2000 Lake Vilbig Survey

March 31, 2000

OBSERVATIONS by Al Kohutek

After 2 reschedules due to bad weather, the survey finally got under way. Brad Metzler and Mike Deiter of Pond King showed up at the boat ramp 10:15 AM and we were in the water by 10:30 AM.  The survey ended at about 3:00 PM.   Al Kohutek, Jon Griffin, Tom Root, Paul Poole, and Brandon Wooddell were present during the survey.  Brad used a small John boat with a portable generator and a Coffelt shocking box. These boxes are used by the Texas Parks and Wildlife and are reportedly the safest available. Brad did 30 minute shock intervals starting at the boat ramp and working down the Rusdell channel, stopping midway in the channel to weigh and measure the bass and forage fish.  He continued on down the channel and along Mike Walter's peninsula to almost the tip.  Here Brad and Mike again measured and weighed the bass and the forage fish.  There were a total of 6 check points.   He shocked most of the shore line around the lake.  The only areas missed were the very tip of the Food Lion cove, Poo Poo lagoon, the Fish bowl, and the north side of the Rusdell Island.  Of the bass surveyed, 17 bass were over 3 lbs. and one was over 8 lbs.   Brad had a way of examining the stomach contents of the bass with out causing any injury to them.  One bass ate a catfish, some had bluegill, yellow bass, and craw fish in their stomach.  Only 2 crappie were shocked.  Brad said this was due to crappie being suspended in the deeper water.  He also said he saw no signs of bass spawning and said the spawn should start soon. The weather was cloudy with light to gusty winds early in the morning and calming later that day. The water was murky due to the recent rains.   The high air temperature was about 66 degrees and we got sprinkled on at about 1:00 pm.  Fifty-seven carp, three gar, and five drum were taken out of the lake.  Heath Wagner's old boat was pulled behind Jon's and it served as the carp transporter.   Debby Kohutek made some great sandwiches for the entire crew.    

I was very impressed by Pond Kings professionalism .   All bass and forage fish were released unharmed and in excellent condition after the measurements were taken.   You can visit Pond King's web sight at www.pondking.com     The following information was taken from  Pond King's survey report:            

  

FORAGE

Bluegill Sunfish – The bluegill population consisted of both native and coppernose strains.  We sampled a slightly higher number of natives, but neither was overabundant.  The average size was approximately 5 – 6 inches.  Bluegill that were smaller or larger than this were found in very low numbers.  Evidence of survival of last year’s spawn was sparse.  This indicates that there are too few spawning adults to keep up with the number of predator fish feeding on young of the year.  The lack of 6 inch plus bluegill is another indicator of poor year to year recruitment of new spawning adults.  Basically the bluegill are surviving but not thriving.

Redear Sunfish – Densities of redear were not high enough to consider them a functional part of the food chain.  The survival rate of fingerlings stocked in an environment with an abundance of small bass is usually fairly low.

Gizzard Shad – The average gizzard shad measured 9 –10 inches in length.  It takes an 18.5 inch or larger black bass to swallow a shad this size.  These shad are not as prolific as threadfins, but they do produce a food source for the big bass.  The trick is to have enough big bass to keep the numbers of large shad under control.

Threadfin Shad – We found about ten groups of threadfins that were from a late spawn of last year.  These fish are predominately responsible for the survival of the bluegill and the condition of the largemouth bass.  Maintaining high fertility levels and visibility at a maximum of 24 inches will greatly increase their production rates.

We also sampled smaller numbers of longear sunfish, silversides, warmouth, and juvenile yellow bass that contribute to the food chain.

 

LARGEMOUTH BASS

To understand the condition of the bass population as it interacts with the present food chain, we are going to split it into three sections.

