Clemens, Benjamin J., Lance Wyss, Rebecca McCoun, Ian Courter, Lawrence Schwabe, Christopher Peery, Carl B. Schreck, and Margaret F. Docker. (2017). Behavioral flexibility in spawning migrations of Pacific lamprey Entosphenus tridentatus. Hydrobiologia. DOI 10.1007/sl0750-017-3096-4.
To address questions about the spawning migrations of Pacific lamprey, Entosphenus tridentatus, we tested three hypotheses: 1) body size is not related to migration distance; 2) lamprey show a single, random migration behavior, moving in a continuous, upstream direction; and 3) there is no association between migration behavior and genetic differentiation. Adult Pacific lamprey were implanted with radio tags and non-lethal tissue samples were sampled for genetic analyses. The fish were released into the Willamette River Basin, Oregon (USA) during 2009 – 2010. A total of 372 (72.2%) fish were detected (3,044 total records), providing migration histories for analyses. Body size explained little (≤ 7.4%) of the variation in migration distances. We rejected the hypothesis of a single migration behavior: migratory behaviors varied considerably and fish often showed multi-directional movements. Cluster analysis identified nine statistically significant migration behaviors, defined by distance and direction traveled, net migration distance and season in which fish were tagged. Eight microsatellite loci were used to test the hypothesis that the migratory clusters constituted genetic population structure, yet there was no statistical evidence to support this hypothesis. We hypothesize that the different migration behaviors shown by Pacific lamprey are flexible responses to environmental and pheromonal cues.