Sustainable Harvesting Flashcards
What is sustainable harvesting?
The largest amount of harvest activity that can occur without degrading the productivity of the stock.
What factors need to be considered to enable sustainable harvesting?
- Population size
- Precision of population estimate
- Rate of population increase
- Rate of harvesting
- Ethics
How is population size measured?
It is measure differently to each species based on distribution, abundance, density (unit/area), and dispersion.
Describe ‘distribution’ in relation to population size.
Where the things are, it is dimensionless and important for conservation and disease control.
Describe ‘abundance’ in relation to population size.
How many things there are, important for conservation, species management, disease. Needed in conjunction with distribution.
Describe ‘dispersion’ in relation to population size.
How clumped the organisms are.
Describe ‘Density’ in relation to population size.
Quantification taking into consideration dispersion.
How do you estimate the change in population size?
Future population size = Current size + #Births - #Deaths.
What affects both birth and death rates?
demography, survivor-ship, and life history strategies.
What is the life history of an organism?
“How a species lives it’s life”
- Description of when an organisms reproduces
- How many offspring it makes
- How much investment in offspring
- How many times it reproduces
What is semelparity?
An organism that puts a big investment into quality of offspring rather than number. (The focus is on quality)
What is iteroparity?
When an organism puts less of an investment into the offspring but has more rounds. (The focus is on number)
What defines an equilibrial species?
They reproduce late in life and live for a long time, mortality rates are low, iteroparous (High investment in a few offspring), and often extensive parental care.
What defines an opportunistic species?
The reproduce early, live fast and die young, mortality rates are high, semelparous (Low investment in each offspring but lots of offspring).
What environments select for opportunistic life histories?
Environments that experience frequent environmental disturbance (ie. removal, floods, fires)
