8121 - Laserfiche WebLink

Home Browse Search

sites and is considered the most mobile of the endangered Colorado River fishes (Tyus 1991). The razorback sucker exhibits moderate migrational movements (Tyus and Karp 1991). Some humpback chub stocks (e.g., the stocks in Black Rocks and Westwater Canyons in the Colorado River) do not migrate for spawning (Kaeding et al. 1990) but a lower basin humpback chub stock spawns in the Little Colorado River and uses the mainstem Colorado River in the Grand Canyon during the remainder of the year (Kaeding and Zimmerman 1983). Bonytail movements have not been studied in the upper basin since that species became extremely rare before detailed studies of the endangered fishes were conducted. Dams have fragmented the habitat in the upper basin preventing free movement of the endangered fishes. Therefore, some of the geographic separation among stocks is due to altered habitats. Some interchange has been documented for several razorback sucker, humpback chub, and Colorado squawfish stocks. In most cases, only a few fish were known to move between different river reaches during the spawning season in different years. A small amount of interchange among stocks is a natural phenomenon that provides for evolutionary processes to occur. Stocks with limited interchange will be classified separately until adequate information is available to justify combining these stocks. This conservative classification will prevent or minimize the risk of losing unique genetic attributes of any stock that may be important in the recovery effort. 4. Genetic Identification and Characterization of Stocks. The genetic diversity of endangered fish stocks in the Upper Colorado River Basin will be characterized by identifying genetic markers through appropriate techniques such as electrophoresis for protein analysis and restriction enzyme analysis for DNA. In some cases, morphological analyses are used to identify and characterize fish stocks. Genetic markers are useful in restoration of endangered species because they can be used to characterize the genetic diversity among stocks and can be used to maintain genetic diversity in captive propagation programs that is similar to the parent wild stocks (Allendorf and Phelps 1987; Allendorf and Ryman 1987; Gauldie 1981; Hynes et al. 1981). Verification of inheritance patterns and genetic characters is extremely important to ensure that the markers have a genetic basis and are not due to other factors such as environmental differences, development stage of fish that are sampled, or treatment of samples (Kapuscinski and Jacobson 1987). Ir addition, early detection of inadvertent introgression from stocking will allow changes in stocking procedures that could preserve the genetic integrity of remaining wild endangered fish stocks (Hynes et al. 1981). Genetic (genotypic) and systematic (phenotypic) analyses will be directed at the identification and characterization of endangered fish stocks in the upper basin. The genetic analyses of the Colorado squawfish and razorback sucker from the upper basin will be provided in a final report that is scheduled for completion during 1994. An 8 1 J