TPWD 1957 F-6-R-4 #275: Job Completion Report: Basic Survey and Inventory of Species Present in Casa Blanca Lake

Marion Toole Coordinator by Alvin G. Flury Project Leader DingellmJohnson Project F-6—Rmh, Job B—T July 1, 1956 June 30, 1957 Ho Do Dodgen m Executive Secretary JOB COMPLETION REPORT State of TEXAS Project No. F6Rh Name: Fisheries Investigations and Surveys of the waters of Region =Bo . Job Noo BwT Title: Basic Survey and Inventory of Species Present in Casa Blanca Lakeo Period Covered: July 1, 1956 through June 30, 1957 WWW ABSTRACT: Casa Blanca Lake near Laredo, Texas is an artificial impoundment of about 665 acres and is owned and operated by Webb County as a public recreational area. Completed in 1950, the lake has furnished good bass and crappie fishing From July 1956 through June 1957 the project leader with.two field assistants made regular monthly trips to the lake and took water samples for chemical analysis and made seining and netting col- lections for data on the fish population, A map of the lake,9 charts and tables showing the results of the investigations and discussion is given in the reporto Although bass and crappie fishing remains good, it has apparently fallen off since 19590 Gatfishing is nonuexistent in spite of numerous reports that it was very good in 1952 and 19530 Commercial netting was very productive in 1959 for Smallmouth Buffalo and Carp but in 1955 only small, unmarketable river carpsucker were taken by the comm merical netters who then abandoned work on the lake, Our netting results showed a high population of river carpsucker and a moderately high number of gizsard shad Recommendations are made for the control of these two speciesu OBJEOTIVES: To determine the chemical and physical characteristics of the lake and the fish species present and their relative numberso TECHNEQUESE During each month of the period a three day trip to Casa Blanca Lake was made by the project leader and two field assistants. On the first afrernoon floating experimen- tal gill nets 125 feet long and 8 feet deep consisting of one 125 foot section each of i”, 1:”, 2" 21” and 3" square mesh were set at netting stations #1 and #2 {See Map l for the general layout of the lake and the locations of netting, seining and water sampling stations) Early the following morning the nets were picked up and the fish weighed and measured and the data recorded Seining collections and water sample collections were then made from seining stations=#l and #2 and water sampling stations #1 and #2. Chemical analysis of the water samples were run immediately but the seining collections were preserved in 10% formalin and the fish tabulated later in the laboratory. Late in the afternoon the nets were set at netting stations #‘3 and #t. Early the morning of the third day the nets were picked up and the fish processed after which we returned to Mathis headquarters. Conferences were held on several of the trips with the local dame wardeny County Engineer. Soil Conservation Service? the dounty Commissioner in charge of the park and various fishermen who knew the lake. Our trips were usually made between the 5th and 10th of each month. FINDINGS 3 History and Ph sical_Description a Case Blanca Lake is located approximately five miles east of Laredoy Texas on Arroyo C soon just north of U. S. Highway 59 leading to Freer. It is just east of the larcdo Air Force Base and is part of a webs County recu reation area. Private owners first bought part of the area and built a Country Club and golf course. The City of Laredo bought the area and flooding easements up to the at? foot contour were bought on Arroyo Shanon above the dam. A dirt filled dam was completed on April 22, l9h9 but an area wide rain of about 18 inches washed out a large section within a week. Repairs and enlargment of the dam was begun immediately and completed in the summer of l95d. The total cost for the lake was over a million dollars The new dam has a maximum height of 85 feet above the stream bed and M65 feet above mean sea level. it is 5300 feet long and contains an estimated iytooyooo cubic feet of dirt. Fourteen hundred feet of sheet steel pilings up to 21 feet long were driven into the site of the break. The spillwey was graded around some low hills east of the dam to drain the lake at at? feet above sea lewel. When fully the lake would have a surface acreage of about l6?9 acres. on average depth of about l2 feet and contain about 205000 acremfeet; there would be about 15% miles of shoreline. Drainage area is about ll? square miles and Arroyo Shanon drains to the Rio Grande. Map 1 shows the outline of the lake with the water level at about h36 feet above sea level {ll feet below spillway which was about normal for the period of the investigation}. :he surface acres at'b35 fggt is 665 and egpgeity