TPWD 1958 F-7-R-6 #377: Segment Completion Report: Experimental Control of Undesirable Fish Species in Lake Diversion, Project F-7-R-6

Segment Completion Report State of TEXAS Project No. F-7—R—6 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: 1958 - May 31: 1959 Abstract: An estimated minimum of 185 tons of fish, mostly shed and drum, was removed from Lake Diversion by an experimental selective-kill treatment in March 1957. Inventory was made by nets and seines from ten months before to 26 months after the treatment in order to compile comparative data which may indicate possible effects of the treatment. A total of h,385 fishes have been collected by gill nets from which data concerning food habits, sexual development, spawning success, coefficient of condition, and patho- logical conditions were recorded, and as far as possible, reduced to tabular form. A total of 1,381 of the h,385 fishes taken for study has been collected during the period covered by this report. The most significant changes in the fish population immediately following the treat- ment were: (1) increase in "K" factors for all species; (2) reduction of the shad popu- lation; (3) increase in the relative abundance of carpsucker and buffalo, and (A) increase in average weight of all species except shortness gar and carp. Two years after treatment, condition factors of rough fish species either increased or remained the same as they were during the preceding year; whereas game fish species and shad showed a decrease in "K". Although some species have a lower condition factor during the segment, as compared to the previous segment, all species are equal to or higher than during the period preceding the selective-kill treatment. Although having been reduced from 36.6 percent to 6.8 percent by the treatment, shad have replenished themselves to 22.5 percent of the fish population within two years. Game fish species increased from lh.9 percent during the 1956-1957 segment to 20.2 percent during the 1957-1958 segment, but dropped to 19.6 percent during the period covered by this report. White bass, black bass and channel catfish have made substantial gains, but crappie decreased. Apparently, the rotenone treatment killed the mayfly nymphs in March 1957, removing them from the diet of fishes during 1957-1958. They began to re—appear in stomachs of game fishes, as well as the buffalo fishes, in August 1958. This work will continue until sufficient data is obtained to determine overall effects of the reduction of shad and drum, selectively, with rotenone. 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 selective-kill treat- ment during March 1957. Techniques: Field work on this job began in June 1957. Collections have been spaced one month apart since that time so that data collected during each segment would be comparable to that of the previous segment. Approximately 1,200 feet of gill net, ranging in size from one inch to three inches square mesh, were set on each visit. Each fish taken in these nets was measured, weighed, and the stage of gonadal development recorded. Filled stomachs of predacious species were saved in formalin, along with ripe ovaries and path- ological tissues. Samples of forage fishes were obtained with small-mesh minnow seines and preserved in formalin. Game fish which were taken while seining were identified, counted, and then released. Formalinwpreserved materials were identified and counted in the laboratory and the data recorded. Physical data, including air temperature, water-surface temperature and turbidity were recorded at the lake.