Title: Steelhead trout life history
1Steelhead trout life history
W. Satterthwaite M. Mangel - UCSC, D. Swank,
S. Sogard, M. Beakes - NOAA J. Merz -
EBMUD, Cramer Fish Sciences R. Titus E.
Collins - CDFG
2Thinking about steelhead life history
- Why mature as resident?
- Avoid ocean mortality
- Potentially easier iteroparity
- Why smolt and emigrate?
- Much larger size gt higher reproductive success
- Why take action when young?
- Less cumulative risk of mortality in stream
- Why take action when older?
- Larger size at spawning higher reproduction
- Larger size at emigration higher survival
3Model algorithm
Tradeoff between future growth, further mortality
risk
- Postulates existence of decision windows
- Assess current size and potential for future
growth as parr - Assess expected fitness if smolt/mature at
current size - Compare with expected fitness of growing to a
larger size and making an optimal decision in the
future - (discount for mortality)
- For now, concentrate on females
4Timing is everything (thanks to D. Swank)
Age 4
Age 3
Age 2
Age 1
Age 0
Age 5
rainbow
Birth
1.1
smolt-1
1.2
1.3
freshwater parr
1.4
rainbow
mature resident parr
?
2.1
smolt-2
2.2
smolt
immature ocean
2.3
mature ocean
rainbow
maturity decision
smolt decision
3.1
smolt-3
3.2
3.3
5Timing is everything (thanks to D. Swank)
Age 4
Age 3
Age 2
Age 1
Age 0
Age 5
rainbow
Birth
steelhead
smolt-1
rainbow
freshwater parr
steelhead
smolt-2
mature resident parr
rainbow
smolt
steelhead
smolt-3
ocean steelhead
rainbow
steelhead
smolt-4
maturity decision
smolt decision
. . .
6Timing is everything (thanks to D. Swank)
Age 4
Age 3
Age 2
Age 1
Age 0
Age 5
rainbow
Birth
steelhead
smolt-1
rainbow
freshwater parr
steelhead
smolt-2
mature resident parr
rainbow
smolt
steelhead
smolt-3
ocean steelhead
rainbow
steelhead
smolt-4
maturity decision
smolt decision
X
7Timing is everything (thanks to D. Swank)
Age 4
Age 3
Age 2
Age 1
Age 0
Age 5
rainbow
Birth
steelhead
smolt-1
rainbow
freshwater parr
steelhead
smolt-2
mature resident parr
rainbow
smolt
steelhead
smolt-3
ocean steelhead
rainbow
steelhead
smolt-4
maturity decision
smolt decision
8Timing is everything (thanks to D. Swank)
Age 4
Age 3
Age 2
Age 1
Age 0
Age 5
rainbow
Birth
steelhead
smolt-1
rainbow
freshwater parr
steelhead
smolt-2
mature resident parr
rainbow
smolt
steelhead
smolt-3
ocean steelhead
steelhead
smolt-4
maturity decision
smolt decision
9Dynamic State Variable model
- F(l,g,e,t)
- F expected lifetime fitness
- l size
- g developmental switch, maturity
- e developmental switch, smolting
- t time
- G(l,g,e,t) - future size at time t1
- s(t) - survival to time t1
10Dynamic State Variable model
- F(l,b,g,e,t)
- F fitness
- l size at t end of window
- b size at start of window
- g developmental switch, maturity
- e developmental switch, smolting
- t time
- G(l,b,g,e,t) - updated future size
11Terminal reward - Spawning
- Latest possible spawning
- F(l,g,e,Tsf) ?(l) if g1,
- F(l,g,e,Tsf) 0 otherwise
12Terminal reward - Spawning
- Latest possible spawning
- F(l,g,e,Tsf) ?(l) if g1,
- F(l,g,e,Tsf) 0 otherwise
- Earlier spawnings
- F(l,g,e,ts) ?(l) s(t)F(G(l,g,e,ts),g,e,ts1)
if g1, - F(l,g,e,ts) s(t)F(G(l,g,e,ts),g,e,ts1)
otherwise
13Terminal reward - Emigrating
- F(l,g,e,te) ?(l)? if e1,
- F(l,g,e,te) s(t)F(G(l,g,e,te),g,e,te1)
otherwise - F(l,g,e,t) s(t) F(G(l,g,e,t),g,e,t1)
Updating - Outside Windows
14Terminal reward - Emigrating
- F(l,g,e,te) ?(l)? if e1,
- F(l,g,e,te) s(t)F(G(l,g,e,te),g,e,te1)
otherwise - F(l,g,e,t) s(t) F(G(l,g,e,t),g,e,t1)
Updating - Outside Windows
15Maturity Decision Window
- F(l,b,g,e,tdg) s(t) maxg( F(G(l,b,g,0,tdg),g,e
,tdg1)) - if ge0,
- F(l,g,e,tdg) s(t) F(G(l,b,g,e,tdg),g,e,tdg1
) otherwise.
