Transcript What are fungi?

Great Lakes Fisheries
Presented by:
Dr. Randal J. Snyder
Associate Professor
Buffalo State College
[email protected]
Key Factors: Overfishing
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Peak harvests in late 1800’s were nearly 150 million pounds;
only 63 million today
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Lack of management, improved fishing gear, other stressors
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Key species: lake trout, sturgeon, Atlantic salmon, blue pike,
whitefish, walleye, yellow perch
Key Factors: Habitat Destruction
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European settlement and urbanization
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Deforestation: loss of cover, sedimentation, increased
stream temperatures
Drainage of wetlands: loss of nursery habitat
Dams: block migration routes
Loss of habitat greatly impacted
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Lake sturgeon in Lake Erie
Atlantic salmon in Lake Ontario
Key Factors: Eutrophication
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Cultural eutrophication: accelerated
input of nutrients (esp. phosphates)
into waterways, decreased
dissolved oxygen
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Fertilizers
Detergents
Water treatment plants
“Lake Erie is dead” in the 1960’s
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Canada and US: Great Lakes
Water Quality Agreement in
1972
Phosphorus reductions very
successful
Key Factors: Toxic Pollutants
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Increased use of synthetic organic chemicals since 1940’s –
persistent in the environment
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Dangers first evident with pesticide DDT
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Increased risk of cancer, birth defects, genetic mutation
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Fish consumption advisories
Key Factors: Invasive Species
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Canals (Welland, Erie) and ballast water
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Notable invaders: sea lamprey, carp, smelt, alewives, Pacific
salmon, round gobies, zebra mussels
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Significant effects possible
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Displace native species
Reduce biodiversity
Alter established ecosystems
Costs to industry
Sea lamprey
Round Goby
Smelt and Alewife
Zebra mussels
Current Status of Great Lakes Fish Communities
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Current fish communities are very different from
historical communities!
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Native top predators such as Atlantic salmon and
Lake trout replaced by introduced Pacific salmon
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Supported by hatcheries and stocking
Native prey species such as lake herring and
bloaters replaced by exotic rainbow smelt and
alewife
Lake trout
Lake herring
Current Commercial Fisheries in the Great Lakes
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Commercial fishing has declined significantly since
its peak in the 1940’s and 1950’s
Important current species include
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Walleye
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Yellow perch
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Lake whitefish
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Rainbow smelt
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Alewife (for animal feed)
Walleye
Commercial fishing limited by toxic contaminants and
pressure from recreational fishing interests
Current Recreational Fisheries in the Great Lakes
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Recreational or sport fishing has become very
valuable in the Great Lakes region
Important species include
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Pacific salmon (coho and chinook)
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Walleye
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Yellow perch
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Largemouth and smallmouth bass
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Northern pike and muskie
Muskie
Smallmouth bass
Chinook salmon
The Alewife and Pacific Salmon
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Two exotic species in the Great Lakes that have had
huge impacts
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Pacific salmon (coho and chinook) introduced in
Lake Michigan in 1960’s to control alewives
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World-class pacific salmon fishery developed, but
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Relies on continued stocking of salmon
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Contaminants in salmon
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Dependent upon an exotic species, the alewife
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Obstacle to restoration of native species?
Alewife
Alewife die-off!
Coho salmon
The Round Goby – Our Newest Exotic Fish Invader
• Small fish: 4 - 10 in. with
fused pelvic fin
• Native to Europe
• Ballast water introduction
around 1990
• Has spread rapidly, very
aggressive and tolerant
• Competes with native
species (especially
sculpins), may eat fish eggs
• Good bait for bass, may
have contributed to spread!
Sea Lamprey
Most destructive
invasive species in
Great Lakes history
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Native to Atlantic Ocean
and Lake Ontario
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Spread throughout Great
Lakes via canals by 1947
– major declines in Lake
trout
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One adult lamprey
consumes 20-30 lbs of
fish in its lifetime
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Sea lamprey populations
reduced by 90% by
control programs –
expensive!
The Future of Great Lakes Fisheries
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Overall health of fish communities slowly improving
over time
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Habitat protection and restoration
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Reduction in pollutants
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Better management
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Restoration of native species (Lake trout, Atlantic
salmon, Lake sturgeon)
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Challenges remain
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Fish consumption advisories
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Exotic species
Lake Sturgeon
Great Lakes fishes are a valuable resource
for current and future generations!