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

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CONCi..,uSI0M::>

.c;arli development inl..he ra.zorLaci'~ 3Llc....er is quite rapid.

natching occurs about six days a~id the larvae begi.!1 feeding acti ve-

ly about thrae clays thereafter. ii1e mouth l'eril'.:liIl8 hi a terr:llnal

position up to uaJ 64, but is shifted ventrally by the end of the

larval phase (day 75). Juveniles are ,recognized about Jt months.

after ha.tcJ:1i1.1.6. 11:; d.f;PSb.l'.s tlB.~ d.ev0lopro.lJl1t from juvenile to adult

.il":";Y t~ very slow. TV.fd-ye'J.r-olti ;<'jL'a.uCi:(-;~l rn8asure 15. Ocm in total

length, 1f.il1ile ~d.ul t 1'i8h avel'age d:l:'OUllu.. 43.9 CIft total length. Pre-

lirnin3.ry data-~ based on scale annuli, indicate that. the later may

be in excess of seven years in age. 'l'1'H~ age and le.ngth at whi eh

sexual maturi'cy ensues i~ as yet unu.ls.:::.overe": tor X. tGxanus. In

1i i. e't; or thi s ,it seems reasoLla.wle t.o suggest that stoc:{ing of juven-

ile razorback ~uckers in waters contaifiibg predaceous species should

only be attempted after they have attained a length of at lea.-st

,20. J em. 'ihis should raaximi ze survi vorsl1i p.

The data on differencial sex characteriscics are in general

~;:,~'r'e:;;a8nt \ii LCl knOio.i.Q. patter/is of se;will dimorphism ill a variety of

-\\Ie.s~er.ll North .America/i suci(ers. Horphological cri teria for ..iisl:;lLl-

€ i.:.l snilJ6 '.:.i-;..;;; ,-,~xe s of 1.1 Vllig; AYl'aUGneIl ::Ire lnv,.11u:.iole for's c udies