- Background Information: An estimated minimum of 185 tons of fish, mostly gizzard shed and drum, was removed from Lake Diversion by an experimental selectivewkill treatment in March 1957. Inventory had been taken by gill nets and seines for ten months prior to the treatment, in order to compile data which would be cemparative to that compiled following treatment. Details of the treatment and work done during that period are discussed in the report F—7-R-h, Job Eel. Collection of data continued during the following 12 month period (June 1, 1957 through May 31, 1958) and is presented in the report F-7—R-5, Job E—2. This report pre- sents data collected during 12 consecutive months from June 1, 1958, through May 31, 1959, which is the second 12 month period after the selective—kill treatment. The primary purpose of this work is to compile information which may indicate resulting effects of reducing shad and drum populations by killing selectively with rotenone. Findings: Fish Collections A total of 2,663 fishes was collected from Lake Diversion for study during the segment covered by this report. Gill nets collected 1,381 specimens, and the remaining 1,282 were taken in seine samples. Comparison of the number and percentage of fish taken in gill nets during the 1956» 1957, l957~l958, and l958w1959 segments is given in Table 1. A total of 271, or 19.6 percent, of the fish collected by gill nets during the present segment, was game fish. This is 0.57 percent less than in the previous segment, at which time game fish constitui 20.2 percent of the total. Prior to the treatment, game fish comprised 1h.9 percent of the total. Shad, smallmouth buffalo and carpsucker made up almost 70 percent of the gill net collection during the segment covered by this report. The carpsucker was the most abundant species present, comprising 25.8 percent of the total. Percentage composition, sex ratios, and average weights by sex of fishes collected by gill nets during the 1956-' 1957 segment as compared to the 1957-1958 and 1958-1959 segments is given in Tables 2, 3 and A respectively. The total weight of all species collected by gill nets during the present segment is 2,533.5 pounds. Percentage composition by weight and mean weights of fishes collected by gill nets during the 1956-1957 segment as compared to the 1957-1958 and 1958-1959 segments is given in Tables 5, 6 and 7 respectively. A total of 1,282 forage fishes was collected with small mesh minnow seines. The major forage fishes continue to be Notropis lutrensis, Pimephales vigilax and Dorosoma cepedianum. This information, with a breakmdown of species, is given in Table 8. The total number of fishes taken by both gill nets and seines is given in Table 9. Table 10 presents monthly totals of species collected by gill nets during the segment covered by this report. Food Habits Approximately 20 percent of all game fish collected contained food in their stomachs. Food remains were found in stomachs of 59 specimens; 31 white bass, 13 channel catfish, 8 crappie, A black bass and 3 flathead catfish. Tables 11 through 15 present results of analyses made on food remains found in stomachs of all predacious species that contained food. White bass fed largely upon sunfish, shad, mayfly nymphs and minnows. During the month of March 1959, every white bass that contained food had eaten large numbers of mayfly nymphs. Contents of one white bass taken in February included 17 small bluegills, 2 small orange spotted sunfish and"l shad. Cotton rats, insects, algae and other plant materials made up the bulk of food items contained in channel catfish stomachs. During July, August and September 1958, cotton rats (Sigmodon hispidus) became very numerous in the Wichita valley, and especially so in the area surrounding Lake Diversion. Whether this animal is semi-aquatic in habit or was searching for food or new habitat is not known; however, many were observed swimming aimlessly in the middle of the lake, floating with the current of the headwater river, and dead along the shoreline. At any rate, they were proven to be a very popular food item of channel catfish. It was interesting to note that, apparently, only live cotton rats were utilized for food. Rats that were trapped alive and placed on trotlines were not taken by catfish. Crappie fed mostly on mayfly nymphs, shad and sunfish. The four black bass examined contained only fish and