Fall-run Chinook salmon migration monitoring began two weeks ago (September 9, 2010) on the Tuolumne River with the installation of a resistance board fish counting weir. With only 282 chinook salmon passing the weir last year (Sept. 22, 2009 – Jan. 31, 2010), we are anxious to see if predictions for this year are going to be as good as forecasted. We have counted 17 chinook pass the fish weir (as of September 22, 2010), which is good compared to 0 chinook counted during the same time period last year. However, it is still early in the season and predicting salmon escapement is a complicated business.
We are experimenting with a new weir design in an effort to improve unimpeded migration through the fish passage area in shallow water. An 8 ft wide passing area replaced a 2 ft wide passing chute. The new passing area directs fish into a 12 inch wide opening where fish are counted by a Vaki Riverwatcher before continuing on their journey upriver.
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Photo source: FISHBIO