TPWD 1956 F-4-R-3 #246: Inventory of Species Present in Benbrook Lake, Texas

LOWMAN JOB COMPLETION REPROT ST TE . ['[L-EE a ram Broject No. FHR3 Name Fisheries Investigations and Survexs of the Waters of Region h-Bo Job No. B-§ Title Inventorx of Species Present in Benbrook Lakez Texasc Period Covered: JUne 1253 — October 1256 ABSTRACT 1- Benbrook Lake is located about 15 miles sonthwest of Fort Worth, Texas in Tarrant County. The dam was completed in September 1952. 90 Largemouth bass grew much faster after the lake was Opened to fishing. loo Malnutrition, parasitism, and th e reabsorption of eggs was not present after the crowded game fish condition was alleviated 0 ll” A rapid change in fish pOpulation, either in types or numbers, may upset the lake balance causing it to fluctuate from one extreme to another“ OBJECTIVES To determine the species present and their relative abundance as well as the r‘*‘~r:.«_logical factors influencing their distribution. INTRODUCTION This paper reports on the work done during the third segment of a three-segment survey and summarizes the results of data collected during the entire three and one~ third years of study. The project had as its primary aim the accumulation of data which would show the progressiOn of a new lake during the first few years of its existence. Emphasis was given to the study of changes in the fish pepulation and the problems ass— ociated with such changes. HISTORY OF LAKE Benbrook Lake is located in Tarrant County about 15 miles southwest of Fort Worth, Texas. Closure of the dam was made September 29, 1952. The lake will impound 3,769 surface acres of water at tOp of conservation pool level. A severe drought allowed the impoundment to catch only enough water to fill to about one—third of its normal capacity. The lake is usually clear but sometimes stirred by winds until it is slightly dingy. The lake was stocked with 550,000 fish in 1953 of which 370,000 were largemouth bass. Table 1 lists all fish that have been stocked in Benbrook Lake by State and Federal Hat~ cheries. The impoundment was closed to fishing in September 1953 and remained closed until June 1, 195h. Fishing pressure was extremely heavy the first few days of the Open season but not so intensive thereafter. COLLECTING METHODS The fish population was sampled each month with gill nets during the three and oneuthird years os study which began in June 1953 and ended in October 1956. The nets were 100 or 125 feet long, eight feet deep, and had meshes of l to 3 inches square measure' The bulk of the sampling was done with nets having meshes 1% inches in size. Periodic checks were also made with minnow seines of various types and sizes. The seined samples were preserved in 6 percent formalin and taken to the laboratory for identification. The fish collected by gill nets were worked to obtain their length, weight, gonadal develOp— meat, and stomaCh content. A checklist of fish collected from Benbrook Lake is recorded in Table 2. DISCUSSION Consideration will be given to each major species of fish and the changes that took place in the pepulation of those species throughout the period of study. The effect of the changes in the composition of the fish pepulation on the lake as a whole will be discussed. Table 3 shows the results of the seine collectbns made during the third seg- ment of the survey. Heavy stocking of the lake with fry prevented the data taken at the seine stations from being too indicative of the success of the local spawns. Table A is a tabulation of data taken from the gill net collections during the third segment of the survey. Table 5 records the frequency of occurrence of foodijems cmeerved in the stomachs of the netted specimens. LARGEMOUTH BASS Largemouth bass were caught in large numbers in each net that was set in the lake from August 1953 through May 195M. The lake had been heavily stocked with bass in 1953 and was Closed to fishing in September of that year. The bass averaged 9é-ounces in weight when the netting was begun in August. The fish gained nearly 1% ounces per month for the next two months. Then their growth slowed down and they even lost some wait until they averaged only 11 1/3 ounces in May l95h just before the lake was reopened to fishing. The effect of severely crowded conditions, accompanied by heavy infestations of parasites and a shortage of food, resulted in poor health of the bass. Once a hundred foot gill net with lfi-inoh mesh was checked after being set out c"or only #5 minutes. The net contained #5 bass. The incident points out how crowded the fish were and shows the vast amount of movement that took place as the starving fish fought among themselves for the small amount of natural food available in the lake. Bass ate bass and anything else in the lake that they could swallow. An artifical lure moved through the water attracted dozens of small bass and they would fight over the lure until the hooked fish was removed from the lake. Effects of the overcrowded condition were many. All bass were heavily parasitised. Some died from one cause or another, perhaps many of them starved to death. The mature fish reabsorbed their eggs and if there were any successful spawns there was no indication that any of them escaped the hungry and emaciated adults. many thousands of bass were caught June 1, 195A when the lake was opened to fishing. A fair harvest, but in rapidly decreasing numbers, was made during the next few days. Then bass fishing was very poor for a long time. Our gill nets caught only 18 bass from June through September after the lake was opened to fishing, as compared to dozens and sometimes hundreds of bass that were taken in each net that was set in the lake when the bass population was so highly overcrowded. Larger catches of bass were made in the nets during the lake fall months but never in numbers that would compare with the previous large catches. However, the bass were