Assessing functions of movement in a Great Plains endemic fish

Pelagic broadcast spawning cyprinids are a mobile group of fishes commonly found within semi-arid areas of the Great Plains of North America. In several species, upstream movements of 50 to 200 km have been reported and associated with reproductive migration. Long distance migrations also are associated with finding food and refuge. Goals of this study were to detect synchronous movement of Prairie Chub at specific life stages and relate movement to functions associated with migration (i.e., reproduction, feeding, and refuge). Movement was inferred by quantifying monthly occurrences of age groups using length frequency distributions among five sites in two rivers and supported with range-wide assessment of genetic structuring. Monthly occurrences of age groups among sites were related to reproductive season (i.e., gonadosomatic indices, ovarian condition) for assessing reproductive migration, to food consumption (i.e., gut content assessments) for assessing feeding migration, and to habitat associations (e.g., specific conductance) for assessing refuge migration. Spatial and temporal patterns in age-0, age-1 and age-2 fish occurrences and abundances suggested movement within only one river. Non-synchronized movements were more consistently associated with specific conductance following a high flow event, which was more consistent with a refuge function than reproductive season or food consumption. Our findings suggest that Prairie Chubs are capable of moving long distances, but movement was inconsistently associated with reproductive efforts as previously described. Without synchronized movements, we question whether movement is migration or dispersal and provide a contrasting narrative to the drift compensation theory used to describe broadcast spawning cyprinid migrations.