TPWD 1957 F-2-R-4 #325: Inventory of Species Present in Lake Austin, Texas

--- Page 1 --- STATE PROJECT Be, Job Completion heport John E. Tilton Assistant Project Leader TITLE Tnventory of Species Fresent in Lake Austin, Texas. OBJEC TL VES To determine the species present and their relative abundance. JOR TEAMINATION Although originally scheduled to run from February 1, 1956 through January fhis project was terminated on dune l, 1956. Material collected during the riod, combined with date available from Texas Gawe and Fish Commission Ad ¢ auring G51 and 1952, appeared sufficient for the project. ? 9 YE 2 In addiétion i+ was felt that the time allocated to this project could be more tably spent on. Job Eee, Experimental Locetion of Black Bass in Lake Tre iViS o DS AND MATERTALS Fish collections and ecological chservations were made monthly throughout study perlod. Two collecting methods were employed in obtaining specimens for study. Seine mS were made at random over the lake and To. specimens were taken by this All specimens taken iu seines were pre served in 10 pereent formalin and t sry for identification and stud Both 36 x6 foot bag seines and 30 x seines were used for the Aa ; nS. net Webs Gobet. Cboservations on botlom type, shoreline, vegetation and cover, and turbidity ted for each collecting station. Water se taken each month fa) oxygen, dissalved carbon dioxide th of 10 feet, and where water = a yry ee Fea yers semples were tted, from 15 “SICAL DESOPEITION Lake Austin, impounded by Tow Milier Den, is as 20,000 acre foot lake covering --- Page 2 --- approximately 3,000 surface acres. Although 20 miles in length, the lake hes a maximum width of slightly more than one-fourth mile with a maximum depth of slightly over 50 et near the Tom Miller Dam. With the exception of the old river channel, the lake is <elatively shallow and above the confluence of Bull Creek, water depths rarely exceed 15 feet even in the channel. Tye lake itself if situated in the rugged limestone hilis of eastern Travis County. The surrounding country, with the exception of that portion which lies in a povulous area of Austin, is cedar covered ranch country largely used for production of goats and cattle. The entire lake is incorporated in the city limits of Austin although bank areas in most sections are not included in the city limits. VEGETATION AND COVER Aquatic vegetation, particularly Myriophyllum sp., is a constant problem to poat operators and fishermen. ‘The shallow waters encourage luxurient growth of the aquatics. To combat the vegetation problem the city of Austin lowers the water level of the lake in February and early March for a period of approximately three weeks. The vegetation was definitely retarded during the spring months, although during May the problem was again becoming acute and will undoubtedly be a major problem before the fall months The heevy growth of Myriophylium in the shoreline areas provides abundant cover for the young of many epecies etaeren| the centrarchids. Little other natural cover 48 available in Lake Austin, as the lake is 8 primarily confined to the second bank of the ~{ginal Colorado River bed which was agiiebinetby free of heavy timber and brush. Some willow, Salix nigra, is present and the heavy root eye roc cover as do the natural rock and rock crevices of the lake. Limited numbers of brush piles have been added by individuel land owmers in an attempt to impreve fish ving around priv-= ate docks. In a Game and Fish Conmission personnel, with the permission of cooparating land owners, half cut willows to provide cover in the Turkey Cregs area of the lake. ‘This in was done in 