7617

• UCREFRP Catalog Number: 7617
• Author: Platania, S. P. and K. R. Bestgen.
• Title: Survey of the Fishes of the Lower San Juan River, New Mexico.
• USFW Year: 1987.
• USFW - Doc Type: Albuquerque, New Mexico.
• Copyright Material: NO

additional Colorado squawfish specimens were noted in the August
samples, all fish were very small and field identification was
difficult at best.
The squawfish from River Mile 143.0 was 23.4 mm SL. The
backwater consisted of a nearly cut off high-flow channel.
Dimensions were 100 x 20 m and had a uniform depth of about
0.3 m. Substrate was cobble covered with a thick (15-18 cm)
layer of silt. Water was 260 C (main channel temperature = 160
C) and turbid, presumably from the activity of larger fish.
Other species were abundant and YOY red shiner, fathead minnow,
and mosquitofish dominated the catch.
The other YOY squawfish specimen (River Mile 139.5), 30.0 mm
SL, was taken from a side channel with reduced inflow. The
channel was 300 x 40 m, and had a maximum depth of 0.5 m. In the
pools, substrate was cobble with a 15-18 cm layer of silt
overburden, and the water was turbid. Where the channel rejoined
the river, the substrate was cobble and the water was clear.
This was the site of the largest (n=2,146) and most speciose
(n=10) seine collection examined from the October sampling trip.
Red shiner, fathead minnow, and mosquitofish were the most
abundant species in this backwater.
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