fish remains. One cannibal contained a black bass 73 mm in length. Sunfish, other unidentifiable fish remains, and mayfly nymphs were found in the stomachs of flathead catfish. Sexual Development and Spawning Success The gonads of all fishes captured in gill nets were examined, and the sex and stage of gonadal development were recorded. If the gonads were large and well—developed, ob— viously approaching spawning condition, they were recorded as "ripe". Fish taken shortly after spawning were recorded as "spent". All others were recorded as ”immature". As spawning activities progressed, seining effort was increased in order to determine spawning success of the various species. Immature individuals of the larger fishes taken in seine drags were measured and counted. In addition, notes were made of schools of fry seen, young fishes found in the stomachs of predacious fishes, etc. Females of only two flathead”catfish, one channel catfish, and one carpsucker were found to be spent in April. In the early part of May, females of one channel catfish, one smallmouth buffalo, one carpsucker and two longnose gar were spent. Apparently, the major spawning period was in progress when the lake was checked on June 6, 1959. Almost all shad of spawning size were spent. Fifteen percent of the carp were spent. Twenty—nine percent of all carpsuckers taken were spent. Twenty-two percent of the small- mouth buffalo were spent, and sixty percent of the longnose gar were spent. All other spawning-size individuals of the above mentioned species were ripe and ready. Also in June, large numbers of shad fry were seined, mostly from shallow mudebottomed areas in the upper end of the lake. Fry of carp, carpsucker and buffalo were found only in shallow areas along the shore where water temperatures were in excess of 90 degrees. Black bass fry were found at almOst every seining location, indicating a very successful spawning season for this species. Except in the river above Lake Diversion, white bass fry, although plentiful, were not as numerous as black bass fry. Unfortunately, the present segment termination date for this work occurs during the major spawning period and causes confusion in compilation of data and report writing. Therefore, for this and other reasons, the termination date for this work is being change to December 31 of each year. coefficient of Condition ”K” factors were worked out for all of the larger fishes collected in gill nets as they were during previous segments. Comparison of ”K” factors of all species collected in gill nets for the three consecutive years is given in Table 16. Distribution of ”K” factors for the l958~l959 segment is shown in Table 17. With the exception of smallmouth buffalo, carpsucker, carp and drum, average "K" factors were about the same or lower as compared to the previous segment. Male carp increased from 2.6 to 2.8, and females increased from 2.7 to 2.8. Female carpsucker increased from 2.7 to 2.8, whereas the males remained at 2.7. Smallmouth buffalo of both sexes remained at 3.2. Female drum increased from 2.9 to 3.0 and males from 2.8 to 2.9. Longnose gar remained at .h. All other species displayed a decrease in "K". In general, the "K" factors of rough fish species either increased or remained the same as they were during the preceding segment; whereas game fish species and shed show— ed a decrease in "K". Although some species show a lower "K" factor reading during this segment as compared to the previous segment, they are still equal to or higher than during the segment preceding the selective-kill treatment. Information contained in Table 16, correlated with relative abundance data, indicates that decreasing the numbers of shed and drum improves condition of all game fish species (as well as the remaining rough fish species), and as the numbers of shed (and other rough fish species) increase during the second year following the kill, the condition of game fish species decreases. Physical Characteristics The highest