Small Bass (8 – 11”) – Average relative weights for these fish ranged from 72% to 89%.  They are in the poorest condition of the three sections.  Bass in this size range can only swallow bluegill that are less than 3.75 inches in length.  The frequency of this forage is very low.  Two options to improve the situation include removing small bass or increasing juvenile bluegill concentrations.  The first option is undesirable because these bass produce a good food source for the large bass.  The best way to increase juvenile bluegill concentrations is to stock big bluegill. Survival rates of fingerlings less than 4 inches would be less than 5%.  A 0.5 lb female will produce 15,000 to 25,000 eggs.  Even with high mortality of  eggs and fry, you can still produce a good influx of juvenile bluegill.  Higher densities of juvenile bluegill produce more spawning adults next year. Increasing threadfin production with feeding and fertilization will also help feed these smaller bass.  Growing good densities of healthy small bass is important to increasing numbers of trophy lunkers.   

Medium Bass (12 – 15”)  - Average relative weights for these fish ranged from 88% to 93%.  Bass in this range can only swallow bluegill that are less than 5 inches in length.  Again the frequency of this forage is low.  The majority of their condition is linked to the threadfin shad and other smaller bass. 


Large Bass (16”+) – Average relative weights for these fish ranged from 95% to 124%.  Bass in this range have the widest selection of forage available.  They can consume the majority of the bluegill, threadfin shad, gizzard shad, and other bass less than 12 inches in length. 

 

The following data shows bass over 7 inches in length, what the length of each fish is, the weight, what a bass of this size should weigh,  and the relative percent.  The under 8 inch fish were counted but not weighed. 

