7108

• UCREFRP Catalog Number: 7108
• Author: Johnson, J. E.
• Title: Reintroducing the Natives
• USFW Year: 1985.
• USFW - Doc Type: Colorado Squawfish and Woundfin.
• Copyright Material: YES

164
LARVAL RAZORBACK SUCKER, XYRAUCHEN TEXANUS, IN LAKE MOHAVE, AZ-NV,
kazorback sucker in Lake Plonave are larye and old, with no
evidence of recruitnent for several decades. Adults spawn suc-
cessfully and larvae are produced, Larvae w,:>r~ abundant in the
littoral zone from mid-January into April 1934-?i5, c,rowth fror~
7;nm at hatch to 111-12mrn was 2vidant, but larvae disappearzd at ca.
12m~n. Intensive sampling by trawl failad to locate i3rva~~ in open
wat?rs of the lake. Stomach analyses of littoral and epilimnetic
predators provided little evidence for consum;~t_i~~n of significant
numbers of larvae. Yet, caged larvae :attained lenyths i~ r,xcess
of 3Umm, nearly 3X that of wild fish, and a cohort produc~~1 by
wild adu~its in a predator-free backwater reached lenyths of 2~)nm
in a month, The latter were eliminat?d by ;~red,ation after Ureach
of the backwater; nearly 4Qi~ of invading green SUnflsh containF~d
an average of 3.y larval razorback. Foods of larval razorback
were zouplankters predominated by 6osima and Daphnia. Qualitativ~a
and quantitative differences in zooplankton cor~m~_anitiPs, but not
larval diets, were r~vident between the backwater and Lak~ Plonave.
Food resource availability may in part Jxplain greater size and
increased survival in the former. Predation i~~pacts are likely
significant, but remain unquantified.
Daniel R. Lanyhorst
Center for Environmental Studies
Arizona State University
Tempe, Arizona ,352H7