Lay Lake - Alabama Department of Conservation and Natural ...

Lay Lake
Management Report
Spring 2011
Prepared by
Michael P. Holley
District Fisheries Biologist
E. Dan Catchings
District Fisheries Supervisor
Kevin Baswell
Biologist Aide
Alabama Department of Conservation
and Natural Resources
Division of Wildlife and
Freshwater Fisheries
September 1, 2011

Introduction
The objective of the Lay Lake reservoir management plan is to collect quantitative
biological data to assist district biologists in developing management strategies to enhance the
fishery. The reservoir is sampled periodically to evaluate population metrics of major sport fish
species. A summary of the morphometric, physical, and chemical characteristics of Lay Lake is
listed in Table 1 of this report. Readers are encouraged to utilize the tables and figures located in
the appendix of the report. An angler’s guide to fish management reports is available on the
Outdoor Alabama website at the link below.
http://www.outdooralabama.com/fishing/freshwater/where/reservoirs/guide.pdf.
Methods
Largemouth bass and Alabama bass were targeted during electrofishing surveys on April
12, 2011 and April 13, 2011 at eight randomly selected sites (Figures 1-2). Target species
(largemouth bass and Alabama bass) were measured to the nearest millimeter, and weighed to
the nearest gram. Otoliths were extracted to obtain age, growth and mortality estimates, and
were read whole view by District 2 personnel. Suspect ages, or otoliths that were not readable in
whole view prompted sectioning (Maceina 1988) to authenticate age. Fish collection and general
data analyses were conducted according to the guidelines of the Alabama Reservoir Management
Manual (Cook 1999). Simulation modeling was conducted using FAST software to determine
whether a 15 inch minimum length limit could improve the largemouth bass fishery.
Results and Discussion
Largemouth Bass
A total of 308 largemouth bass (Tables 2- 3) were collected at a rate of 77.0/hr during
electrofishing surveys, which is similar to the lake average (77.7/hr) catch rate (Table 2). Catch
rates improved for most size groups of largemouth bass from 2008 to 2011. The only notable
exception was preferred size fish, which had below average catch rates (Table 2).
The PSD for largemouth was 67, and relative stock density indices exceeded the lake
average for stock (RSD S-Q) and quality (RSD Q-P) size groups (Figure 4). Abundance of
preferred (RSD P-M) and memorable (RSD M-T) largemouth bass fell below the lake average
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(Figure 4). RSD S-Q and RSD M-T values were below the statewide average for Alabama
reservoirs. RSD Q-P and RSD P-M abundance approached the upper 75 th percentile for Alabama
reservoirs (Figure 4).
Largemouth bass ranged from 162 mm to 556 mm total length, and from 1 to 9 years old
(Table 3; Figures 3 and 5). The von Bertalanffy growth curve predicted that it took about 1.4
years for largemouth bass to reach a harvestable size of 10 inches, and about 2.0 years to reach
12 inches (Figure 5). Growth has remained relatively stable at Lay Lake over the last 5 samples
(Figure 6). Relative weight was excellent, and exceeded the lake average for most size groups of
largemouth bass; only memorable size largemouth fell below the lake average (Table 2).
Total annual mortality for age-2 to age-9 largemouth bass from catch-curve analysis was
43% (R 2 =0.96; P

Simulation Modeling - Largemouth Bass
Total annual mortality from catch-curve analysis, suggested that fishing mortality may be
moderately high for largemouth bass. In order to determine whether the largemouth bass fishery
could be improved with a minimum length limit, simulation modeling was conducted to compare
the current fishery (where anglers generally only keep largemouth bass 12 inches and larger) to
the predicted benefits of a 15 inch minimum length limit. At our estimated natural mortality rate
of 0.36, the calculated exploitation rate was 16%, which is only moderate for most black bass
populations, but generally higher than reported from recent creel surveys. If a minimum length
limit of 15 inches was implemented, our model predicted that about 35% more memorable size
(20 inches) largemouth bass would be available to anglers (Figure 12). However, the model also
predicted that about 39% fewer bass would be available for anglers to keep or weigh-in a
tournament (Figure 13). Mean total length of fish in the population was predicted to increase
from 391 mm to 435 mm (just over 15 inches to approximately 17 inches). The yield of
largemouth bass would only decrease about 13% if a 15 inch minimum length limit was
implemented, since fewer, but bigger bass would be available to keep or weigh-in.
