Ecosystems Out of Balance

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Activity 16: Ecosystems Out of Balance Get Started  What do you think population levels would look like if you graphed them for an ecosystem that had no pressure from fisheries?

Activity 16: Ecosystems Out of Balance Get Started  What do you expect to happen to the graph if an important species within the ecosystem were overfished?  If the fishery were sustainable, would you expect the same results?

Activity 16: Ecosystems Out of Balance Pacific Halibut Population

Activity 16: Ecosystems Out of Balance Pacific Halibut Food Chain

Activity 16: Ecosystems Out of Balance Pacific-halibut-dominated Ecosystem

Activity 16: Ecosystems Out of Balance Introduction  Based on what you have seen, do you think this is a sustainable fishery? What indicators are you looking at to determine this? Read the introduction.

Activity 16: Ecosystems Out of Balance Introduction  What would you expect to be different on a population graph for an ecosystem of a fishery that is not sustainable?

Activity 16: Ecosystems Out of Balance  How does information about relationships among organisms help to determine the sustainability of a species and an ecosystem? Challenge

Activity 16: Ecosystems Out of Balance Procedure  As you analyze the graphs, start with the population that is being fished, then work up or down the food chain.  Pay close attention to any factors in Part B that might influence population levels.

Activity 16: Ecosystems Out of Balance Procedure  What else might cause these population changes besides overfishing?

Activity 16: Ecosystems Out of Balance Follow Up  Why do you think that the practices used by the Pacific halibut fishery are not followed by all other fisheries?

Activity 16: Ecosystems Out of Balance Follow Up  Would it change your answer if you knew that the Pacific halibut fishery operates near shore, and only in the United States and Canada?

Activity 16: Ecosystems Out of Balance  Choose one of the four ecosystems, and in your role as a fisheries scientist, explain to the people who run the fishery what you think is happening in the ecosystem. Citing evidence from the graph and from the history of the fishery, write a summary that explains what is happening in the ecosystem. Include in your summary: ◦ A. your explanation of whether you think the fishery is sustainable ◦ B. what changes in the ecosystem indicate that the fishery is or is not sustainable ◦ C. how the overall biodiversity of the ecosystem has been affected ◦ D. what advice you would provide about making the fishery sustainable, based on the other fisheries in this activity. Analysis 5

Activity 16: Ecosystems Out of Balance  How does information about relationships among organisms help to determine the sustainability of a species and an ecosystem? Revisit the Challenge

Activity 16: Ecosystems Out of Balance  fishery  invasive species  population  population growth rate  sustainability Key Vocabulary