is 5609 goremfeet. Table l shows the levels of the lake from . incomplete records in the County Surveyors office. The l956 and 1957 records are from our trips to the lake. The lake and the rest of the area is used exclusively for recreational purposes. Free public access is furnished by graded gravel roads to both ends of the dam. At the west end of the dam there is a concession staid with dance floor and a boat dock_with a few rent boats. A marked off swimming beach is nearby. Natural boat landings are etailable on both sides of the lower part of the lake. A pump near the west end of the dam furnishes water for the grass on the golf course; this is the only use of the lake water other than fishing; swimming and boating. A water level gauge post at the pump suction shows sore feet at b32 feet above see local and l5 feet at spillway clemation. About eight priests homes are located on the middle and upper parts of the lakes all above the flood easement contour. The general area surrounding Laredo is among the dryest areas of the state. The Rio Grands and privately owned small lakes and stock tanks are the only fishing waters; dasa Blanca Lake has supplied a much needed public recreational area for fresh water sports. During our trips fishing pressure appeared to be very light; usually only five or six fishermen being seen each day. Various rem ports indicated that base and crappie fishing had fallen off greatly since l95h and 1955 and formerly good catfishing no longer exists. Webb County is in the Rio Grande Plains area. The uplands are gently to moderately rolling with some low range of hills. Soils are gray} sandy to rocky. vegetation consists of throny brush and c cti with dense thickets of larger trees in the gullies; mesquite; huisachey black brush, creosote and prickly pear are dominantiover much of the area. Of recent years extensive areas of brush have been chained and roller out to encourage grasses. Cattle ranching and oil production are the most important land uses. Alluvial soils along the Rio Grande support expanding irrigated vegetable farms in ' (IQ The arroyos (stream beds) between the low hills are almost invariably dry except immediately after heavy rains. Surface water is seldom found except where arroyos have been dammed to farm stock watering tanks; these vary greatly in size from one_to over one hundred surface acres when full. During dry years many of the smaller tanks go dry. According to Game warden 0. E. Whitentony there are fourteen stock tanks on the watershed above Casa Blanca Lake; all of small to moderate sine. Any management plans for the lake which include fish kills for population control would have to take these tanks into consideration. we. Whitenton treated a small lake and impounded stream channel on Arroyo dhacon that was inundated by Casa Blanca lake just prior to completion of the first dam in l9s9. The effectiveness of the treatment was not determined and? at any rates was eliminated either when the dam broke on the first rains by fish from the Rio Grands coming upstream or fish coming downstream from the tanks. Fish stocking_records from the State Fish Hatchery at Olmitc show that 6.000 white crappieg ll§000 channel catfish and 1559000 black bass hare been stocked in Casa Blanca Lake since 1951. The Eederal Fish hatchery at'Uwalde has not stocked any-fish in Case Blanca Lake. Population is sparse over most of the area due to the large size of most of the ranches. 0f the 1955 estimated population of 6137553 93% was urban; mostly in Laredo; 85% of the population was LatinuAmerican. dli analogical Data m The U. 3. weather Bureau station for Laredo is located at tho-leredo Air Force Bessy about two miles west of Casa Blanca Lake. Information recs sired from the Climatologist there indicated that the area may be classified as semis arid. Normal annual rainfall is recorded as l9.s9 inches star the period l92l through iota. Rainfall since then is as follows: l950 a 10.63? 1951 - l5.d83 1952 - 10.5by ices - 16.66? lost - 13.50. l955 1 9.6l3 1956 - 9.95 and through June ll; 1957 - 10.82. Tansy since the dam was completedy the rainfall has been only 61% of the previous storage. The rainfall for 1956 was only 5l% of normal but the acremfeet of water carried by the lake during the period of our study was only 28% of maximum capacity. The wettest months are way with an storage of 3.18 and September with 3.16 inches. lebruary is the dryest month with an average of .85 inches. dreragc seaporation (from * evaporation pens) for the years 1950 through.l95h was ll9.89 inches per year. The‘ prevailing wind is southeaSt with an average speed of l2.6 miles per hour. Temperatures recorded range from 18 to ll5 degrees Fahrenheit. Northern and fresses seldom reach this far south and the average time between first and last frosts is 300 