TPWD 1957 F-7-R-5 #298: Segment Report: Experimental Control of Undesirable Fish Species in Lake Diversion

--- Page 1 --- Aur SEGMENT REPORT State of TEXAS Project No. F7R5 Name; Fisheries Investigations and Surveys of ee Waters of Region 1-B. Job No. E-2 Title: Experimental Control of Undesirable Fish Species in Lake Diversion. Period Covered: June 1, 1957 through May 31, 1958 ABSTRACT: An estimated minimum of 185 tons of fish, mostly shad and drum, was removed from Lake Diversion by an experimental selective-kill treatment in March 1957. Inventory was made by nets and seines before and after treatment in order to compile comparative data which may indicate possible effects of the treatment. A total of 3,004 fishes was collected by gill nets from which data concerning food habits, sexual development, spawning success, coefficient of condition and pathological conditions was recorded, and as far as possible, reduced to tabular form. The most significant changes in the fish population following the treatment are: (1) increase in "K" factors for all species; (2) reduction of the shad population; (3) increase in the relative abundance of carpsucker and buffalo, and (4) increase in average weight of all species except shortnose gar and carp. OBJECTIVES : To determine the practical application and effectiveness of methods developed under Job E-1 (Experimental Control of Undesirable Fish Species). Specifically, objectives of the work covered by this report were to determine effects of the selective-kill treatment in March 1957. TECHNIQUES ¢ Field work on this job began in June 1957. Collections were spaced one month apart so that data collected would be comparable to that of the previous segment. Approximately 1200 feet of gill net, ranging in size from one inch to three inches square mesh, was set on each visit. Each fish taken in these nets was measured, weighed, and the stage of gonadal development recorded. Filled stomachs of pre- dacious species were saved in formalin, along with ripe ovaries and pathological tissues. Samples of forage fishes were obtained with small-mesh minnow seines, and the complete collections preserved in formalin. Formalin-preserved materials were identified and examined in the laboratory and the data recorded. --- Page 2 --- Physical data, including air temperature, water-surface temperature and turbidity were recorded at the lake. Samples of lake water were saved and the pH and dissolved solids present were determined. FINDINGS ¢ An estimated minimum of 185 tons of fish, mostly gizzard shad and drum, was removed from Lake Diversion by an experimental selective-kill 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 comparative to that collected following treatment. Details of the work done during that period are discussed in the report F7R4, Job E-l. This report presents data collected during 12 consecutive months following treatment, which may indicate resulting effects of reducing of shad and drum populations. FISH COLLECTIONS A total of 1,716 fishes was collected from Lake Diversion during the segment from June 1, 1957 to May 31, 1958. 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 segment is given in Tables 1 and 2 respectively. The total weight of all species collected by gill nets is 3,580 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 segment is given in Tables 3 and 4 respectively. A comparison between the number and percent of the total number of fishes taken in Lake Diversion during the 1956 - 1957 and 1957 - 1958 segments is given in Table 5. A total of 1,964 forage fishes was collected during the segment with small- mesh minnow seines. This information, with a break-down of species, is given in Table 6. The total number of fishes taken by both gill nets and seines is given in Table 7. Table 8 presents monthly totals of species collected by gill nets during the segment covered by this report. WATER QUALITY A complete chemical analysis of the lake water is given in Table 9. There was a considerable decrease in total salts during the 1957 - 1958 segment as compared to the previous segment. This decrease in total salts is most probably caused by the increase in the amount of precipitation during the 1957 - 1958 segment. PHYSICAL CHARACTERISTICS