Summary
The black bass populations in Lay Lake display good growth rates, and excellent relative
weights. Preferred and memorable size largemouth bass were slightly less abundant than the
lake average, however, stock and quality size largemouth bass were abundant and should recruit
to larger sizes in forthcoming years. Year-class strength of largemouth bass has been relatively
constant since 2002. Alabama bass catch rates were high, and several year-classes were
represented with constant recruitment since 2004. Moderately high total annual mortality
prompted the evaluation of minimum length limits to possibly improve the largemouth bass
fishery. Although a 15 inch minimum length limit could improve size structure, a substantial
decline in number of bass available to anglers was predicted. The current number of memorable
size largemouth bass was low at Lay Lake, and if this trend continues, a minimum length limit,
such as 15 inches may be beneficial in improving numbers of big largemouth bass. Total annual
mortality estimates suggested that, even though catch and release may be high from creel
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surveys, fishing mortality may be increasing through hooking mortality and tournament mortality
for both largemouth bass and Alabama bass.
Conclusions
1. Re-sample the black bass populations in a timely manner, to follow trends in size structure,
age and growth, and mortality of black bass populations.
2. No changes to the current black bass regulations should be implemented at this time.
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Literature Cited
Cook, S.F. 1999. Alabama reservoir management manual. Alabama Department of
Conservation and Natural Resources. Montgomery, AL.
Anderson, R.O., and R.M. Neumann. 1996. Length, weight, and associated structural indices.
Pages 447-482 in B.R. Murphy and D.W. Willis, editors. Fisheries Techniques. 2 nd edition.
American Fisheries society, Bethesda, Maryland.
Haffner, J. B., J. L. Moss, and J. M. Piper. 2008. Management report for Lay Lake. Alabama
Department of Conservation and Natural Resources. Montgomery, AL.
Jenkins, R. M. 1967. The influence of some environmental factors on the standing crop and
harvest of fishes in U.S. reservoirs. Pages 298-321 in Reservoir Fishery Resources
Symposium. Southern Division American Fisheries Society, Bethesda, Maryland, USA.
Maceina, M.J. 1988. A simple grinding procedure for sectioning otoliths. North American
Journal of Fisheries Management 8:141-143.
Ryder, R. A. 1965. A method for estimating the potential fish production of north-temperate
lakes. Transactions of the American Fisheries Society. 94:213-218.
Welch , P. S. 1948. Limnological Methods. McGraw-Hill. pp. 93-94.
6

Appendix 1
Tables and Figures
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Table 1. Morphometric, physical and chemical characteristics of Lay Lake.
Surface area
12,000 acres
Drainage area
9,087 sq. mi.
Full pool elevation
396 feet-msl
Mean annual fluctuation
0.5 feet
Shoreline distance
289 miles
Shoreline development index 19 (Welch 1948)
Mean depth
22 feet
Maximum depth
88 feet
Outlet depth (upper) 362 feet
(lower) 342 feet
Thermocline depth None
Stratification index 10.16
Total dissolved solids
118 mg/l
Morphoedaphic index
5.4 TDS/mean depth(ft)
(Ryder 1965)
Growing season
210 frost free days
(Jenkins 1967)
Year impounded 1914
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Table 2. Relative stock density, catch per effort, and relative weight of black basses from Lay Lake, Spring 2011.
