TPWD 1974 F-5-R-21 #1581: Region I-B Fisheries Studies: Ecological Evaluation of Striped Bass in Lake E. V. Spence

PERFORMANCE REPORT As Required By FEDERAL AID IN FISHERIES RESTORATION ACT TEXAS Federal Aid Project No. F-5-R-21 REGION I-B FISHERIES STUDIES Objective XV: Ecological Evaluation of Striped Bass in Lake E. V. Spence Project Leader: Billy J. Follis Assistant Project Leader: David J. Morris Clayton T. Garrison Executive Director Texas Parks and Wildlife Department Austin, Texas Lonnie J. Peters Robert J. Kemp, Director chief, Inland Fisheries Fish and Wildlife Division ‘March 15, 1974 Abstract This report represents one part of a study undertaken to measure the ecological factors that may influence and be influenced by the success of striped bass introductions in Lake E. V. Spence. Three enclosures (2.33 acres) in Lake E. V. Spence were treated with rotenone to obtain a total fish kill. Of 363 marked fish introduced into the enclosures, 204 (56.20 per cent) were recovered. There were 5,595 unmarked fish weighing 292.13 pounds recovered. A total standing crop of 4,272.76 fish per acre weighing 223.13 pounds per acre was estimated. This standing crOp exceeded that of 1972 probably because of the rapid lake expansion in 1971. Essentially, a new lake had been created and carrying capacity had not been reached by the time of the 1972 rotenone sampling. Monthly physicochemical profiles obtained near the dam and elsewhere indicated stratification from May through August. Striped bass, which prefer cooler water, may have concentrated in a narrow zone above the thermocline in late summer because of the low oxygen levels below 30 feet. A significant fresh- water influx in March affected chemical readings in March, April and May. State: PERFORMANCE REPORT Texas Project Number: F-5-R-21 Project Title: Region I-B Fisheries Studies Study Title: Ecological Evaluation of Striped Bass in Lake E. V. Spence Contract Period: From March 1, 1973 To February 28, 1974 Program Narrative Objective Number: XV Objective: To measure the ecological factors that may influence and be II. influenced by the success of striped bass introductions in Lake E. V. Spence. Segment Objectives: 1. To determine, by rotenone sampling, species composition and estimated standing crop of fish in Lake E. V. Spence. 2. To collect and analyze basic limnological data. 3. To tabulate data for comparison with the results of other studies of striped bass introductions in Texas and other states. Summary of Progress: In August, 1973 a 0.50uacre cove, a 0.92-acre straight shoreline area, and a 0.92-acre shallow open-water area in Lake E. V. Spence were blocked off with 3/4—inch mesh netting. Test fishes, each marked with a hole punched in its caudal fin, were introduced into each enclosure. Rotenone (5% powder) was applied at the rate of 4 pounds per acre-foot. Fish were collected from each enclosure for 48 hours following treatment, sorted and counted by species and inch-groups (total length). Test fishes were counted separately to estimate overall recovery percentages. Ten or more unmarked fish of each species inch- group were weighed to estimate the total weight of fishes in each cove. Between the 10th and 20th days of each month from March, 1973 through February, 1974, water samples were collected and hydrologic measurements made at one or two stations in Lake Spence. The temperature profile was determined with an electronic probe in the deepest water near the dam. A water sampler was used to collect samples from the surface and the bottom. Part of each sample was preserved for analysis by the regional chemist and the remainder analyzed on the spot for dissolved oxygen content. If the temperature profile revealed evidence of stratification, additional samples were obtained from the top and bottom of each distinct stratum. Also additional measure— ments were taken at a sampling station midway up the lake. -2- A summary of the actual recovery of unmarked fish by species is shown in Table 1. The total treated area from which these fish were recovered was 2.33 acres. A summary of marked fish releases and recoveries by species and length classes is shown in Table 2. Of 363 marked fishes released in all 3 enclosures, 204 (56.20%) were recovered. Table 3 is an estimate of the total standing crop per acre by Species. This figure was derived from total number and weight of fish recovered on 2.33 acres adjusted by the percentage of marked fish recovery (56.20%). Although the treatment sites were selected to be as representative as possible of the different lake environments, several species of fish known to be present in the lake were missing from the sample: white bass, blue catfish, black bullhead, flathead catfish, and golden shiner. Small fishes such as silversides and minnows were underrepresented because of the difficulty of recovering them with dip nets, predation of dying fishes by larger fishes during the treatment, and the