. LENGTH WEIGHT SIZE CLASS NORMAL % RELATIVE
.    (Inches)    (Pounds)        (Inches)   (Pounds)          (%)
1 18.5 3.19 19 3.561 90%
2 14.75 1.5 15 1.729 87%
3 16 2 16 2.241 89%
4 15.25 1.688 15 1.923 88%
5 15.5 1.625 16 2.026 80%
6 17.5 3 18 2.983 101%
7 13.75 1.25 14 1.382 90%
8 18 3.875 18 3.263 119%
9 18.5 4.313 19 3.561 121%
10 17.5 3.25 18 2.983 109%
11 15 1.75 15 1.825 96%
12 17.5 3.563 18 2.983 119%
13 17.25 2.688 17 2.849 94%
14 13 1.188 13 1.156 103%
15 12 0.875 12 0.896 98%
16 15.75 2.438 16 2.132 114%
17 11.25 0.563 11 0.729 77%
18 14.5 1.813 15 1.638 111%
19 12.25 0.875 12 0.957 91%
20 14.5 1.5 15 1.638 92%
21 11.5 0.688 12 0.782 88%
22 12 0.75 12 0.896 84%
23 11.5 0.688 12 0.782 88%
24 13.5 1.125 14 1.304 86%
25 11 0.625 11 0.679 92%
26 11.5 0.688 12 0.782 88%
27 8.5 0.188 9 0.298 63%
28 10.5 0.5 11 0.585 85%
29 15.25 2.125 15 1.923 110%
30 19 3.5 19 3.877 90%
31 19.5 3.688 20 4.212 88%
32 12.75 1.063 13 1.087 98%
33 11.75 0.813 12 0.837 97%
34 11.75 0.813 12 0.837 97%
35 17 2.875 17 2.720 106%
36 16 2.313 16 2.241 103%
37 12.5 1.125 13 1.020 110%
38 15.5 2.313 16 2.026 114%
39 17.25 2.688 17 2.849 94%
40 8.5 0.25 9 0.298 84%
41 13 1.063 13 1.156 92%
42 12 0.75 12 0.896 84%
43 12.5 0.875 13 1.020 86%
44 19.25 4 19 4.042 99%
45 14.5 1.25 15 1.638 76%
46 13.75 1.188 14 1.382 86%
47 14.5 1.5 15 1.638 92%
48 16.25 2.313 16 2.355 98%
49 12.25 0.813 12 0.957 85%
50 13.75 1.375 14 1.382 99%
51 10.5 0.5 11 0.585 85%
52 17.5 3 18 2.983 101%
53 15.75 2 16 2.132 94%
54 10.75 0.563 11 0.631 89%
55 11.75 0.688 12 0.837 82%
56 15.5 1.75 16 2.026 86%
57 10.75 0.625 11 0.631 99%
58 10.75 0.563 11 0.631 89%
59 10.5 0.563 11 0.585 96%
60 16.5 2.438 17 2.473 99%
61 15.5 1.938 16 2.026 96%
62 14.25 1.625 14 1.549 105%
63 10 0.5 10 0.501 100%
64 10.75 0.563 11 0.631 89%
65 10.25 0.438 10 0.542 81%
66 15.75 1.75 16 2.132 82%
67 9.5 0.375 10 0.425 88%
68 15.25 1.75 15 1.923 91%
69 12.5 0.938 13 1.020 92%
70 14.5 1.625 15 1.638 99%
71 11 0.688 11 0.679 101%
72 8.75 0.25 9 0.327 76%
73 11.75 0.813 12 0.837 97%
74 14.25 1.25 14 1.549 81%
75 12.75 0.938 13 1.087 86%
76 12 0.75 12 0.896 84%
77 12.5 1 13 1.020 98%
78 9.25 0.313 9 0.391 80%
79 8.5 0.188 9 0.298 63%
80 7.75 0.188 8 0.222 85%
81 18 3.25 18 3.263 100%
82 17 2.625 17 2.720 97%
83 12.5 0.813 13 1.020 80%
84 16.5 2.375 17 2.473 96%
85 16 1.938 16 2.241 86%
86 16.75 2.5 17 2.594 96%
87 16 2.625 16 2.241 117%
88 16.5 2.188 17 2.473 88%
89 18 2.625 18 3.263 80%
90 11.5 0.75 12 0.782 96%
91 20 5.188 20 4.566 114%
92 16 2.125 16 2.241 95%
93 10 0.375 10 0.501 75%
94 16.25 2.125 16 2.355 90%
95 16.5 2.625 17 2.473 106%
96 15.5 1.875 16 2.026 93%
97 11.5 0.813 12 0.782 104%
98 13 1 13 1.156 86%
99 11 0.625 11 0.679 92%
100 11.75 0.75 12 0.837 90%
101 12.5 0.938 13 1.020 92%
102 10 0.438 10 0.501 87%
103 16.75 2.438 17 2.594 94%
104 16 2.125 16 2.241 95%
105 19.25 4.313 19 4.042 107%
106 11.5 0.563 12 0.782 72%
107 11.75 0.75 12 0.837 90%
108 11.75 0.813 12 0.837 97%
109 11 0.563 11 0.679 83%
110 16 2.063 16 2.241 92%
111 11.5 0.563 12 0.782 72%
112 16.25 2.438 16 2.355 104%
113 14 1.313 14 1.464 90%
114 16.5 2.438 17 2.473 99%
115 17.5 3.5 18 2.983 117%
116 16.25 2.125 16 2.355 90%
117 16.5 2.75 17 2.473 111%
118 16.25 2.125 16 2.355 90%
119 10 0.438 10 0.501 87%
120 8 0.188 8 0.246 76%
121 10.5 0.563 11 0.585 96%
122 11.75 0.625 12 0.837 75%
123 13 1 13 1.156 86%
124 13.25 1.125 13 1.228 92%
125 16.25 2.063 16 2.355 88%
126 13.5 1.25 14 1.304 96%
127 15 1.625 15 1.825 89%
128 11 0.5 11 0.679 74%
129 17.5 2.75 18 2.983 92%
130 10 0.5 10 0.501 100%
131 15.25 1.688 15 1.923 88%
132 12.75 1 13 1.087 92%
133 11.75 0.75 12 0.837 90%
134 8.75 0.25 9 0.327 76%
135 8.25 0.188 8 0.271 69%
136 22.5 8.25 23 6.648 124%
137 22.25 6.5 22 6.415 101%
138 15.25 1.688 15 1.923 88%
139 17.25 2.438 17 2.849 86%
140 15.5 2 16 2.026 99%
141 14.75 1.438 15 1.729 83%
142 18.5 4 19 3.561 112%
143 16 2.063 16 2.241 92%
144 15.75 2.125 16 2.132 100%
145 15 1.75 15 1.825 96%
146 17 2.625 17 2.720 97%
147 15.5 1.938 16 2.026 96%
148 13 1.25 13 1.156 108%
149 10.5 0.563 11 0.585 96%
150 10.5 0.5 11 0.585 85%
151 11.25 0.625 11 0.729 86%
152 11 0.625 11 0.679 92%
153 8.25 0.188 8 0.271 69%
154 8.5 0.188 9 0.298 63%
155 12 0.75 12 0.896 84%

