4211

• UCREFRP Catalog Number: 4211
• Author: Ulmer, L.
• Title: Management Plan for the Razorback Sucker ‎(
• USFW Year: 1985.
• Copyright Material: NO

,._ C~._
~~A
Lo~~ter Basin: ~.ri.rz-,_t4,, hdc~vadt~, i~Cti~d Mr~xico, Calif_orrria
Fishery sui:veys sine the erlt~ 197C~s l~iave confirm~d~ a
continued. decline of razorback suc~sc:r_ iri tYtE: low~::r. Colorado River
basin (i~ii_nck.ley 1973, 1983) . records of occurrerlcU are s~~caradic
and isolated. A ft~w large ind_ivid~~~als ~aer~e collected in 1973 by
AGFD from Imperi<~l P~eservoi.r. , Arizona-C~rliforr7ia. Individuals
were occasionally taken by CDFG from Davis ~>,:~;~r south to Trrperial
Dam in the zrrid~ and late 1970s, yet a 198% CDFG netting survey of
the lower-Colorado River from Par4;~r Dam sout;r to the tI.S. slid
Mexican boundary caught none in 2,5~~1 hours of netting effort,
despite use of_ guar known to be selective for the species
(Louder~iilY. a.nd tumor 1985) . Young razorback suckers were
captured in 1973 and 1974 from ponds filled from the East Highline
Canal near Ri.land, Calit:or_nia (St. Arnant et al. 1974). Iri 19II4,
seven young r:~:aorbacks s~.er_e collected i.n lateral reservoirs nea~~
the Coachella Car7ai. Ydater supply to both these canal syst;~rns is
from tyre X11-,~r~erican Canal, diverted :Er.om tale Colorado River gat
Ii~per..ial Dam (Imperial i2~;ser_voir). A small, remnant population of
adult ra;.or_back sucher_ in~ Senator 4°~dash R~se~rvoir, Im~~erial County.
Califcsrrz7.a, which a7.so is associated ~Fa•ith Ir~Eaerial _rtesori~air, 3~as
b een ~:nowr~ since the late 19 7Cs. Ct7r'G has studied this
pot~irl~~ti err, a su~n.~rar.y of ~~~hi ch i.s given belo~~r. A cor.r;,,lete rec:orc3
of razor'aac's: ~•~rcker~ co:l._1_.c~r..t~.r:~ns in i`,=r7.i,.Eo~_t7ia front 19~~~ to the
L~r~~;>=rit:. is i.n I_,,~pendia~- T .
_
l I l ~ r 1 is O'il ~`? 1 n C~ LRv ~! °•T ,:z d ~~ ~ :"+°~ 7Il r'r 2a i ! ~. _ r. ~ '/.: C) k"" ~:7 r:i l"`.'Y.: ~y ~? is _L 4~ 1.: 1(~ n ~ ;i t 1..1 , _
QC:l~llr~ .I. f'1 ~.,~_~~:~~"_ ~C1i~.i:~.'i~~fv czr.?C~ it:..WAfsy ~:~ 3_~~: ¢,~'b'iE? '"i+.)ii~~\;.'~ ~~C.i~'el.r~.%?el'J?~1
- ~ ...a ~. ~ .~ ~ ~ s -w
i'~~~~~ t,.,.,~ .l '_Tst.3 T.~'.lE? L=":i~`.~C3`3L .<?"t.7L'i] _;.). ,)~~e!.~3~:~.t'.`11 '_11 I .:~i:~ll'~ ~E.CiU t.