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Overexploitation
Tokyo Tuna Market
Types of Overexploitation
• Commercial exploitation
• Subsistence exploitation
• Recreational exploitation
• Incidental exploitation
• Indirect exploitation
• Pet and garden market
Commercial exploitation• Potential market for wild products is enormous
• Given market, people will exploit wild species for financial gain
• Domestic substitutes for wild products are not identical in value
• Market price for wild products increases as product becomes rarer
• Wild resources are communal resources owned by no one or everyone
Morel Mushrooms for Sale
Coral harvested for jewelry
Rhinoceros exploitation
Rhino hornProducts – Dagger marketin Yemen
Rhino Horn in Traditional Medicine
Wild Blueberries
Wild Salmon
Egret plumes and feathered hat
Tragedy of the Commons
Japanese Whaling Ships
Subsistence exploitation
Subsistence Fishing
Ojibway wild rice harvesting
Recreational exploitation
Hunting as Recreation
Shell Collection
Gordon Alcorn
Photographic safari
Cheetah on Land Rover
Dive boat damage to coral reefs
Incidental exploitation
Trawling
Kemp’s Ridley Sea Turtle
Shrimp net with TED – turtle exclusion device
Indirect exploitation
Overgrazing
Domestic cats preying on small birds
Pet and Garden Market
Gray Parrots in Smuggler’s Crate
Tropical Fish for Aquarium Trade
Cactus Market
Saguaro Cactus
Consequences of Overexploitation
1. Population Effects
- Reduction in population size
- Age structure
- Sex ratio
- Genetic structure
2. Ecosystem Effects
Age Structure: A – fish in typical populationB – fish taken by fishing
Sex Ratios – The Fisher
Fisher Distribution
Genetic Structure – Coho Salmon
Genetic Structure – Coho Salmon
Ecosystem Structure – Loss of Large Trees
Giant Redwood
Redwood Forest in the Air
Planting Sequoias
Ecosystem Structure – Loss of Snags
Loss of Keystone Species - Sea Otter with Sea Urchin
Loss of Keystone Species - Glyptodont
Maclura pomifera – Osage Orange
Exotic Species
Mrs. Black Horse, Cheyenne Nation, and dog travois
American Chestnut
Cracking From Chestnut Blight
Exotic Species
• Conservation biologists typically call introduced species “exotic species” - species which live outside their natural range
• Botanists typically refer to exotic plants as alien species
• Other terms you may see include biological invaders, introduced species, invasive species, non-indigenous species, non-native species (my preferred term)
How Do Exotic Species Get Dispersed?
1. Stowaways
2. Subsistence and Commerce
3. Recreation
4. Whimsy or aesthetics
5. Science
6. Biological Control
Norway Rat as ship rat
Earthworms and pre-exotic distribution
Lumbricus terrestris
Cars transport seeds via mud stuck to car
Ballast Water Discharge
Commerce and Subsistence
Commerce and Subsistence
Monterey Pine
Blue Gum Eucalyptus
Feral Pig - Florida
Bighead Carp
Carp Jumping
Recreation - Brown Trout
Ring-necked Pheasant
Chukar
Red Deer – New Zealand
Whimsy or Aesthetics – European Starling
House Sparrow
Exotic plants in New Zealand
• Native flora of 2065 species
• 24,774 documented introduced alien species
• About 2200 exotics have become established (naturalized)
Multiflora Rose
Tree of Heaven - Ailanthus
Light blue – counties where Ailanthus is present
Scotch Broom
Walking Catfish
Cherry Headed Conures in San Francisco
Monk Parrots – Chicago, Harold Washington Park and Hyde Park
Science - Gypsy Moth
Africanized Honey Bees
Movement of Africanized Honey Bees
Movement of Africanized Honey Bees
Biocontrol
Klamath Weed – aka – St. John’s Wort
Chrysolina beetle
Prickly Pear Hedge - Tunisia
Prickly pear in Australia – before control
Cactoblastis cactorum
Prickly pear – same location after control
Red Fox - Australia
With native Bobuck possum
Red fox - Australia