Post on 18-Jan-2016
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Role of Tidal Saltwater Habitats for Juvenile Salmonids
(Myths vs Reality in the Columbia River Estuary)
Ed CasillasNWFSC, Seattle, WA
(Contributors – UW, OSU, OHSU, WDFW, PSU, COE, BPA)
Current Drivers - Population viability & resilience, habitats salmon use and need• Productive feeding area
• Refuge from predators
Role of EstuariesHistorical Drivers – Production, abundance, mortality• Conduit – Connect upstream spawning and rearing areas to
ocean habitat
• Transition to saltwater
2002 2003 2004
J M M J S N J M M J S N J M M J S N J M M J S N
Log
10 C
PU
E
0.0
0.5
1.0
1.5
2.0
2.5
3.0
2005
Marine
Mixing
Tidal fresh
Marine
Mixing
Tidal Fresh
Myth - Juvenile salmon use the estuary for a short period of time (as individuals and as populations)
Reality – Juvenile salmon present in the estuary year around
Myth – Salmon populations predominantly use the subyearling and yearling strategy to succeed
Reality - All ESUs use a variety of juvenile life history strategies to succeed
Alevins
Fry 40-60mmFingerlings 60-90mm
Subyearlings/Yearlings100-200 mm
Size seen in the ocean, composed of juveniles using fry, fingerling, subyearling, and yearling strategy
Fry – distributes throughout the river, estuary and oceanFingerlings – rears near spawning area for 1-2 months, then distributes throughout river, estuary, and oceanSubyearling/Yearling – rears in river, then migrates to the ocean
>50% of juvenile enter estuary at < 60mm
Month
Mea
n Pe
rcen
t
Monthly Fry Proportion
Fry a Dominant Strategy in the Columbia River Estuary
Fry
Month
J F M A M J J A S O N D
Size
(m
m)
30
35
40
45
50
55
60
Lower estuary
Mixing zone
Tidal freshwater
WC-F WC-SpSCG-FUCR-Su/FWR-SpSnake-FRogue
Fry Strategy Used by Many Chinook ESUs in the Columbia River
Myth - Juveniles only use the estuary to transit to the ocean
Reality – Juveniles grow in the estuary
0 30 60 90 120 150 180 210 240 270 300 330 360
Mea
n F
L (
se)
20
40
60
80
100
120
140
160Lower EstuaryMiddle estuaryTidal Freshwater
Day of yearJ F M A M J J A S O N D
Corollary – If juveniles grow in the estuary, they then must reside in the estuary
• Juveniles enter the estuary over a wide range of sizes
• Residence time decreases with size at estuary entry
Data from Lance Campbell
Point Adams Beach 2004
May-Aug
y = -0.9705x + 110.91
R2
= 0.5172
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120
Back Calculated Fork Length at Estuary Entry (mm)
Res
iden
cy (
day
s)
Estuary habitat use and residency is size related
• Small size classes frequent shallow, nearshore and wetland habitats
• Few juveniles > 90 mm enter or remain in interior marsh channels
Chinook Length Frequency in Wetland ChannelsWhich Habitats are Used
by Juvenile Salmon April
0
10
20
30
40
50
60
35 40 45 50 55 60 65 70 75 80 85 90 95 100
Fork Length (mm)
Fre
qu
en
cy
May
0
5
10
15
20
25
30
35 40 45 50 55 60 65 70 75 80 85 90 95 100
Fork Length (mm)
Fre
qu
en
cy
June
0
2
4
6
8
10
12
14
16
35 40 45 50 55 60 65 70 75 80 85 90 95 100
Fork Length (mm)
Fre
qu
en
cy
July
0
1
2
3
4
5
6
7
35 40 45 50 55 60 65 70 75 80 85 90 95 100
Fork Length (mm)
Fre
qu
en
cy
April
May
June
July
n = 155
n = 122
n = 39
n = 19
2004
Freq
uenc
y of
Occ
urre
nce
Fork Length (mm)
Scrub-Shrub
Forested
Emergent
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
CS WSI PAB PE UCC ETI LES
% I
RI
Diptera (adult) A. salmonis A. spinicorne Cladocera Other prey items
tidal freshwatermarine estuarine mixing
Myth – Juvenile salmon feed primarily on benthic aquatic organisms
Reality – Juvenile salmon feed dominantly on terrestrially derived insects
40-80mm70-120mm 60-90mm
Myth – The Columbia River Estuary Benefits Lower River stocks only
Reality - Most all ESUs use estuarine habitats -Stock composition varies through the year
0%
10%
20%
