Blue catfish_Jug Line Sampling

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Blue catfish_Jug Line Sampling
Zach Ford
Resource Scientist - Aquatic Ecologist
Missouri Department of Conservation
Grassland Systems Field Station
Clinton, MO 64735
27 January 2012 - Catfish Sampling Workshop
SDAFS Spring Meeting, Biloxi, MS
Harry S Truman Reservoir is 22,539 ha
(55,600 acres)
Lake of the Ozarks is 22,397 ha
(55,300 acres)
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Sampling Method
 Jug
lines
 Effective at catching stock size (≥12”) and larger
blue catfish at Truman and Lake Ozark
 Commonly used by anglers at both reservoirs
 Used at large reservoirs in other states to target
quality size (≥20”) and larger blue catfish
 Management objectives are focused on protecting
intermediate-size (≥24”) and larger blue catfish
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Sampling Method
Examples of anchored jug line (left photo) and
unanchored jug line (right photo).
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Jug Line Design
 Buoy-style PVC Floats (5 in. dia. x 11 in. long)
purchased from Memphis Net & Twine Co.
 0.5 in. PVC pipe for core with glued end caps
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Jug Line Design
 Bait line: 30 ft of #18 nylon braided twine (gold color)
 1.0 oz egg sinker and barrel swivel tied above leader
Hook: size 9/0 Eagle Claw Offset Circle Hook
 Anchor: 2-4 lb concrete weights w/inserted wire loop

 60 ft of nylon braided twine (half-hitched shallower)
 Trot line clip attaches anchor to loop tied on PVC pipe of jug
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Jug Line Design
 Each
jug individually numbered
 Also labeled “MDC Do Not Disturb”
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Bait – Fresh or Fresh-frozen Gizzard Shad
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Bait – Cut Gizzard Shad
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Experimental Design
 Complete
list of sampling sites known to be
good locations to catch blue catfish was
compiled
 30 sites + 10 overdraw sites/reservoir selected
from master list using simple randomization
 New random site selections used each year
 Pectoral
spines collected in both pre- and postreg periods to evaluate age/growth
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Example Sampling Sites
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Example Sampling Sites
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Anchored jug lines used during August-November
 Two sampling teams/reservoir (2-3 person teams)
 A set of jug lines = 50 jugs anchored at a site

 ~1.5 h to bait/deploy 50 jugs / ~3 h needed for retrieval
Min. sample size of 10 blue catfish per site (≥12”)
 Length, weight, eye injury, fin clip, spine pulled,
and released

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35.3 in TL – 22.1 lb Blue Catfish
9.27.2011
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QUESTIONS
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