1951 and some cover was still : 1959 segment period. WATER CONDITION ON Lake Austin receives its water from Lake Travis through the generators of Maus- field Dam. The water entering Lake Austin comes from a depth of over 160 feet and at the time of discharge from the generators is cold and oxygen deficient. The water is throughly serated in the first hundred yards by extremely swift currents over rubbl and howlder bottom. Twoehundred yerds below the actual point of discharge the wate contains a satisfactory oxygen content. During the four month — period no adver thermal or chemical conditions were noted. Water temperatures varied slightly with e a 56°F high in February to 61°F high in May. During the segment eet no measurable tempe erature difference was found between the surface and 10 feet. i a) Dissolved oxygen averaged 9.2 ppm with a high of 10.6 ppm and a low of 8.4 pp. Dissolved carbon dioxide was consistently low with a high of three pom in March. ‘The ~H varied from 7.8 to 8.6 ppm, with an average of 8.2. Throughout the segment period the water was quite clear due to the filtering action of the five lakes above the impoundment. --- Page 3 --- FISH COLLECTIONS A total of 34 specimens were found to occur in Leke Austin and a checklist of species is included in Table 1. Records are available on 763 netted specimens from Lake Austin including 396 individuals from the 1951-53 period and the 367 specimens taken during the short 1956 segment period. Of the 763 fish total, 614 or 80.47 percent were rough or forage species. Desirable game eapecies including channel catfish, blue catfish, flathead cate fish, white bass, the centrarchid bass and white crappie made up only 11.92 percent of the total, with channel catfish accounting for over half of this figure. The gizzard shad was the most abundant species with 296 individuals or 35.26 percent of total. numbers. Freshwater drum with 149 individuals or 19.52 percent of total numbers would appear to rank second in abundance. However, one 200 foot gill net set produced 137 of the 149 individuals, predominantly sexually mature males in spawning condition. Quite probably the net set was made in the path of a spawning migration and this figur docs not represent a true relative abundance figure for this species. Tn total weight rough and forage species, excluding sunfish, contributed a Soh .43 pounds of the 943.06 total or 85.31 percent. Smallmouth buffalo made up 35.31 percent of the total weight with 336.82 pounds. The gizzard shad was second with 15.99 percent of total weight or 150.76 pounds. Game species, excluding sunfish, contributed only 13.64 percent of total weight ith chennel catfish again making up about 50 percent of this figure. Table 2 gives the number of specimens taken in gill nets, by month during the short 1956 segment period and includes totel numbers and percent of total number. Table 3 presents the same informaticn for the 1951-53 period but is broken down into quarterly rather than monthly totals. Tables 4 and 5 give the total weight and percent cf total weight figures for the two collecting eHiods » Table 6 presents a consolidated total ineludine total number, percent of nuuber, totel weight, and percent of total weight by species for all netted specimens from the two collecting pericads Table 7 shows the success of gill netting in terms of number and pounds of fish for the 1956 segment peciod only. A conrparison ef results from the two collecting periods shows reasonably similar figures for most species. However, smalimouth buffalo, gizzard shad, and freshwater drum show significantly different results. ‘The freshwater drum relative abundance