days. The normally clear? dry days with a steady breeze account for the high evaporation rate. Water Analysis m Water analysis was run on samples .aken from each of two stations during each of the monthly visits to the lake. water sampling station #1 was in the approximate center of the main part of theilhhe near netting station #1 face Map 1}. The water was usually fairly clear. about 18 feet deep and subjeet to wind action and oonsequent oireulation. Three sample bottles each were filled from the surface, l0 foot depth andp when available. the 20 foot depth. Oxygen samples were fixed in the boat and the rest of the analysis was run at the boat landing. Water sampling station #Q was located in the upper part of the lake near what might be called the mouth of the impounded Arroyo Shanon.- The water here was shallower. more turbid and p more protested from wind action. many drowned trees and bushes were scattered through , the area. The results of chemical analysis during the period may be found in Table lit? Water temperatures ranged from 58 to 85 degrees F. with an average of 71.2 degrees at station #1 and 72.6 degrees at station #2. The maximum vertioal temperature range was 10 degrees, from 5813.. 10 and so feet to 68 at the Streets at station #1 in Deeember 1956. This appeared tube the short term result of warm air temperatures (l5g at the time the sample was taken). Otherwise the greatest vertical range was five degrees at both stations in June» l957. Dissolved oxygen varied from 0.8 to ll.h ppm with an average of 6.6 at station #1 and 6.1 at station #2. As was erpeotedfi dissolved oxygen was higher during the winter than during the summer and higher in the eleer water than in the turbid water. No etidenoe was found to indieate a shortage of water suitable for fish in regard to temperature or oxygen oontent. Carbon dioxide varied from Q to 8.0 ppm with an average of l.6 and 2.3 ppm at the two stations. The high of 8.0 ppm was found at 20 feet at station #l in October? 1956; during the other months the winds were apparently strong enough to oiroulete the water of the main lake and prevent assumulation of 602. -Four to seven ppm of dissolved 092 were oommonly found at station #2. Methyl orange alkalinity ranged from le to 300 ppm with an average of l83 and l?? ppm at the two stations. Jackson turbidimeter readings varied from 25 (or less) to has ppm with averages of st to 122 ppm at stations-# l and # 2. All readings over as ppm at station #‘l were from the bottom and aseidental inolusion of some bottom sediments in the samples probably sensed the higher readings. The highest surfase reading at station #2 was 10? ppm. The variation in pH was ?.5 to 8.6 averaging 8th at ++iou #1 and 8.1. at station #2., The most signifioant differenoe shown by the water analysis between the two stations'was in turbidity whioh influenoed the oxygen and oarbon dioxide content. Ale though tle upper end ofvthe lake was mush less subieot to wind agitation than the main late. it was eonsistently more turbid. This was probably due to the shallower water requiring less agitation than the deeper water to bosons muddied. Perhaps the large embers of riwer oarpsuoker in the lake oontribnted to the turbidity of the upper lake “"1 n. bet a higher persentage of this speoies was taken in the gill nets in the diner water stations. a hasty rain in May. l95? raised the late lerel-about three feet and when as tisited the lake on June ll the water in the upper part of the lake was definitely olearer than normal. With normal rainfall and a rise in the surfeoe elewation of the Ashe by sereral feet the upper end of the lake would probably olear oonsiderably. ' ionsidering t.e moderately strong and almost oontinuous windsg-it is doubtful that the ! lass? seen if full? would dewelop thermal stratifioation. Beoause oft heilaea of a good turf oorer on the watershed and the typioal heavy rains following dry periods. the late will besome more and more silted with the passing years and eventually beoome too turbid for dflfld prgdagtign 0f bleak bass? white orappie and eatfish (if stoshed suooessm fully) would then beoome the chief game fish in the lake. but good blank bass fishing should oontinue for quite a long time. Fish Gelleetione - Table III is a list ef the 36 epeei the lake flaring the period of study. Aceeaate of the iheividua up later in this report. es of fish recorded from is species are taken Experimental gill mete dyed green were eet overnight once each month from July 1956 thre ugh Jane 1957 at each of the fear netting statioee ehewa on Map l. Fieh eelleeted free the nets were taken to the boat landing and counted weig ehed, measured, eeaed and these data with other pertinent oheervatiene were recorded an Fish Celleetion Sheete. Beale samples were taken from all black haee ant efew