TPWD 1962 F-6-R-9 #732: Basic Survey and Inventory of Fish Species Present in Anzalduas Reservoir

JOB COMPLETION REPORT As required by FEDERAL.AID IN FISHERIES RESTORATION ACT TEXAS Federal Aid Project No, F~6—R—9 FISHERIES INVESTIGATIONS AND.SURYEYS 0F THE.WATEES;0F REGION 8-H Job No. Bel? Basic survey and Inventory of Fieh Species Present in.Anza1duas Reservoir Project Leader; Alvin Flury H! De Dodgen Executive Secretary Texas Game and Fiah Commission Austin, Texas Marion Toole Eugene A4 Walker DuJ Coordinator Director, Program Planning .January 16, 1962 ABSTRACT Anzalduas Reservoirs a newly built channel impoundment of approximate- ly 530 surface acres on the Rio Grande River near Mission, Texas was surveyed during 1960 and 1961 to determine its chemical and physical characteristics and to determine the relative numbers of the fiSh Species present in its fish pepulation. It was found to be highly saline due to salt water entering the reservoir from.a creek on the Mexican side of the river. During 1961, this salinity reached a level too high for the water to be used for irrigation and the lake was therefore drained and flushed in December 1961. Prior to draining the lake, netting studies showed the fiSh papu- lation to be comprised of 82 per cent rough fish Species, which accounted for 88 per cent of the weight of the total Specimens collected“ Rough fish Species present included: alligatora Spotted and longnose gars, gizzard shad, small~ mouth buffalo, striped mullet, freshwater drum and Rio Grande perch. The principal game fish present were channel and blue catfish, and white bass. Because the lake has a small capacitya an unstable water level and a deeply silted bottomgit is doubtful if any freshwater game Species other than catfish will become establiShed in numbers sufficient to create a good Sport fishery. It is recommendeda however, that periodic reconnaissance be made to determine any gross changes in the fish population. I JOB COMPLETION REPORI State of Texas Project No. F~6~R~9 Name: Fisheries Investigations and Surveys of the Waters of Region 8~B Job No. Bel? Title: Basic Survey and Inventory of Fish Species Present in Anzalduas Reservoir Period Covered: January 1 through December 312 1961 Objectives: To determine the chemical and physical characteristics of the Anzalduas Reservoir and the relative numbers of fish Species presentu Techniques Used: Field trips were planned on a bimonthly schedule but were actually made in March, April3 June, September, October and December. Bad weather or time Spent on other project work prevented making the scheduled bimonthly trips. Experimental gill nets and a nylon seine were used to sample the fish pOpulation. The netted Specimens were weighed in grams and measured in millimeters, They were then dissected to determine sex and stage of sexual maturity. Food in the stomachs of carnivorous Species was identified in the field. Seined Specimens were preserved in 10 per cent formalin and taken to the Mathis laboratory for identification and-tabulation. Water analyses were made in.Apri13 October and December. Tests were made for dissolved oxygen? carbon dioxidea alkalinity and pH. Notes concernm ing physical and general ecological conditions were made and recorded» A list of fish taken during the surveyfi giving both scientific and common nemesa is included as Table l. The scientific and common names used in this table were taken from Hubbst é_Checklist g£_Texas Fresh-Water Fishesg Texas Game and Fish Commission, IF Seriesg No. 3, June3 1961. Findings: Anzalduas Reservoir is a new Channel impoundment on the Rio Grande River approximately 8 miles SE. of Mission in Hidalgo Countyfl Texaso Recently completedS it was c00peratmve1y built by the United States and Mexico and is administered through the International Boundary and Water Commission. The 1.2:. Table 1.. Checklist of Fish Species Recorded from.AnzalduaS