摘要：We synthesize findings from several field and laboratory studies of the silver lampreys (Ichthyomyzon unicuspis). Catches of upstream migrant lampreys in the Fox River during the years 1994-1999 were inconsistent with a quasi-cyclical pattern suggested by an earlier analysis of Fox River data for 1979-1993. Peak catches occurred from mid-April to early May, and mean date of catch did not differ between males and females, but there was a tendency for larger lampreys to be caught earlier in the season. Females tended to be larger than males, both in samples from the Fox River and in a sample of parasitic-phase lampreys removed from paddlefish (Polyodon spathula) in the Wisconsin River. Small silver lampreys from the Wisconsin River attached readily to common carp (Cyprinus carpio) in captivity, but they seemed to have difficulty forming puncture wounds on carp and did not exhibit appreciable growth. However, larger lampreys removed from carp in the field had created wounds with free-flowing blood. Captive lampreys attached to carp primarily in dorsal regions, and significantly more attachments occurred during the dark phase of the diel cycle. Spawning silver lampreys in the Oconto River tended to occur at greater depths in nests with sea lampreys (Petromyzon marinus) than in nests without them.
