9675

• UCREFRP Catalog Number: 9675
• Author: Hoffnagle, T. L. and e. al.
• Title: Parasites of Native and Non-native Fishes of the Lower Little Colorado River, Arizona - 2000 Annual Report.
• USFW Year: 2000.
• USFW - Doc Type: \
• Copyright Material: NO

Parasites of Native and Non-native Fishes of the Lower Little Colorado River, Arizona - 2000 Annual Report

Study Area
The Little Colorado River is the major tributary to the Colorado River in Grand Canyon.
Its perennial flow comes from Blue Spring and a series of lesser springs which discharge
approximately 6.3 m3/s of 200 C water which is supersaturated with calcium carbonate and
charged with free CO2 (Johnson and Sanderson 1968; Cole 1975). This study is conducted in the
lower 21 kIn of the Little Colorado River, Grand Canyon, Arizona. These lands are administered
by the Navajo Natural Heritage Program (Navajo Reservation) and U. S. National Park Service
(Grand Canyon National Park).
The study area was originally divided into three reaches. Reach 3 is above the
Atomizer/Chute Falls Complex (RK 13.6; RK = distance upstream in the Little Colorado River
from its confluence with the Colorado River). This reach usually contains only speckled dace
and non-native common carp Cyprinus carpio and fathead minnow Pimephales promelas
(Robinson et al. 1996; D. Stone, USFWS, personal communication), due to the waterfall barrier.
This reach was not sampled during 2000 because river conditions did not permit us to land a
helicopter there. Reach 2 is in the area of Salt Trail Canyon (RK 10.8) and is a middle reach of
river containing all fish that complete their life cycles in the LCR and rare migrant rainbow trout
Oncorhynchus mykiss (Robinson and Clarkson 1992; U.S. Fish and Wildlife Service 1994). This
reach also contains three clear water, saline springs (Big Canyon Creek, Big Canyon Spring and
Salt Creek), which were sampled, as well. Reach 1 is in the vicinity of Boulder Camp (RK 2)
and ranged from RK 2.6 to the mouth (RK 0). This area contains all species present in the LCR,
including those that move into the LCR from the Colorado River, such as rainbow trout and
brown trout Salmo trutta (Robinson and Clarkson 1992; Hoffnagle et a11997; Brouder and
Hoffnagle 1998).

Methods
We conducted three sampling trips in 2000: 9 - 21 April (Trip 1),4 - 15 June (Trip 2)
and 25 September - 4 October (Trip 3). We entered the Little Colorado River Canyon by
helicopter from the Salt Trail helicopter pad on the Navajo Reservation. Reaches 1 and 2 were
sampled during each trip.
Fish were collected by commonly used gears such as seines, minnow traps, hoop nets,
gill nets and trot lines. Additionally, less commonly used gears, such as spear guns and

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Hoffnagle et al. 2000