Long-distance movements by Flannelmouth Sucker in big river habitats

Authors: Matthew J. Breen, Trina N. Hedrick

Year: 2010 (xlii)

Abstract

Flannelmouth Sucker (Catostomus latipinnis) is currently listed as a Tier I Sensitive Species in Utah due to reductions in their historical range. Although recent investigations indicate that viable, self-sustaining Flannelmouth Sucker populations persist in the Green and White rivers of Utah, relatively little is known about their movement patterns in this large un-impounded section of the upper Colorado River basin. From 2007-2009, we marked a total of 3,058 Flannelmouth Suckers with Passive Integrated Transponder (PIT) tags throughout the Green (314 continuous river km [RK]) and White (107 continuous RK) rivers. Spring (April-June) and summer (July-August) electrofishing surveys from 2008-2010 yielded 71 Flannelmouth recaptures. Mean movement distance was 61.0 ± 9.0 km (range = 0 - 360 km), where movements were positively associated (rS = 0.355; P = 0.003; N = 71) with Flannelmouth total length (433.1 ± 7.7 mm; range = 196 - 507 mm). Inter-drainage movements were detected by seven Flannelmouth; five fish migrated from the Green into the White River in spring, one fish making the same movement in summer, and one fish traveled from the White into the Green River in summer. Movement into the White River occurred from below (six fish) and above (one fish) the confluence. Forty-one percent of recaptures moved downstream, 72% doing so in spring, and 58% moved upstream, 75% in the spring. However, there was not a significant difference in movement distance by season (U = 433; P = 0.432; N = 71) or direction (U = 562; P = 0.703; N = 70). Additionally, we observed substantial within-season movement (i.e., tagged and recaptured in spring) in the downstream direction (mean distance = 124.9 ± 35.6 km; movement rate = 10.5 ± 3.2 km/day). Our results indicate that Flannelmouth Suckers are highly migratory, with a maximum recorded movement distance of 360.0 km; the longest movement documented for this species to our knowledge. Given the timing and extent of observed movements, as well as size-related movements, we hypothesize that Flannelmouth in big river habitats maintain summer home ranges that are widely separated from distinct spring spawning areas. However, the timing of spawning migrations likely differs greatly by metapopulation. Flannelmouth Suckers utilized large portions of the upper Colorado River basin, including multiple drainages, which is likely an important factor for successful recruitment by this species.