7006

• UCREFRP Catalog Number: 7006
• Author: Gustafson, E.
• Title: Early Development, Adult Sexual Dimorphism, and Fecundity of the Razorback Sucker,
• USFW Year: 1975
• Copyright Material: NO

, .

, (

i.NTB.ODUC'l iOi~

'l'he razor'cacx suc~~er, Ay I'dUCl'idi teXatiUS ,. is a large cato-

sto:uid fi sh endeillic to ti1e Color'ado Hi ver drainage basin. 'fhi s

mo.notypic genus wa.s formerly aou.i.ldant in the Colorado mainst:ceam

aI;ld all its larger tri butari~s; it has declined steadily in numbers

since the early decades of the 20th Century (Miller, 1961; Minckley

& tDeaeo.!:!, 1963). The demise of ,,(y.cauchen ancl other illdigenous

f1 shes of the Colorado drainage sy stem may be at tri 'outed to chaIlges

in Ilabitat resul~ing 'fro~ manls modlfication of various aqua~ic en-

VirO!lmer:..ts. (Dill, 19l;.4; Niller, 191.;.6 & 1955; Beland, 1953; Ni:lckley

'0'
de U.:::aCO{l, 19b ).

'l'hese fiiodifications LiClude: erection of river

'Li..i.poundlli8H ts, cha.c..n811 za t ion, lOv.'81'in8;of subsurface -water taules,

pollutiollal effects a.nd introdi.ActioIJ.3 of co.iflpetitive exotic spe.....

clas. Currently, Xyrauchen is protected by state law in ~evada

aaJ. California.

The larg~st reproducing population of razorback suckers is

thought to occur in L:",,:(e HOllave :ceserlioir on the Colorado River

(fig. 1); ho...evcr, all inai viduc....l s encountel'ed there arc large,

perhaps iudicat.ing low l'f~productivd SUCL.<~ss. cr'he species is near-'

ly extinct in the lo~er tasin below Davis Dam (Mlnckley, 1973).

'. -'

... -'--~'-_.t~'~~"!l-""h'" ,"' '-....--"'~....\

-.-