Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7493
Title: Behavior and potential threats to survival of migrating lamprey ammocoetes and macrophthalmia
Author: Mary L. Moser, Aaron D. Jackson, Martyn C. Lucas, Robert P. Mueller
Publication Year: 2014
Journal: Reviews in Fish Biology and Fisheries
Volume: 25
Issue: 1
Pages: 103-116
Keywords: Lamprey, juvenile lamprey, migration behavior, predation,

Upon metamorphosis, anadromous juvenile lamprey (macrophthalmia) exhibit distinct migration behaviors that take them from larval rearing habitats in streams to the open ocean.  While poorly studied, lamprey larvae (ammocoetes) also engage in downstream movement to some degree.  Like migrating salmon smolts, lamprey macrophthalmia undergo behavioral changes associated with a highly synchronized metamorphosis.  Unlike salmon smolts, the timing of juvenile migration in lamprey is protracted and poorly documented.  Lamprey macrophthalmia and ammocoetes are not strong swimmers, attaining maximum individual speeds of less than 1 m s-1, and sustained speeds of less than 0.5 m s-1.  They are chiefly nocturnal and appear to move along the bottom in the thalweg.  At dams and irrigation diversions, macrophthalmia can become impinged on screens or entrained in irrigation canals, suffer increased predation, and experience physical injury that may result in direct or delayed mortality.  The very structures designed to protect migrating juvenile salmonids can be harmful to juvenile lamprey.  Yet at turbine intakes and spillways, lampreys, which have no swim bladder, can withstand changes in pressure and shear stress large enough to injure or kill most teleosts.  Lamprey populations are in decline in many parts of the world, with some species designated as species of concern for conservation that merit legally mandated protections.  Hence, provisions for safe passage of juvenile lamprey are being considered at dams and irrigation diversions in North America and Europe. 

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Theme: Recovery and rebuilding of marine and coastal species
Foci: Characterize the population biology of species, and develop and improve methods for predicting the status of populations.
Develop methods to use physiological, biological and behavioral information to predict population-level processes.