TPWD 1959 F-7-R-7 #466: Experimental Control of Undesirable Fish Species in Lake Diversion, Segment Completion Report, Dingell-Johnson Project F-7-R-7, Job E-2

Report of Fisheries Investigations Experimental Control of Undesireble Fish Species; in Lake Diversion by Lonnie J. Peters Assistant Project Leader Dingell—Johnson ProJect F-T-R-T, Job 3-2 . June 1, 1959' - December '31, 1959 H. B. Dodges - Executive Secretary Texas Game and Fish Commission Austin, Texas Marion Tools Kenneth c. Jurgens a. William H. Brown . Coordinator Assist-ant. Coordinators ABSTRACT Tabulation of data collected during the seven consecutive months prior to the selective kill treat- ment of Lake Diversion revealed a fish population consisting of 85.1 percent undesirable fish. Gizzard shad, smallmouth buffalo, and carpsucker alone con- stituted 78.8 percent of the total fish taken during this period. The lake was treated for the selective control of shed and drum in march 1957. The immediate results of this treatment are given in Jdb Completion Report F-TwR-E, Jdb E—l. During the segment following the treatment, netting showed that shed had been reduced from 36.3 percent to less than 7 percent of the popu- lation. It was found that game fish increased in numbers, and were in better condition. This may have been due to a change in their feeding habits, or perhaps due to less crowded conditions. Mayfly nymphs, an important food item of game fish in Lake Diversion, were killed by the treatment. At present they are once again abundant in the lake. Shad have gradually increased since their re- duction, but game fish, which have done very well in the absence of an abundance of shad, have decreased in relative abundance and have become poorer as the shed reinfested the lake. Conditions have in general almost returned to the point they were before the treatment. During the segment covered by this report, the relative abundance of shad increased almost 10 percent. The relative abundance of buffalo decreased slightly, and the relative abundance of carpsucker decreased 6 percent. Crappie showed a gain of 3 percent, but all other game fish decreased. Segment Completion Report State of TEXAS Project No. FuTwR-T Name: Fisheries Investigations and Surveys of the Waters of Region l—B. JOb No. E-2 Title: Experimental Control of Undesirable Fish Species in Lake Diversion. Period Covered: June 1, 1959 — December 31, 1959 OBJECTIVES To determine the practical application and effectiveness of methods developed under Job E-l (Experimental Control of Undesirable Fish Species). Specifically, Objectives of the work covered by this report were to determine effects of the Selec- tivemkill treatment during March 1957. TECHNIQUES Prior to the selective kill treatment in March 1957, monthly gill net and seine collections were made. Netting was done at six stations using approximately 200 feet of net at each station. The nets that were used consisted of one length of experi- mental net comprised of equal sections of l—lé—2-2é-3-inch mesh, and one length of three inch mesh net. Seining was done with twenty foot, one-fourth inch mesh minnow seines. All fish taken in gill nets were measured, weighed, sex determined, and inspected for abnormalities. All game fish stomachs were opened and contents noted. If stomach contents consisted of fish remains too well digested to be identified, they were re~ corded as simply "fish remains m unidentifiable". These data as well as physical data were recorded in the field and tabulated in the lab. Seine samples were preserved for later identification. In order to have comparable data, these same techniques have been used during all segments of this job. BACKQROUND INFORMATION For background information concerning this report, readers are referred to the following 30b completion reports; F-7-R-u Job E-2 F-T-R—5 Job E-2 FuT—Rw6 JOb E~2 F~7~R~5 Job E—l Readers are also referred to Table 1 which gives the numbers and percents of species taken during each of the four segments of this jab. FINDINGS Fish Collections During the segment covered by this report a total of 10,1h8 fish was collected. Eight hundred and fortwaour were taken in gill nets. The remainder was taken by seine. Of the 8th fish taken by gill nets, 267 were gizzard shad, 167 were buffalo, and 165 were carpsucker. Carpsucker, gizzard shed, and buffalo together comprised 71 percent of the total catch. Game fish-totaled 15.29 percent of the catch which is h.3 percent less than during the previous segment, but O.h percent more than before the treatment. Crappie increased 3 percent during this segment, but all other game fish decreased. Although only two largemouth bass were taken, it is believed that a good population of bass exists. Bass fishermen reported very good catches during late summer and early fall, and numerous