Fish movement and colonization in the Wyoming Range 2018-2019

Fish colonization ability may be one factor affecting population resilience after disturbance. We conducted displacement experiments in headwater streams in Wyoming, U.S.A. to evaluate mottled sculpin (Cottus bairdii) and mountain sucker (Catostomus platyrhynchus) colonization ability. Specifically, we (1) determined if fish could colonize sites rapidly after displacement, (2) evaluated site-level factors affecting colonization, and (3) compared species-level differences in movement and colonization capabilities. For the colonization experiment, we removed fish from 31 experimental 100 m reaches to create an experimental displacement and examined short-term colonization dynamics in relation to initial fish abundance and habitat characteristics in 2018 and 2019. We selected four additional sites during 2018 to conduct a movement study and compare species mobility in the absence of experimental displacement. We calculated movement distances for all fish relocations, which included short-distance movements within short (200-meter) PIT tag resurveys and recaptures from long-distance surveys at the four movement sites, as well as six incidental recaptures during fish monitoring efforts across the entire study system.