Detection of Razorback Sucker Xyrauchen texanus reproduction in the Colorado River of the Lower Grand Canyon and where to go from here
Authors: Eliza I.* Gilbert, W. Howard Brandenburg, Adam L. Barkalow, Stephen P. Platania, Ron B. Kegerries, Brandon C. Albrecht, Ron J. Rogers, Mark C. McKinstry
Year: 2015 (xlvii)
Abstract
On 25 June 2014 the front page of the Grand Canyon News read, Á¢â‚¬Å“Endangered Razorback Sucker makes a comebackÁ¢â‚¬Â. Headlines of other publications read Á¢â‚¬Å“TheyÁ¢â‚¬â„¢re Back! Endangered Fish Spawns in Grand CanyonÁ¢â‚¬Â and Á¢â‚¬Å“So long, sucker? Not yet: Endangered Razorback Sucker makes comebackÁ¢â‚¬Â. The excitement was due to the fact that adult Razorback Sucker, which had not been detected in the Grand Canyon since the 1990s, was captured in both 2012 and 2013. In 2014, as part of a collaborative research effort to document Razorback Sucker, larval surveys were undertaken to determine if reproduction by this species was occurring in the lower 100 river miles of the Colorado River in the Grand Canyon. In 2014 and 2015 larval Razorback Sucker was captured throughout the entire study area, (river miles 180-280, Lava Falls to Pearce Ferry). Data from 2015 indicated Razorback Sucker commenced spawning in February and persisted through early July. This is an earlier spawning date and a more protracted spawning period than documented in many other populations of Razorback Sucker. In 2015, as in 2014, larvae were captured at the top of the study area indicating spawning adults were present above Lava Falls, the most upstream portion of the study area. Now that we have two years of data indicating Razorback Sucker in the Colorado River of the lower Grand Canyon are spawning, the questions to address grow rapidly. What is the distribution of spawning Razorback Sucker in the Grand Canyon? Are spawning fish residents of the river or immigrants from Lake Mead? What is the role of water temperature in cuing movement to spawning grounds and initiation of spawning? Are there physiological/ecological aspects of Razorback Sucker larvae, which limit their ability to recruit in the same environment that supports the common suckers, Bluehead Sucker Pantosteus discobolus and Flannelmouth Sucker Catostomus latipinnis? Continued survey efforts and effective research to address these questions will assist managers in conserving this important population of Razorback Sucker.