Management of anadromous lampreys: Common threats, different approaches

Ten anadromous lamprey species (Petromyzontiformes) are recognized around the world, including four species in the Southern Hemisphere and six in the Northern Hemisphere. Eleven threats to these anadromous lampreys have been identified: climate change, shifting oceanographic regimes, artificial barriers, low water quantity/flow management, habitat degradation, poor water quality, reduced habitat availability, host and prey availability, predation, overharvest, and disease. Artificial barriers are a well-recognized threat to anadromous lampreys. Management strategies to improve access to spawning and larval rearing habitats have involved modifying these barriers, providing passage, and translocating adults around them. Habitat restoration targeting other fishes may also benefit some anadromous lampreys; however, research targeting lamprey responses to habitat restoration is lacking. The absence of recreational and commercial fisheries on many of the anadromous lampreys has created a paradigm where funding is unavailable to monitor and manage them. This has led to a general lack of awareness and scientific understanding for anadromous lampreys. We discuss management actions for each of the anadromous lampreys, and highlight key information gaps. Key information gaps include aspects of freshwater biology, distribution and abundance of anadromous lampreys, and the need to improve understanding of how to mitigate threats. In general, larger-bodied lampreys are the subject of more human interest (more harvest, research, and management).