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001755 32 Work Group as approved by the Secretary of the Interior. GCMRC recommends continuing implementation of experimental treatments under the current experimental flows plan for years 3 and 4. Humpback Chub The GCMRC reported a continuing decline in the Grand Canyon population of humpback chub (Gila cypha) in 2002. Cause for the decline is unknown, but stock synthesis models indicate a lower recruitment for most of the previous 10 years. In response to concerns about the status of humpback chub, on January 29, 2003, the Glen Canyon Dam Adaptive Management Work Group (AMWG) created the Humpback Chub Ad Hoc Committee and directed that the committee"... will consider actions to implement a comprehensive research and management program for the HBC (humpback chub) .. . (and make) a recommendation to the AMWG ...." The motion that was approved further indicated that the Ad Hoc Committee would consist of AMWG, TWG (Technical Work Group), and GCMRC, and science advisors which would again develop recommendations and report to AMWG at a special session. Meetings of the Ad Hoc Committee were held February 12, March 12, April 1, 21, and 22, and May 6, 2003. Conference calls were held April 16 and 25, 2003 An overview of the status and trend of the Grand Canyon population of humpback chub was prepared by GCMRC for the AMWG on April 22, 2003. That report stated that recent analyses of historical data on humpback chub in Grand Canyon have caused considerable concern, because of uncertainties about the current size of the population and the strong probability that the population has been declining steadily for at least a decade. The most recent assessment model indicates that the spawning population is probably somewhere between 2,000 and 4,000 age-4 and older fish. A different estimate, using the "Supertag" assessment model, resulted in an estimate of 1,100-1,200 adults in 2001. Estimates of the LCR spawning population for 1992-1995 were 2,000-4,700 adults (Douglas and Marsh, 1996). The assessment model also determined a lower level of recruitment (i.e., fish reaching maturity at age-4) over the last decade. The GCMRC report also stated that if recruitment continues to be stable at an average of the 1995-98 rate, the population will likely stabilize at 1,000-3,000 adults. Recovery goals exist for the humpback chub in the Colorado River Basin, and include all six populations (U.S. Fish and Wildlife Service, 2002). The Recovery Goals provide guidance on recovery of the species, basin-wide, and identify sitt~-specific management actions, and GCMRC FY2006 Annual Work Plan (Draft February 15,2005)