 

This data places the 155 bass in an inch class giving the average relative weight.  Our 9 inch bass are the most out of sync, weighing in at only 72% of the average. 

 
INCH   CLASS TOTAL NUMBER OF BASS  IN THIS RANGE AVERAGE RELATIVE WEIGHT
8 4 75%
9 7 72%
10 7 88%
11 18 89%
12 23 88%
13 15 93%
14 8 92%
15 15 92%
16 25 95%
17 14 97%
18 9 104%
19 6 103%
20 2 101%
21  0                      
22 1 101%
23 1 124%
24 0  
25 0  
26 0  
27 0  
28 0  
29 0  
30 0  

 

CONCLUSIONS

The main goal for Lake Vilbig is to increase the frequency of largemouth bass that are 17 inches plus.  The three keys to accomplishing this goal are maintaining a harvest program for the bass, maximizing threadfin production, and establishing the bluegill population.

RECOMMENDATIONS

1)     Harvest about 1500 to 2000 bass in the 11” – 15” slot this next year.  Keeping harvest records with length and number kept will be very important.  You might want to have special tournaments harvesting the slot.  Harvesting aggressively at the beginning of the year leaves that much more forage for the rest of the bass during the growing season.  We occasionally have a market for bass of this size.  They trade out at the rate of about $3 per pound.

2)     Depending on visibility, fertilizing at 1 – 4 gallons per surface acre will increase lake production by 300 – 400%.  The immediate benefactors of such a program are the threadfin shad.  They are filter feeders and weight gain is directly linked to lake fertility.  Increasing their numbers will take feeding pressure off of the bluegill and improve the relative weights of the smaller bass.

3)     Stock adult coppernose bluegill (6”+).  Seventy-eight percent of the bass that were sampled cannot eat a bluegill greater than 5.5 inches in length.  The other 22% of bass have an abundance of food sources available.  Survival rates of these bluegill would be near 90% and they will begin spawning immediately.  Cost of jumbo coppernose when available is $.65 each.    Feeding a floating fish food is also a great way to increase growth rates and overall production.

click here for pictures 

Stocking Notes 

(Taken from conversations with Brad Metzler)

        It takes 10 pounds of forage to gain 1 pound on a bass.

        In our lake, shad are a big part of the bass diet.  Right now we have an excellent shad population but shad populations cycle.  Some years are good and some are bad.  If we have a bad shad year without the needed bluegills to fall back on, then our bass will suffer greatly. 

        The best time to build up the bluegill population is when there are large populations of shad that the bass can feed on.  This gives the bluegill a better chance to take hold.

        Bluegill should be the main forage food of the bass.  They do not have cycles like shad and once established in good numbers then they can be maintained without stocking. 

        When culling our fish we can be selective.  Bass with high modeling (lots of the black marks, dark in color, and football shaped) can be released in the slot.  These are most likely the Florida bass stocked over the years and we want to keep them in gene pool.   The bass that are plain, with little marking, light in color, and that are in the slots should be culled.  These bass can be traded for bluegill if not eaten.

        It is important to keep counts and measurements on our cull bass.

        Average bluegill stocking is 400 per acre.  Stock what you can.

 

           


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