The surface of the open water reached temperatures as high as 85 degrees F. in summer and as low as 45 degrees F. in winter. During some cold snaps, a layer of ice formed in shallow areas along the shore and in the river above the lake. The water was relatively clear, and readings on the Jackson turbidimeter were always less than 25 (clear). The secchi disc readings were not considered as valid because of variations in light and difference in vision of persons taking the readings. The same person always read the Jackson turbidimeter. Physical conditions of Lake Diversion water are given in Table 10. --- Page 3 --- FOOD HABITS Food remains were found in stomachs of 81 specimens; 22 channel cat, 2 flathead catfish, 5 black bass, 27 white bass, 2 black bullhead catfish and 23 crappie. Tables 11 through 13 present results of analysis made on food remains found in stomachs of all predacious species that contained food. The bulk of food items identified were fish, fresh-water shrimp and insects, in that order. Gizzard shad was the fish most often present, with sunfish next. White bass fed almost entirely on fish, mostly shad. Freshwater shrimp were found on two occasions. The only insects were taken in June when remains of a few damsel fly larva were identified in one stomach. Crappie fed exclusively on small fish, mostly shad. Only one stomach contained remains of insects, a water beetle. Channel cat fed almost exclusively on mayflies throughout June and July. Thereafter, fish comprised the main part of their diet, along with a few bugs, beetles, freshwater shrimp and plant remains. The five black bass stomachs examined contained 1 white bass (3"), 1 sunfish (53"), 1 shad (23"), and 3 unidentifiable fish remains. Two flathead catfish stomachs contained 5 shad (2" to 3"), 1 unidentifiable fish remains, and cattail or bullrush fiber. Two black bullhead stomachs contained one sunfish, 6 unidentifiable fish re- mains, 4 earthworms and plant fiber. SEXUAL DEVELOPMENT AND SPAWNING SUCCESS All fishes captured in gill nets were opened in the field, their gonads examined, and the stage of development recorded. If the gonads were of medium- size or smaller, and were poorly develoned, they were recorded as “immature”. If they were large and well-developed, obviously approaching spawning condition, they were termed "ripe". In those instances where a fish was captured shortly after spawning, it was called "spent". Immature individuals of the larger fishes were taken in seine drags and measured and counted. In addition, notes were made of schools of fry seen, young fishes found in stomachs of predacious fishes, etc. Except for beginning a little later, spawning habits of fishes in Lake Diversion during this segment were quite similar to those of the previous segment. The smallmouth buffalo was the only fish to show any appreciable change. Spawning of this species usually begins in late March or early April, and continues through June. This year, however, no spent males or females were taken until April, at which time only two spent females were taken. All of the rest were ripe, except for a few immature specimens. In May, only two spent males were taken, no spent females, with all others being either ripe or immature. --- Page 4 --- PATHOLOGICAL CONDITIONS Three white bass captured in gill nets were blind in one eye. This may have affected the health of two of these individuals because their "K" factors were somewhat below average (2.40 as compared to an overall average of 2.98). One white bass was found to have one hardened and one normal ovary. One carp- sucker possessed only one ovary. COEFFICIENT OF CONDITION "K" factors were worked out for all of the larger fishes collected in gill nets. A comparison of the distribution and yearly averages of "K" factors for fishes in Lake Diversion between the 1956 - 1957 and 1957 - 1958 segments is shown in Table 14. The "K" factors of all species increased, to some extent, over the preceding segment (1956-1957). The selective-kill treatment was given about 2 months before the 1957 - 1958 segment began; therefore, it is most probable that the increase in "K" is the result of the reduction of shad and drum populations. DISCUSSION: The most significant changes in the