D. Stich1*, M. Bailey2, J. Zydlewski3,1

1Department of Wildlife Ecology, 5755 Nutting Hall, University of Maine, Orono, ME; 2U.S. Fish and Wildlife Service, Central New England Fishery Resource Office, Nashua, NH; 3U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit, 5755 Nutting Hall, University of Maine, Orono, ME.

*Email: daniel.stich@maine.edu

Survival of Atlantic salmon smolts through a hydropower complex in the lower Penobscot River, ME USA

INTRODUCTIONAtlantic salmon smolts in the Penobscot River

• 18-month smolts

• Most are hatchery-origin

• 500,000+ stocked each year

• PRRP

• Balancing hydropower with sea-run fishes

• Dam removal in main-stem

• Power-generation increases

INTRODUCTIONPenobscot River

GreatWorks

Dam

• PRRP

• Balancing hydropower with sea-run fishes

• Dam removal in main-stem

• Power-generation increases

INTRODUCTIONMarsh Island hydropower complex

Gilman Falls

Stillwater Dam

Orono Dam

Veazie Dam

Milford Dam

INTRODUCTIONObjectives• Passage path and survival through Marsh

Island complex

• Relations between discharge, path choice, and survival

METHODSAcoustic array

• ~ 200 receivers

• > 250 km coverage

• > 2000 smolts tagged since 2005

• Cooperative effort between:

• USGS• UMO• NOAA

METHODS

• Survival (Φ)

• Detection probability (p)

• State-transition probabilities (ψ)

Multi-state acoustic survival models

MethodsPath choice at Stillwater: individual-based model

Stillwater Penobscot“1” “0”

RESULTSPath choice at Stillwater from MS models

Hatchery

Wild

~ 12 %

RESULTSUse of Stillwater Branch vs. discharge

RESULTSAcoustic Survival

• Survival lowest at Milford

• Survival through Stillwater Branch higher than main-stem

• Survival at Veazie & Great Works high prior to dam removal

Free flowing

Regulatory std.

0.91 ± 0.02

0.98 ± 0.02

0.99 ± 0.00

0.97 ± 0.02

1.00 ± 0.00

1.00 ± 0.00

RESULTSSurvival at Milford Dam vs. discharge

Free flowing

Regulatory std.

• ψStillwater : low

• ΦMilford : low

• ΦVeazie ,ΦGreat Works: high

• ΦStillwater ,ΦOrono : high

• ψStillwater ,ΦMilford: with flow

DISCUSSIONMain findings

1.00

.97

DISCUSSIONRelative risks prior to changes

.91

.96

25-(0.97 * 1.00 * 25) = 0.75

6-(0.97 * 1.00 * 6 )= 0.18

<1% contributed by Stillwater dams

94-(0.91 * 0.98 * 94) = 10.17

75-(0.91 * 0.98 * 75) = 8.11

N = 100 75 - 94%6 - 25%

25-(0.97 * 1.00 * 25) = 0.75

6-(0.97 * 1.00 * 6 )= 0.18

94-(0.91 * 0.99 * 94) = 9.3

75-(0.91 * 0.99 * 75) = 7.4

.98.99

94-(0.91 * 0.99 * 94) = 9.3

75-(0.91 * 0.99 * 75) = 7.4

25-(0.96 * 0.96 * 25) = 1.96

6-(0.96 * 0.96* 6 )= 0.47

8 –10% contributedby main-stem dams7 – 9% contributedby main-stem dams

9-11% Loss through complex

8-10% Loss through complex

~2% contributed by Stillwater dams

9-11% Loss through complex

.96

94-(0.91 * 0.99 * 94) = 10.17

75-(0.91 * 0.99 * 75) = 7.4

.92.93.94.95.96

94-(0.92 * 0.99 * 94) = 8.38

75-(0.92 * 0.99 * 75) = 6.69

94-(0.93 * 0.99 * 94) = 7.45

75-(0.93 * 0.99 * 75) = 5.9

94-(0.94 * 0.99* 94) = 6.52

75-(0.94 * 0.99 * 75) = 5.2

94-(0.95 * 0.99 * 94) = 5.59

75-(0.95* 0.99 * 75) = 4.46

94-(0.96 * 0.99 * 94) = 4.66

75-(0.96* 0.99 * 75) = 3.72

7 – 8% contributedby main-stem dams5 – 7% contributedby main-stem dams

9-10% Loss through complex

7-9% Loss through complex

7-9% Loss through complex

5 – 7% contributedby main-stem dams4 – 6% contributedby main-stem dams

6-8% Loss through complex

4 – 5% contributedby main-stem dams

6-7% Loss through complex

DISCUSSIONSummary

• Restoration is species-specific and life-stage specific.

• Dam removal will have little effect on smolt survival, other species benefit greatly

• Opportunity for improving passage at Milford Dam

• Potential sub-lethal effects of Veazie & Great Works in estuary

• Future uncertainty in passage through Stillwater Branch

ACKNOWLEDGMENTSLogistic & technical support:

Alia Al-Humaidhi, Matthew Altenritter, Megan Altenritter, Dan Anderson, Wesley Ashe, Charlie Baeder, John Beeman, Kevin Bernier, Brandon Capron, Matthew Dzaugis, Kevin Gallant, Graham Goullete, Graham Griffin, Ann Grote, Jim Hawkes, Ed Hughes, Chris Introne, Betsy Irish, Mike Kinnison, Ian Kiraly, John Kocik, Kevin Lachapelle, Phillip Lung, George Maynard, Andrew O’Malley, Ana Rapp, Silas Ratten, Chip Reier, Margo Relford, Peter Ruksznis, Doug Sigourney, Chandler Smith, Randy Spencer, Erin Snook, Steve Stich, Haley Vieman, Trevor Violette, Matthew Wegener, Gayle Zydlewski, Orion Zydlewski

Financial support:American Recovery and Reinvestment ActBrookfield Renewable Power (Great Lakes Hydro America)National Oceanic and Atmospheric AdministrationPenobscot Indian NationPenobscot River Restoration TrustUniversity of MaineUnited States Geological Survey