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

SEGMENT REPORT State of TEXAS Project No. FTRS 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 12 1957 through may 31: 1958 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 before and after treatment in orde1 to compile comparative data which may indicate possible effects of the treatment. A total of 3,00h 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: (I) increase in "K" factors for all species; (2) reduction of the shed population; (3) increase in the relative abundance of carpsncker and buffalo, and (h) increase in average weight of all species except shortness 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 smallwmesh minnow seines, and the complete collections preserved in formalin. Formalinmpreserved materials were identified and examined-in the laboratory and the data recorded. Physical data, including air temperature, watermsurface 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 gissard 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 comparative to that collected following treatment. Details of the work done during that period are discussed in the report F7Bh, Job Ewl. This report presents data collected during 12 consecutive months following treatment, which may indicate resulting effects of reducing of shed 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 a 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 a 1957 segment as compared to the 1957 m 1958 segment is given in Tables 3 and h 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 1,96h forage fishes was collected during the segment with smallm mesh minnow seines. This information, with a breakmdown 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. WATERHQUALITI .1 A complete chemical analysis of the lake water is given in Table 9. There was a considerable decrease in total salts during the 1957 1 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 m 1958 segment. PHYSICAL CHARACTERISTICS The surface of the open water reached temperatures as high as 85 degrees F. in summer and as low as #5 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. 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 shed 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"), l sunfish (5%"), l shad (2%?), 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 rem' mains, h 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 mediums size or smaller, and were poorly developed, they were recorded as ”immature”. If they were large and wellmdeveloped, 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. 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.h0 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 or 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 — l958 segments is shown in Table 1h. The "K" factors of all species increased, to some extent, over the preceding segment (1956ul957). 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 shed population; (3) increase in average weight of all species except shortnose gar and carp. "K" 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 shed, was a marked increase in their average weight. Average weight of shad collected during the 1957 w 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 population was greatly reduced by the selectivewkill treatment. Bur» ing the 1956 a 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 smallmonth buffalo. Garpsucker 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 h00,000 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 overmpopnlation 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 prom ceding segment, however, gill netting failed to show this reduction. 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 overmabundant shed 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 shed and carpe 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 immedim 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 selectivemkill 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 selectivemkill treatment can be ascertained. Authorisation has been approved to continue this work until at least May 31, 1959. Prepared by: Leo D. Lewis Approved by: {1‘1 . ‘ I‘ll-.4 Project Leader Chief Aquatic Biologist and Richard Otto Assistant Project Leader Date: June 23 1958 TABLE E0. 1 PERcEETAcE COMPOSITION, sax RATIOS AND AVEEAsE HEIcsTs BY SEX OE EISHES COLLECTED BY GILL EETs FROM LAKE DIVERSION, 1956 2 1957 Number {3, of I _A. Female." I _Gies _Taken Total .- . _ » .. W61 iht . 2.....2... ......... —_—--— twosome eeaedianum ' __--——-. 12 2.22 ., a _69 28.6 I 2.h0 3.0 5.90 J. an. Ii .1: 5h.2 #8.t 55.3 hh.7 . .72 52.6 . .Tt 71.t 1.27 3.82 iiodes car ' C prinus oarpio Ictwlurus punctatus Roccus chrysops 7 ' 1233 h 51.6 _ l..!. _ LA) (.JJ 5...: \J} 03 9terus salmoides _ 2 "F." C) I 42‘ C) Pomoxis annuleris . Aplodinotus grunniens 0 5525 D .80 n3 er 03-4 ca 4r g._ a* a". ma 0\ !!|%l“||||ll||l||!!|i%l T .2 100.0 -_P lodictus olivaris 100.0 Total 1288 TABIE NO. 2 PERCENTAGE COMPOSITION, SEX'BATIOS, AND AVERAGE WEIGHTS BY SEX OF FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION, 1957 a 1998 _ _ Number % Of % Avg. Female,” Leaisosteus osseus l? . _ . 5:2 1. _- 11.6 _- . 6 [m— n- 620 _F... 4:: _Ictalurus annotatus Ictalurus melee Roccus chrysops 121 Micro;terus salmoides Pomoxis annularis ‘ Aplodinotus grunniens Pylodictus olivaris 3 o I I LL} fr .4 1...; CD C) H O 0 ON i=4 4 4: . O I I [.J 3...; G\ ' 0\ O\ O C) O . PO 100.0 79 TABLE NOo 3 PERCENTAGE COMPOSITION BY WEIGHT AND MEAN WEIGHTS 0F FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSION9 1956 m 1957 “Species Weight (lbs) h Lepisosteus osseus _ _ _l66.1 _ _ --~'.-.--~; Meafi‘Wéight % of Total waight \o _p: lllli"i|"i| -q ip—xm F’ In ,_;rpicsrteus platestomus _ Lepisosteus productus H \0 || Doroaoma gapedianum _ D Icticobus. bubalus ' 2m 2‘7 08‘1‘10665 Gario m:— _- 1005 _- ‘ 14500 -- O 4.: 4:0 Pomoxis annularis A.ladinotu8fi:runnien8 _Pylodictua olivaris na-q E) O 0 0 0 03-4 c> 10000 i...| OO O fur-=4 E” 4:03 VJ} Total 1.763.2 _ TABLE NOo r h PERCENTAGE COMPOSITION BY WEIGHT AND MEAN WEIGHTS 0F FISHES COLLECTED BY GILL NETS FROM LAKE DIVERSIONp 1957 a 19580 :. LEpiscstaus osseua 1latestomua DOTOEOEE cegedianum 1&908 o. Pyladictua olivaris 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 TABLE N0. \JI “11-2" ., . II Ghryfiops- __Mierosteruslsalmoides Roccus Pomoxis annularis . 1161011118 f'lodictus olivaris 1211 _ 116 _ _ 9. ITABLE N0° 6 TOTAL NUMBER OF FORAGE FISEES TAKEN FROM LAKE DIVERSION, 1957 e 1958 , S-ecies Number Taken Leoisoeteue oeseue — 129 ;_| F4 an . lU||U||U|UUHU||||| PO 1...: 739 thrOcis_lutreneie __.Notropis_delieioeue _ H begnethue olecite _ Pimephelee vigilex H U0 395 Ictelurue punetetus 11* l-’ 3k 2% Pyledictue elivaris Gembueie effinie Reccue ehr sous IMieropterus selmoides Leaomis e enellus Legemis miereloghue _ .Lepemis macroehirue ||llH f4 i o H LA) CI) domie humilie Pemexie ennulerie . Pereine eeprodee k1 e1_. l|||EE|lE||€|E|| Aplodinotue granniene _ Tetel _ 1,9611 " * _ 9 channel Get returned to lakea ** l fletheed returned t0 lakeo *** 3 white base returned to lake“ **** 93 black bees returned to lekeo ***** l creppie returned to lake. 100 TABLE NO. 7 TOTAL NUMBER OF FISHES TAKEN Teen " LAKE 1311111251011» 1957 =— 1958 G prinue ear ° Phenoeobius mirebilis Notropie beirdi _ Notropie lutreneie NotTOgie delicioeue Ephesnethue Pimeahelee Vi° :ilex Ictelurue punetetue Ietelurue melee ' lodietue oliverie Gembueie effinie Eocene ehryeops Mieresterue selmoidee Lepomie mierelophue Lepemie meeroehirne b.0mie humilie Pomoxie ennulerie Pereine ce_¢rodee _%_‘I-Aplodin0tue grunniene