fish populations following the treatment are: (1) increase in "K" factors for all species, including shad; (2) reduction of the shad population; (3) increase in average weight of all species except shortnose gar and carp. "kK" factors for male shad increased from an average of 1.86 to 2.17. Female shad increased from an average of 1.85 to 2.32. Along with an increase in "K" factors, in shad, was a marked increase in their average weight. Average weight of shad collected during the 1957 - 1958 period was more than twice as much as for the preceding period. Increase in average size may be due to the possibility that more small than large shad were killed and young of the year were mostly too small to be taken in gill nets. If this is the case, then, naturally, the average weight would be greater. The shad pcpulation was greatly reduced by the selective-kill treatment. Dur- ing the 1956 - 1957 period, shad comprised 36.6 percent of the total number of fish taken, whereas during the present segment, shad made up only 6.8 percent. This constitutes a drop of 29.8 percent. While there was a decrease in the numbers of shad, there was an increase in carpsucker and smallmouth buffalc. Carpsucker increased from 28.6 percent to 36.1 percent, and buffalo from 13.6 percent to 26.6 percent, (almost doubled). Discrepancies in the methods of sampling fish populations for drum were emphasized again during this segment. According to gill netting results prior to the treatment, the drum population was 0.7 percent of the total. During the treatment, an estimated 400,000 drum weighing 99.8 tons were killed. According to gill netting results following the treatment, the drum population was still 0.6 percent of the total. The method of sampling fish populations by gill nets failed to indicate either the great over-population of drum before the treatment or the decrease in drum population following the treatment. It is a proven fact that the drum population was much smaller during this segment than it was during the pre- ceding segment, however, gill netting failed to show this reduction. --- Page 5 --- Increase in "K" factors for all species, as well as increase in average weight for most species, can probably be explained by the fact that the fishes present after the treatment no longer need to compete for food and space with the over-abundant shad and drum populations, as in the past. Therefore, there is more food and space available for fewer fishes, and as a result, the betterment of condition for those remaining. : There are indications that a direct relationship exists between shad and carp- sucker, buffalo and carp. Experiments on other large bodies of water have shown that when shad populations decrease, carpsucker and buffalo, or carp populations greatly increase. An attempt to discover explanations for this, as well as many other unknown factors, will be made during future segments when natural history studies will be conducted on these rough fish species. The opening of flood gates at Lake Kemp, which empties into Lake Diversion, has long been considered as a source of contamination by rough fish for Lake Diversion. An effort was made to confirm or deny this possibility in May 1958, when the flood gates were opened from a closed position to 30 and 80 inches. Many dead drum and only a few dead crappie and sunfishes were observed floating down the river immedi- ately below the gates. It is presumed that these fish were killed by the sudden change in pressure from the bottom of Lake Kemp to the atmosphere in the river below. Since none of the other rough fish species were observed, it can be concluded that either (1) they are not being released through the gates; (2) they are not floating after death until much farther down the river than observations were made, or (3) they are surviving the pressure change and are entering Lake Diversion. Studies will be continued during future segment periods to determine condition of all species released through the gates from Lake Kemp. Time has not permitted creel census or collection of detailed reports of fishing success from Lake Diversion sportsmen. However, a meeting was attended with the Lake Diversion Cabin Owners Association, at which time a talk was given concerning