AQUATIC EXOTICS
1
Exxon Valdez Oil Spill
Valdez, Alaska 1989
2
“By the end of the 21st century,
biological invasions will
become one of the most
prominent ecological
issues on Earth.”
OTA Report (1993)
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OTA Report
• > 4,500 species established
• > 205 species arrived since 1980
• 59 might cause damage
• Control costs will approach $100 billion
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Infestations Are Increasing
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Interrupt the Pathways
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

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Shipping and barge traffic
Aquaculture and public stocking
Wild bait harvest
Recreational boats
Live bait
Nursery trade and aquascaping
Aquarium and pet trade
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Great Lakes Exotics
•
•
•
•
•
Purple loosestrife
Zebra mussel
Quagga mussel
Spiny waterflea
Fishhook waterflea
•
•
•
•
Eurasian ruffe
Round goby
Alewife
Trout and salmon
7
Where Did They Come From?
Eurasia
Atlantic
Asia
Mississippi
Pacific/Southern U.S.
Unknown
Total:
(data taken from Mills et al. 1993)
77
18
12
7
7
18
139
8
How Did They Get Here?
Ships
Unintentional release
Multiple
Unknown
Deliberate release
Canals
Railroad/Highway
41
40
27
14
11
5
1
9
What Are They?
Plants (mostly marsh)
Invertebrates
Fish
Algae
Fish pathogens
% of Species
42
21
18
17
2
10
Why Do Exotics
Cause Problems?
 Aggressive
 Mature
and prolific
quickly
 Leave
behind diseases,
parasites, predators, and
competitors
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The Good
The Bad
The Ugly
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The Good
13
The Bad
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Adult
Veliger
Can produce up to 1.6 M eggs/yr!
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Zebra mussel colony
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Byssal
threads
17
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Impacts of Zebra Mussels
•
•
Feed by filtering particles from water
Each adult can filter 1 L water/day
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Impacts of Zebra Mussels
•
•
Increase weed growth
Disrupt food webs
20
Impacts of Zebra Mussels
Fouled boat
Clogged pipe
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Impacts of Zebra Mussels

Control costs in the Great Lakes = $120 million
from 1989 - 1994
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Impacts of Zebra Mussels
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Zebra Mussel
Distribution
 Spread as larvae
and adults
 Only 10 states
with inland
infested waters
(WI, MI, MN, PA, IL, IN, OH, NY, CT, VT)
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Quagga
Mussel
Distribution
 Lakes Erie, Ontario
and Michigan
 Ohio and
Mississippi rivers
(WI, MI, IL, IN, OH, NY, CT, VT)
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ID and Early Detection

Newly settled mussels feel like fine sand paper

Grow to look like coarse grains of pepper
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
Cause serious damage

Industrial control is costly

No method of control in natural ecosystems

Preventing the spread is critical
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Rusty Crayfish
•
•
•
•
Replaces native crayfish
Competes with fish
Raids fish nests
Eradicates aquatic plants
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U.S. Distribution
Drainages with native populations
Drainages with introduced populations
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Rusty Crayfish Spread
•
•
•
•
Anglers and commercial harvesters
Ballast water
Biological supply houses & schools
Life history facilitates spread
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Rusty Crayfish ID
• Can grow up to 8 in
• Rust spots on carapace
• Large gray-green/red-brown claws
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Rusty Crayfish
• No environmentally-friendly control method
• Preventing the spread is critical
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Round Goby
• Small, strange-looking bottom fish
• Came from Eurasia in ballast water
• Considered a nuisance by anglers
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Round Goby Impacts
mottled
sculpin
• Out-compete native species
• Quickly dominate local fisheries
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Round Goby Impacts
• Feed on lake trout and sturgeon eggs
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Round Goby Identification
• Fused pelvic fins
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Eurasian Watermilfoil
• Forms dense mats
• Replaces native plants
• Degrades food, shelter, and nesting sites for fish
• Limits swimming and boating
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Eurasian Watermilfoil
• Spreads by fragmentation
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Eurasian Watermilfoil
• Can be spread by recreational water users
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U.S. Distribution
Adapted 1999 from
USGS-Gainesville
States with nonnative records
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Optimistic News
• Traditional control methods costly
• Native weevil feeds on Eurasian watermilfoil
– Can cause stems to fall to lake bottom
– Reduces canopy
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Spiny Waterflea

