Freeing the Elwha (Salmon Farming; A Potential, But Not Ideal Solution)
OverviewSalmon farms seem like an ideal solution for helping wild salmon and increasing the worldwide demand for salmon production, what are the problems associated with salmon farming and are there ways of solving these problems?
This lesson focuses on the economic and ecological values and costs of salmon farming. Salmon farms have been seen by many as an opportunity to help wild salmon runs, by producing fish to meet increased worldwide demand for salmon and taking some of the pressures off wild salmon by commercial fisheries. However, salmon farms have developed several serious ecological and economic problems that must be addressed. Escaped salmon from farms represent competition for food resources and spawning grounds. Their dense populations are susceptible to disease outbreaks and parasite infestations. Their food contains high concentrations of chemicals such as PCB's and mercury which bioaccumulate in their bodies and contaminate the nearby environments.
- Aquaculture- Raising aquatic organisms in contained units for the purpose of producing marketable products. This can include algae, shrimp, oysters, fish, and others.
- Parasite- An organism that feeds on another organism, causing long-term harm to the host without generally killing it.
- Eutrophic- An ecosystem containing high levels of nutrients and therefore supporting high productivity. However, an overly eutrophic environment can result in algal blooms that cause the waters to become deficient in oxygen through the bacterial consumption of dying algae. These anoxic aquatic environments can then become dead zones to all but algae.
- Bioaccumulation- The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism. Bioaccumulation takes place within an organism when the rate of intake of a substance is greater than the rate of excretion or metabolic transformation of that substance
- Biomagnification- The increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain. As a result of biomagnification, organisms at the top of the food chain generally suffer greater harm from a persistent toxin or pollutant than those at lower levels.
- Lesson 19- Salmon Farming.pptx
- Fisheries Management Paper.pdf
- Reflection Journal pages (printable handouts)
- Vocabulary Notes (printable handouts)
Review Essential Question; introduce Guiding Question.
Hand out the Vocabulary Notes. With this lesson you may want to define the words before presenting the PowerPoint Lesson.
Read: Articles on natural/organic fish farms, aquaponics/self-contained farms, etc.
Fisheries Management Paper.pdf