the fisheries improvement work and a request was made for the sportsmen present to render their opinion as to effects of the selective-kill treatment. Without exception, those who expressed an opinion reported increases in fishing success and were in favor of the work performed. Additional time, continuous study, and surveys of fishing success of sportsmen are necessary before the feasibility and benefits of the selective-ekill treatment ean be ascertained. Authorization has been approved to continue this work until at least May 31, 1959. Prepared by: Leo D. Lewis Approved by: Vy - Project Leader Chief Aquatic Biologist and Richard Otto Assistant Project Leader Date: June 23, 1958 --- Page 6 --- TABLE NO. 1 PERCENTAGE COMPOSITION, SEX RATIOS AND AVERAGE WEIGHTS BY SEX OF FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION, 1956 = 1957 epey.es Taken Total Males episosteus osseus Avg. Male Weight Sx Females Weight | atl : Lepisosteus platostoms | 4 | 3 | 25.0 | 28 | 75.0 | 3.7 | Le poo pisosteus oroductus | Dorosoma _cepedianum | 36.6 | 4e6 | 65 | sre | 75 | i L i 28 3. eat 6 [oerpiotea earpie 1369 | 286 | skeen = 158 2 aa Pon nena pee as i | 9 | 7 , » Aplodinotus grunniens Pylodictus olivaris 1288 _| 100.0 TABLE NO. 2 PERCENTAGE COMPOSITION, SEX RATIOS, AND AVERAGE WEIGHTS BY SEX OF FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION, 1957 = 1958 pecie Taken Total Males Weight Fema Weight Le 2 ere ee | we | g-2 | | oT 2 34 - 80 t % | Tepizosieus opseus | 33 | = 6.6 | gut Lepisosteus platostomus 100.0 6.8 ° Sh 36. ks > 42 34 © | Dorosoma_ cepedianum 7 g ale 13 od 4] | 6 .0 | 6 | 6.8 | wo | 136 | 60.0 | 162 | 2. 86 2 13 crpetiinerteraiie | ow | 6 | uo | ae _ictalurus punctatus ee eee eee 2 | og | A |e | | | 7h Ictiobus bubalus Carpiodes carpio A ny © RA, Ictalurus melas Roccus chrysops RD "4 L “jo ° = | 3.7 | re | 63.6 | 0 Micropterus salmoides Aplodinotus grunniens Pylodictus olivaris [ots fa Oo Oo | nF oO wt Co OV jCo wi On k ° & id ° ° ° Q in) 100.0 --- Page 7 --- Te TABLE NO. 3 PERCENTAGE COMPOSITION BY WEIGHT AND MEAN WEIGHTS OF FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION, 1956 ~ 1957 Weight (lbs) % of Total Weight | Mean Weight | Lepisosteus osseus 166.1 a ee | Lepisosteus platostomus Ps et; Lepisosteus productus a Species ————— Oo Teticbus bubalus 26.8 [ternsen serie Mpg | _Rocous_chrysops a Micropterus salmoides ee eg Aplodinotus” grunniens | Total 1,763.2 100.0 TABLE NO. 4 PERCENTAGE COMPOSITION BY WEIGHT AND MEAN WEIGHTS OF FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION, 1957 = 1958. 9.4 27.2 r = : LT ; ~ Weight (lbs of Total Weight ee iebieontens cowane re Lepisosteus platostomus ee ee ey 149.8 pe eee a a ezine aareie agp tetniome guscatue __}__aph.e | sat a Es Ictalurus melas Roceus chrysops Micropterus salmoides Pomoxis annularis _aplodinotus- grunniens a Pylodictus olivaris 34 8 --- Page 8 --- O. TABLE NO. 5 COMPARISON OF THE NUMBER AND PERCENT OF TOTAL OF FISH TAKEN IN GILL NETS IN LAKE DIVERSION DURING THE 1956 - 1957 and 1957 - 1958 SEGMENTS Species 1956 - 19 species ae? aken a of Tota er Ta 31 } Lepisosteus platostomus = bt Le) Dorosoma cepedianum ma nO 36.6 13.6 28.6 ° Ictiobus bubalus VYOPLOUS arpio [retaturus melas | [Roccus chrysops _—=|__—78 |Micropterus salmoides 7 Pomoxis annularis Aplodinotus Pylodictus olivaris 2 = ~~] WS] ee i O ro oO _ ld NO Ov pe) (eo) — wa ON \xe S ®) kr & = - oO’ oy ) 1 5.9 0.5 223 Oo7 Oo ine) 1288 100.0 --- Page 9 --- 96 TABLE NO. 6 TOTAL NUMBER OF FORAGE FISHES TAKEN FROM LAKE DIVERSION, 1957 - 1958 | Iepisosteus osseus | : 7 L Phenocobius mirabilis a Notropis percobromus 2 Species Number Taken Notropis bairdi Ictalurus punctatus Pylodictus olivaris Gambusia affinis % HE Roccus chrysops akeked 1 Pimephales vigilax Micropterus salmoides _iepomis cyanellus PK Lepomis microlophus ee Lepomis macrochirus Notropis lutrensis po |_Botropis deliciosus | Hybognathus placita a 7 Pomoxis annularis Ss) pomis humilis 2 8 \ 0 o al 9 3 2 1 1 2 | Percina caprodes | [_Aplodinotus grunniens a 1 2 13 39 1 13 1 Total - % 9 channel cat returned to lake. HE 1 flathead returned to lake. KKK 3 white bass returned to lake. HERE 93 black bass returned to lake. HRERE 1 crappie returned to lake. --- Page 10 --- 10. TABLE NO. 7 TOTAL