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<br />f. '1', <br /> <br />. <br /> <br />. <br /> <br />Wirth/Sheftel <br />Page 2 <br />May 2, 1990 <br /> <br />evidence supporting the Service's non-jeopardy Biological Opinion remains un- <br />changed. The population of the endangered Colorado squawfish in the San <br />Juan River, although reproducing, is still extremely small. Populations of <br />squawfish in the Green and Colorado Rivers are many magnitudes larger. <br />Any loss of squawfish population in the San Juan River would not jeopardize <br />the continued existence of the species. The Agency [Bureau] Review Draft <br />of the Colorado Squawfish Recovery Plan, dated July 14. 1989, supports the <br />conclusion that the Green and Colorado Rivers are the primary squawfish <br />habitat and that the down-listing of the endangered species status of the <br />squawfish can only occur in these two river systems. <br /> <br />Biological investigations of the endangered fish population in the San Juan <br />River conducted from 1987 through 1989 by the Bureau, the states of New <br />Mexico and Utah and the Service also confirm these conclusions. In those <br />investigations, a total of only eight adult squawfish were captured in the San <br />Juan River in the area from Shiprock, New Mexico to the inflow area of Lake <br />Powell, and adult squawfish was captured in the inflow area of Lake Powell in <br />April of 1987 and -recaptured five months later near Bluff, about 145 kilome- <br />ters upstream from its original capture location. In addition to adult fish <br />captured in this reach, a total of only -18 young a year were captured. Most <br />of these collections were made in Utah in 1987 in the reach just above the <br />inflow area of Lake Powell. No endangered fish were recovered in biological <br />investigations of the San Juan River in 1989. No squawfish in age classes <br />between young of the year and adult were found. Fifteen adult razorback <br />sucker. a species currently under review for federal endangered species <br />listing. were found at Piute Farms, the inflow area to Lake Powell, although <br />one razorback sucker was captured in the San Juan River near Bluff, Utah. <br /> <br />Despite the 1987 finding of reproduction of squawfish in the San Juan, the <br />extent of annual recruitment and of the survivability of young fish has not <br />yet been determined. In all likelihood. recruitment of these age classes, <br />other than young of the year, is limiting the population of the squawfish in <br />the San Juan. The explanation to account for limited recruitment, however, <br />is unclear. Many explanations have been formulated to account for limited <br />recruitment in other areas occupied by the species, predation by non-native <br />species such as channel catfish, red China, fathead, minnow and common <br />carp; changes in water quality. including temperature. conductivity and <br />pesticides; and changes in available habitat because of regulation of the <br />river. <br /> <br />As part of the San Juan River investigations initiated in 1987, a Fishery <br />Management Plan will be prepared by the cooperating natural resource <br />agencies in Utah and New Mexico and the Bureau of Reclamation. The <br />Fishery Management Plan will summarize the 1987-1989 biological information <br />and review the hydrology of the San Juan River Basin as affected by existing <br />projects. The Plan will assess the conditions of the river as related to <br />non-native proliferation, overall fish habitat availability, and presence or <br />absence of federally listed species. Further, the Plan will recommend needed <br />studies and identify action which might be beneficial to the recovery of the <br />