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MAY: 03-2010 MON 06 : 08 AM FAX NO. P. 07 <br />FWS Position Paper on Lineage GB populations outsicle the historic ra.ngc ofthe <br />Greenback Cutthroat Trout <br />I3ttelcgrotincl <br />The greenb;.i.cl; cutthroat trout (Onehorr lhvnchlm clcr *i AO MUM) was li sted as an <br />endangcred species in 1961 Lmder a precursor to the Fri.dangered Species Act (Act). It <br />was re-listed aS endangered under the CU1Tent Act in 1974, and downlisted to threatened <br />sLalus, with a 4(d) rule allowing, catch and release fishing„ in 1978. <br />Gi,eenbacks are cortsi IC.recl native to the .headwaters of the South Platte and Arkansas <br />South Platte <br />River (lrai.llages in eastern Colorado, and a few headwater tributaries of tile <br />in a sma.l I area of southeastern Wyoming (3e.hnhe 1992). Another cutthroat trout <br />subspecies, the COOK) River cutthroat trout (Onchvrhyrrchus cJc.rr lci??7ccn i?icar,sj, occurs <br />in the Colorado and Green River drainages in the west slope of Colorado, southwestern <br />Wyoming, and eastern Uwb. <br />C'Tenctics ?and 'laxongmic lssLle'S <br />Shwe. 2006, a number of genetic studies have been undertaken to try to determine the <br />genetic relatlonslaips between greenback, Colorado River, Llnd Rio Grande cutthroat trout <br />(Onchor•hyneh-us elar•ki vir;tiin.alis) (;Mitto.n et a.l. 2006, Metca.11'et at. 2007, Metcalf 2007, <br />Rogers 2008). Mitt.on et ill. (2006) :f°ou11d all 3 sLbspecies to be Closely related, and did <br />.not believe that any of them warranted. su.bspeci..fic designation. Metcal.1 et al. (2007) <br />Lised molecular markers from the naitochondrial and 11LlClear 1,7e11o111es to analyze <br />individuals h-om greenback and Colorado Diver cutthroat trout. Their suidies revealed <br />two divergent lineages within the ranges of greenback and Colorado River cutthroat trout <br />consisting, of 10 unique hapIntypes, which they determined corresponded with the two <br />described subspecies. These lineages are known as GB (greenback) and CR (Colorado <br />River). Subsequent sampling and analysis found that of 45 4SSunlecl Colorado River <br />cutthroat populations, 12 were assigned to lineage GIB. In addition, of 12 assurned <br />greenback populations present on the east side ofthe Continental Divide. 1 1 were <br />assigned to the C R lmeag,e (Rogers 2008). Since publication of Rogers (NOS), additional <br />sampling has identified additional lineage G13 populations on Lhe west slope ol'Coloradcl <br />and in e;a.sm-n Utah (Rosenlund 2009 hers. corn). The current Rice Grande lineage <br />1-K)pulations seem to fit well within the Rice Grande drainage. <br />To datennhe whether any taxonamk revisions to green1mck or Colorado River Cutthroat <br />troul should be Imposed. the Greenback Recovery Team is working on two research <br />projects: ( I ) AtternMing to see if the lineage markers can be found in the tevvcutthroaal: <br />mit smapfes collected in the 1 BUf.}'y. and currently scared In museums. and (2) <br />ALienipting to deWnWne i{ there is a physiclil difiurcn.ce bel'weel} the three DNA <br />lineages (Lreenbaick. Colorado River. and Rice Grandcl through moi-phc logy and nleWcs <br />analyses, WSL141, Offl-WSC pi'cljects are not 0XPQ ICd {ol' a.L least t~,,\o years (Rc?stnlund <br />`?CS hers. mr. ).