NUMBER OF FISHES TAKEN FROM LAKE DIVERSION, 1957 - 1958 Species Number Taken senleosteus slatos =o! episosteus platostomus ‘Dorosoma cepedianum Ictiobus bubalus ss Carpiodes carpio Phenocot a —— Phenocobius mirabilis 7 13 Pimephales vigilax Ictalurus punctatus Ictalurus melas Pylodictus olivaris Gambusia affinis Roccus chrysops Pp cs | gs | Cid a ae a ee | Ps —————— [Ltepomis cyanelius [| Lepomis microlophus | [lepois.sxerechines _____{__ags__ | Pomoxis annularis Td | Percina caprotes = | Sgeneantes seematets 8 _—__ --- Page 11 --- QZT| 0°00F 962 (2) (eo) ine) = \O i (e) oO (2) ke wn er) 99 |0°OOT | ELTK atdderg eyTuM ysti7e9 peeuielTa PPR ° sseg yortTd sseg ogTUM tH ° | yeo TeuuFUg oTesgng yNoUTT ew dayonsdieo Jeaty peus paezztsT 8sou710U"Ug “ON WidVvib 8 'L “MOTSHHAIC GIVI NI SLAN TIID 44 GHLOPTION SALOHdS AO SIVLIOL ATHINOW ce i --- Page 12 --- 12. TABLE NO. 9 CHEMICAL NATURE OF THE WATER AT LAKE DIVERSION, 1957 - 1958 Few _|na | er [scr | cox | 003 | nota | oe 210 | 330 497 | 448 6 8h. 210 127 6/24/57 8/6/57 9/3/57 10/7/57 11/7/57 12/3/57 --- Page 13 --- 13. TABLE NO. 10 PHYSICAL CONDITIONS OF LAKE DIVERSION WATER, 1957 - 1958 : Turbidit ; Secchi Disc Jackson Turbidimeter 800 1000 plus clear (less than 25 ppm) slaz/i/sr | up | us | 50 | cea (2ess than 25 ppm) ~faya/s8 | vo | es 870 | cea (tess than 25 ppm) je/xse_ | 58 | ks 580 clear (less then 25 ppm! clear (less than 25 ppm) clear (ess than 25 ppm) 1000 plus clear (less than 25 ppm) --- Page 14 --- 1h. TABLE NO. il STOMACH ANALYSIS OF WHITE BASS ®OLLECTED FROM LAKE DIVERSION, 1957 =~ 1958 Frequency of Total Number Food Item. Occurrence Identified Shad (Dorosoma 1 @ . Black Bass (Micropterus : [cSeopie (Poucis) Sunfish (Lepomis) 12 Fish remains (Unidentifiable} 20 Freshwater shrimp Dausel fly larva | Drum (Aplodinotus ) TABLE NO, 12 STOMACH ANALYSIS OF CRAPPIE COLLECTED FROM LAKE DIVERSION, 1957 - 1958 Food Item Occurrence fied um_(Aplodinotus} [Fish remains (Unidentifiable) | 9 | 15 Water beetle --- Page 15 --- 15% TABLE NO. 13 STOMACH ANALYSIS OF CHANNEL CAT’ COLLECTED FROM LAKE Frequency of DIVERSION, 1957 ~ 1958 Occurrence identified 20 2 4 19 iL Food Item Shad (Dorosoma) Sunfish (Lepomis) Aj | eo Channel Cat (Ictalurus | 2 | le _| Drum (Aplodinotus) 3 fy Fish remains (Unidentifiable ——— Fish scales L ee re 2 Crayfish Freshwater shrimp remains Mayflies Stink bug (Pentatomidae) Scavenger water beetle (Hydrophilidae } Vespid Wasp (Vespoidae) Caterpillar (Noctuidae) Grasshopper Bird leg (Mudhen) Plant remains Plant seeds Bullhead catfish Insect larva aL --- Page 16 --- 16 TABLE No. 14 DISTRIBUTION OF "K" FACTORS FOR LAKE DIVb...ION FOR 1957 - 1958 AS SOMPARED TO 1956 = 1957 ae 195G - -1957/ Factor |2.0 | 2.1 2.7 | 2.8 = Average "K" Males 2 1 27 | 35 2,64 Females = = 23 20 Factor [1.7/1.0 ]1.9] 2.0 [2.1 [2.2 |2.3 [2.4 | 2.5 Males 1] <= = i 2 k 6| 22] 32 Females = 1 = 1 2 1 7 12 32 Females Lepisosteus osseus 1956 = 1957 Factor | .3 |.4 5 Males h 115 Females L 1 _ 1957 - 1958 Factor «6 Average "K" Males 1 0.42 Females Lepisosteus platostc omus * ~ «1956 - 1957 | Pactor Males _Females Factor Factor Males Average "kK" 0.60 1957 - 1958 “a cepedienum ~ 1956 = 1957 2.1 2. 3 13 19 2. : 2 1957 = 1958 2.1/)/2.2[ 2.3 [2.4 Carpiodes carpio Average 1.86 NK ie --- Page 17 --- bel “I TABLE NO. 14 (CONTINUED) DISTRIBUTION OF "K" FACTORS FOR LAKE DIVERSION FOR 1957 + 1958 AS COMPARED TC 1956 = 1957 | Males | Females | Factor i Averase "K le emales 1957 - 1958 Factor 2.4 12.5 |2.6 [2.7 12.5 12.9] 3-0 | 3-1] 3-2] 3-3] 3 Males 1 1 1 1 6 3 4 5 2 5 7 Females 4 2 3 8 7 9 9 h y 2 Roccus chrysops 1956 ~ 1957 Factor Males Females 1957 - 1958 Factor > 3.07 3.1 | 3-2] 3.3] 3.4] 3.5 ~l|Average "K Males 4 7 5 3 3 - Females ) 7 7 5 7 - Micropterus salmoides 1956 = 1957 Factor , Average "K" Males 2-39 ,emales 2.42 Factor Males Females « --- Page 18 --- - 1958 aS 14 (CONTINUED) DISTRIBUTION OF "K" FACTORS FOR LAKE RSION FOR 1957 rus ialas COMPARED TO 1956 - 19 Aplodinotus grunniens 1958 Factor Average " Males 2o1T | Females 2093 Factor Males M2 1957 = 1958 Factor Males Females Ictiobus bubalus ele 1.9 [Average "K" 1} if 2 1956 - 1957 Factor 6 | 4.2 [Average "K" Males Females Factor Males | Females 2.0 [2.9 de ae Cyprinus carpio 1950 ~ 195 _ 1957 = 195 3 as Average "Kr