of the ether fish and atomaehe were collected from game species and preserved iea lG% formalin if they eentained any food matter. Qeeles and stomachs were studied later in tr he Mathis laterater3; the f1-néi1ngs are discuaeed-later in this report. Netting station #1 was in the ahpreximate eeater ef the main lake. The site was in epeh water with he adjaeeht eater awe heegeet te eeeeiflerahle‘aind action. The water wee abeat 15 to 90 feet éeep aha was aeuall3 elear te eiightly murk3. Because the bottom wee eeverefl with many drewned shruhe aha email treee, all sets were made at the surfeee te prevent entanglement and lees 0f Leta. a tetei ef tee fish (3Q.68% of tetal eateh) wee teheh at this station. Tee 0f the meet see we liieh reatreefi, gizzard shed and river eerpsueker, preferrefi thie eeee eleer eater flee itat ahe eentrihuted heavily te the high count. Mere white erepeie and fewer hleeh tees were taken here than at ah3 ether station. hettiag-etatien #2 was in a bay en the east eaere hi the lake aheut 7/3 the flietahee free the dam te the head ef the lake. The water tee fair , .lear, abeut 8 to 10 feet eeep it the center at the ha3 time ereteee ea aha there aee e :eeifi erablee sever alehg the hahhe in the form ef dean treee etsi hiaeh eeefi la the eeeeer1 tme .ee mete 0f Pet;r beset. The eeeehd highest eeaat ef t“se {ell er QT.e33) was ie‘ 11 here. River eerpaaeh r were seamen and mere bluegill aunt ish were tear: thar at any et;1er station. bleak haeefi white erappie and freehaater drum were eetmew hettiaa etatien133 wee about lhfl 3ards eff the east ehere aM1e1t midway up the he. The :et r was shallow (three te eix feet); aaaey aha eahjeet ta e'i he astien; ' were my emeraeht deadt greee ahe shrahs in the eeee The h 1.red and twelve 1h were teheh (20. 83%). gieeard shad he ag the meet mentem. River eerpaueker and ‘1 eeeiieh aumhera were eefihite 3r lever that in the ele ear eater etatiens. Blae haae aha freahwater drum were preeeat in aheet equal hamhe 1e ea at stetieh Q. More eerp were taeeh here than at any ether etetiee. Wettieg station #a tee in e emel . ha3 hear the heat at the lehe fer the first eaten meathe er the ated3, thee meeee a.ee at tee i1 ' 1 l s e the ehanhel ef the impehheea arreyo. The water area h ta 8 feet e,e3 aha ahee3 see Mp daring the last meath when itm might be eell parti3 mneay The area wee seetee ad free the'eiad and much eeter frem emergent dead trees and ehreee eee 3 en 1 .1 3 t iish'were taken retresenti g Qfi.963 er the tetal het heath in the regelerle eet etet GJE. Giezard shad aha river ewe paeeker numbere were leaer hut bleak ’ ea eae freeheater area numbere were higher them at eh3 ether atation. .1 J 1 3...: "i Q Tehle IV ahm we the is urteea e1eeies 0i fieh Jeeeh ir theae hate and the percent ef the tatafi eateh by etati.eh aha eeeei a. elee eheae i a and 3e reentagee of 1e ” ' -, a reugh aha game eta eiea taLsa at the fear atat' ee. aeteel hameer” and Ear eentages shew inere rct1agh iish were tahea at the Jear we.ter euitiehe,-%l aha f2? thee at the more tart ifi atatiehe up late. This ma3 iefireate eet hiai jeealetier liftereeees or perhape the game fieh3 being unable te eee the hate ee well ih the aaae3'eeters at etatiehe‘#3 and #‘: me3 hate netted better there. * Table V shows the numbers of fish taken in the experimental gill nets by species during each month of the study, Percentages by species and by the month, are given as well as numbers and percentages of game and rough fish Total numbers, percent of rough_fish and percent of game fish seem to ."peak" in July, again in September and October and again in February. The September, October peak is probably correlated with the lowering of Summer temperatures rising temperatures together with spawning activities probably achhuhtt~fortthe_February peak, Lake conditions were unknown to us prior to the July collections, so that apparent peak is not eXplainableo- The months of June, January and August showed-the loweSt numbers of fish taken, ' Table VI shows the weight in pounds of the fish taken in the experimental gill net eaten The percent by species and a comparison as rough to game fish weights by the month are shown The over abundance of rough fish compared to game fish is shown more clearly (78 32% to 21 68%) than in the previous tablee River carpsucker comprised 51 25% by weight of the fish taken; Table VII shows the success of experimental gill netting in terms of numbers and pounds of fish taken per net and per foot.of net, The average number (31,17) and the average weight (28,78 lbs,) of fish per net is higher than that recorded in LakejCorpus Christi, perhaps indicating better fish production in theucheared waters of the Casa Blanca Lakeo - I Table VIII shows the rank by number and weight of the fish caught in the experi-_ mental nets and their