Flannelmouth sucker distribution, movement and growth within the Colorado River, Arizona

Authors: Robin J. Osterhoudt, David L.* Rogowski

Year: 2015 (xlvii)

Abstract

The flannelmouth sucker, Catostomus latipinnis, is one of four remaining native fish species found within the Colorado River between Glen Canyon Dam, Arizona and Lake Mead, Nevada. Flannelmouth sucker undergo large migratory movements, but since the impoundment of Glen Canyon Dam, they are now restricted to a smaller closed-off regulated system. Alteration from historical Colorado River conditions has adversely impacted native fish fauna, and while much effort has been expended toward the endangered species (humpback chub, razorback sucker) little effort has been directed towards flannelmouth sucker. We investigated movement and growth of flannelmouth sucker from PIT (Passive Integrated Transponder) tag mark and recapture events using a dataset from long-term monitoring studies conducted by Arizona Game and Fish Department, U.S. Fish and Wildlife Service, and Grand Canyon Monitoring and Research Center (1991-2015). Flannelmouth occur throughout the Colorado River between Glen Canyon Dam and Lake Mead (~460 km) but tend to be more abundant in the lower reaches below the Little Colorado River (LCR; ~120 km below Glen Canyon Dam). The LCR is the largest and most influential tributary in this study area, and flannelmouth sucker are commonly found there, particularly during seasonal spawning. From a random subset of the total marked fish 40% of marked flannelmouth suckers were captured at least once within the LCR. For analyses fish were categorized as subadult (150-349 mm) and adult (¡Á 350 mm). Movement and annual growth of flannelmouth suckers varied with size. Subadult fish moved relatively little (37.9 km/yr), while adult moved significantly greater distances (147 km/year). Subadult flannelmouth suckers grew an average of 85.6 mm per year, while adults grew an average of 58.8 mm per year. Future analyses will investigate growth, movement, and survival in relation to dam operations and environmental factors.