Reservoir Common Name Scientific Name HAlligator gar _ Lepi SoSte_us spatula Lacepede _Spotted gar Lepisosteus oculatus (WinChell) Longnose gar _Le isosteus osseus (Linnaeus) .Threadfin shad Doro soma _etenense (Gunther) \Gizzard shad Dorosoma .cepedianum vLeSueur) MeXican&fietra .AstyanaX.meXicanus QFilippi) Smallmouth buffalo Ictiobus bubalus QRafinesque) Speckled chub HyboESis aestivalis QGirard) Tamaulipas Shiner NotroEis braytoni Jordan and Evermann Ghost Shiner NotroEiS buchanani Meek Bullhead minnow Pimephales vigilaX (Baird and Girard) Channel catfish Ictalurus punctatus (Refinesque) Rio Grande blue catfish Ictalurus fureatus'QLeSueur) Gulf killifish Fundulus grandis Baird and Girard Sheepshead minnow Cyprinodon variegatus Lacepede MosquitofiSh. Gambusia affinis QBaird and Girard) Amazon molly IMollienesia formosa (Girard) Striped mullet Mugil cephalus Linnaeus Tidewater silverside Menidia beryllina QGOpe} White bass Roccus chrysoES (Rafinesque) FreShwater drum Aplodinotus grunniens Rafinesque Rio Grande perch , GiChlasoma cyanoguttatum (Baird and Girard) a3... reservoir's primary_purpose is to provide gravity-flow water to large irrigation ditches on both the American and Mexican_side of the Rio Grande Valley. The reservoir.is approximately 25 miles in length, has an approximate capacity of 4,240 acrewfeet.and covers some 530 surface acres. Since the bulk of the water is contained within the natural river banks, there is little or no flooding of adjacent lands. Netting Collections Four netting stations were set up approximately 2, 8, l4 and 20 miles above.the dam, all on the Texas side. One net was set at each station six times during the survey with the exception of Station 4. No net was set at this station in December because the water in the reservoir was being flushed out to reduce accumulated salinity. All told. 23 getting collections took .281 fish3 of 11 Species, which weighed 473.2 pounds. Table 2 shows the numbers of fish netted and Table 3 shows the weight in pounds of fish taken each month. Table 4 shows the numbers and weights of fish taken at each. station during the survey. Rough fish Species including alligator gar; spotted garp longnose gar, gizzard Shad, smallmouth buffalo, striped mullet; freshwater drum.and Rio Grande perch comprised 82,21 per cent of the number and 88.26 per cent of the weight of the fish netted. Gizzard shad alone comprised over 42 per cent of the number of fish taken in the nets} while longnose gar comprised over 19 per cent and Rio Grande blue catfish comprised almost 14 per cent. Curiously. carp, gyprinus_carpio Linnaeus, are found in Llano Grande, Campacuas, Fort Brown9 Delta Orchards, Falcon and Casa Blanca Lakes but not in Anzalduas Reservoir. Also? river carpsuckers, Cagpiodes cagpio (Rafinesque),are found in Casa Blanca and Falcon Lakes but not in Anzalduas. White crappie, Pomoxis 'annularis Rafinesque, are found in numbers in many lakes in south Texas but,- againfi none was found in Anzalduasa Besides Rio Grande blue catfish? channel catfish and one Specimen of white bass were the only representatives of game fishes feund. However? it is known that the flathead catfish, gylodictus olivaris (Rafinesque), is also present. In September two fishermen reported catching a "nice" (lOu to 12~pound) flathead on a trotline using "cut perch"a -The white bass taken at Station 33 approximately 14 miles upstream from the damp probably-came from.Falcon Lakea about 85 river miles upstreama It is a known fact that anglers take many largemouth bassgiMicroEterus salmoidegu CLadépEde)3and white bass in the Spring and fall below Falcon Dam. For that reason5 it was anticipated that these species might become established in Anzalduasa but thus far they apparently have not. Table 4 shows the numbers and pounds of fish taken at each netting station; Two alligator gar; taken at Station 23 weighed over 20 pounds each and are not included in the table. The maximum.measurable weight of the project scales is 20 pounds. Table 5 shows the lengtheweight statistics of fish taken during the survey. 