TPWD 1954 F-5-R-1 #61: Inventory of Species in San Angelo Reservoir

STATE Texas PROJECT NO. FwaRel, Job B~3 PERIOD June 22, l953 « June 22, lQSN m_ah_h__"____"fl_m_m_____fl_mmw_mm Segment Completion Report Lawrence Campbell in g Project Leader 5 -”' TITLE Inventory of Species in San Angelo Reservoir. OBJECTIVES To determine the species present and their relative abundance as well as to deter- mine the ecological factors:mfluencing their distribution. PROCEDURE Fiftyefour gill net collections were made at 23 netting stations in the San Ange~ lo Reservoir. Experimental nylon gill nets measuring 125 ft. long x 8 ft. in depth and made up in five, 25 ft. sections, were used. Mesh size for these nets increased progres~ siveiy in each following section at oneuhalf inch intervals beginning with onewinch mesh and terminating with a three inch mesh section. Nineteen seining collections were made at fourteen localities along the lake shore. Tn nearly all colle ctions both 26 ft. %" mesh bag seines and i5 ft. %” mesh common sense ines were used. To estimate relative abundance a count was made of all individuals tak- en in two hauls with a 26 ft. fi” mesh bag seine for each collection. In addition, sein~ ing where abundance data was not taken, a four ft. common sense seine with a l/lo” mesh was used to collect fry after the spring spawning by fishes. Water analysis for dissolved carbon dioxide and oxygen content was taken each month and surface temperature, pH and the climatic condifions mere recorded for one h netting and seining collection. Turbidity was recorded on four occasions. To make a detailed study of the largemouth black bass population, 2,237 individuals of that species were tagged and released at eight localities in the reservoir. In net collections, most fish were identified, counted, weighed, measured and seem ed in the field. A sample number of each species were examined for stomach content and a scale sample taken. On occasion it was necessary to preserve an individual, its stomach or some other organ for more detailed examination in the laboratory. When this was re- quired, the speciment was preserved in lO% formalin. FINDING is located approximately 6.5 miles above the confluence of the South and North Concho Rivers, Because the dam is primarily for flood control, the maximum lake elevation prac~ tical for permanent water conservation is l,908 feet above mean sea level. At that ele— tion, the lake would have S,hhl surface acres and contain about90,000 acre feet of water. Elevation l,886 is designated as dead storage, the area allocated for siltation. The water rights for the area between l,886 and 1,908 are owned by the City. The water, ll? .1. used primarily for municipal and industrial purposes. However, ossibility. t elevation 1,936 emergency spillway level, the Main about 391,000 acre feet and have 12,698 surface acres. Maximum “s l,OOQ acre feet. In June l95t, the lake level was at 1,891. The contributing watershed of l,677 square miles is predominately San Angelo sand“ stone formation and top soils are usually Abeliene sands and Frio silts and loans. Vegan tative cover is primarily mesquite-grassland association and the area is used almost ex— clusively for farming and ranching. Climate for the watershed is semi—arid, having an average annual rainfall of 19.83 inches. The average annual discharge of the North Con— cho River is h7.h c. f. s.; however, a maximum discharge of 9h,600 c. f. s. was recorded in September of l936 and recent discharges have averaged 1.67 c. f. s. in 1952 and 39.3 c. f. s. in l9§3. The laheis water is usually clear and no recordable turbidity was observed except following floods. Maximum surface temperature recorded was 79 degrees F. and a minimum was to degrees F. pH was 8.3 _ 8.h. A maximum carbon dioxide content of 1h ppm was re— corded an the minimum dissolved oxygen, taken at that time, was 4 ppm. Dissolved carbon dioxide is usually about ll - 12 ppm and oxygen usually about 5 m 8 ppm. Excepting algae and small pleagic forms, there is no aquatic vegetation in the San Angelo Reservoir. The areas north of the river channel to elevation 1,886 and south of the channel to elevation 1,908 were cleared of all woody vegetation prior to inundation. NETTING COLLECTIONS As shown in Tables 1 and ll, fifty-four experimental gill net sets resulted in the capture of 1,7sl individuals of fifteen species, an average of .257 fish per ft. of not set. In Table l, collection data shows a marked increase in the numerical percentages of .rp (Cyprinus