ALP 3

Contents
trout developed a black spot in the top of their head 24 hours after testing that lasted for about
two days but did not cause mortality (Becker et al., 2003).
The juvenile life stage of rainbow trout are probably most likely to survive reservoir discharge
(Becker et al., 2003) but it is unknown if they could also survive sleeve valve passage. However,
juvenile forms of rainbow trout and other trout species are being introduced regularly as game
fish into this segment of the Animas River making any unintentional introduction
inconsequential. Warm water fish that are physoclistous species, such as largemouth bass and
bluegill, have a closed bladder that changes its air content throttgh diffusion to the blood system
of the fish are not expected to survive reservoir discharge passage due to the rapid pressure
differential they will experience. However, it is unknpwnJf phystomous fish can survive
sleeve valve passage.
Embryos from fish are probably the least likely"b be
their proximity to the discharge outlet. Rainbovv"trot
where the eggs are covered with several inches ofd
fast moving water such as those found in mountain b
abundant and widespread native saltttoitd in western
been introduced into the Animas River vvatershcd exi
their nests next to submerged objects like"logs oe_'bo
gravel, or debris littered,.substrate at depths pf 0.5 —
were one of the first hciwative "fish introduced, into C
(0.20 percent) of the k h sampled by Valdez (200,8)J
spawning is similar tom largemouth bass wh6lit 1
adhere to eravel, sand or debris -14 t� iud, however.
the 10 years of sampling by
ome entrained intodischarge water due to
lay their eggs in gravel ,, nests called redds
vel and the nests are usually ,located in cool
butariees. ,Rainbow trout are the most
North"America (Moyle, 2002) and have
;nsively, ".Largemouth bass typically build
ders where; their eggs adhere to sand,
__etas (Moyle, 2002). Largemouth bass
ildtWo, "and are tine -fifth of one - percent
the lower Animas River. Bluegill
s are deposited at shallow depths and
all life stages of bluegill are rarely found at
has not been found in the lower Animas
The fat%sd minnow are native to Colorado's eastern slope and have been introduced in western
portions of Colorado through"acc�identallusion with fish plants of other species and through
bait bucket releases. Fathead itinnows may spawn 12 times or more throughout the late spring
and summer months where egloa, re deposited on the underside of any material in or on the
water. Fathead mmito;ws are p parily herbivorous and feed on algae and other plant material
and may be the most wilply distributed fish in Colorado being found in almost every watershed
in the state (Woodling, 145). The white sucker is also native to Colorado's eastern slope and
does not build nests to spawn. In rivers, they prefer a gravel substrate and moving water where
eggs are fertilized before drifting downstream and adhering to the substrate in pools and in
smaller eddies. In lakes, white sucker eggs may be scattered on the lake bed (Woodling, 1985).
The white sucker and fathead minnow are both found in the lower Animas River comprising 1.13
percent and 0.24 percent respectively (Valdez, 2008).
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