figure has been explained but the great variation in relative abundance of smallmouth buffalo is nov understood. From observations of the catch of commercial fishermen it is known that a large population is present and maay were seen spawning in shallow sloughs. Although #ill nets were set at rendon over the Leke very few buffailc were tsken. From observa» tions of commercial catches and spawning concentrations the small mouth buffalo is une doubtediy more abundant than the collecting figures for the 1956 segment period would Indicate. Although netting results for gizzard shed show strikingly different results, it is probably a difference in individuel size and not abundance. As shown in the 1951-53 --- Page 4 --- 4, seining collections the gizzard shad was ebundant in Lake Austin at that time but the bulk of the population was composed of young shad, too small for gill net capture. During the 1956 segment period few small shad were taken. Although still very abundant in the lake, the population is primarily composed of large adults easily taken by nets. Apparently some factor or combination of factors has reduced the shad spawn or young during the previous year, leaving a population of large individuals. Seining produced a total of 7,778 specimens during the combined collecting periods. Of this number, only 724 individuals were taken during the 1956 period. Twenty-four seining collections were made and frequently less than 15 specimens would be taken at a station. The most abundant species taken in the seining collections was the gizzard shad with 2,721 individuals or 34.98 percent of the total. Second in abundance was the spot- tail shiner. Of the more important game species only the spotted and largemouth bass were abundant, with a combined total of 399 individuals or 5.11 percent of the total seined specimens. All sunfish combined made up 23.27 percent, with the bluegill account- ing for over 50 percent of the sunfish taken. Table 8 gives the number of specimens taken in seines during the 1956 collecting period. Table 9 presents the same informa- tion for the 1951-53 period and Table 10 is a consolidated total for all seining collec- tions. DISCUSSION Lying within the city limits of Austin and easily accessible from all sections of the adty, Luke Austin has become a major recreational area. The lake shore is exten= sively developed with beth permanent homes and weekend cottages. With the tremendous increase in boat traffic, water skiing and other aquatic sports over the past few years, the ardent fishermen have turned to the quieter waters of the larger lakes im the Colorado chain. The configuration of the lake itself leaves little room for the fishermen. Narrow and lacking the sloughs and inlets of the lerger lakes, it is very difficult to escape the violent wakes of the fast moving motor boats. Netting on Lake Austin was accomplished by setting nets as near dark as poss= ible and retrieving them before daylight in the morning, as working witb nets during daylight hours was seriously hampered by the heavy traffic. Fishing pressure on Lake Austin was extremely lignat during the short segnent pericd considering the lakes proximity to a population center of nearly 200,000. Overabundant aquatic vegetation, a large rough fish populaticn, crowding of available water by many boating enthusiasts, oll combine to discourage the fishermen. Because of its location near a population center of thie size, Loke Austin could again become a very popular lake end draw a far lerger share of the local anglers, Several years ago fishing was very popular on the lake as it wes poseible for Austin Residents to fish the