This weekend I went on a field trip to the Bonneville
Dam. It was for marine biology, so
instead of focusing on generating power, we focused on how they engineered it
to have less impact on the salmon populations.
Fish ladders are more complicated than creating a series of pools that
salmon can jump between. The fish also
need areas where they can rest. If the
water flow is too turbulent or fast the fish won’t be able to rest enough to
finish their journey. Their solution is
basically to make a maze to slow down the water and allow for resting areas
partway up the fish ladder.
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| A steelhead taking a break |
If you’re interested in seeing migrating salmon (or
steelheads or lampreys), take a trip to Bonneville Dam during
September-October. We were at the latter
end of the migration and on a slow day because of the weather, but we still saw
dozens of salmon. The visitor center has
underwater viewing stations so you can see the fish as they rest in the “maze”
after moving up the ladder.
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| An angry salmon wanting to go in a closed gate |
To try to increase salmon numbers, there’s also a fish
hatchery. I was amazed at the number of
fish they had, but salmon mortality rates are very high so having thousands of
baby fish makes sense because so many will be eaten before they grow up. In addition to the salmon, they also have
some really huge white sturgeon and a few trout ponds where you can feed the
fish. It was a really cool trip and it was fun to do some learning outside of the classroom. I recommend it as a weekend activity if you have any interest in learning about salmon or the local biology
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| A huge sturgeon |
If you have any questions, feel free to email me at
ameliaberle@lclark.edu