Emigration behavior of resident and
anadromous juvenile O. mykiss:
exploring the interaction among genetics,
physiology and habitat
Sean Hayes, Chad Hanson, Morgan Bond, Devon Pearse,
Andrew Jones, Carlos Garza, Bruce MacFarlane
Scott Creek
•Small watershed (75km2)
•23km of stream accessible to
anadromous fish
•“native” resident fish above
barriers
•Small hatchery
•Dynamic flow regime
(28m3 s-1 to 0.1m3 s-1)
•Small Estuary (closes
seasonally)
Map: Rob Schick, NMFS
Scott Creek O. mykiss
life history strategies
Ocean
upper watershed
estuary/lagoon
Upstream resident
Mature in estuary
(never enter ocean)
Scott
Creek
Instream
PIT tag
readers
x
x
x
Smolt
trap
X= barrier
3 km
Adult
weir
Seine, hook & line, and electrofishing
Do rainbow trout and steelhead differ?
Big Creek Above
Big Creek, Boyer
Scott Creek Above
Mill Above
68
63
Resident populations
“diverged” >100 yrs ago
92
76
Big Creek Adults
60
Scott Creek Adults
Hatchery Juveniles
Weir Adults
Lagoon Juveniles
Neighbor-Joining distance tree, with bootstrap values for supported nodes
?
x
x
x
Proportion of fish assigned to Resident or Anadromous
ancestry by habitat
100%
90%
80%
70%
Anadromou
60%
Resident
50%
40%
30%
20%
10%
0%
Above
Barrier
Upstream
Smolt trap
Estuary
Frequency
0.40
0.30
Genotype distribution in upper
watershed
Resident (n=128)
Anadromous (n=209)
0.20
0.10
0.00
Fork length
Emigration rate
from above
anadromy barrier
• 400 fish PIT
tagged above
• 2.3 % over the falls
• 1.8 % detected at
smolt trap
+
Na
6
Physiology
?
8
Above Barrier
Upstream
ATPase activity
ATPase activity
8
+
K -ATPase
4
2
0
6
Smolt Trap
Estuary
4
2
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
+
Na
+
K -ATPase
Physiology
Upstream samples
Resident
Anadromous
6.00
4.00
2.00
0.00
0
2
4
6
Month
8
10
Frequency
ATPase
8.00
12
Resident
Anadromous
6
4
2
0
0
2
4
6
8
10
ATPase
12
14
16
Why do wild fish migrate at such small sizes?
Frequency
0.16
Typical steelhead smolt size distribution
0.12
0.08
0.04
0
Fork Length (mm)
Does estuary serve as nursery habitat?
(Morgan Bond’s thesis)
Estuary- Open to Ocean (Jan.-June)
Lagoon- Sand Bar Closed (July-Dec.)
Is the estuary a nursery?
Black lines indicate upper watershed growth
Blue lines indicate migration to estuary and growth
Fork Length (mm)
250
200
Size threshold
for ocean
survival
150
100
Mean
5th %
95th %
50
0
Jan
YOY
Jul
1+
Jan
Jul
2+
Jan
Jul
3+
Jan
Jul
Jan
85% of returning
adults use estuary
pathway
Ocean
upper watershed
estuary/lagoon
What happens when water quality degrades?
>45% detected moving
Upstream each fall
(probably >90%)
3 km
Size of recaps at smolt trap in spring
20
18
16
Upstream
Estuary (previous summer)
Frequency
14
12
10
8
6
4
2
0
60
80
100
120
140
160
180
200
Fork Length
220
240
260
280
300
A tale of two watersheds
(in Central California…)
No estuary available
Year 1
Year 2
Year 3
Functional estuary present
Year 1
Year 2
Year 3
Acknowledgements
Funding
•
•
•
•
NMFS
DFG FRGP
NURP
California Sea Grant
Land Owner support
•Big Creek Lumber Company
•The Wilson Family
•Monterey Bay Salmon and Trout Project
•Cal Poly Swanton Ranch
•Lockheed Martin
Implications of resident trout studies
• Should residents be counted in steelhead
populations for delisting criteria?
• Residents may become steelhead, but this
probably happens at low frequencies
• Results of resident contribution to
anadromous breeding pending
Estuary Environmental Conditions
“Lethal”
levels
Influence of genotype on
To seamigration
or not to behavior
sea?
Genotype Frequencies
1
Frequency
Resident
0.8
Anadromous
0.6
0.4
0.2
0
Upstream
Smolt trap
Steelhead in Scott Creek
Typical spring downstream migrant (smolt?)
After 5-6 months rearing in estuary
85% of returning
adults use estuary
pathway
100mm
Big smolts are less likely to stay
25
20
15
10
5
0
<
<150
>150
Fork Length (mm) at Trap
Conclusions
Central Coast steelhead adapt for estuarine use
Steelhead strategies without estuary
• Longer upstream rearing
• Fewer smolts, reduced anadromy?
Density-dependent Estuary
Growth in Steelhead
Figure 5. Estimated lagoon yearly population sizes and yearly mean growth rates from 2003-2006 (left y-axis).
The bar graph (right side y-axis) represents mean fork length of fish sampled in the estuary in late fall of each
year, just prior to winter storm season and lagoon opening. Years match points within labeled column. All
data are means ± SE, R2=0.99. Regression P= 0.005
SGR length as a % per day
1.0
2004
2005
0.8
0.6
0.4
2003
2006
0.2
0
500
1000
1500
2000
2500
Estimated Lagoon Population
3000
Implications for Local Rivers
• Larger river- may have more rearing
capacity= larger smolts upstream
• BUT… is there enough water?
• Estuary issues
– Breaching
– Estuary size reduced?
– Enough flow to connect with watershed?
Lagoon fish move upstream in the fall and then back
down in spring
Lagoon fish PIT tag reader detections
350
>45% lagoon fish detected moving upstream
300
Upper watershed
Frequency
250
Lower watershed
200
150
100
50
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Month
Aug
Sep
Oct
Nov
Dec
Early 20th century spawning
population was 4-10 times larger
Escapement ??
Why is estuary growth so good?
(Jeff Harding’s diet studies)
Lots of food!
Diet consists of Corophium and Eogammarus sp.
But where does food come from?
•
•
•
•
Upper watershed growth poor
Insect diet
Low flow
Low light
– low nutrient input into estuary
Hypothesis- Nutrient flow from marine derived
nutrients (kelp) enhances productivity
Marine
(Alison Collins senior thesis)
13C
and 15N from Juvenile Steelhead
d15 N (0/00) +/- SD
16
14
12
10
Juv. Steelhead - Lagoon
Juv. Steelhead - Above Fall
8
Adult Steelhead
6
Coastal Marine Fish
-26
Terrestrial
-24
-22
-20
d13 C (0/00) +/- SD
-18
-16
-14
Marine
Why don’t all fish recruit to the
estuary?