TPWD 1956 F-2-R-3 #249: Inventory of Species Present in Lake Granite Shoals, Texas

STATE Texas PROJECT F~2mRm3 Job Bmlg PERIOD June 1955 through Januar 1955 SEGMENT COMPIETION REPORT 1 ll[ JOHN E. TILTON Assistant Project Leader TITLE Inventory of Species Present in Lake Granite Shoals, Texas. OBJECTIVES To determine the species present and their relative abundance. METHODS AND MATERIALS Fish collections and ecological observations were made monthly throughout the segment period. Three collecting methods were used in obtaining specimens for study. Seining and netting provided the largest number of individuals for study and were the primary collecting methods employed. One rotenone sample was obtained from a slough containing approximately three acre feet of water. Seine collections were made at random over the lake and specimens were pres served in 10 per cent formalin for later laboratory identification and study. Gill net sets were also made at random? but all Specimens taken were identified; weighed} measured, and checked for gonadal development in the field. Seining and netting locations are shown on Map I. Ecological data was recorded with each fish collection made. In addition water samples were taken and analysed. Two sampling sites were selected and one was visited each month. Samples were taken at 10 feet intervals from the surface to 30 feet. Temperaturefl in degrees Farenheit, dissolved oxygen in ppm, dissolved carbon dioxide in ppm, and pH were recorded for each depth. PHYSICAL DESCRIPTION Lake Granite Shoals is a lTTSOOO acre foot impoundment, constructed by the Lower Colorado River Authority. The lake is slightly over 19 miles in length, measured from Alvin Wirts Dam to the Arnold Dam at the head of the lake. Maximum width of Lake Granite Shoals is slightly less than 1.5 miles and the total area inundated is approxm imately 6,300 acres. The lake is designated asstpower supply reservoir and maintains a constant level, with water level fluctuations over two feet uncommon. The lake forms the boundary between Burnet and Llano Counties, with the dam about four miles from the town of Marble Falls, Burnet County, Texas. Alvin Wirts Dam, impounding Lake Granite Shoals, was completed in 1952 to become the sixth dam constructed on the Colorado River and stands third in the chain? below Lake Inks and Lake Buchanan. The major tributaries of Lake Granite Shoals are the Colorado River, Llano River, and Big Sandy Creek. The lake above the juncture of the Llano river is narrow, less than 200 yards in width, while below the river junction the lake increases in width and reaches its maximum of 1.5 miles a short distance above Alvin Wirtz Dam. The lake is located in the Central Basin of Texas in rugged hill country on the Burnetleano County line. The economy of the area is based on livestock, with cattle, sheep, wool, goats, and mohair as principal income sources. In addition, a fair tourist trade is enjoyed by both Llano and Burnet County with four lakes, excellent hunting, and some guest ranches available. Little farming is done in the area surroundw ing Lake Granite Shoals as the rocky, rolling country is much better suited to ranching. Dense growths of cedar, mesquite, post oak, and hackberry are found on the hills surrounding the lake while pecan, cottonwood, and willows are found in the creek bottoms and around the lake edges. The soils in the immediate area are derived from the underlying granite and in many areas solid granitic intrusions with little or no topsoil form the shoreline of Lake Granite Shoals. Rubble, granite gravel, mud, sand, and solid granite bottom types are all found in the lake with mud banks and bottom restricted largely to the upper end of the lake, while sloping sand, rubble, and granite bottoms characterize the lower end. Large areas of sandy shoals provide excellent spawning grounds for the centrachid fishes, while the sand and gravel shoals above the junctures of the three tributaries provide spawning areas for large numbers of white bass. The water in Lake Granite Shoals is generally clear, as Lake Buchanan and Lake Inks settle out a large portion of silt carried down by the Colorado River. As a recreation area, lake Granite Shoals is moderately popular with thirteen major resorts providing cabins and other facilities for tourists. Approximately 130 boats are available for rent from eighteen boat docks on the lake. Bait, tackle, and fishing information, are also available in a number of stores throughout the area. In addition, several free camp sites are found along the lake shore, erected by the L.C.R.A. and Burnet County for use by both local citizens and tourists to the area. AQUMTEC VEGETATION AND COVER Lake Granite Shoals supports a large growth of aquatic plants with two types, coontail, Cerataphvllum sp., and parrot feather, Myriophvllum sp., accounting for the bulk of the shallow water vegetation. During the late spring, summer, and fall months, shoreline areas to a depth of over ten feet, are so