young base were taken in minnow seines. Table 2 shows percentage composition, sex ratios, and average weight by sex of all fish taken by gill nets during this segment. A total of 1,297 pounds of fish was taken, of which gizzard shad, smallmouth buffalo, carpsucker, and carp comprised 1,0h2 pounds, constituting 80.33 percent of the total weight. Table 3 gives the percentage composition by weight, and mean weights of fishes taken by gill nets. Seining produced a total of 9,30% forage fish. Gizzard shad were by far the most common forage fish taken. They comprised 58.87 percent of the catch. Notropis lutrens and Pimephales vigilax were also common. Table h gives the numbers and percentages of forage fish taken. Table 5 gives the number of all fishes taken by both gill nets and by seining. The average number of fish taken by gill nets each month was approximately 120 fish. The most fish taken in one month was 206 in June. The least number taken was 56 in December. Table 6 gives the monthly totals and percentages of each species taken. The only black bullhead taken from_Lake Diversion during this segment was during a Job 3-3.5 {NATURAL HISTORY) gill net collection. Several abnormal fish were taken during this segment. On two occasions shad were taken that had large, bulbous, spongy masses of tissue protruding from their head. One drum that had symptoms of brain tumor was picked up. Its eyes were greatly protruded and bloodshot, and its movements at the surface were violent and erratic. Examination of gills, and body cavity showed nothing that could have caused such conditions. One buffalo had extremely large fleshy lips. This may have been due to the continuous sucking of food from hard surfaces rather than due to a pathogenic organism. Food Habits Of the 129 game fish taken, 58 had identifiable food in their stomachs. Shad, mayfly nymphs, and unidentifiable fish remains were the most frequently occurring items. Tables 7 through 11 give food items of each species of game fish, frequency of occur— rence, and the total number identified. The only black bass found to have food in its stomach had eaten three shad. A flathead catfish had one shed in its stomach. Crappie were found to feed mostly on shad and other forage fish. White bass fed on a variety of items including shad, sunfish, minnows, mayflys, mayfly nymphs, and other insects. Eleven different food items were noted in channel catfish stomachs. Grasshoppers, fish remains, and mayfly nymphs were most often present. The remains of one cotton rat, Sigmodon hispidus, Were found in one channel catfish. Table 12 gives the aggregate of food items of all game fish. Sexual Development and Spawning Success A11 fish taken in gill nets were opened and the stage of gonadal development was recorded. If the gonads were large and approaching spawning condition, they were re- corded as being "ripe". Gonads of immature fish, and gonads of fish that were not approaching spawning condition were both recorded as "immature". Gonads of fish taken shortly after spawning were recorded as "spent". In June, 20 percent of the buffalo taken had spawned, while in July, 75 percent had spawned. Thirty percent of the carpsuckers taken in June were spent and in July, 90 percent were spent. Most of the shad apparently spawned in late May or early June. Seining in the upper portions of the lake in early June produced many hundreds of young shad. One short seine drag in Boggy Bay took 1,986 small shad. One spent channel catfish was taken in June; two were taken in July. Two ripe channel catfish were also taken in July. Many ripe carp were taken in both June and July, but only a few were taken that were spent. Most carp seemed to have spawned in August and September. Some apparently did not spawn at all, for ripe carp have been regularly taken almost every month. Spent crappie were not taken until September. Coefficient of Condition in general, average "K" factors were fairly near the same as during the last segment, however, there were a few changes that should be mentioned. Shad "K" factors for hoth.males and females decreased. During the last segment they were 2.1 and 2.2 respectively. This segment they were 1.9 and 2.1. This decrease in "K" is probably due to a reduction of food brought about by the increase in numbers of shad. ”K" factors for both longnose and shortness gar, smallmouth buffalo, and carp were unm changed. Males of bigmcuth buffalo, carpsucker,and channel catfish showed a 0.1 increase in ”K". Two male flathead catfish, the first males of this species to be taken under this job, had an average "K” of 1.7. The only female flathead catfish taken had a ”K” factor of 2.2. ”K” factors for female white bass and white crappie remained at 2.? and 2.8 respectively, while the males of these species showed a den crease. Table 