The dams were constructed between 1938 and 1975, including ladders to help spawning salmon continue their journey up and down the river. By tagging the fish and installing interrogators at the dams, scientists have learned how long it takes for salmon to get from one dam to the next, and at what point many of them are not making the crossing at all. More recently, researchers have been using the tags to determine when fish are captured by birds, what happens to them out at sea and how shoreline development affects them.
Just as important, scientists have been able to learn how they can improve the thoroughfare for salmon at the dams, says Chris Peery, assistant research professor at the
University of Idaho, Moscow. And as improvements are made to the dams, the
RFID system has had to keep up with those adjustments.
Now, BPA and the
U.S. Army Corps of Engineers are testing a giant tube that shoots salmon downstream in great numbers, reducing the bottlenecking that can lead to salmon mortality. Tracking fish through this chute will require some technological updates, however. The short
read-range in the water has already been a problem since typical readers can only scan a salmon’s
tag within about 18 inches, Peery says.
The new chute at the Bonneville Dam, however—which Peery likens to a waterslide in a amusement park—measures at least 10 feet across and will make many of the tags unreadable because of its size alone. The speed at which the salmon will pass the
reader antenna is an issue—they’ll be traveling as fast as an average highway vehicle, making capturing data off 134 kHz tags almost impossible.
Therefore, Digital Angel is developing a $1.4 million solution in a series of 16-by-16-foot antennas, the largest RFID antenna system in the world according to the company’s marketing director, Debra Skoog. The antennas will read RFID tags inside the salmon up to 3 feet away as they pass at up to 60 miles per hour on their way to the ocean. BPA is funding the new antennas at its dam—the last dam salmon cross before reaching the mouth of the Columbia River and the ocean.
Digital Angel hopes to have the antenna working this winter to test its
read range, Peery says. If testing goes well, researchers won’t be up a creek when it comes to fish tracking.