minimum, maximum and average standard lengths, weights and "K" factorsc Table IX shows the numbers of largemouth bass, white crappie and freshwater drum which were infested with visceral round worms, More discussion of theSe tables is given under the species accountso _ During April, may and June, 1957, an additional experimental gill net was_set adjacent to (within 50 to 200 yards) each_of the regular green_dyed net sets, These extra nets were white and were bleached with Purex after each tripo This was done in order to compare, if possible, the "catchability" differences between white and green nets, Table X shows the results of the test, Contrary to our expectations, the white nets almost invariably caught more fish than the green nets, Net station #h in May was the only exceptiono In each pair of nets set, the_white nets caught from.h5,59% to 78,97% of the two net catch, averaging 70%0 At the clear water stations-#1 and #2, where we expected the most difference shown by a larger catch in the green nets, the total catch was 75% to 25% in favor cf the white netso In the muddy water stations #3 and #h less difference was shown, as'expected, but still 6106 to 380h% in favor of the white nets, Among the six most common species of fish taken, the largemouth bass showed an even number of fish taken in each type of net in clear water and more Rio Grande perch were taken in green than in white nets, Gizzard shed and white crappie differences were so great that they definitely appear to catch better in the white nets, Some of these differences may be due to Sampling-error or to better locations of the_white nets (es- pecially at near shore net stations #2 and #h) but the nets were set as much-as possible under the same apparent conditions and, if sampling error alone were involved, we should expect at least-a few of the catches to be in favor of the green nets, That the-differ— ences were less pronounced in muddy than in clear water may indicate that visibility is at least of some importance in the catchability of the netso The only possible concluseon from this test is that white nets, on the whole, catch better in Casa Blanca than do those that are dyed green. Scale samples were taken from 77 largemouth bass, ll river carpsucker, 1 white crappie and l carp during the period. Table XI gives the sexual condition of the six most common kinds of fish taken in the experimental gill nets and Table XII show the results of stomach analysis of eight largemouth bass and five white crappie stomachs collected. These items are discussed more fully under the species accounts. Two seining collections were made each month, one at a boat landing near the west end of the dam, the other near the head of the lake (see Map I). A 30 by 6 foot bag seine with one-fourth inch square knotted mesh was used. Seining beach was in clear water and had a gravel, sand and silt bottom. During the summer months dense beds of Potomogeton grow a long the beach and into water about five feet deep. Whenever possible the seine was dragged through part of these weeds. Drags were,tparallel to the beach, about 50 feet long and covered the area between about one foot to four and one half feet deep. Beach #2 was in muddy water with a soft mud bottom and depths up to three and one half feet deep. The only cover was dead trees and brush which had to be dodged to prevent snagging the seine. Drags were made by starting about 50 feet out from shore and bringing the seine straight into shore. A total of #572 specimens of 19 species were taken in the 2h seining collections as shown in Tables XIII and XIV. Only 13 percent of the total fish seined were considered to be desirable forage fish. Annotated Species List Lepisosteus osseus — Longnose gar. Only one gar was recorded from Casa Blanca Lake during the jab. It was taken in the last special white net set near net station #h at the head of the lake. It was a female with a total length of 750mmu.,,weight of lhh6 grams and ”K" factor of .52. It seems strange that only one gar was taken because they net very easily when present. It is stranger still, in view of the break in the first dam"“ which presumably allowed many native fish to enter the lake from the Rio Grande, that the other two species of gar (Alligator and Spotted) and the blue catfish known to be common in the river did not enter the lake in considerable numbers. Perhaps the flow of water through the break was too strong to allow fish to come upstream to enter the lake and the native fish now present in the lake (Gizzard shad, smallmouth buffalo, river carpsucker, carp, black‘bullhead, white crappie, freshwater drum and Rio Grande perch) first ascended from the river into the stock tanks above the lake during runoff rains and, after the dam was built, were washed downstream into the lake. Various stock