Early Spawning by the American Brook Lamprey (<em>Lethenteron appendix</em>) in Southeastern Minnesota

Abstract

Record-setting warm temperatures in the upper Midwest during early 2012 resulted in early spawning by the American Brook Lamprey (Lethenteron appendix) in southeastern Minnesota. American Brook Lampreys in a total of five streams in three drainages spawned up to one month earlier than typical. Mean day of year of spawning groups observed in 2012 was significantly different from the mean for groups observed during the period 2002–2010, but mean water temperature was not significantly different. Limited historical data are not sufficient to show an effect of climate change on spawning phenology because some data are confounded with the effects of latitude and year-to-year variability in thermal regime.