Spring mating period in Orconectes limosus: the reason for movement

Thirteen adult Orconectes limosus males (carapace length 32.5 +/- A 2.48 mm; weight 10.8 +/- A 2.63 g) were radio-tagged and tracked during and after the spring mating period, April-June 2008. Average distances moved per day were higher in the mating period (14.9 +/- A 21.4 m) due to mate searching activity. During the mating period, movement did not correlate with water temperature, and crayfish were active during daylight hours. They moved rapidly upstream and downstream, a maximum 118 and 95 m per day, respectively. When water temperature increased over 10A degrees C, this initiated the end of mating and the start of spawning, and the spring migration abruptly ceased. An influence of water temperature on movements was observed during the non-reproductive period. Orconectes limosus was highly mobile in small watercourses, signifying a threat of penetration into native crayfish habitats, and potentially enabling the transmission of crayfish plague. This threat was increased during the mating period due to increased activity.