Passage Considerations for Anadromous Lampreys
Mary L. Moser and Matthew G. Mesa
Abstract.—Both juvenile and adult anadromous lampreys encounter a variety of obstacles to passage during migration. Hydropower dams can delay or obstruct adults, and turbine entrainment or screen impingement can injure or kill juveniles. Lampreys also face less dramatic obstacles such as culverts, irrigation diversion dams and screens, weirs, and other low-elevation structures. The extent to which most structures affect juvenile and adult movements is not known. However, recent research on lamprey swimming performance and migration behavior has provided new insight into the physical and performance factors that may limit lamprey movements. We drew from both field and laboratory studies to review lamprey swimming performance and migration behavior and the effects of water velocity, attachment sites, light, and temperature on lamprey movements. Based on this review, we identified the following as primary research needs for all lamprey life stages: determination of cues lampreys use to orient during migration, documentation of lamprey endurance limits, and evaluation of energy expenditure during migration and its effects on lamprey fitness.