NO. OF TOTAL SUBSTOCK RSD S-Q RSD Q-P RSD P-M RSD M-T TOTAL
SPECIES YEAR SAMPLES EFFORT NO. CPE SSR NO. CPE PCT. Wr NO. CPE PCT. Wr NO. CPE PCT. Wr NO. CPE PCT. Wr NO. CPE
LARGEMOUTH BASS 2011 8 4.00 17 4.2 6 96 24.0 33 103 113 28.3 39 99 76 19.0 26 99 6 1.5 2 94 308 77.0
LARGEMOUTH BASS 2008 4 2.02 9 4.5 7 26 12.9 20 96 44 21.8 34 97 59 29.2 45 91 2 0.9 2 90 140 69.3
LARGEMOUTH BASS 2004 3 1.51 24 15.9 24 35 23.1 35 93 31 20.5 31 93 33 21.8 33 94 1 0.6 1 93 124 81.9
LARGEMOUTH BASS 2001 3 1.11 20 18.0 18 38 34.2 33 94 33 29.7 29 97 38 34.3 33 99 5 4.5 4 106 134 120.7
LARGEMOUTH BASS 1997 4 1.68 4 2.4 4 28 16.6 27 94 49 29.1 48 94 23 13.7 23 93 2 1.2 2 94 106 63.0
LARGEMOUTH BASS 1992 4 1.80 7 3.9 7 14 7.8 13 94 49 27.2 47 99 37 20.6 36 105 4 2.2 4 105 111 61.7
LARGEMOUTH BASS 1987 3 2.00 38 19.0 37 20 10.0 19 39 19.5 38 38 19.0 37 6 3.0 6 141 70.5
LAKE AVERAGE 9.7 15 37 18.4 26 96 51 25.2 38 97 43 22.5 33 97 4 2.0 3 97 152.0 77.7
ALABAMA BASS 2011 8 4.00 0 0.0 0 20 5.0 16 111 39 9.8 31 108 58 14.5 46 109 10 2.5 8 109 127 31.8
ALABAMA BASS 2008 8 4.05 0 0.0 0 8 2.0 6 109 42 10.4 29 111 77 19.0 53 110 17 4.2 12 103 144 35.6
ALABAMA BASS 2004 10 5.03 5 1.0 6 9 1.8 11 99 27 5.4 33 97 31 6.2 37 100 16 3.2 19 97 88 17.5
ALABAMA BASS 2001 6 2.88 8 2.8 6 27 9.4 21 102 32 11.1 25 103 48 16.7 38 103 19 6.6 15 108 134 46.5
ALABAMA BASS 1997 8 3.69 3 0.8 3 6 1.6 6 103 31 8.4 29 105 47 12.7 44 104 23 6.2 21 107 110 29.8
ALABAMA BASS 1992 10 5.00 0 0.0 0 13 2.6 23 121 18 3.6 32 107 18 3.6 32 109 8 1.6 14 109 57 11.4
ALABAMA BASS 1987 10 5.00 4 0.8 4 27 5.4 28 33 6.6 34 27 5.4 28 9 1.8 9 100 20.0
LAKE AVERAGE 0.8 3 16 4.0 16 108 32 7.9 30 105 44 11.2 40 106 15 3.7 14 106 109 27.5
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Table 3. Number-at-age, catch-at-age, and mean total length of largemouth bass collected from
Lay Lake, Spring 2011.
Age Year Class Number Percent CPE Mean TL SE Range
1 2010 69 22.4 17.3 224 3.3 162-286
2 2009 93 30.2 23.3 298 2.8 226-377
3 2008 81 26.3 20.3 357 4.2 223-440
4 2007 31 10.1 7.8 414 6.1 340-490
5 2006 16 5.2 4.0 421 13.1 350-493
6 2005 8 2.6 2.0 479 15.1 393-531
7 2004 4 1.3 1.0 505 28.8 424-547
8 2003 3 1.0 0.8 500 6.2 493-512
9 2002 3 1.0 0.8 487 34.7 449-556
Total 308 100.0 77.0
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Table 4. Number-at-age, catch-at-age, and mean total length of Alabama bass collected from
Lay Lake, Spring 2011.