tendency of small fishes to appear briefly on the surface and, then, sink and decompose rapidly on the bottom. Comparison of 1973 (Table 3) with 1972 (Table 4) rotenone sampling results indicates a larger standing crop in 1973. A graph of lake level fluctuation (Figure 1) shows that Lake Spence expanded greatly in 1971 (from 1808.1' ESL on May 26 to 1855.1' on September 29). This rise increased the total lake surface 1,000% and its volume more than 5,000%. Essentially, a new lake was created and carrying capacity of fishes had not been reached at the time of the 1972 rotenone samples. Cfi¥The lake was at or near carrying capacity by the time of the 1973 samples. Table 5 summarizes Lake Spence temperature profiles near the dam from March, 1973 through February, 1974, A strong temperature gradient was evident from 45 to 50 feet below the surface in May and a distinct thermocline was detected at the 35-40 foot level in June, July and August. The stratification had dissipated by September 14, probably due mostly to high winds and rain in early September (remnants of Hurricane Delia). Table 6 shows dissolved oxygen concentrations at various depths during the year. In August, lake water with oxygen concentrations higher than 1.2 ppm wasrat temperatures from 780 to 85°F. Striped bass, which prefer cooler water, were probably concentrated in narrow, cooler lake zones and were relatively inactive at this time. This may explain why only two were collected in the August rotenone sampling. Selected chemical parameters, from analyses made by the regional chemist on Lake Spence water samples, are shown in Table 7. The samples were collected concurrently with the dissolved oxygen and temperature measurements shown in Tables 5 and 6. Lake chemistry appeared generally stable. Lower values for total hardness, chlorine, total dissolved solids, and conductivity in March, April and May probably resulted from a substantial influx of fresh water in early -3- Table 1 LAKE E. V. SPENCE AUGUST 1973 ROTENONE SAMPLE RECOVERY OF SPECIES BY NUMBER.AND WEIGHT Total area treated: 2.33 acres Species Number Wei ht lbs. Threadfin shad 863 9.88 Gizzard shad 2,538 140.63 River carpsucker 31 17.89 Carp 30 28.15 Red shiner 24 0.08 Blacktail shiner 10 0.04 Bullhead minnow 91 0.18 Channel catfish 67 27.29 Mosquitofish 2 0.01- Tidewater silverside 109 0.18 Striped bass 2 0.10 Largemouth bass 98 15.35 Warmouth 17 0.56 Green sunfish 195 4.46 Redear sunfish 19 0 23 Bluegill 1,363 43.39 Orangespotted sunfish 26 0.37 Longear sunfish ~ 98 1.84 White crappie 3 0.31 Freshwater drum 9 1.20 TOTAL RECOVERED 5,595 292.13 .14. — RENEEEEENMNENEEEMEE Wm <._.O._. a nun. n nuummmnmm-w- m n -- Hun-wini— o..._ m E.- I-nun—EE-I g... i E.- -- nun-=- s nun-IMEEEEEE .80 m .- IiIImIIIIIIIE _ :fiér as E... Ill-II IEIIIII .Eéjél as m III-IIEEEI III-III. resin 25 m EmmfimmmmmmfimmlmlIll .éaéio a? E IllnllIllIIIIIfimmVi Eario 82 E III IIIEEEEEEEIII I to 1.. m sun-I-mmm-mnun-E-u Fauna 95. an «N a on e e m. z e N. z o. a o s a n l. m Scam, owwwumwwm ”Mn ...... w E $848 52 §m>8mx ImE GEM/>2 QmZmEOu .ZHOH mna. HflDQD< @5373 MZDthbm muzmmw .>.m_ .524 N a: ion—n _5_ Table 3 ESTIMATED STANDING CROP OF FISHES IN LAKE E. V. SPENCE Based on rotenone sampling with 56.20% marked fish return Total area treated: 2.33 acres August 1973 Species No./Acre Wt.g1bs)/Acre Threadfin shad 659.05 7.55 Gizzard shad 1,938.20 107.40 River carpsucker 23.67 13.66 Carp 22.91 21.50 Red shiner 18.33 0.06 Blacktail shiner 7.64 0.03 Bullhead minnow 69.49 0.14 Channel catfish 51.17 20.84 Mosquitofish 1.53 Trace Tidewater silverside 83.24 0.14 Striped bass 1.53 0.08 Largemouth bass 74.84 11.72 Warmouth 12.98 0.43 Green sunfish 148.92 3.41 Redear sunfish 14.51 0.18 Bluegill 1,040.89 33.14 Orangespotted sunfish 19.86 0.28 Longear sunfish 74.84 1.41 White crappie 2.29 0.24 Freshwater drum 6.87 0.92 TOTALS 4,272.76 223.13 -5- Table 4 ESTIMATED STANDING CROP OF FISI—IES IN LAKE E. V. SPENCE Based on rotenone sampling with 45.45% marked fish return Total area treated: 3 acres August 1972 Species No./acre Wt.§1bs)/acre Threadfin shad 147.3 0.93 Gizzard shad 1,567.7 60.48 River carpsucker 9.7 5.97 GoldfiSh 0.3 0.14 Carp 137.3 81.02 Golden shiner 9.0 0.35 Red shiner 0.7 Trace Channel catfish 20.3 8.84 Blue catfish 1.0 0.15 Black bullhead 1.0 0.09 Flathead catfish 0.3 0.01 Silverside 0.3 Trace White bass 0.3 0.32 Striped bass 3.7 0.13 Largemouth bass 18.0 8.58 Warmouth 23.3 0.24 Green sunfish 130.3 2.40 Redear sunfish 3.3 0.08 Bluegill 1,232.7 20.70 -7- Table 4 ESTIMATED STANDING CROP OF FISHES IN LAKE E. V. SPENCE (Continued) Species No./acre Wt.(lbs)/acre Orangespotted sunfish 32.3 0.31- Longear sunfish 47.7 1.01 White crappie 12.0 2.64 Freshwater drum 3.0 0.37 TOTALS 3,401.5 194.76 mow. .223 ""l'" 0:: mum...“ l" ME. hard. " II 93. «who. E mun. mdeN 0mm. hum“. li JM>MJ (mm ado... scion mow. 2(m: Ill m>om< Emu oao._h cam. mm... .5 I mm. do. 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