Download Control and Eradication of Invasive Northern Pike in Southcentral Alaska

15th Annual Invasive Species Workshop
Control and Eradication of Invasive Northern Pike in Southcentral Alaska
Kristine Dunker, Alaska Department of Fish and Game, Division of Sport Fish
Northern pike are an invasive species in Southcentral Alaska. Illegal introductions of northern pike began
in the Upper Susitna drainage in the late 1950s. Subsequent expansion coupled with continued illegal
introductions have resulted in the widespread distribution of northern pike from the Matanuska-Susitna
Valley to the Kenai Peninsula. Northern pike are highly piscivorous and reduce ecologically and
economically valuable salmonid populations throughout Southcentral Alaska.
The Alaska Department of Fish and Game has taken an adaptive management approach with northern
pike. Protocols chosen for control activities in a water body are dependent on its unique conditions.
Northern pike control efforts have included liberalized harvest, increased outreach, fish passage
barriers, gillnetting operations and piscicide applications. Piscicide applications are conducted to
eradicate northern pike populations, restore fisheries and prevent northern pike from spreading.
Recently, ADF&G began an annual large-scale gillnetting project to control northern pike in Alexander
Creek, a tributary of the Susitna River, where some of the worst fishery losses have occurred. ADF&G
also conducts research on northern pike movement patterns, diet and bioenergetics, effective control
methods and detection methods such as eDNA. All control, eradication and research projects are
directed by the Management Plan for Invasive Northern Pike and prioritized through a strategic planning
process.
Northern Pike Control in Southcentral Alaska
Photo by Jim Lavakras, Compliments of ADN
Kristine J. Dunker
Northern Pike Control Committee
Alaska Department of Fish and Game
Division of Sport Fish
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Northern Pike
Esox lucius
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Range of Northern Pike in Alaska
Native Range
Introduced Areas
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Pleistocene Glaciers in Alaska
85,000 – 11,000 years ago
Image Credit: Kaufman and Manley, 2004
Northern
Pike
Dispersal in
Southcentral
Alaska
Bulchitna Lake
1950s – 1960s
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Northern
Pike
Dispersal in
Southcentral
Alaska
1970s
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Northern
Pike
Dispersal in
Southcentral
Alaska
1980s
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Northern
Pike
Dispersal in
Southcentral
Alaska
1990s
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Northern
Pike
Dispersal in
Southcentral
Alaska
2000s
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Current
Northern Pike
Distribution
in
Southcentral
Alaska
> 120 water bodies with
invasive pike
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Northern Pike Habitat
Alexander Lake
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Ecological Concerns
• Apex predators
• Sit-and-Wait Ambush
predation
•Opportunistic Feeders
•Primarily piscivorous
•Habitat overlap with
rearing salmonids
•Fishery declines
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Economic Concerns
Pike predation 
• Reduce productivity
of wild stocks
•Discontinue
hatchery stockings
Commercial
•Threatens an
industry valued at ~
$1 Billion
Recreational
Subsistence
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ADF&G Has Aggressively Worked
to Control Invasive Northern Pike
•
•
•
•
Educating the public
Identifying distribution
Liberalizing harvest
Implementing control and
eradication actions
Control Netting
Rotenone Treatments
for Eradication
Outreach
Public Outreach