growing and were showing the effects of an avail~ able food supply. By December 195A fat bass weighing 2 and 3 pounds were caught. The bass population had begun to revive. Although not present in numbers as great as in the previous year, the health and general condition of the bass was excellent. The bass population remained fairly good throughout the rest of the study. It apparently drOpped some in numbers during the last segments survey but gained in average weight and coeff— iciency of condition of individual fish. Table 6 shows the average catch per net set and average weight and ”K" factor of bass captured during each segment of the survey. WHITE CRAPPIE White crappie are the only species of crappie that have been taken from Ben- brook Lake, although it was stocked with about two to one in favor of the black crappie in 1953. In August and September of 1953 five crappie were caught in gill nets. They were thought to be Specimens that-were in the river system prior to formation of the lake. There were no more caught for one year then a few, mostly small ones, were captured each month from October 195A to August 1955. In September of that year the first good catch of crappie was taken with gill nets. A large harvest of 6 to 8 ounce size crappie was made in November and good catches were netted rather consistently each month thereafter. Reports from.fishermen of their hook and line harvest indicated that their first good catches of crappie coinsided very closely with our first favorable net catches. It will be noted that it took the crappie from 2% to 3 years to build up a population_ that showed up favorably in either our net catches or the fishermen‘s harvest. We do not know what effect the stocking of crappie had on the lake with the exception that the black crappie did not survive. It is possible that the present pepulation of crappie were spawned from the few specimens that were in the drainage system when the lake was impounded. One reason for the rather slow increase in the number of crappie may be attributed to the small amount of water and the very few Specimens of crappie that were present when the dam was constructed. The progression of the crappie population is shown in the lower part of 1figure 1. It may be of interest to note that the average "K“ factor of white crappie screased as the number of fish in the lake increased. The converse is true of the large- mouth bass which showed an increase in the average ”K” factor as the population of that species decreased. The crappie pOpulation was good at the end of the survey (October 1956) and will probably offer productive fishing for the next several years. CHfiNNEL CATFISH The channel cat population has not fluctuated too severely in the lake. It is true that the best not catches of channel out were made during the first segment of the survey when 32 channel cat were captured with an average weight of 2.73 pounds per fish. Evidently many or all of them were fish that were in the pot holes of the river when water was impounded in the lake. Evidently, their growth was quite :naphi due to the expansion of the lake which offered very fertile feeding grounds and new food supplies. The bulk of the catches of channel out during the last two periods of the survey consisted of smaller fish. Reference is again given to Table 6 which shows that the number of fish per hundred feet of net dropped considerably during the second segment but began to increase during the last survey period. The increase in numbers and decrease in average size indicates that spawning has been successful. Spawning facilities are good and as forage fish are abundant the channel cat pepulation should continue to be pretty good in the lake. There are no yellow cats (flatheads) in the lake. BLACK AND YELLOW BULLHEAD CATFISH The bullhead population has been relatively high during the entire period of study. The impoundment has a number of creeks entering it from.the drainage area and a considu erable amount of shallow brushy areas that are conducive to good bullhead production. Both black and yellow bullheads are present but the yellow bullhead is rapidly disappearm ing from the lake and should soon become extinct. The black bullhead may also be deem reasing in numbers but evidence of such is much less conclusive than the decrease in- dicated for the yellow species. It is uncommon for the bullhead species to remain in large numbers very long after a lake has been formed in this area. It is possible the.+ the absence of a yellow cat population,'which is normally feund in host of our lakesza is often given credit for preying on bullheads, is the reason that the bullhead population has been able to sustain itself in Benbrook Lake. Bullheads are found quite often in the fishermens‘ creel, especially those of young children and colored people. SPOTTED SC;;Q; The rapid expansion of the population of spotted suckers in Benbrook Lake has been an interesting development. The species has not been found in any of the other local lakes, although none are on the same drainage as Benbrook, therefore it should probably be considered as indemic to the Clear Fork of the Trinity River. The first spotted sucker netted was an adult specimen caught October 13, 1953. Several additional fish wre captured during the following January, march, and April. Each weighed about one pound and those taken during Marsh and April were ready to spawn. Young suckers averaging 5 to 6 ounces in weigxt were<nnufirt during October and November of 195%. Other mature fish were collected during the spring of l955 and boxy that weighed almost a pound each were taken in late:flaLl_of 1955. The catch of spotted suckers was high during the remainder of the netting study. Gonadal development indicates that the fish spawn in April and May and netting catches show that the young weigh 5 to 7 ounces by the end of that year. These fish seem.to be capable of spawning when