13 gives a comparison of ”K” factors for the four segments that this job has been in effect. Table 14 gives the distribution of "K" factors, by sex, for each species. Physical Characteristics Physical conditions at the time of each collection were recorded. Recorded data included air and water temperatures, wind speed and direction, barometer readings, and weather conditions. The highest recorded water temperature at one foot below the surface was 86 degrees F. on August 15. The lowest temperature was uh degrees F. on December 3. The water temperature rose during December, and on January 13, 1960, it was t9 degrees F. lake Diversion water remained quite clear except for short periods following heavy windso Broad shallow bays and the river above the lake were often more turbido Table 15 gives water and air temperatures on the days that collections were madeo DISCUSSION As stated in the Objectives, the purpose of this job is to collect data from_which the overall effects of the selective kill treatment of Lake Diversion in March 1957 can be determined, Thus far several important results have been notedo First it was found that although gizzard shed and drum were not totally eliminated, they were greatly reduced, This removal of shed and drum affected the game fish population. Game fish grew better and apparently increased in numbers. In the absence of great numbers of shad and drum, game fish probably had to move about more in search of food. This in- creased fishing successo Those shad that survived the rotenone also faired very well° With less competition for food they too were in better conditiona Their reproductive capacity increased and they produced many offspringo Shad have increased steadily, and now, after three years, are once again present in abundance, Table 16, which gives the average weight of species taken during each of the segments of this jab, shows that the average weight of shad after the treatment was loh3 pounds, but at present their average weight is 0.51 pounds, This shows that smaller shad are greatly dominant now. Data collected by present netting techniques has failed to show the true relative abundance of specieso At present we still do not know the status of the drum in Lake Diversiono It is believed that drum and black bass both are much more abundant than our data shows them to bag It will probably be necessary to make a rotenone sample in an enelesed bay in order to see just how abundant the drum have become. During the next segment netting techniques will be changedo Different types of specially rigged gill nets will be used, and possibly more netting stations will be selectedo It is believed that by varying our sampling methods, more complete and accurate data will be obtainedo If at the end of the next segment (December 31, 1960), it is found that conditions have stabilized and that all changes due to the rotenone treatment have been learned, then this job will be terminated and final conclusions will be made. If, however, new changes are realized, this job will be continued, Prepared by Lonnie J. Peters Approved by ‘:;;5€;:2/¢“L1P71//cx/beflp4fié/ Assistant Project Leader Director Inland Fisheries Division Date April 8, 3.960 bmmmemamSm enmesm HmonOmamSm uHmaOmaosom wonomoam omemmamnss HoaHQGSm oneHomHHSm HadHOGSm dcwmwcm omnewommm omwwwo owowwscm omewwo Hnamwoacm venodmacm Hnamwcasm smHmm tawoaaodSm owwdmwam ages E Ewosowamesm mmHsowmmm wososwm msoswmewm waogwnoasm messewmom Hoaawm m. swamsmnos ammo - ammo. 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Species Longnose gar Shortness gar Shad Smallmouth'buffalo Bigmouth buffalo Carpsucker Carp Channel catfish Flathead catfish White bass Blackibass Crappie Drum Totals Weight (LbS-) 113.05 1h.70 137.11 523.54 12.29 23h.16 1h6.99 A1.60 12.86 30.00 1.h5 2h.61 n.56 1,296.92 Percent of Total Weight 8.71 1.1h 10.57 no.36 0.95 18.06 11.3h 3.21 0-99 2.31 0.12 1.89 0-35 100.00 Percentage Composition by Weight and Mean weights of Fishes Taken from Lake Diversion. June 1, 1959 - December 31, 1959. Mean weight 2.90 1.h7 0.51 3.13 h.10 1.h2 2.72 2.19 v.29 0.65 0.73 O.h2 0.h6 8. Table h. Total Number of Forage Fish Taken from Lake Diversion June 1, 1959 — December 31, 1959 Scientific Name Number Dorosoma cepedianum 5,h78 Ictiobus bubalus 32 Carpiodes carpio 25 Phenacobius mirabilis h Notropis brazosensis 2 Notropis bairdi 13 Notropis girardi 2 Netropis lutrensis 1,190 Notropis deliciosus 18 Hybognathus placita 2 Pimephales vigilax 1,289 Pimephales promelas 1 Ictalurus punctatus 2 Gambusia affinis 176 Roccus chrysops 127 Micropterus punctulatus 1 Micropterus salmoides 5h Lepomis cyanellus 15 Lepomis punctatus 126 Lepomis microlophus 18 Lepomis macrochirus 281 Lepomis humilis 285 Lepomis megalotis 7 Pomoxis annularis 8 Percinac caprodes 139 Aplodinotus grunniens 9 Totals 9,30h