recorded temperature at one foot under the surface of open water was 80 degrees F. on September 12, 1958. During December and January, ice formed in protected shallows and in the river thick enough to impede boat traffic and prevented net setting. Turbidity readings were not taken, but the water was generally clear, as usual. Water and air temperatures are given in Table 18. Discussion: The primary purpose of this work is to accumulate comparative data and record perti~ nent observations over a period of years from which possible effects of shad and drum reduction with rotenone can be determined. Although certain facts appear to be significant from the data that has been collected, no attempt will be made at this time to make any definite conclusions concerning the overall effects of the selective—kill treatment. All data will be grouped and carefully perused after sufficient data has been collected in an effort to conclude as many facts as possible. Noteworthy are changes in the relative abundance of shad. According to gill netting results, shad were decreased from 36.6 percent before the treatment to 6.8 percent during the segment following the treatment. During the second year after treatment, they in~ creased to 22.5 percent of the fish population, proving their reputed reproductive capabil— ities. The average weight of shad increased from .7 pound to l.h3 pounds after the treatment, but dropped to .97 during the period covered by this report. Increase in average weight is possibly due to the great reduction of smaller shad, which are more susceptible to the effects of rotenone, and the decrease in average weight may be due to the additional capture of progeny of the surviving larger shad two years after treatment. The gill net method of sampling fish populations failed again to show significant changes in the drum population, although they were greatly reduced by the treatment. The use of rotenone will probably be required to determine the status of drum. Game fish increased from lh.9 percent during the 1956-1957 segment to 20.2 percent during the 1957-1958 segment, but dropped to 19.6 percent during the period covered by this report. White bass, black bass and channel catfish have made substantial gains, but crappie decreased from 5.3 percent to h percent. Condition of all game fishes except female black bass, as determined by ”K” factors, has decreased since the 1957~1958 period, but they are still in better condition than before the treatment. Mayfly (Hexagenia) and mayfly nymphs have been proven to be very important food items of game fishes in Lake Diversion. They were represented in stomachs of most predacious type fishes before the treatment, but were practically absent during the segment follow- ing the treatment. Mayflys began to reoccur in the latter part of 1958 being found in the stomach of a flathead catfish in August 1958, and were found to be an important food item again, especially of white bass and crappie, by March 1959. It appears that rotenone killed the mayfly nymphs in March 1957, removing them from the diet of fishes during 1957~l958. They were probably restocked into Lake Diversion from irrigation canals, Lake Kemp and other nearby waters and were again present in abundance after the summer of 1958. More than two years have passed since the selective—kill treatment at Lake Diversion. Progeny of surviving individuals of all species are now over two years old and will be represented in gill net samples in increasing numbers during the remainder of this study. Collections will continue until sufficient data is obtained to determine overall effects of the reduction of shed and drum, selectively, with rotenone. Prepared by Leo D. Lewis Approved by ,58887148VC‘cx/Zfiafifl4éggfl" Project Leader Director Inland Fisheries Division Date July 17, 1959 Table 1. Comparison of the Number and Percent of Total Fish Taken in Gill Nets in Lake Diversion During the 1956~1957, 1957~1958 and 1958e1959 Segments. Number Taken fi of Total