choked with these plants that shore fishing is difficult and boat travel in the shallow area practically impossible. Probably due to the relatively short time the lake has been inundated, other aquatics are not too numerous. Some willows, Salim nigra; saw grass, Zizaniopsis sp; and Cattails, Typha sp. are found along bank areas, but to date present no problem from over abundance. The coontail and parrot feather provide excellent cover for sunfish, black 3. bass, a variety of shiners and other small fish. In addition, large areas of the lake are former timber land and which was imperfectly cleared before impoundment, and now provide submerged timber and natural brush piles throughout the lower portion of the lake. Large granite boulders, rubble, and man made break waters provide many crevices and nooks as cover. CHEMICAL CHARACTERISTICS water samples were collected from one of two sampling sites each month, depending upon which section of theiake was being worked. Samples were taken at ten foot intervals from surface to a maximum of 30 feet. Dissolved oxygen, dissolved carbon dioxide, pH, and water temperature were recorded from each depth sampled. No unusual chemical or thermal conditions were found in the waters of Lake Granite Shoals throughout the segment period, and no traces of pollution were noted. The results of chemical analysis are found in Table I. FISH COIIECTIONS Table II contains a checklist of species taken in Lake Granite Shoals during the segment period. A total of 29 species were taken and undoubtedly the list will be increased during the next segmemzperiod when the area near the mouth of the Llano River is more intensively worked. Table III shows the results of seining collections during the segment period. A total of 1,396 individuals representing eighteen species were collected and identified in the laboratory. The spottail shiner, Notro is venustus, was the most abundant species taken in seines, with a total of A25 or 30. per cent of the total number, while the bluegill, Lepomis macrochirus, was second with 193 specimens and 13.82 per cent of the total number. Of the more desirable game fish, the largemouth black bass, Micropterus salmoides, was the most abundant with #1 individuals making up 2.93 per cent of the total. It is interesting to note that during the segment period, rough fish and forage species excluding sunfish, made up 71.71 per cent of the total number of seined specimens. Table IV lists the number of specimens taken in gill nets during the segment period. The data is presented by months and includes consolidated total both in num« bers and per cent of total. ' The gizzard shad, Dorosoma cepedianum, accounted for the largest number of individuals, with #31 specimens and 27. 2 per cent of the total number taken. Second most abundant species netted was the river carpsucker, Carpiodes carpio, with 225 inm dividuals and 1h.52 per cent of the total. The white bass, Morons chrvsops, and white crappie, Pomoxis annularis, were the most numerous game fish with 197 white bass (12.71 per cent of total number5 and 176 white crappie (11.37 per cent of total number) taken during the segment period. As in other lakes on the Colorado River chain, rough fish dominated the catch with 991 specimens of a total of 1,5h9 fish taken, or 63.98 per cent of the total. However, as shown in Table IV, rough fish made up less than onemhalf of the total weight netted with t65.85 pounds, or t5.58 per cent of the 1,022.11 pounds taken in gill nets during the segment period. A game species, the white bass, cone tributed the largest amount of total weight with 217.9M pounds and 21.33 per cent of total weight. The river carpsucker, Carpiodes carpio, was second with 181.h5 pounds and 17.76 per cent of the total. The flathead or yellow catfish, Pilodictus olivaris, h. contributed 135.33 pounds to the total, due primarily to the capture of several large individuals in the upper end of the lake near the mouth of the Llano River. Table VI records the number of pounds of fish per foot of net both in con- solidated totals and by month. One rotenone collection was made in January on a small slough containing approximately three acre feet of water. The average depth of the treated area was seven feet and maximum depth was twelve feet. It was felt that a large fish population would be present in the area even though water temperatures were in the low 50's. The area was treated with rotenone and the result was extremely disappointing, although a complete kill was assured by the amount of rotenone used. A total of #15 fish were taken, including 288 bluegills under four inches in length. With the exception of one channel catfish, I. punctatus, three log perch, P. caprodes, and one orangethroat darter, E. spectabile, all individuals were juveniles. Rotenone specimens were not included in total weight or total number figures in the report. DISCUSSION Lake Granite Shoals is undoubtedly one of the best fishing lakes on the Col- orado chain. The lake is easily