Freeing the Elwha (Hatcheries, Saviors or Scourge for Wild Salmon?)
OverviewHatcheries seem like a good idea, but they are fraught with problems, how are hatcheries both a danger and a blessing to wild fish?
This lesson focuses on the history and roles that hatcheries serve in sustaining commercial fisheries, native fish populations, and saving endangered fish stocks. Hatcheries were historically a popular tool for propagating large numbers of fish for sustaining commercial fisheries, however, a series of problems have resulted in increasing controversies over their use. Some of the problems include the use of non-native stocks, the development of non-competitive behaviors, and over-stocking fish beyond the natural carrying capacity of the environment at the expense of wild native fish. However, as wild fish runs become threatened with extinction, hatcheries are also proving to be a valuable tool for saving these wild native runs.
- Hatchery: A facility used to rear juvenile fish for the purpose of stocking rivers or lakes, producing fish for commercial fishing activities, or restoring endangered fish populations.
- Carrying Capacity: The largest number of individuals an ecosystem can support, based on food availability, behaviors, and space limitations.
- Gene pool: The total number of genes of every individual in an interbreeding population. A large gene pool indicates high genetic diversity, increased chances of biological fitness, and survival. A small gene pool indicates low genetic diversity, reduced chances of acquiring biological fitness, and increased possibility of extinction.
- Lesson 17- Hatcheries, Saviors or Scourge for Wild Salmon.pptx
- Reflection Journal pages (printable handout)
- Vocabulary notes (printable handout)
- Hatcheries, Saviors or Scourge for Wild Salmon? Pro and con handout.
Review Essential Question; introduce Guiding Question.
Students should take a few minutes to respond to the first reflection prompts. Discuss their answers and any questions they've generated.
Some web articles on salmon hatcheries: