7781

• UCREFRP Catalog Number: 7781
• Author: U.S. Fish and Wildlife Service.
• Title: Recovery Plan for WOUNDFIN,
• USFW Year: 1979.
• Copyright Material: NO

~~
temperatures, lengthening daylight and declining spring run-off. It
would appear advantageous for woundfin to spawn as the high spring run-
off is declining because eggs spawned prior to this would likely be
carried away by the current 9r buried in silt. Limited spawning in
sheltered areas during high spring flows may occur.
Because of the maturation of gonads in March, April, and May (Peters,
1970) and because of the appearance of fry in June (Cross, 1975), it
is assumed that woundfin begin spawning in late May. As fry have also
been found through late August, it is apparent that limited spawning
occurs throughout the summer. Peak activity is probably in late May
and early June.. Recent information (Deacon, 1977a) indicates woundfin in
downstream reaches of the Virgin River begin spawning more than one
month earlier than fish near LaVerkin Creek. In 1977, first appearance
of young ranged from June 3 to July 23.
Even though the time of year when peak reproduction appears to be known,
less information is available as to the exact spawning locality within
the stream. Deacon (1977) reported apparent spawning activities on
April 17, 1977, in the Virgin River south of Mesquite, Nevada. Water
temperature was 14.5°C. A female, accompanied by 3-4 smaller males,
would move out of a pool area into flowing current. Additional males
would join the group as they swam around deeper pockets in the stream
bed. Following violent activity within the group, the female would swim
back upstream into the pool.
When fry appear they are generally found in shallow areas lateral to the
main current and in the main channel only when water levels are low. The
fry are conspicuously absent from pools containing potential predators
such as Gambusia affinis, Lepomis machochirus, Micropterus salmoides, and
Gila robusta seminuda. By late August, young-of-the year woundfin between
20 and 30 mm long have been observed. Growth appears good until October,
but from then through December is masked by high mortality rates. The
period of highest mortality coincides with the period of lowest flows
and lowest temperatures and appears related to these two factors. Deacon
(1977 a,b) noted differential survival of young woundfin from the reaches
above and below the Virgin River Gorge and related it to low flows and
water temperatures.
MOVEMENTS
Data on Plagopterus suggest that the fish may be unusually mobile.
Collections over a number of years give this impression (Deacon, unpub-
lished data). More recently, systematic collecting in the Virgin River
indicates an as-yet unexplained disappearance of larger individuals of
Plagopterus in late summer, suggesting either movement or mortality.
Relative abundance of woundfin, may become exceedingly high at times.
Occasionally, Plagopterus is the only species taken in a seine haul,
and as many as 200 individuals may be taken in a single haul of an 8-meter
8
i
t
t

s

J
1

t