they are two years old and have attained a weight of about a pound. The largest sucker captured from the lake weighed 1 po rd and 12 ounces. The expansion of the sucker population has been very rapid. The few specimens that originally populated the Clear Fork of the Trinity three years ago developed into one of the major species of Benbrook Lake. Figure 2 shows the incre “e in. the spotted sucker population as indicated by the percen of the total not catch that the species represented. WE FISH f we POPULATION 50 Table 7 records the data regarding the game fish and rough fish populations and shows the changes in the composition of the population during the three segment surveyo Figure 3 shows the percentage, by number and weight, of the total net catch represented by game specieso STQCKING Benbrook Lake has been heavily stocked with game fish» There were 1,65%,295 largemouth black bass fingerlings or fry stocked in the lake between 1953 and l956, both years inclusiveo This averages more than lSOO bass per surface acreo Bass fishing has been fairly good at times and very poor at other times on the lake” There were also 23,650 black crappie reportedly stocked in the lake during 19530 A 17 month creel census and a 3 1/3 year netting survey failed to produce any specimens of that species, Evid- ently the lake is not suitable for the production of black crappie and additional stoch- ing of that species would be futileu PQLLUTION AND FISH KILLS There are no known sources of serious pollution affecting Benbrook Lake” No doubt there has been some siltation but so far it has not been seriouso There are no cities or factories emptying their effluent into the drainage systems But there here been a few fish kills on the lakeo Several small kills occurred during the summer in isolated water holes for up the Glear Fork of the Trinity Rivero Chemical analysis of such areas, taken early in the morning, revealed a very low oxygen contento Lack.of oxygen during the latter part of the night probably caused the fish to suffocate, Almost every year, during early spring, fish die on the main body of the lake from apparently unknown causeso ‘Usually the hill is not serious but during the spring of 1956 a large numberjof’mature bass diode A few specimens of other species were off» acted but'the bulk-oth e fish that died were two to four pound basso The cause is not known but there seems to be certain conditions that can be correlated between Benbrook kills and similiar incidents that have happened on other lakeso These conditions will be watched closely during the coming spring, FUTURE OF LAKE Benbrook Lake has two major factors in its favor for good fisheries production during the next few yearso The first and probably most important item.is the large area of land that has not yet been inundatedo There still remains about twowthirds of the normal lake that will be flooded for the first time when the impoundment fills, A great deal of the new area is composed of fertile flatlands that should add considerable to the prom ductivity of theclakeu The second factor in favor of good fishing in the near future is the large numbers of local anglers available for fishing the lease It seems that a fairs ly heavy fishing pressure is preferred for most lakeso On the other*hand, there are a few factors present that could be detrimental to the success of the future fishing on the lakes number one is the rapidly increasing rough fish population, composed primarily of Spotted sucker, that may affected the game fish productiono Number two is the insistence of various local citizenry on heavy stocking, restricting of'harvest or in other ways interfering with the normal development and harvest of the game specieso REGQ-I “Hi It is recommended that the monthly netting of Benbrook Lake be discontinued but that some provision be provided for an occasional check on the lake in order to obtain data regarding any future major changes in the fish population, It is further recomended that some consideration be given to methods of contrc or harvest of the rapidly expanding spotted sucker pepulation. \ Prepared by Robert N. Hambric Approved by W ../ 9‘94 Assistant Project Leader Chief Aquatic Biologist Date . A ril 1.0 l 57 _ Hoops Ho moeoaosw mdoowwom ow Waco we woooeooa Hose» echoes new mew easosmo Ooeoooe memo meanest Homo Home Homo. Home eases HocmosoSew deow doom wqocwmm Howcooo wsowdo HcHrotOQo Hcmmrommm messes assess: mocmmm Hmtmmo mwcwww Homcmom oosmmsop meadows mmcwmm Hmcmmo mwtwww mmcwom eessosemsoe monsoon Hoodoo mwowww mmcoow eases rewcoem Hoocooo emommo Hammocoom Hoommcwme 8. Table 29 Checklist of Fish Species from Benbrook Lake, Texas, 1953 - 56. Common Name Scientific Name Gizzard shad Dorosoma cepedianum River carpsucker Carpiodes carpio Grey redhorse beostoma congestum Spotted sucker Minyprema.melanops' Carp Cyprinus cagpio. Suckermouth minnow Phenacobius mirabilis Redfin Shiner NotroEis umbratilis { Brazos river Shiner Netropis brazosenSis Blacktail Shiner (Spottail) Notropis venustus Red Shiner (Redhorse) NotroEis lutrensis Silvery'minnow Hypognathus nuchalis Plains minnow Hypognathus plaCita Parrot minnow Pimephales vigilax Fathead minnow Pimephales promelas Stoneroller Campostoma anomalum Southern channel catfish Ictalurus punctatus Black bullhead Ictalurus melas Yellow bullhead Ictalurus natalis Tadpole madtom Schilbeodes mollis Blackstripe topminnow Fundulus notatus Gambusia Gambusia affinis Kentucky spotted bass Micropterus punctulatus Largemouth black bass Nficropterus salmoides warmouth Chaenobryptus gulosus Green sunfish Lepomis cyanellus Small sunfish Lepomis symmetricus Redear sunfish. ' Lepgmis microlophus Bluegill sunfish Lepomis macrochirus Orangespotted sunfish Lepomis humilis Yellowbelly sunfish Lepomis auritus White crappie Pomoxis annularis Dusky darter Hadropterus scierus Logperch Porcine caprodes W m. 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