leke before working hours in the morning and after five in the afternoon. To draw the fishing public back to the lake, some form cf equalization for aveilable water between fishermen end other aquatic sports enthusiasts would be necassery, “peed boating and heavy fishing pressure are not compatible on this lake. --- Page 5 --- Ww The one most important problem in restoring good fishing is undoubtedly ~ugh fish control. The extremely large rough fish and forage fish population supplies ae lake with an overabundant natural food source for the geme fish population. What effect the annual lowering of the lake, during the early spring, has on the game fish population was not ascertained but it is doubtful that there is any ad- verse effect... Further study of Lake Austin is recommended when a teasible plan for rough fish control has been proven. Present procedures for rough fish eradication would be difficult to carry out on Lake Austin because of the city water supply and the number of residences and business establishments on or near the lake shore. SUMMARY 1. Lake Austin, a 3,000 surface acre impoundment on the Colorado River was ine ventoried for species present. In addition, relative abundance estimates were made for the fish population. 2, Collections from the 1956 short segment period and data from 1951-1953 Texas Game and Fish Commission records were used for this report. £ 3. Rough and forage species excluding sunfish were found to constitute over 80 percent of the collected material. 4, The most abundant species was the gizzard shad. 5. Chennel catfish were the most numerous game fish taken by gill nets while oleack bass were the moet numerous in the seine collections. 6. Heavy boat traffic and numerous water skiers tend to discourage fishermen from using the lake. --- Page 6 --- Table 1. Checklist of Species Found to Occur in Lake Austin. Scientifie Name Le episosteus osseus _ Dorosoma cepedianum _ Ictiobus bubalus _ Carpiodes carpio carpio Moxostoma congestum Cyprinus carpio Notemigonus ¢ crysoleucas* Opsopocodus emiliae? emi lise* Notropis roseus. Notre is venustus ocr Spc Notropis _ lutrensis Pime paales ° vigilax* Plier toast promelas* anomalum* Lorena omer me ae Ictalurus punctatus _ Levels furcatus 3 punctulatus s* re tL eculi a a a em salmoides _cyanellus unctatus® eraaae otus grvumniens _ Cichls asoma cyanogutta yitus coronarius ocean | ene RCE NS oe Common Name longnose gar gizzard shad smallmouth buffalo river carpsucker gray redhorse sucker European carp golden shiner pugnose minnow central weed shiner spottail redhorse shiner parrot minnow fathead minnow stoneroller channel catfish blue catfish yellow bullhead flathead catfish blackstripe topminnow common mosquitofish white bass Kentucky spotted bass Texas spotted bass largemouth black bass warmouth green sunfish spotted sunfish redear sunfish bluegill sunfish yellowbreasted sunfish longear sunfish white crappie Llouperch freshwater drum Rio Grande perch * Species taken in Lake Austin in 1951-1952 by Texas Game and Fish Commission personnel but not taken in this segment. A ERR. ER CE LETT LE TEN TN IO POETIC NE AAT PES CMS IEE i aL AMC is ven e --- Page 7 --- Table 2. Number of Specimens Taken by Gill Nets From Lake Austin, February 1956 through May 1956. oa NE see ee om RE or gg A a eR A ee OE NY eR a a A A NL se Fish Species February March April May Total % of Total Longnose gar fe) @) 3 31 3h 9.25 Gizzard shad 46 ie) 57 56 208 56.68 Smallmouth buffalo 0 3 2 2 7 1.90 River carpsucker \ 11 5 6 26 7.09 Gray redhorse sucker fe) 3 e) @) 3 0.81 European carp ) 2 0 2 4, 1.09 Channel catfish 6 2 ut 5 17 4.6) Blue cetfish fo) 1 3 fe) 4, 1.09 