16Maturity Decision Window
- F(l,b,g,e,tdg) s(t) maxg( F(G(l,b,g,0,tdg),g,e
,tdg1)) - if ge0,
- F(l,g,e,tdg) s(t) F(G(l,b,g,e,tdg),g,e,tdg1
) otherwise. - F(l,b,g,e,tde) s(t) maxe( F(G(l,b,0,e,tde),g
,e,tde1)) - if ge0,
- F(l,g,e,tde) s(t) F(G(l,b,g,e,tde),g,e,tde1
) otherwise.
Smolting Decision Window
17Inputs Survival and Growth
- Survival CJS MARK-recapture model
- Pit tagged fish recapture rates
- Separate analysis of YOY vs older fish
- Seasonal but not yearly variation
- Biased low - confounded with emigration
18Inputs Survival and Growth
- Survival CJS MARK-recapture model
- Pit tagged fish recapture rates
- Separate analysis of YOY vs older fish
- Seasonal but not yearly variation
- Biased low - confounded with emigration
- Growth
- Energy balance, optimal foraging
- Temperature dependencies and allometries from
literature, gut capacity and BMR from lab fits
19Coastal Growth
Valley Growth
20Coastal Growth Model Comparison with Data
21Life History Predictions - Coast
smolt
mature
wait
smolt
wait
22Life History Predictions - Coast
No residents
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24Life History Predictions - Coast
Many age 1 smolts gt age 2 emigrants, a few older
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26Coastal Growth - Estuary Effects
Hayes et al TAFS
27Life History Predictions - Coast
Threshold size of 110mm in late December
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29Evidence for smolt threshold?
Length lt100 gt100 max p
Scott recap 30 0 98 0.0008
not 237 91
Soquel recap 56 21 230 0.84
not 223 61
GSF recap 7 0 89 0.053
not 81 13
BDG S recap 4 22 197 0.532
not 14 139
ASBRY recap 20 13 153 0.087
not 25 18
30Evidence for smolt threshold?
Length lt100 gt100 max p
Scott recap 30 0 98 0.0008
not 237 91
Soquel recap 56 21 230 0.84
not 223 61
GSF recap 11 0 89 0.026
not 79 13
BDG S recap 21 8 230 0.84
not 120 30
ASBRY recap 24 13 153 0.080
not 24 18
31Life History Predictions - American
mature
smolt
wait
- All smolt as YOY and emigrate age 1
- Threshold size of 150mm in late December
- (higher threshold than coast)
32Predictions - Mokelumne
mature
smolt
wait
- Most smolt as YOY and emigrate age 1
- Potential for slow growers to mature as parr
33Effects of changing environment
- Short term compare new growth vs. old thresholds
(no response to survival changes) - Coast much faster growth could yield mature
parr. Easy to change average age at smolting.
34Effects of changing environment
- Short term compare new growth vs. old thresholds
(no response to survival changes) - Coast much faster growth could yield mature
parr. Easy to change average age at smolting. - Valley slow growth might yield mature parr.
Need to preserve good growth environment in late
summer.
35Effects of changing environment
- Short term compare new growth vs. old thresholds
(no response to survival changes) - Coast much faster growth could yield mature
parr. Easy to change average age at smolting. - Valley slow growth might yield mature parr.
Need to preserve good growth environment in late
summer. - Long term
- Both Most sensitive to emigration survival
- Importance of estuaries, passage through delta
36Future directions
- Bet-hedging
- Explicit estuarine state and decisions
- Refine functional relationship between
temperature, flow, and growth - Males
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38smolting decision window
time of emigration
Decent chance of survival. Extra benefit from
another years growth outweighed by river
mortality, generation time.
Size
Too small to stand much chance of survival
Time
39smolting decision window
time of emigration
Decent chance of survival. Extra benefit from
another years growth outweighed by river
mortality, generation time.
Size
Too small to stand much chance of survival
Time
40smolting decision window
time of emigration
Decent chance of survival. Extra benefit from
another years growth outweighed by river
mortality, generation time.
Size
Too small to stand much chance of survival
Time
41coast
valley
Beakes et al. in prep
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