Life History and Genetic Variability of Lampreys in Interior Alaska Rivers

Lampreys share many of the same habitats as salmonids in freshwater ecosystems, yet receive comparatively little management or research attention.  The current belief is that two lamprey species reside in interior Alaska: anadromous Arctic lamprey Lethenteron camtschaticum and freshwater-resident Alaskan brook lamprey L. alaskense.  We examined the life history, morphological and meristic characteristics, and mitochondrial genetic variability of lampreys in Yukon River drainages.  Lamprey species could not be differentiated using pigmentation density/patterns or trunk myomere counts.  Further, there was no evidence of genetic differentiation, suggesting that there are no distinct lamprey populations or species in this drainage.  No larvae were collected in upper river locations, where habitat was characterized as gravel, cobble, and small boulder substrates and swift flow.  However, middle and lower river sites all supported larvae, and these habitats had silt-sand substrates with woody debris and slow flow.  Lamprey size structure was similar among systems, as were estimates of larval lamprey diet composition (organic detritus), assimilation efficiency (>70%), and gut fullness (< 0.2 mg diet ash-free-dry-mass).  These findings suggest that management decisions must incorporate the contrasting biology and life-history variation of anadromous and freshwater-resident lampreys in interior Alaska drainages that are sustained with a shared gene pool.