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3 GLEN CANYON DAM ADAPTIVE MANAGEMENT PROGRAM Project 02 I. Title: Remove humpback chub from mainstem Colorado River at 30-Mile to maintain genetic stock in refugia. II. Relationship to Adaptive Management Program, Recovery Goals, and Biological Opinion Goal 2 in the AMP Strategic Plan (August 17, 200 I) is "Maintain or attain viable populations of existing native fish, remove jeopardy from humpback chub and razorback sucker, and prevent adverse modification to their critical habitat". Management Objective 2.2 is to "Sustain or establish viable HBC spawning aggregations outside the LCR in the Colorado River ecosystem below Glen Canyon Dam to remove jeopardy." The Adaptive Management Work Group, in their April 24, 2002 meeting, recommended that the Secretary "Initiate all needed activities (consultation [include HBC], compliance, development of a science plan, public outreach, development of a captive breeding population of Grand Canyon Humpback Chub.)" The Biological Opinion requires a second spawning population of humpback chub (in addition to the Little Colorado River (LCR) aggregation). The 30-Mile aggregation of HBC has been documented to spawn occasionally and young fish have been collected immediately downstream of the 30-Mile location however there appears to be no recruitment to the aggregation. The genetic relationship between the 30-Mile aggregation and the Little Colorado River (LCR) aggregation are unknown. Genetics studies are currently underway (GCMRC), but it is unknown if they will identify any unique characteristics of the 30-Mile fish. A genetics management plan and refugia plan are desired prior to removal of fish from the wild. However, if the wild stock is only comprised of 50 old adults, and they represent a unique genetic stock, it may be critical to remove fish before a genetics management plan and refugia plan are fully developed. III. Study Background/Rationale and Hypotheses: Valdez and Ryel (1995) estimated a population of approximately 52 HBC at 30-Milc, comprised primarily of large (> 350 mm) adults and occasionally young-of-the-year (y.o.y.) fish. Young-of-the-year fish were collected in 1993, 1994, and 1995 between 30-Mile and 45-Mile, frequently in a backwater at 44.27 mile (GCMRC unpublished data). These young-of-the-year fish were presumed to have originated from the 30-Mile aggregation. However, juvenile sized fish (> 125 mm to < 330 mm) have not been collected near 30-Mile. The 30-Mile aggregation is likely comprised of old, large adults with little or no recruitment to the spawning population. There is a concern that if the 3D-Mile aggregation represents a unique stock offish that are better suited to mainstem spawning they should be protected. If the 30-Mile HBC are not recruiting, natural Created on 5/6/20035:41 PM , .