Pacific lampreys pass through Bonneville Lock & Dam using fish ladders and special ramp-like lamprey passage structures seen here through viewing windows at the Bradford Island Visitor’s Center, July 6, 2023. Pacific lamprey, an ancient, eel-like fish species, are seeing returns 170 percent higher than the 10-year average (2013-2022) at Bonneville Lock and Dam this year. Lamprey numbers are also 252 percent higher than the four-year average, according to biologists responsible for reporting the number of fish counted as they migrate upstream past mainstem Columbia and Snake River dams. Pacific lampreys belong to a primitive group of fishes that are eel-like in form but lack the jaws and paired fins of true fishes. Pacific lampreys have a round sucker-like mouth, no scales and gill openings. Identification of lampreys depends largely on the number, structure and position of teeth found in adult lamprey. (USACE photo by Kerry Solan)