jumbo annex reservoir - colorado parks and wildlife survey...jumbo annex reservoir last updated:...
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General Information: Jumbo Annex is an 80 acre water located on the Red Lion State Wildlife Area. Anglers can expect to catch largemouth bass, smallmouth bass, channel catfish, black crappie, and bluegill. Smaller numbers of walleye, saugeye, and wiper can also be caught. Electric motors are permitted. Location: Logan County. From I-76 take Exit 155 and head 3 miles north to Hwy 138. Take Hwy 138 1 mile northeast to CR 95. Take CR 95 ¼ mile north to the reservoir. Recreational Management: Colorado Parks and Wildlife Fishery Management: Warmwater angling Purchase a Fishing License: http://cpw.state.co.us/buyapply/Pages/Fishing.aspx
Jumbo Annex Reservoir LAST UPDATED: MARCH 2020
FISH SURVEY AND MANAGEMENT DATA Mandi Brandt - Aquatic Biologist (Brush)
Previous Stocking 2019
Channel catfish Black crappie
Walleye
2018 Channel catfish Black crappie
Walleye
2017 Black crappie
Walleye and Saugeye
2016 Black crappie
Walleye and Saugeye
2015 Channel catfish Black crappie
Walleye and Saugeye
2014 Channel catfish Black crappie
Walleye and Saugeye
Sportfishing Notes Largemouth and smallmouth
bass The south half of the reser-
voir produces more fish. Small (black) spinners work
well.
Channel catfish Fishing the bottom off of
the dam or east shoreline is recommended.
Cut carp, cut shad, chicken liver, or shrimp as bait work well.
Black crappie
Fishing off of the dam or near downed timber from April-June is recommended.
Spinner jigs and 1” twister tails work well.
Amenities Informational kiosk Fishing (open water and
ice) Small game hunting Wildlife viewing
Regulations
Min. size for largemouth and smallmouth bass is 15”.
Min. size for crappie is 10”. Statewide bag and
possession limits also apply. Electric motors are permit-
ted. Gas motors are NOT permitted.
Jumbo Annex Reservoir LAST UPDATED: MARCH 2020
FISH SURVEY AND MANAGEMENT DATA Mandi Brandt - Aquatic Biologist (Brush)
Table 1. Summary data for fish caught during the 2019 annual survey at Jumbo Annex Reservoir. Data are based on 85 hours of gillnetting, 55 hours of trap netting, and 1.4 hours of electrofishing.
2019 annual survey
Jumbo Annex Reservoir LAST UPDATED: MARCH 2020
FISH SURVEY AND MANAGEMENT DATA Mandi Brandt - Aquatic Biologist (Brush)
Largemouth and smallmouth bass
Largemouth and smallmouth bass catch-per-unit effort (CPUE) generally increased from 2006 to 2011 (Figure 1), indicating an increase in the size of both bass populations. While larger population sizes can elevate angler catch rates, they also create more in-tra- and inter-specific competition for resources, decreasing growth rates. The number of larger-sized small-mouth bass caught during annual sur-veys has generally decreased since 2007 (Figure 1). Though this trend could be partially attributed to anglers creeling fish ≥15”, the 15” minimum size limit was established prior to 2006. Therefore, it is likely that the bass population may be experiencing some level of stunting. In an effort to increase growth rates, bass stocking rates were decreased in 2012 and 2013, and bass have not been stocked since 2014. Lower (or no) stocking rates will continue to be used until adequate growth rates are achieved. However, both largemouth and smallmouth bass naturally reproduce in the reservoir, exacerbating intra- and inter-specific competition. To decrease competition, predatory walleye and saugeye were added to the stocking schedule in 2012 to prey upon young-of-the-year bass. Changes in the bass stocking schedule and the addition of predators did begin to reduce the size of the bass population, as indicated by the general drop in largemouth and smallmouth bass catch-per-unit-effort (Figure 1). The only exception to this general de-crease in catch-per-unit-effort was the catch of largemouth bass in 2019 (Figure 1). This high catch-per-unit-effort was due to a very successful natural spawn. Hopefully these changes will continue to increase the size-structure of the bass populations in the future. Based on the bass population sizes, anglers can expect a good catch-and-release fishery during the 2020 fishing season (Figure 1; Table 1). However, anglers should not expect to catch many keeper-sized bass since no smallmouth bass, and very few largemouth bass, greater than 15” were caught during the 2019 annual survey (Figure 1; Table 1).
Figure 1. Largemouth (A) and smallmouth (B) bass catch-per-unit-effort (CPUE) during the 2006 to 2019 annual surveys at Jumbo Annex Reservoir. The reservoir was not sampled in 2008 or 2009. For comparative purposes, the number of fish collected was standardized for one hour of electrofishing.
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Jumbo Annex Reservoir LAST UPDATED: MARCH 2020
FISH SURVEY AND MANAGEMENT DATA Mandi Brandt - Aquatic Biologist (Brush)
Figure 2. Walleye/saugeye catch-per-unit-effort (CPUE) during the 2006 to 2019 annual surveys at Jumbo Annex Reservoir. The reservoir was not sampled in 2008 or 2009. For comparative purposes, the number of fish collected was standardized per gillnet.
Walleye and saugeye
Walleye and saugeye were first stocked into Jumbo Annex Reservoir in 2012. Walleye and saugeye found in Jumbo Annex Reservoir prior to this time were fish that had made their way to the reservoir from upstream via the inlet canal, or fish that had been salvaged (and transport-ed) from Jumbo Reservoir during low water years. Wall-eye and saugeye were purposefully stocked in 2012 to help alleviate intra– and inter-specific competition among fish species that naturally reproduce within the reservoir such as bluegill, green sunfish, gizzard shad, largemouth bass, and smallmouth bass. Intra- and inter-specific competi-tion has slowed the growth rates of each of these species, decreasing the size of fish available to anglers. Walleye and saugeye will continue to be stocked into the reservoir until the size-structures of these other species improves. Though walleye and saugeye provide another fishing op-portunity, anglers are encouraged to release these sport-fish so the predators can complete their purpose of allevi-ating competition among other species. Annual surveys show the walleye and saugeye populations grew considera-bly through 2017 (Figure 2). The drop in catch-per-unit-effort from 2017 to 2019 can be attributed to angling pres-sure (Figure 2). The 2019 annual survey showed there are four robust size-classes present (Figure 2). The largest saugeye and walleye measured and 21.93” (2.67 lb) and 17.72” (2.04 lb), respectively (Table 1).
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