accessible to fishermen, facilities for the sportsman are available, and excellent catches of all game species were observed during the segment period. However, several problems are forming in regard to continued fishing and fishing success. Aquatic vegetation, particularly, Myriophyllum sp. is becoming a distinct prOblem. With little water level fluctuation and relatively mild winters, this plant species has gained a solid foothokiand threatens to congest the lake to such an :tent that fishing will be difficult or impossible. large sections of the lake, part- icularly shallow sloughs and shoreline areas are becoming more congested each year. Camp operators and boat dock owners carry on a year round campaign to open boat paths for access to the lake, relying on mechanical means which is both an expensive and temporary measure. An effective method of vegetation control or eradication is needed to prevent the further encroachment of Myriophyllum sp. into the better fishing waters of the lake and to open areas which are now closed to fishermen. Rough fish, a constant problem in Texas lakes, are already extremely abundant in Granite Shoals, and with the passage of time will undoubtedly increase tremendously in both numbers, and particularly, in total weight. The average weight for all species of rough fish taken in Granite Shoals is now below the average for other lakes which have been surveyed on the Colorado chain. With a relatively high fertility and too few large predators, the rough fish will continue a rapid growth, taking a high percentage of the natural productivity of the lake, to the detriment of the more important game species. With abundant cover, excellent spawning areas and a variety of habitats, Lake Granite Shoals produces large numbers of game fish to the sports fishermen. Fishing pressure is light on this lake and it is felt that a desirable recreation area is not being utilized to its potential and that much larger quantities of game fish could be taken if fishing pressure were increased. Probably only a small segment of the potential crop of edible fish is now being harvested, leaving a large surplus untouched and wasted each year. Results of stomach analyses have not been included but will be presented in .e Job Completion Report at the end of the next segment. SUMMARY 1. Lake Granite Shoals, the third lake in the Colorado River chain of lakes was inventoried for species present and relative abundance. 2. A large rough fish population was found to occur, although average size of individuals was relatively small due to the age of the lake. 3. Over abundant aquatic vegetation, particularly parrot feather, is rapidly becoming a prdblem, as it is closing large shoreline and shallow areas to fishing and boat travel. ‘ A. A large game fish population of desirable size individuals was found to occur in the lake and good catches of game fish by sportsmen were observed during the segment period. 5. No adverse thermal or chemical conditions were found and no evidences of pollution noted. Table 1. Lake Granite Shoals water Analysis, July 1955 through January 1956. Depth Air water DATE in Temp. Temp. pH 02 C02 Feet 0F 0F ppm ppm __1____111_1________________1______1l1_._.____1_________._l_l_______ll____ll__l_.___________ July 1 85 85 8.2 8.8 h 10 85 8A 8.1 8.6 5 20 85 8A 8.1 8.1 12 August 1 95 90 8.2 8.7 5 10 95 86 8.0 8.3 7 20 95 80 7.6 7.6 1h 30 95 80 7.# 7.5 17 September 1 93 86 8.2 10.0 0 10 93 82 7.9 6.5 10 20 93 81 7.6 u.0 20 30 93 81 7.6 1.0 30 October 1 93 8h 8.1 9.0 3 10 93 83 7.8 2.0 7 20 93 82 7.6 5.0 10 30 93 81 7.5 0.0 9 November 1 70 69 7.8 10.0 trace 10 70 69 7.8 8.2 2 20 70 69 7.7 7.0 6 30 70 69 7.7 5.h 12 December 1 67 58 8.2 9.0 O 10 67 58 8.2 6.0 3 20 67 57 8.1 u.o 6 30 67 57 8.1 u.0 10 January l #1 55 8.3 -~ trace 10 ' #1 5A 8.3 8.7 trace 20 Al 53 8.2 8.6 trace 30 A1 51.5 =8.1 7.h 1 7. Table 2. Checklist of Species Found to Occur in Granite Shoals Lake. Scientific Name Lepisosteus platostomus Lepisosteus osseus Dorosoma cepedianum lctiobus bubalus Carpiodes carpio Moxostoma congestum Cyprinus carpio Notropis venustus Notropis lutrensis Pimephales vigilax Campostoma anomalum lctalurus punctatus Pilodictus olivaris Gambusia affinis Morons chrysops Micropterus punctulatus Micropterus treculi Micropterus salmoides Chaenobryttus coronarius Lepomis cyanellus Lepomis microlophus : 3mis macrochirus Lepomis auritus Lepomis megalotis Pomoxis annularis Percina caprodes Etheostoma spectabile Aplodinotus grunniens Cichlasoma cyanoguttata Common Name shortnose gar longnose gar gizzard shad smallmouth buffalo river carpsucker gray redhorse carp spottail redhorse shiner parrot minnow stoneroller channel catfish yellow catfish gambusia white bass- Kentucky spotted bass Texas spotted bass largemouth black bass warmouth green sunfish redear sunfish bluegill sunfish yellowbelly sunfish longear sunfish white crappie logperch orangethroat darter freshwater drum Rio Grande perch m. 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