Fall is in the air, and that means it’s time to start counting salmon in California! Chinook salmon are starting their fall migration, or long journey from the ocean to the rivers where they were born. FISHBIO counts all the salmon that return to the Stanislaus River every fall, and last year we started sharing the number of salmon that we counted every week with the fourth graders in Oakdale and some third graders in Modesto. These students put these numbers (which scientists call “data”) on a graph to follow the migration as it happened in their own backyard. One classroom decorated their graph with some great salmon art shown above.
Now we are about to start counting salmon in the Stanislaus River again. Scientists try to make a lot of predictions about the salmon migration before it happens, but when it comes to how the fish will actually behave, we have to wait and see. At the beginning of the migration season, we never know just how many fish will actually return to the river, or what the timing of their migration will be. Will they come all at once, with a big spike in fish numbers? Or will they come more slowly, but steadily?
Here is the final graph from last year that compares weekly salmon counts in 2013 (blue) and 2014 (red). Most of the salmon arrived early in 2013, with a big spike in mid October, while in 2014, the fish arrived more gradually. In the end, the total number of salmon that arrived by December 31 was quite similar in both years, about 5,400 fish. The graph shows how two different patterns in the timing of the fish’s migration can give the same end result. The 2015 fall salmon migration is now underway, and we will be watching the numbers with lots of interest. Want to know how we actually count the salmon? We’ll write another post soon to tell you!