River lampreys are ancient jawless fish that spawn in clean gravel rivers and whose larvae spend years as filter feeders in river sediment. Their welfare and conservation are linked to river water quality and the removal of migration barriers.
River lamprey welfare is tied to the quality of their freshwater environment throughout their extended larval phase. Fine sediment pollution that clogs river gravels suffocates larvae unable to filter-feed or breathe. Migration barriers prevent adults from reaching spawning grounds, meaning they die without reproducing after their long larval development. River restoration that removes barriers, reduces agricultural runoff, and maintains natural gravel beds benefits individual lamprey welfare and population viability. The ancient lineage of lampreys gives their conservation additional evolutionary significance.