PNNL

Abstract

Background: Little is known about the transformer stage of the parasitic lampreys, a brief but critical period that encompasses juvenile out-migration from rivers to lakes or oceans to begin parasitic feeding. Information about this life-stage could have significant conservation implications for both imperiled and invasive lampreys. We investigated tag retention, survival, wound healing, and swim performance of newly transformed sea lamprey (Petromyzon marinus) implanted with a new micro-acoustic transmitter, the eel-lamprey acoustic transmitter (ELAT), in a controlled laboratory environment. Results: The 61-day survival of our tagged subjects was 71%, within the range reported in similar studies of juvenile lampreys. However, survival was significantly lower in the tagged animals (vs control), with no effect statistically attributable to measures of animal length, mass, condition, or population of origin (Great Lakes vs. Atlantic drainage). Mortality in tagged fish was concentrated in the first four days post-surgery, suggesting surgical injury. Tagged animals burst swam significantly slower (-22.5%) than untagged animals, but were not significantly different in endurance swim tests. A composite wound healing score was a significant predictor of maximum burst swim speed, and wound condition was related to animal mass, but not length, at the time of tagging. Conclusions: Impairments to survival and swim performance of juvenile sea lamprey implanted with the ELAT transmitter were within currently acceptable ranges for telemetry studies with small, difficult to observe fishes. The ability to track migratory movements of imperiled and pest populations of parasitic lampreys will improve our ability to estimate vital rates that underlie recruitment to the adult population (growth, survival), and to investigate the environmental factors that regulate the timing and rates of movement, in wild populations.