Salmon by Andy, Mason, and Marshall
Something's fishy here in Washington... it's salmon run time! Salmon are great swimmers. They're born in rivers and lakes, but they swim all the way to the ocean. They hang out there for 2-8 years. Then they return back home to lay eggs and die. That's their whole cycle. One hundred years ago, millions of Puget Sound salmon made this trip, but now only about 10% do it. This means their habitat may be in trouble, so we wondered if more salmon thrive in the Dewatto River or Union River?
What did we do?
We checked out three things to judge how healthy each river is. First, we counted the number of live salmon we saw on a half-mile stretch of each river. Then we weighed and measured five fish in three different places along the rivers. Lots of large growing salmon are a good sign. Another good sign is dead adult fish, believe it or not. If we see lots of dead fish, that means the salmon made it back from the ocean. Plus, their bodies make food for the young fish. Lastly, we checked other properties of the river, like water depth, pollution and nearby human influence like roads or buildings.
What did we find out?
We counted 75 live fish in the Dewatto River, but only 39 live fish in the second river. It was just the opposite for dead fish. We found more in the Union River than in the Dewatto. The young salmon were a little smaller in the Dewatto, which probably means they aren't finding enough to eat. Both rivers seem to have low water levels because of a drought. We saw very little trash in either river and there were few roads and houses. Overall, these rivers were in pretty good shape.
- Check out the health of your local stream! Mark the area by laying a 1 meter string along the bank. Observe the water and write down what you see. Now use a goldfish net to scoop the water. Describe or draw a picture of the things you catch. Record how many of each item you find. How do you think human activities like construction, fishing or pollution affect your stream? What natural phenomena made your stream what it is today?
- Salmon have a unique life cycle, migrating from river to ocean and back again to lay eggs. Learn more about the life cycles of other animals. Choose an "exotic" animal like a koala bear or python and an "everyday" animal like a chicken or a frog. What similarities do both creatures share? How do they differ? Look at the life cycle of an endangered species like the bald eagle, grey wolf or lynx. Is there any aspect of their life cycles that are threatened by their surroundings?
- How do the salmon know where they're going? Do they remember the way back to the river a few years later? Do some research about animal navigation.
- Use this life science investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!