Yellow pull hend 1 1 ) 0) 2 0.54 White bass i 2 1 fe) 4 1.09 xas spotted bass 0 Q 2 0) 2 0.55 Largemouth black bass ) 1 1 i. 3 0.81 Warmnouth 9) 1 3 ¢) y 1.09 Redear sunfish 0) 1 0 1 2 0.55 Bluegill sunfish 9) a) 13 22 35 9.54 Longear sunfish ) 6) 1 ) 0 0.28 White crappie 9) 1 5 Ql 7 1.91 Freshwater drum fe) 0 2 1 3 0.81 Rio Grande perch G 3) 1 fe) 1 0.28 Totals 58 78 103 128 367 100.00 (Sen a en A ERE NEE EA A OER AE A A OE RI ERR, AN RO EN SAUNT AOE nA RACES) REN AE EA RM an SOOT SN NE A Saeco se eRe --- Page 8 --- &. Table 3. Wumber of Specimens Taken by Gill Nets From Lake Austin, May 1951 through January 1953. (Aen erm ence a a eee remanent Fish Species May 1 through Aug. 1 through May 1 through Aug. 1 through Nov. 11952 ‘Total July 31, 1951 Oct. 30, 1951 July 31, 1952 Oct. 30, 1952 through No. wan. 31, 1953 Longnose gar 2 5 C 2 10 2.53 Gizzard shed 6 37 L 11 61 15.40 Smellmouth buffalo ) 33 35 2 70 17.68 River carpsucker 12 11 3 2 33 3.33 Gray redhorse sucker 0 1 0) Cc 2 O~51. European carp 0 4 0 ) b 1.01 ‘Channel catfish 10 6 2 i 33 8.33 Blue catfisa 1 i 1 2 T L.Tf Flathead catfish He fe) © 1 2 0.50 White bass 2 i 1 1 7 1.77 Largemouth black bass 6) iL 9) 1 2 0.51 Redear sunfish O L 0 ie) i 0.25 Bluegill sunfish 8 5 ?) fe) 13 3,28 Longear sunfish 2 6) 8) ie) e 0.51 White crappie 1 1 0 1 3 0.75 Freshwater drum 137 5 0 0 146 36.87 Totals 182 112 43 3h 396 100.00 --- Page 9 --- Table 4. Pounds of Each Fish Species Taken by Gill Nets From Lake Austin, February 1956 through May 1956. Fish Species rere meme ern eee ee LSC Longnose gar Gizzard shad Smallmouth buffalo River Carpsucker Gray redhorse sucker European carp Channel catfish Blue catfich Yellow bullhead White bass Te ; spotted bass Largemouth bases Wazmouth Redear sunfish iuegill sunfish Longear sunfigh White crappie Freshwater drum Rio Grande perch reese Totals —, February 0.00 29.48 0.00 7-13 0.00 0.00 9.81 0.00 0.63 0.63 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 48.08 March 0.00 26.50 9.38 19.94 11.00 12.81 2.94 9.44 0.82 2.50 0.00 0.69 0.13 0.06 0.00 0.00 0.23 0.00 0.00 96 . 33 seers naam A nate Se RR April May Total % of Total 5.06 52.44 57.50 15.88 34.50 33.56 124.44 34.36 5.69 10.50 25.57 7.07 10.25 11.00 48.32 13.34 0.00 0.00 11.00 3.04 0.00 8.13 20.9% 5.78 5.75 16.00 34.50 9.53 8.19 0.00 17.63 4.87 0.00 0.00 Lh 0.40 0.50 0.00 3.63 1.00 0.50 0.00 0150 0.14 2.88 0.50 4.07 1.12 0.38 0.00 0.51 0.15 0.00 0.19 0.25 0.05 2.38 3.06 5 4 0.13 0.00 0.13 0.03 2.94 0.25 os 0.92 1.75 0.50 2.25 0.62 0.63 0.00 0.63 0.18 81.53 136.13 362.07 100.00 seaeeeeinadaieineiemanmiadiniehammanenenemtaeen --- Page 10 --- LO. Table 5. Pounds of Each Fish Species Taken by Gill Nets From Lake Austin, May 1951 through Jenuary 1953. neem nents eee tenn gente enone -eerrnngerainent Longnose gar Gizzard shad Smallmouth buffelo River carpsucker Gray redhorse sucker European carp Channel catfish Blue catfish Flathead catfish White bass Largemouth black bass Redear sunfish Bluegill sunfish Longear sunfish White Crappie Freshwater drum G et P 169] May 1 thro July 31, 1981 Oct. §.56 3.94 0.00 45.06 0.00 0.00 12.81 4.75 1.69 0.00 0.00 1.88 0.50 0.31 54.06 136.62 Aug. 1 ohne ugsn May 1 Kame 7} 30, 1951 duly 32, 20.63 No Recorded 17.06 Weights 146.9% for this Period Smee Seiad fuge 1 Cct. 30, ¢ 0.00 0.00 2.75 koh 0.00 1.94, 0.00 0.06 0.00 0.00 170.20 Shrough ve i, Total of Total hrough — Lbs. me3L, 1953 __ 8,89 38.08 6.55 4.63 26.32 4453 8.56 311.25 53. 