Species 195grl957 1957rl958 1958“1959 195 “1957 1957ml95 195 “1959 Lepisosteus osseus 37 113 68 2.9 6.6 h.92 Lepisosteus platostomus h 6 11 0.3 0.3 0.80 Dorosoma cepedianum M72 116 311 36.6 6.8 22.52 Ictiobus_cyprinellus 0 O 2 0.0 0.0 0.15 Ictiobus bubalus 175 A56 291 13.6 26.6 21.07 Carpiodes carpio 369 620 356 28.6 36.1 25.78 Cyprinus carpio ' 31 he 6h 2.h 2.6 h.63 Ictalurus punctatus 38 95 71 3.0 5.5 5.1h Ictalurus males 0 3 0 0.0 0.2 0.0 Pylodictus olivaris 2 3 7 0.2 0.2 0.51 Roccus chrysops 76 121 121 5.9 7.1 8.76 Micropterus salmoides 7 18 17 0.5 1.0 1.23 Pomoxis annularis 68 110 55 5.3 6.h 3.99 Aplodinotus 9 11 7 0.7 0.6 0.50 Total 1,288 1,716 1,381 100.00 100.00 100.00 Table 2. Percentage Composition, Sex Ratios and Average Weights by Sex of Fishes Collected by Gill Nets from Lake Diversion, 1956 - 1957. Number % of % AVg. Male % Avg. Female Species Taken Total Males ‘Weight Females Weight Lepisosteus ggsggg 37 2.9 5t.0 2.9 t6.0 6.t Lepisosteus platostomus hi .3 25.0 2.8 75.0 3.7 Lepisosteus productus 0 .00 .0.0 0.0 0.0 0.0 Dorosoma cepedianum #72 36.6 t2.6 °65 57.h .75 Ictidbus bubalus 175 13.6 6u.0 2.22 36.0 3.5a Carpiodes 333239 369” 28.6 5u.2 1.27 u5.8 1.33 Cyprinus 3&5219 . 31 2.h0 t8.h 3.82 51.6 h.u7 Ictalurus punctatus 38 3.0 55.3 1.58 tu.7 1.68 EQEEEE chrysops - 76 5.90 A7.u .72 52.6 .72 Micropterus salmoides 7 .5 28.6 .7u 71.h 1.80 Pomoxis annularis 68 5.3 h7.0 .3h 53.0 .53 Aplodinotus grunniens 9 .7 55.5 .80 hu.5 .92 Pylodictus olivaris . 2 .2 _ 0.0 100.0 1.h0 Total 1,288 100.0 Table 3. Species Lepisosteus osseus Lepisosteus platostomus Dorosoma cepedianum Ictiobus bubalus Carpiodes carpio Cyprinus carpio Ictalurus punctatus Ictalurus melas Roccusflchrysops Micropterus salmoides Pomoxis annularis Aplodinotus grunniens Pylodictus olivaris Total Number Taken 133 116 1456 620 Mt 95 121 18 110 ll 1,716 % of Total 6.6 0.3 6.8 26.6 36.1 2.6 5.5 0.2 7.1 1.0 .35.. 51A 0.0 no.0 5h.8 use h3.9 26.3 0.0 38-7 33.3 1+3.6 63.6 0.0 Avg. Male Weight 1.07 1.88 0.56 0.7a ‘59 Female 48.6 100.0 60.0 15.2 511.7 56.1 73.7 100.0 65.3 66.7 56.11 36.11 100.0 Percentage Composition, Sex Ratios, and Average Weights of Sex of Fishes Collected by Gill Nets from Lake Diversion, 1957 — 1958. Avg. Female Weight 7-97 meoowmm HomHmOmamcm common HmewmomamCm mHmaOmaoacm Hdeo :. wOHOmosm Hodwoccm ommomwmoca onHHcowwcm HoaHOdcm.ondecm omeHomom mmwwmw ommewocm omemwo HodoHsHCm E HoaeHchm smHom mNHomwodSm owwemnwm w00ocm 0U mo m zwowomaomsm mmHeonmm monomwm mosswmwwm bmHOQHUOdsm Hoaow muscowmom 20. Bowen mm HH wHH moo wmm m: 4H Hop on mm H.wmp HOde :.mm 0.m0 mm.mm 0.Hm mp.04 mm.4m :.mw m.~: 0.00 0.mp 0.4m H.mw w.00 O.mo HO0.00 asses eoamw bdm. 20. a as. as. mm mm.0: mm.mm m.w0 m :m.sm , w.:m .mm mm m0.mm m:.mo .mo H m0.00 w.Hm w.pm Haw 00.:m www.mo w.0m Ham mw.Hm www.mw H.ww mm m0.00 m:.mw H.ap mm wm.0w ma.mq m.ws 0 0.00 0.00 0.00 0 0.00. 0.00 0.00 so -ww.mm mm.ma .mm m m0.:p m.mm H.mm He mm.:m Hm.H0 .mm s ma.os s.:m H.HH mom H.0am.pw Monmwmm Hoamw new. 20. a ed. as. Wm :4.0m www.mm 4.w0 m m:.mm a.we H.mw mom 40.:m msm.0m H.Hw H m0.00 H.m0 H.m0 Hem r0.mm wmw.m0 w.0m was em.mm m::.4m H.:H mm m0.00 4:.:4 m.ww as mo.0a www.mp m.m0. 0 0.00 0.00 0.00 a H00.00 w:.4: n.0m m0 mm.pm 40.44 .0m Hm 40.m0 mm.0w m.H4 so 4s.mm mm.:w .mm m rm.mm :.Hm H.wm 400 H.smm.w0 monomsammm oosoomedeooe mom wmawoms one rememmm sowmwdm 0% mom 0% mHmWom oowwoadmm 0% QHHH 20am mace Home wwdommwoos HWmm I Hmmw. Table 5. Species Lepisosteus osseus Lepisosteus platostomus Lepisosteus productus Dorosoma cepedianum Ictiobus bubalus Carpiodes_carpio Cyprinus carpio Ictalurus punctatus Roccus chrysops Micropterus salmoides Pomoxis annularis Aplodinotus grunniens Pylodictus olivaris Total 10. Weight (lbs) 166.1 13.8 0 335.4 t72.0 h79.5 128.7 61.7 58.5 10.5 30.0 7.7 2.8 1,763.2 % of Total weight 9.h .8 19.0 26.8 27.2 7.3 3-5 3.1 1.7 100.0 Percentage Composition by Weight and Mean Weights of Fishes Collected by Gill Nets from Lake Diversion, 1956 — 1957 Mean Weight h.5 3-85 0 .71 2.7 1.3 11.15 .72 1.50