PRoCEEDIhIGS oprgE DxErr Rsrru Cornctr,, 1995 SYT,FoSILIM VoIl’lvG)OftTI. RJKjSIm 1946

Authors: poblaciones de western mosguito fish Gambwia_afink que fue establecido hace aproximadamente 50 afros.Mosquitofish de hr{bitat termicarnente estable, BJnhamy Garrett springs, fueron caracterizad.os por tardaren madurar’ alto contenido de grasa, v embriones gr*rrdes. En co“r.t ““te las hembras de *n habitattermicamente inestable, wabuska Springs, fueron caiacterizadas por madurar en edades pequeias

Year: 1995 (xxvii)

Abstract

In fail 1994, the Rio Grande sucker Catostomus plebeius was li.sted as a Colorado state endangeredspecies’ Recovery efforts will rely on t-ransiocations to increase the number of populations but initiairesearch is locatinggellldty appropriate_dono_r popuiations and identifl,ing limiting factors. Work at HotCreek, Colorado in 1994 showed that Rio Grande sucker ab’ndance ;as weakiy related to rnesoscglehabitat characteristicg -prompting us to examine in 1995 how habitat and anthropogenic stresses mayinteractu’ith fbod availability to limit Rio.Grande sucker populations. Rio crande sucker is thought to beprimarily herbivorous whiie the exotic x’hite sucke r Catostomus commersoni is primarily benthivorous. wehlpothesized that anthropogenic sediment loading would reduce periph;,Lon availabiiity and increase dietcnrerlap between the two species’ we measurea t6ialry, sed.imentation, sucker densily and condition, andperiphycon standing stoclq q’untified land r-rse; and collecred diet samples from i3 sites in Nel’ Mexico andcolorado s’ith and without $rite suckers. Among sites, substrate composition varied widell, (perceni finesranged < I % to 22%) , Rio Grande sucker densit! ranged from I .7 fish/h/l o0 m2 to 107 fish/h/l o0 m2 andurite sucker density ranged from 0 fish,tr,/m2 to io.g fi’sh./h,/m’. Midsumrner data showed that Rio Grandesuckers tottt**td a ngn proportion of plant marter (mean:3D7g%, SE:3D7) at all sites regardless ofwhite sucker Presence. we will present the analysis of all lgg5 data and evaluate the effects ofanthropogenic stresses on Rio Grarrde sucker pop,riations. RE.S[/A4EN En otoflo de 1994, el rnatalote dei Rio Bravo, Catostomus pbbeius fue considerada en el estado deColorado como una especie en peligro. Esfuerzos de recuperaci6n depender6n de traslocaciones paraincrementar el nirmero de las pobiaJo*.r.- Investigaci5nes jrefiminares estan en marcha para locaiizar apobalciones donadores geneticamente apropiadas yp*“ identihcar los factores limi&ntes. Trabaios en Hot B7