3.56 67.53 11.64 0.60 3.19 0.55 Q.00 6.31 1.09 5.38 29.69 5.11 9.13 é1.57 3-71 0.94 2.63 0.45 1.25 8.19 LAL 0.75 1.56 0.27 0.00 0.13 0.02 0.00 2.94 0.51 0.00 0.50 0.09 0.33 1.44 0.2 9.00 59.56 10.26 43.47 580.99 100.CO --- Page 11 --- ) oo Table 6. Combined 1951-53 and 1956 Netting Totals. Fish Species Longnose gar Gizzard shad Smallmouth buffalo River carpsucker Gray redhorse sucker European carp Channel catfish Blue catfish Yellow bullhead Largemouth black bass Warmouth Redear sunfish Bluegill sunfish Longear sunfish White crappie Freshwater drum Rio Grande perch Number hb 269 TT 29 11 Fw ine] ta) 48 % Total No. Pounds % Total Lbs. 5+ 76 95.58 10.13 35.26 150.76 15.99 10.09 336.82 35x11 7-73 115.95 12.30 0.66 14.19 1.50 1.05 27.25 2.89 6.55 64.19 6.81 14h 39.20 415 0.26 1th 0.16 0.26 2.63 0.28 LAS 11.82 1,25 0.26 0.50 0.05 0.65 5.63 0.60 0.53 0.51 0.05 0.39 0.38 0.04 6.29 8.36 0.89 0.40 0.63 0.07 1.31 1.76 0.50 19.52 61,61 6.56 0.14 0.63 0.07 100.00 943.06 100.00 --- Page 12 --- le. Table 7. Success of Gill Netting in Terms of Number and Founds of Fish, February 1956 through May 1956. Month Number Nuaber Munber Number Average Average Average Average No. of Nets of Foot of Fish Lbs. Fish Number No. Fish No. lbs. lbs Fish per Set Net Set Caught Caught Fish/Net Ft. of Net Fish/Net Ft. of Net February 6 750 58 48.06 9.67 208 8.01 0.06 March 6 750 73 96.32 16.00 2kO 16.05 o,13 April 6 750 103 81.50 13.50 14 13.58 0.12 May 6 750 128 136.13 22.67 olT 22.69 0.18 Total 2h. 3000 367 362.00 15.29 12 15.08 0.12 --- Page 13 --- 13. Table 8. Number of Specimens Taken in Seines from Lake Austin, March 1956 through May 1955. Fish Species March April May Total % of Total AA RRS CN ESI CER SE PEEPS A SSE ASAE ON ANAS A OR DORE ME Hea enmenaongn STE IONE UNE CHO SRACEER Ip cepedianun 87 fe) 3 90 12.43 pe roseus 6 2 fe) 8 1.10 Fe venustus 61 256 6 363 50.14 N. lutrensis i 1. 14 16 2.21 F. notatus _ 6 3 3 12 1.66 Gs Aftinis 12 0 0 12 1.66 M. treculi © 0 1 1 O.1h M. salmoides T 9 14 30 415 L. cyanellus 1 0 0 1 0.13 L. micvolephus 16 2 8 26 3.59 “z. macrochirus 92 14 48 154 21.28 ds geo toe 9 0 0 g 1.2k L. megalotis 9) 1 0 1 0.14 P. ennularis 0 ¢) 1 1 0.14 SAREE CARE RIS A AACR A MAO A A RR AEA AR NR A SE RY te AOA HH snot etme eS OREN AOI a ET REIMER Total 298 288 138 72h 100.00 (RR Corr meee TES SEE RITE aa 2 ACT Ca VE AP LN ce ee LC AS TE AA RRA RAE nt MET: RC RSC nar g --- Page 14 --- ih. Table 9. Number of Specimens Taken in Seines from Lake Austin, April 1951 through April 1952. om i ORO A CN I RT Fish Species os D. cepedianum Cyprinus carpio N. erysoleucas O- emiliac N. roseus N. yenustus N. lutrensis Pe vigilax Eo_promeias _ C. snomaLum 2. noteius M. punctulatus M. salmoides C,. corcnarius Le. punctatus ae Le microlophus P. annularis 2, caprodes G. cyanoguttata Lotals L. macrochirus 2519 2 2 eer sa ACEP LS HOI ee AN RI PONE CER EOE April thru August thru July, 1951 October 1951 April 195e iil 109 ) fo) 0 14 420 185 17 186 458 fo) 1h 50 naa nu Ak AON SA AA SO RAE IMAC IEE RCI LEI, AE IOI A AC 15S February thru 3 fe) ie) eg 17 331 pean nes amage enema nen «CR ee Total. Number 2631 2 2 2 26 1951 wn Ww ee! AS3) VOL 363 32 68 sage Came anaeO A 7O5u. ect SAE SARE NE ES ERE ON ASE AOE OEE NORE 2 SE ene ces cme % of Total or 2 I OT IT I LE 37-29 wi 2 fe --- Page 15 --- 15 Table 16. Combined 1951-53 and 1956 Seining Totals. Sot SORE ES Pn ARERR SARACEN nA EAR SR CARR: RYN en Ae ne en nc taeenen ea Ce a cat Fish Species Number Percent of Number Me eR EAE EN et a NC An So 2721 34.98 us GAaArpio 2 0.02 Ne ceysoleucas & 0.03 2 0.03 34. . 0.43 2314 29.75 174 2.2h. 53 0.68 1 0.01 h . 0.06 17 6.21 1ah 1.86 fed 0.01 Ee Tee ees 47 0.60 350 450 Sih 0.40 2 0.03 101 1.30 Lophus 389 5.0 1277 16.h2 Le suritus 9 0.11 a 0.01 2 0.03 32 O.2 G. cyancgutta 68 0.87 7778 100.00 ee IN IS RRR RTS I A 8 ACCES LO A EEC CC PR A SN RN RR nC See nts ewe rec ecra t