tanks which have been checked in the general area but in different small watersheds have often been populated by the above fish species, apparently originating from the Rio Grande and entering the stock tanks during runoff rains. Gar are seldom present in these tanks; perhaps they are unable to ascend the wide shallow spillways and get into the tanks. Dorosoma petenense — Threadfin shad, These small, desirable forage fish were found in small numbers in the lake, 2h were seined from Beach #1 in clear water and 5 from the muddy water of Beache#2. They were taken only when the water was rather cool, in November and from February through May. If a selective kill of gizzard shed is carried out on this lake, it might be profitable to restock threadfin shad after the kill, if they are available. Dorosoma cepedianum - Gizzard shad. One of the most common fish in the lake, this species represented 31.56% of the fish taken in experimental nets to rank first in number and fourth in weight of the larger fish. In the seining collections, 9.5h% of the fish taken were young gizzard shad, ranking them third by number of the smaller fish; Most of the adults were taken in the clear water of the middle and lower portions of the lake~but a large majority of the young were from the muddy waters of seining s station #2. Among the forage fish, this same distribution was noted in several other species and may be due to heavier cropping by predacious species in the clear water. However, the only four spent adults taken were at station #h which may indicate that spawning takes place at the head of the lake which would account for more young occur- ,ring in the upper area. No ripe shad were taken but from the numbers taken that were almost ripe (sexual condition #2; see Table XI) they apparently spawn in March and April. Although the gizzard shad is not as over abundant in Casa Blanca Lake as in many Central Texas Lakes, a selective kill would almost certainly improve bass and crappie fishing by reducing the amount of forage available to them. . Astyanax fasciatus a Mexican tetra. Only one specimen was recorded from the lake and it was taken from a hook on a broken off fishing line. Tetras are very common in the Rio Grande and are sold for bait to be used in Casa Blanca. The absence of large numbers of tetras seems to indicate that few fish entered the lake from the Rio Grande when the first dam broke. They are known to be good base and crappie bait minnows and the introduction of a breeding stock in Casa Blanca would probably be beneficial after a gizzard shad selective kill. They would be more desirable than gizZard shad because they are prolific but do not reach a size too large for bass’to eat. Ictiobus bubalus — Smallmouth buffalo. Only five specimens were recorded but they were large, averageing over 5% lbs. Considerable numbers were reported to have been tak by commercial fishermen in l95h but in 1955 their catch was almost entirely of river carpsucker and netting was abandoned. The absence of small and medium size buffalo indicated that spawning had been_unsucccettul perhaps due to competition with the large population of river carpsucker or the lack of fresh runOff water. Spawning would apparent-- ly occur_in early to mid~summer5 a ripe male was taken in July and a spent female in June. Although buffalo are not considered desirable in a“lake, they are certainly more desirable than carpsucker because they do reach a large enough size to be harvested and controlled to some extent by commercial netting. Carpiodes carpio - River carpsucker. Ranked second in number and first in weight of fish caught in the experimental gill nets. Average weight was two pounds, maximum weight four pounds, not large canough to be of commercial value. Ripe fish ready to spawn were taken in all months'mexcept January and September but the largest number (11 ripe males) was recorded in February. 'Spawning may depend on the entrance of fresh water into the lake and could possibly occur at any time of the year after heavy rains. Largest spawns would probably occur in late winter if fresh water flowed into the lake. Table XV shows the size range oF the river carpsucker taken. From the graph, it seemed that all these fish were in the same year class (probably spawned in the late May rise in 195M) and there have been no successful spawns since then. However, of eleven scale samples taken (5 in September, 1956 and 6 in June, 1957), two were from fish spawned in 1953, three in l95h, four in 1955 and two in 1956., It was Obvious from the scales that the greatest growth was in the first year since any annuli visible were crowded at the edge of the scale. From past experience in south Texas, we didn’t expect scales to be of any use in determining the age of fish, otherwise, a complete scale collection would