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1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br />~J <br />1 <br /> <br />r~ <br />2. Two self-sustaining populations (e:g:,-mainstem and/or tributaries are <br />maintained over a 3-year period beyond downlisting, starting with the first point <br />estimate acceptable to the Service, such that for each population: <br />a. The trend in adult (age 4+; >250 mm TL) point estimates does not <br />decline significantly, and <br />b. Mean estimated recruitment of age-3 (150-249 mm TL) naturally <br />produced fish equals or exceeds mean annual adult mortality, and <br />c. Each point estimate exceeds 4,400 adults (MVP). <br />Four self-sustaining populations (minimum viable population of 4,400 <br />adults); two in the upper basin and two in the lower basin. <br />Humpback chub <br />Overview: <br />1. Genetic variability is identified and a genetic refuge is maintained over a 5- <br />year period. <br />2. Two self-sustaining populations are maintained over a 5-year period. <br />Downlisting Criteria: <br />1. The Grand Canyon population is maintained as a core over a 5-year period, <br />starting with the first point estimate acceptable to the Service, such that: <br />a. The trend in adult (age 4+; >200 mm TL) point estimates does not <br />decline significantly, and <br />b. mean estimated recruitment age of age-3 (150-199 mm TL) naturally <br />produced fish equals or exceeds adult mortality, and <br />c. each core population estimate exceeds 2,100 adults (MVP). <br />Delisting Criteria: <br />' 1. The Grand Canyon population is maintained as a core over a 3-year period <br />beyond downlisting, starting with the first point estimate acceptable to the <br />Service, such that: <br /> <br /> <br />47 <br /> <br />