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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,j uvernle iJev81v!Jm~tlC:

S\"age 4): Scale Ruciirn~!.i.cs: Ut.:...Y 105; 2520 hr; 43.0 rnTll.
,

i::Icale ruuiments have <:<.ppear'ed Otl ~tje siues otthe fish. The
lliediaa fin membrane has ~i8appeared cOG~letely.
st:Jge 44: Scales: day 125 (about 4 mOtlttlS) i )iJOJ hr; 4:5.0 InITi.
Scales are <.iistinc~ly visible cxcep~ medially on the. aorsum and
ventrum.

90.0 LTLIi.

. iIJucI1al Keel:
(Fig. 10).

day 227 (about 7i months);

~44S
:;; .

hr;

C' "5
L.J{:;ag~:

The scales are everywhere developed. . The lateral line is fully

develo peJ. frOlil head to tail. The nuchal ~:~f:; 1 is not .yet vi si bIe; but,
it can be felt beneath the skin of tiF~ predor;::-:il reg i ;:lilr '
.w.~V~l..:t. 10 ~ L:;r::,Ler' ~e,j (:;lopll'.8~t of the nuchal keel, rnorphogenesi s
in its mor'c obv1ous features .is ended,

Juvenile fish obtQia~d ~s a result of the March 1974 broodstock

recovery erfore are now approaching two years in age. These fish

average about 150.0 ITJL'1 in total le.1gti1. -'l;he nuchal keel, which is

the most distinctive superficial, anatomical feature of Xyrachen. is

lW\>j vi si ole as a shallot-,r ridge running from ti1e posterior margin of

t.he neurocranium co the a.clcer'iol' origLl of tl1e dqrsal fin.

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