Species
A term for a species which other species depend on and their importance is disproportionately related to their biomass
What is a Keystone Species?
A term for a species that provides high reproductive output that supports a top predator
What is a Keystone Prey Species?
Give an example of a Keystone Species
Gopher Tortoise, Sea otter, Wolves in yellowstone, Pistaster.
the name of a model that assumes..
1. that fish are density dependent
2. that fish are equal
3. that extraction of fish is evolutionary neutral
What is the Economic Fishing Model?
On a cost benefit graph: The rational maximum harvest will always be to the ______ of the maximum sustainable yield in a private fishery
Left
A term for a species that when protected, indirectly protects other species.
What is an Umbrella Species?
A term for a species that benefit other organisms by providing a mutualistic relationship. Without them, ecosystem composition would change drastically.
What is a Keystone Mutualist?
Give an example of an umbrella species
Florida Scrub Jay
Grizzly Bears
What happened to the Atlantic Cod?
Overfishing led to a decrease in the population's large breeding females, which resulted in a decrease of fitness and population fecundity.
Impossible for fish to recover due to slow growing rate
Over-predation of seals led to decrease in population size
Warming temperatures and lack of cod to migrate caused respiratory stress and death in fish
Where fishing is unregulated... fishers will fish where ____=_____
Marginal cost= marginal benefit
A term for a group of species that serve as an umbrella
What is a Focal Species?
A term for a species that creates a habitat that many other organisms depend on.
What is a Keystone Modifier?
Give an example of a Focal Species
Sharks and Rays
Amphibians
Fishery Models must include (2 things)
Economic component
based on biological science
Looking at a cost vs benefit graph: Fishing at the point of marginal cost and marginal benefit results in a profit to the ______of the maximum sustainable yield. This is VERY UNSUSTAINABLE
Right
Characteristics of an Umbrella Species
Large
Wide home range
non-migratory (salmon exception)
Low temporal variation
Relatively abundant
Process limited
Characteristics of a Focal Species
Easy to census
Economically important
Represent diversity of lifeforms
Give an example of a Keystone Modifier
Gopher Tortoise: make holes that other species use such as snakes and mice to escape fires
Beavers: make dams suitable for small fish, growing organisms
What is the problem with fisheries?
Majority are not owned. No regulation of fishing or biomass of fish caught. Leads to over-fishing and over-exploitation of fish.
Needs to establish ownership to enforce these management techniques for more sustainable fishing
Lack of ownership= commons: used by all and owned by no one
What is the problem with a Keystone Species Conservation Concept?
If ecosystems are driven by a few keystone species, then failure to maintain them would result in a failed conservation strategy.
Preservation of a keystone species may be dependent on abundance of other species. Removal of such a species could cause a top-down cascade event. Unpredicatable to what trophic level it will effect.
What is the problem with a Focal Species Conservation Concept?
Megafauna are not the most informative species. May end up working with a species that no one cares about. Hard to obtain public interest.
More costly than an Umbrella concept
Unreasonable number of species needed in a complex system.
What is the problem with an Umbrella Species Conservation Concept?
Easy to choose the wrong species. Important to get a species that encompasses a wide range of habitat in hopes highest number of species protected within in. But habitat chosen may not be suitable for most.
Example: A habitat suitable for a bear may not be suitable for butterflies. Protection is limited
What is the problem with the Economic Fishery Model?
1. fish are not density dependent, they are recruitment limited
2. Fish are not equal, Larger fish have higher fitness/fecundity than smaller fish
3. Extracting large fish from a population leads to a decrease in fish populations, selective pressure on population that leads to smaller fish.