30%
40%
50%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovFrom David Teel
Stock Composition Chinook Salmon 2002 - 2006
All Beach Seine Sites Combined
Minor contributors Only
0%
20%
40%
60%
80%
100%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
UCR Su / F
W Cascade F
W Cascade Sp
Spring Cr F
Willamette Sp
Snake F
Deschutes F
Rogue F0%
10%
20%
30%
40%
50%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
0%
10%
20%
30%
40%
50%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovFrom David Teel
Stock Composition Chinook Salmon 2002 - 2006
All Beach Seine Sites Combined
Minor contributors Only
0%
20%
40%
60%
80%
100%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
UCR Su / F
W Cascade F
W Cascade Sp
Spring Cr F
Willamette Sp
Snake F
Deschutes F
Rogue F
CREST
Myth – Only subyearling from lower river stocks use wetland habitats
Reality – Subyearlings and yearlings from interior basin also use wetland shallow water habitats
Pit tag detector array in secondary wetland channel
2009 DetectionsLower Columbia River Chinook salmon, N=32
Lower Columbia River coho salmon, N=5Snake River fall Chinook salmon, N=1
Snake River spring Chinook salmon, N=1Snake River summer steelhead, N=3
From Burke, 2005. Data from Rich (1920) & Dawley et al. (1985)
If estuaries provide opportunity for diversification of life history strategies and diversity is an attribute of healthy salmon populations, how does the Columbia River system fare?
Estimated changes in the relative proportions of juvenile salmon life histories
Jan Mar May Jul Sep Nov Jan Mar May Jul
Rel
ativ
e A
bu
nd
ance
Fry with platelets only
Fry (<60 mm)
Fingerling - Recent Arrivals
Fingerling - Fluvial rearing
Fingerling - Estuarine Rearing
Fingerling - Fluvial and additional rearing
Yearling
Historic
Jan Mar May Jul Sep Nov Jan Mar May Jul
Jan Mar May Jul Sep Nov Jan Mar May Jul
Rela
tive
Abu
ndan
ce
Fry
Fingerling Natal / Fluvial Rearing
Yearling
Contemporary
Simplication of life histories may undermine resilience and recovery of Columbia River Chinook salmon
Can Salmon Life History Diversity be Restored?
Estuarine restoration, life history strategies, and adult returns; the Salmon River story
1975
0
20
40
60
80
100
1976
CPU
E (n
umbe
r/se
ine
haul
)
0
20
40
60
80
100
1977
Mar May Jul Sep Nov
0
20
40
60
80
100
Lower estuaryMid estuary
Upper estuary 75' seine (1977)Upper estuary 125' seine (1977)
2000
0
20
40
60
80
100
2002
Mar May Jul Sep Nov
0
20
40
60
80
100
2001
CPU
E (n
umbe
r/se
ine
haul
)
0
20
40
60
80
100
Lower estuaryMid estuaryUpper estuary
• Life history diversity has expanded with increased wetland opportunity
Can Life History Diversity be Restored? After Estuary RestorationBefore Estuary Restoration
Size at Estuary Entry for Juveniles at Mouth (BY 2001 & 02)
Emergent Fry < 45mm 7%Spring (MAM) 47 – 64 mm 10%Summer (JJA) 55 – 96 mm 77%Fall (SON) 97 – 109 mm 6%
Myth – Estuarine restoration does not affect adult returns
Reality – Recovered life history strategies contribute to adult returns
Size at Estuary Entry for Adults (2004 RY; n=145)
Emergent Fry < 45 mmSpring (MAM) 47-64 mmSummer (JJA) 65-96 mmFall (SON) 97-110 mm
17%14%57%12%
Summary – Estuary as Salmon Habitat
• Based on distribution preferences and growth characteristics, estuary a habitat for smaller juvenile salmon to grow
• Shallow water, low velocity, and low salinity surface environments with associated wetland vegetation are features that define habitat
• Diverse distribution of habitat a surrogate for diversity and spatial structure of salmon population
• All juveniles benefit from estuary habitat through food webs and predator refuge
• Preservation and restoration of shallow water, low velocity, and low salinity environments an important strategy for recovery of salmon and to mitigate for anthropogenic modifications