Age Year Class Number Percent CPE Mean TL SE Range
1 2010 4 3.1 1.0 200.0 10.6 183-231
2 2009 20 15.7 5.0 271.2 5.1 243-321
3 2008 51 40.2 12.8 344.5 3.5 272-402
4 2007 27 21.3 6.8 388.6 5.9 278-441
5 2006 11 8.7 2.8 406.6 6.0 372-428
6 2005 9 7.1 2.3 417.3 11.4 348-453
7 2004 4 3.1 1.0 449.3 11.4 419-470
8 2003 1 0.8 0.3 438.0
Total 127 100.0 31.8
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Figure 1. Lay Lake sampling locations north of “the narrows”, Spring 2011.
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Figure 2. Lay Lake sampling locations south of “the narrows”, Spring 2011.
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Number
60
Age - 9
50
40
30
20
Age - 8
Age - 7
Age - 6
Age - 5
Age - 4
Age - 3
Age - 2
Age - 1
10
0
75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 525 550
Length Group (mm)
Figure 3. Age-length frequency for largemouth bass collected from Lay Lake, Spring 2011.
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RSD (%)
60
50
40
Lake Average
30
2011
20
Statewide average
10
0
S-Q Q-P P-M M-T Trophy
Incremental RSD Categories
Figure 4. Relative stock density of largemouth bass collected from Lay Lake, Spring 2011.
Orange bars are the 2011 sample, red bars are the Lay Lake average, and yellow
diamonds are the statewide means.
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Length(mm)
600
500
400
300
200
Linf = 534.552
K = 0.302
to = -0.760
100
0
0 1 2 3 4 5 6 7 8 9
Age
Figure 5. Von Bertalanffy growth curve for largemouth bass collected from Lay Lake,
Spring 2011.
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Mean Total Length
550
525
500
475
450
425
400
375
350
325
300
275
250
2011
Lay Lake Average
225
200
175
150
0 1 2 3 4 5 6 7 8 9 10 11
AGE
Figure 6. Mean lengths-at-age for largemouth bass collected from Lay Lake.
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Number
100
Z = -0.5637
S = 57% (95% CI 51 - 64)
r 2 = 0.9580
10
1
2 3 4 5 6 7 8 9
Age
Figure 7. Catch-curve for largemouth bass, ages 2-9, collected from Lay Lake, Spring 2011.
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Number
30
25
20
15
10
Age - 8
Age - 7
Age - 6
Age - 5
Age - 4
Age - 3
Age - 2
Age - 1
5
0
175 200 225 250 275 300 325 350 375 400 425 450
Length Group (mm)
Figure 8. Age-length frequency for Alabama bass collected from Lay Lake, Spring 2011.
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RSD (%)
70
60
50
40
Lake Average
2011
Statewide average
30
20
10
0
S-Q Q-P P-M M-T Trophy
Incremental RSD Catergories
Figure 9. Relative stock density of Alabama bass collected from Lay Lake, Spring 2011.
Orange bars are the 2011 sample, red bars are the Lay Lake average, and yellow
diamonds are the statewide means.
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Length(mm)
500
450
400
350
300
250
200
150
100
Linf = 462.497
K = 0.394
to = -0.397
50
0
1 2 3 4 5 6 7 8
Age
Figure 10. Von Bertalanffy growth curve for Alabama bass collected from Lay Lake, Spring
2011.
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Number
100
Z = -0.7311
S = 48% (39-59)
r 2 = 0.9602
10
1
3 4 5 6 7 8
Age
Figure 11. Catch-curve for Alabama bass, ages 3-8, collected from Lay Lake, Spring 2011.
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Number at Memorable Size
30
25
20
15
10
12" 305 mm
15" 381 mm
5
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Exploitation
Figure 12. The predicted number of largemouth bass reaching memorable size in Lay Lake over
a range of exploitation rates and minimum length limits. The vertical light-blue line
represents the predicted current fishery.
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Number Available
450
400
350
300
250
200
150
100
50
0
12' 305 mm
15" 381 mm
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Exploitation
Figure 13. The predicted number of largemouth bass available to anglers in Lay Lake over
a range of exploitation rates at different minimum length limits. The vertical light
blue line represents the predicted current fishery.
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