7402

• UCREFRP Catalog Number: 7402
• Author: Nesler, T. P.
• Title: Aquatic Nongame Research, Endangered Fishes Investigations.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

RESULTS

Job 1.

Title: Gamefish species life historv data

Objective: To determine 3-year trends in abundance, distribution, reproductive
success, and size structure of non-native, non-salmonid gamefish
populations in Upper Basin rivers in eolorado.

- .

Northern pike - Yampa River

Northern pike were captured in all four of the study reaches, and appear
to be distributed throughout the Yampa River from RM 45 to RM 170 (Table 1).
Counting only northern pike captured in 1987-1988, it appears pike were evenly
distributed over the four study reaches with the exception of the Juniper
Springs reach. The cause behind this scarcity of pike in the Juniper reach is
uncertain. Colorado squawfish occupy the three downstream reaches (RM 114 to
45) shown in Table 1. From 1987-1988, 85 Colorado squawfish were collected,
compared to 70 northern pike.

Table 1. Distribution of northern pike captured in the Yampa River, 1987-
1988.

~

Sample Reach

River miles

No. of Pike Sampled

Hayden - Craig
Juniper Springs
Maybell-Sunbeam
Lilly Park - Deerlodge

115 - 170
90 - 114
58 90
45 - 56

31
3
35
32

Including seven pike captured in 1986 for initial radio-tracking
observations, 108 fish, averaging 647 rom TL and 2,200 gm, were sampled through
October 1988. Pike ranged from 283 to 947 rom in length and from 200 to 5820
gm in weight. Frequency distributions indicate most of the pike sampled were
560 to 840 rom total length, and 1200 to 3800 gm in weight (Figure 2). Only
eight pike were collected that were smaller than 400 rom in length. All of
these fish came from the Hayden to Craig reach (RM 1l5-l70). The rest of the
pike sampled were 480 rom in length or larger, suggesting a distinct gap

.

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