Needed for a Steelhead Cohort
0
100
200
300
400
500
600
700
800
Fry 0+ Parr 1+ Parr
Life Stage
Num
ber
in
Coh
ort
-
20
40
60
80
100
120
140
160
Ter
rito
ry R
equi
red
(m̂2)
Fish Territory
From Rand et al. (1993) and Mangel and
Sattherthwaite (2008).
Modeling Growth in FreshwaterGrowth = anabolic gains – catabolic losses
Factors influencing growth:
1) Temperature
2) Food availability
Stream temperature (°C)
0 5 10 15 20 25
Gro
wth
(g
/day
)
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
Mainstem Growth
0
100
200
300
400
500
6002
6-J
un
24
-Se
p
23
-De
c
23
-Ma
r
21
-Ju
n
19
-Se
p
18
-De
c
17
-Ma
r
15
-Ju
n
13
-Se
p
12
-De
c
12
-Ma
r
10
-Ju
n
8-S
ep
7-D
ec
7-M
ar
5-J
un
3-S
ep
2-D
ec
2-M
ar
31
-Ma
y
29
-Au
g
27
-No
v
Time since emergence
Fo
rk le
ng
th (
mm
)
Age-0 Age-1 Age-2 Age-3 Age-4 Age-5
Spawning27-Mar
Emergence26-Jun
Growth of PIT-tagged Wild SteelheadRecaptured 1 yr after Tagging
Keifer et al. 2004
Salmon & ClearwaterRiver tributaries
Relationship Between Temperature & Trout Biomass
Salt River Basin (Isaak and Hubert 2004) L
og
10(B
iom
as
s)+
1
2
1
05 10 15
Mean Stream Temperature (oC)
MWAT (oC)
12-14 14.1-16 16.1-18 18.1-20 20.1-22 22.1-24 24.1+
Mea
n c
oh
o d
ensi
ty (
no
./m
2 )
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Juvenile Coho Density vs. Temperature 260 Oregon Coast Sample Sites
Extended Bar shows 2 Standard Errors
0.0
0.2
0.4
0.6
0.8
1.0
12 14 16 18 20 22 24 26
Conclusions
• Channel size, flow and temperature are key factors that determine carrying capacity for resident fish over 250 mm, and may determine which of the two ecotypes will dominate
• Data are available in the Yakima Basin to predict how carrying capacity for O. mykiss will be affected by flow, temperature, and channel morphology
• We can test how well we understand the factors driving life history of O. mykiss by: – Using what we understand to build a life cycle model for O.
mykiss– Plug in actual values for habitat and environmental factors,– Compare how the predicted and observed distributions of
the two ecotypes match
Growth is a Key Driver
• Growth determines size at age
• Size determines the area of habitat occupied
• Size at age determines winter survival in freshwater
• Size at smolting determines ocean survival
Hypothesis
Variation in flow conditions influence the distribution of the two ecotypes across subbasins
Substantial declines in summer discharge will reduce carrying capacity for adult resident fish and promote a migratory life-history strategy
Hypothesis
Over-winter Survival
Fork length (mm)
60 80 100 120 140 160 180 200 220
Ove
r-w
inte
r su
rviv
al N
ov-
Feb
(%
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Smith and Griffith (1994)
Adjusted curve
Length at emigration (mm)
100 125 150 175 200 225 250 275 300
Mar
ine
surv
ival
sca
lar
(% o
f m
ax)
0
20
40
60
80
100
120
Data from Ward and Slaney (1989)
Marine Survival
Rearing capacity = Habitat Area (m2) / Territory size (m2)
0.0 0.5 1.0 1.5 2.0
# o
f O
bse
rvati
ons
0
200
400
600
800
1000 Cum
ula
tive F
requency0.0
0.2
0.4
0.6
0.8
1.0
Depth (m) (Upper Bound)
0.0 0.5 1.0 1.5 2.0
# o
f O
bse
rvati
ons
0
500
1000
1500
2000
2500 Cum
ula
tive F
requency0.0
0.2
0.4
0.6
0.8
1.0Riffles
Pools
7 Basins528 km5,886 pools
4,900 riffles
Atlas of Pacific Salmon (2005)
Tributary Growth
0
50
100
150
200
250
300
350
4001
3-J
ul
11
-Oct
9-J
an
9-A
pr
8-J
ul
6-O
ct
4-J
an
3-A
pr
2-J
ul
30
-Se
p
29
-De
c
29
-Ma
r
27
-Ju
n
25
-Se
p
24
-De
c
24
-Ma
r
Time since emergence (months)
Pre
dic
ted
fo
rk le
ng
th (
mm
)
Age-0 Age-1 Age-2 Age-3
Spawning date3-Apr
Emergence13-Jul
