Pacific lamprey have been declining rapidly in the last several decades (see Oregon Field Guide video). One idea to help aid their recovery is to build ladders that help them get over dams and reach larger parts of their historical range. Although ladders for salmonid fish are relatively common, ones designed specifically for lamprey are rare. Recently, McNary Dam on the Columbia River installed a lamprey ladder, with the hopes that more lamprey will make it to historical parts of their range.
Pacific lamprey have a life cycle that is similar to salmon and steelhead: eggs hatch in freshwater environments and larvae will remain in these freshwater habitats for 2 to 7 years, after which they transform into juveniles and migrate to the ocean. Pacific lamprey spend 1 to 3 years feeding in the ocean, after which they return to freshwater, spawn in gravel-bottomed streams, and die. Pacific lamprey are also affected by many of the same stressors that affect salmonids, including poor water quality, barriers to migration, water diversions, and water pollution. Here’s hoping that the new ladders give lamprey a boost!