3.8 Lesson Name: Improve upstream survival around dams.

Returning adult salmon on the Columbia River must pass over several large hydroelectric dams on their way to the spawning grounds. Even though all dams have fish ladders to help salmon over the dams, some mortalities still occur. How much does improving upstream survival of adults increase spawning escapements?

Analysis Approach:

Prespawning mortalities are simulated in CRiSP Harvest by the IDL (inter-dam loss) parameters. The analysis approach is to record escapements for the Lyons Ferry stock under the default management strategy, change the future Lyons Ferry IDL parameters to simulate improved survival, re-run the model, and record the new escapement trend.

How To Do It:

1. Launch and run the model.
2. Set the Default Stock to Lyons Ferry.
3. Click the Stocks Menu.
4. Click Stocks Graph.
5. Click Escapements.
6. Record the trend and value in year 2017 (or print the graph).
7. Close the Escapement Graph.
8. Click the Stock/Inter Dam Loss button.
9. Select the tab with year 2000.
10. Click the "Y Box" at the top of the window.
11. Set the IDL value for year 2000 to .900. This will increase the prespawning survival rate for the Lyons Ferry stock to 90% for all simulation years.
12. Click apply and OK.
13. Click the Run button on the tool bar.
14. Repeat steps 3 through 6 to observe the new escapements.

1. Do you think it is more effective to improve survival near the end of a fishes life (e.g., prespawning survival rates) or at the beginning (e.g., brood year survival rates)?