Education
Brochures
Web sites
PSAs
Fishing DVD
Message: Northern pike are
invasive in Soutchentral.
Illegal stocking has negative
consequences.
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Legal Ramifications
Penalty
• Class A misdemeanor
• Restitution for damages
AS 16.35.210 (c)
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Increase Sport Harvest
Sport Fish Regulations
• No possession limit
• Multiple harvest methods
• Spear, bow, 5 lines (ice)
• Illegal to release pike alive
in NCI waters
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Research
• Distribution
• Habitat utilization
• Diet analysis
• Movement patterns
• Control methods
• Detection methods
•eDNA
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Northern Pike Control
Gill Netting
Purposes:
•Detect presence
•Monitor populations
•Targeted control
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Northern Pike Eradication
Rotenone
Rotenone treatment of Union Lake, Kenai Peninsula, 2014
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Invasive Northern Pike Management Plan
ADF&G Mission: Protect the fish and game resources of the state,
and manage their use in the best interest of Alaskans
Plan Objectives:
 Increase public awareness
 Prevent future introductions
 Public processes to gain support
 Pike control / eradication
 Improve fish populations
 Restore fisheries
The current plan is under revision and will be out for review in 201521
Strategic Planning
Developed Scoring Matrix in 2010
•Criteria based on:
•Threats to fisheries
•Habitat significance
•Watershed characterization
•Cultural significance
•Economic impacts
•Feasibility
Pike committee meets every two years to update the
priority list
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Strategic Planning (2010-2014)
ADF&G Sport Fish Division Priority Projects:
1. Alexander Creek Pike Control
2. Cottonwood Creek Drainage Pike Suppression
3. Soldotna Creek Northern Pike Eradication – Phase 1
4. Soldotna Creek Northern Pike Eradication – Phase 2
5. Stormy Lake Northern Pike Eradication
6. Otter Lake Northern Pike Eradication
7. Cabin and Nancy Lake Pike Suppression
8. Kenai eDNA Research
9. Lower Fire Lake Pike Eradication
10. Alexander Creek Northern Pike Movement Study
11. Knik, Prator, Memory, North Rolly, and Taniana Lakes Pike Eradication
12. Susitna Pike Movement and Diet Study
13. Tote Road Lake Pike Eradication
Estimated Total Program Cost: $5,325,000
14. Anchorage Lake Pike Assessment
Funds Received To Date:
$3,295,000
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Alexander Creek Pike Control
Top northern pike priority
•Susitna River tributary
•Very productive King fishery
prior to 2000
•Pike in the lake for decades
•Discovered in lower river in late
1990s
•9 lodges and float plane charters
operated there
•King numbers crashed
•Other systems were thriving
•All fisheries now closed
•All lodges and businesses closed
Alexander Creek Chinook Escapement
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Alexander Creek Pike Control
Side-Channel
Sloughs
Goal: Drive down pike abundance to
allow increased survival of rearing
salmonids
Side-Channel
Slough
• Reduce pike in side-channel sloughs with gillnets
• Began in 2011
• During pike spawning
• 3 Field crews target ~60 sloughs
• Annual effort (15,500 pike removed since 2011)
• Surveys to evaluate juvenile salmonid abundance
• Minnow trap surveys throughout open water
period
• Pike stomach content analysis
• USGS bioenergetics research
Gillnetting
Sloughs
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Alexander Creek Pike Control
Document Increase/ Decrease
in CPUE of Salmonids Between
Years and Study Sections
3
2
1
Alexander Creek Pike Control
7,000
Adult Chinook Salmon Returns
6,000
5,000
4,000
Escapement
Goal Range
3,000
2,000
1,000
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
0
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Alexander Creek Pike Control
• Radio telemetry to study pike movements between
Alexander Lake and Alexander Creek
High priority pike
control project
Aerial
Tracking
150 pike tagged
-125 in the lake
-25 in the creek
Creek pike overwinter in the lake
9 lake pike moved into the creek
• Alexander Lake
pike control would
be complex
• Can we accomplish
our goal focusing on
sloughs?
- All were caught in gillnets
Location of Radio Tagged Pike
Creek Pike
Lake Pike
• Yes, all pike that left
the lake were
Stationary
caught in gillnets
Receivers
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Rotenone
 One of only two proven methods for eradicating fish
 Comes from tropical plant roots
 Used in the U.S. since 1930s
 Inhibits cellular respiration
 Absorbed through gills
 Used in small concentrations
 Not harmful to mammals or birds
 Commonly used for fisheries
management throughout the world
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Permitting Process
 State Process:
 Obtain Alaska Board Of Fish approval
 Receive certification to apply pesticides
 Obtain a NPDES permit
 Obtain Alaska Pesticide Use Permit

Conduct a public process
 Federal Process:
 NEPA Review


Preparation of environmental assessments
Finding of No Significant Impact
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Project Preparation
• Bathymetric Surveys
• Water Quality Monitoring
• Biological Inventory
• Fish Removal, Donation,
and/ or Rescue
• Bioassays
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Rotenone Application
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Rotenone Projects
Cheney Lake - 2008
Arc Lake - 2008
• Small, closed lakes, formerly
stocked with rainbow trout
Sand Lake - 2009
Goals: Restore fisheries
Learn application techniques
Increase public awareness
Scout Lake - 2009 • Treatments were successful
• Fisheries restored
Stormy Lake Northern Pike Eradication
Stormy Lake - 2012
High priority pike eradication project
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Stormy Lake Rotenone Treatment
•Drainage = 240 square miles of
ideal northern pike habitat
•Coho productivity at risk
•Outlet stream blocked with fyke
nets for 10 years
•Native fish restoration
Stormy Lake
-Largest treatment to date (400 acres/ 50’ deep)
-Goal is to prevent pike from spreading to the Swanson
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Current Rotenone Projects
Otter Lake
Soldotna Creek
Both are high priority pike eradication projects
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Soldotna Creek Northern Pike Eradication
Treat Area One: Union, West and
East Mackey and Derks Lakes
and interconnecting streams
Then treat Area Two: Sevena
Lake, Tree Lake and Soldotna
Creek (creek treated 2X)
Temporary fish barriers
• First treatment in large, open system
•4 years to complete
Goal: Prevent pike from spreading to the
Moose River (where >40% of Kenai’s coho productivity occurs)
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Environmental DNA (eDNA)
Water samples can be used to detect aquatic species in low
abundance using DNA
Pike Study:
•eDNA marker development for pike
•Quantity of water for positive detection
•Detection at different distances
•Detection post-mortem
•Detection pre and post-rotenone
•Detection in open systems with and
without pike
Final high priority project that
is currently underway
Environmental DNA (eDNA)
Northern Pike
16 non-target species*
Baseline fluorescence
Ct = 45
Cytochrome oxidase 1 (EluCOI)
‘F-5’CCTTCCCCCGCATAAATAATATAA3’
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Preliminary Results
Pike Stocking
Sampling Locations Near Shore
40m
10m
1m
pike
Submerged
Cage
• Pike eDNA can be detected 40 m from source
• Detection probability increases closer to source
• Pike eDNA does not persist longer than 1 week
• More to come….
Post-mortem
Where Do We Go From Here?
• Update Management Plan
• Continue Prioritization
• Continue Education and Outreach
• Continue Eradication Efforts
• Continue Control Efforts
• Prevent Spread
• Protect Fisheries
Projects Funded By:
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