Predaceous zooplankton

Causes declines in native zooplankton
– May impact fisheries
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45
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Fishhook waterflea
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Eurasian Ruffe
• Arrived in mid 1980s via ballast water
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Eurasian Ruffe
• Spawn 2 – 3 times/season
• Mature rapidly
• Feed during day and night
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Eurasian Ruffe Impacts
• May compete with yellow perch
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Predicted impacts of
Great Lakes-wide infestation is
estimated at $105 million annually
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*
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White Perch
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•
•
•
Native to Atlantic coast
Found in all Great Lakes
Feed on zooplankton, invertebrates, and fish
Prefer shallow areas
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White Perch
white perch
white bass
• Easily confused with native white bass
• Transported to several inland lakes in Ohio
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White Perch
• Can grow up to 10” long
• Commonly stunted and undesired by anglers
• Can have high levels of PCBs
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Threespine Stickleback
• Native to Hudson Bay, the Atlantic coast, and Lake
Ontario
• Spread to lakes Superior, Michigan, and Huron
• Little known about potential impacts
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Threespine
Stickleback
Fourspine
Stickleback
• May compete with native sticklebacks
• 3 or 4 spines on dorsal fin, respectively
– Native sticklebacks have 5 or more spines
on dorsal fin
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Purple Loosestrife
• Perennial from Europe
• Invades moist areas
• Crowds out natives—reduces biodiversity
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U.S. Distribution
Adapted 1999 from
Biological Invasions by GLP
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Good News!!
• 5 species approved for release
• Galerucella weevil
– Feeds on leaves and growing shoots
– Defoliates, reduces flowering, can kill plant
• Releases could reduce loosestrife by 80-90%
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We can
make a
difference!
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Three-State
Exotic Species Boater Survey
• How best to reach boaters
• Determine if boaters taking action
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Source For Exotics Information
Minn
•
•
•
•
Newspaper
Television
Magazine
Boat Launch
92
90
75
82
Wisc
Ohio
81
79
67
55
84
73
74
32
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How Effective Are The Following?
Minn
Wisc
Ohio
77
63
61
63
62
60
57
52
50
59
58
48
53
48
41
29
34
24
Highest Ranked
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•
•
•
Signs at Accesses
In Fish/Boat Regs
Brochures
Inspection/Ed
Lowest Ranked
• Laws
• Road Checks
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What Influenced You Most?
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•
•
•
Out of “My” Lake
Personal Responsibility
Signs at Access
Prevent Property Damage
Minn
Wisc
Ohio
88
82
68
38
74
63
47
43
63
56
31
55
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Why Didn’t You Take Precautions?
Not a Problem
Didn’t Boat in
Infested Waters
Didn’t Know
What To Do
Ohio
Wisc
Minn
Didn’t Have
Time
It Won’t Help
0
10
20
30
Percent response
40
50
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What Works?
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Survey Conclusions
• Boater education changes behavior
• Boaters believe it is important to prevent the
spread of aquatic exotics
• Best information outlets are media, access signs,
brochures, fishing and boating pamphlets
• Educational efforts must continue
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Education Works

Rate of inland lake zebra mussel infestations is slowing

Eurasian watermilfoil infestation rate has slowed

Eurasian ruffe have not spread to inland lakes

Round goby spread to inland waters is limited
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Prevent the Spread
• Know how to identify exotics
• Know which waters are infested
• Know the laws concerning prohibited exotics
• Learn the five simple steps to prevent spread
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Prevent the Spread
BEFORE launching….. BEFORE leaving
1. Remove aquatic plants and animals.
2. Drain lake or river water.
3. Dispose of unwanted live bait.
4. Rinse equipment with high pressure or 104 F water.
OR
5. Dry everything for at least 5 days.
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Written and produced by
Doug Jensen and Jeff Gunderson
2001
With support from:
Editors: Glenn Kreag, Sharon Moen, Marie Zhuikov, and Pat Charlebois
Digital Production Coordinator: Debbie Bowen
Funding for this project was provided by a grant from
the U.S. National Oceanic Administration to the
National Sea Grant College Program through an
appropriation by Congress based on the National
Invasive Species Act of 1996.
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