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Alaska Fisheries Sonar

Copper River
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A park sign across Copper River from Childs Glacier warns of the big waves the glacier can create. The waves have attracted the attention of extreme surfers. At the sonar site, the river bed and shores of the Copper River sonar site are made up of mostly large rocks and boulders. To detect fish, the Copper River sonar site uses a type of sonar known as DIDSON. The Copper River sonar site is downstream of Miles Lake Glacier and Million Dollar Bridge, and upstream of Childs Glacier. In this photograph taken from the bridge, Childs Glacier is pictured in the background. The sonar site’s left-bank shelter and the top of a submerged sonar transducer is pictured in the lower left-hand corner. The ice chunks are always much bigger below the surface than they are above and are difficult to remove or break up. During spring breakup, large chunks of ice floating downstream can get stuck on or knock over the submerged sonar transducers. During the summer the Childs and Miles Lake Glacier calve frequently. Childs Glacier, pictured above, is particularly close to the site and on occasion the calving glacier has created waves so big they knock over the site’s sonar transducers. Cables from the submerged sonar transducer carry sonar data to a computer in a shelter just above the bank. In this photo taken from the right bank, the Million Dollar Bridge—upstream of the sonar site—is pictured to the upper left. From each bank, a sonar transducer mounted on an H-frame stand is submerged just below the surface of the water and close to shore. Cables from the sonar transducer carry sonar data to a computer in a shelter just above the bank.