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NNNln ssmxosm HNHHnHmHH oHsmrmN mosxwm assenomN N¢¢1m¢ NosonNmH meHuNws mqoquqoq o dam Amaasm sav Names: oo.wm h©¢m5H oo.N¢N 00.0mm mm.mam om.mm~ aN.qqm Hmsowu om.oun ow.HNm oo.mow o mHoh4 Amuouosflaaflav ouwuoa thwpdmum wmlwm nosed apnoea 0am OMNINo Ev Hmuwbpfimwhm NeNnNeN mama snags ommxomm umHHss emaHsum mmnImmH fimfiwumo oan museum OHM Nemioea anemone Honnmeo Nemsmma oaommsn eusoaaHmam Nwmxmma poem pumuNaU Ommnmoq . new moonwdoq Neolomq how.vouuomw mowamom new soumwaHHa mmfi 0.9. m HomH .aHosummmm maseHaNaa .muaz HHHo HauaaaHumaxm_suHs nosae.amHm to moHumHuaum unmamsasnwamH .m mHnaH in.the condition of netted Specimens. Table 6 gives a summary on the success of netting in terms of numbers and.weights of fish caught during the twelvewmonth.survey. The heaviest catch was recorded in June. Sixtywone fish were taken in the four nets. They weighed a total of 131.4 pounds. A total of 45 fish onus taken in three nets in December. This amounted to 15 fish per net, which was second only to the catch in June. Most of the fish were.caught at Stations 1 or 2, in.the lower portions of the lake, According to Table 4, 207 or 74 per cent of the 281 fish collected were caught at Stations 1 and 2. - - Seining Collections Results of the 13 seining collections are given in Table 7. The most frequently caught fishes were the mosquitofish, the Amazon molly, the Mexican tetra, and the Tamaulipas Shiner. In all, 1,089 fish of 15 Species were taken in the seining collections. Both threddfin and gizzard shad were collected in the seining collections at all stations. A careful check of the shad collected in the nets was made and no threadfins were found. Tidewater silversides were expected to be found in larger numbers because of their abundance in Falcon Lake. However, they comprised only 5.15 per cent of the fish taken in seining collections in Anzalduas.l Stations A.and,B were located in*Silt 8~inches.f deep but Station C was located on a sandy beach. “ Ecological Conditions- Secchi disc readings were made at each of the.netting-stations except at Station 4 in October and December. It was found that the water was decidedly clearer in the lower portions of the lake, that is, from the dam upstream about 10 miles. The average Secchi disc reading from the lower two stations is 14.7 inches as compared to an average of 9.9 inches for the upper two stations. Clearer water in the lower part of the lake can be explained in part by silt settling out before it reaches the lower portions of the lake. Chemical analyses of water in Anzalduas were not carried out as planned because of insufficient reagents, low water conditions, or a lack of time. water sample stations were establiShed at net Stations 2 and 4. Samples were taken from the surface down to a depth of approximately 15 feet. :Five sets of analyses were made during the-course of this job: two in April, two in October, and one in December. The water was tested for dissolved oxygen, dissolved carbon dioxide, methyl orange alkalinity and pH._ The chemist at San Marcos made salinity determinations for the samples taken.in April. Dissolved oxygen ranged from‘6.2 to 13.6 parts per million and dissolved carbon dioxide ranged from 2.0 to 14.0 parts per million. ‘Methyl orange alkalinity ranged from 106 to 198 parts per million with the average about 155 parts per million. The pH ranged from 7.8 to 8.6. All of these values are considered to be normal for this part of South'Texas. Salinity ranged_from-l,200 to 2,600 parts per.million. The higher reading was obtained from a sample taken about three miles below the mouth of E1 Murillo Drain, an extremely saline creek draining into Anzalduas from the