carpio), carp suckers {Carpiodes carpio) and drum (Aplodinotus grunniens) and a corresponding decrease in largemouth black bass (Micropterus salmoides). In_Table ll, the over all average percentages are believed to be somewhat misleading for that ream son. however, it is possible that percentage81hr river carp suckers, largemouth bass and southern channel catfish (Ictalurus punctatus) may be excessive. Drum and white crappie {Pomoxis annularis) are probably more numerous than indicated. In all instances {except three} four experimental gill nets were set at established netting stations. In June and July 1953, insufficient equipment prevented setting a standard for sampling and two experimental nets were set for each of those collections. In January, six experi» mental nets were used. The January collection is also known to be biased because three nets were set in the upper lake where water was confined to the old river bed. The usual number of nets set in that station is one. Of 212 river carp suckers taken in the colleen tion, 168 were from the three nets set in the upper lake and advanced sexual development in that species indicated a pre—spawning concentration. SElfilflfi CGLLECTIONS Suitable permanent seining stations were difficult to locate and because of lake level fluctuation (from 7,736 acre feet in June 1953 to a maximum of h7,372 acre feet in June of 195t.3, changes in the location of all seining stations were necessary. For that reason, the numerical percentages for several species shown in Table 111 are believed to bezh error. The biasinduced by the required relocation of seining sites makes the reliw ability of all seining data questionable. However, this data appears to be a more rew liable indicator of the actual numerical percentage of some of the smaller forage species (notably Notropis) and for sunfishes (Lepomis). The selectivity of this method is damn estrated by its failure to capture any southern channel catfish (Ictalurus punctatus), smallmouth buffalo {Ictiobus bubalus) carp (Cyprinus carpio), freshwater drum (Aplodinotus grunniens) or several other species known to occur in the lake. La.) REMARKS Both netting and coining collections produced a greater number of individuals a,i s-ecies in the third and fourth quarters than were taken during the first half of th period. For the named reasons, inconsistency in data for the period because the lace is increasing but is seventeen feet below conservation pool elevation and because it is believed much can be determined by a continued study of population trends, it is concluded that at least another year’s work is necessary before this inventory can be completed. "”5 1. 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'1‘“. 151 Checklist 0f F1 5h June 22, Common Name Langnfise gar Gizzard shad a11m0ufih buffalo River carpsucker G13“ redhsrse sucker Galden Shiner Blacktail Shiner Red Shiner Parrafi m1nnow Southarn channel catfifih Yel1gw bullhead Flathead atfish gamma n moaquibmfish Whifie bass 1ask bafia Largamfiuth b waymauth 118$ Spfitted Sunfish Bluegill @rangaapmttcfi sunfis.h {$11 Sunfigh w 3Mb11y Western langear sunfish Freahwater drum f R; Cr" Reserqoir a11 Angalo 31 195h Scientific Name 'Lepisasteus osseus Darosoma cepedianum Ictiobus bubalus Carpiodes carpia meostoma congestum Cyprinus carpig Notemiganus crysaleucas Notropis ventstus Notrapis lutrensis Pimephales vigilax Ictalurus punctatus Ameiurus natalis Pilodictus alivaris Gambusia affimig :1r0ne ehrys Ops U M1nrap+nrug 13.111916 ea Qhaanabryttug caranariufi Lepamis cyanellug Lepamis microlcphus Lepomis punctatus Lepomis macrochirus Le 890 M1 humilis Lepomia auritus Lepamig megalot1s Aylod1n01us grunniens Fiftvmfour will net eolleetione end nineteen seinin cdlections were made. J e Water enelyeie wee taken each month: Climatic conditions recorded end all fiehee captured‘were identified Fer population etudiee, a sample number 0f each species were weighed, mee« enred and ether pentinent data recorded" Food, growth and age etudiee were begun for the more impertent species, A special etndy of largemoeth bleek bees wee started” 2,237 individuals were tagged“ in abundance and dieteibutien work, 1,7hl individuals of fifteen species were taken by gill nets and 2,5QT individuals of 16 species were taken by eeining. Eeeenee of inconsistencies in date taken thus far, end because the lake is below the elevation deeigneted as its conservation level, further work is required before the inventory can be completede SAN ANGELO RESERVOIR ARDEN ROAD