TPWD 1967 F-6-R-14 #1111: Job Completion Report: Experimental Stocking of Largemouth Bass and Threadfin Shad in Ponds in South Texas, Federal Aid Project No. F-6-R-14

--- Page 1 --- JOB COMPLETION REPORT As required by FEDERAL AID IN FISHERIES RESTORATION ACT TEXAS Federal Aid Project No. F-6-R-14 FISHERY INVESTIGATIONS - REGION 5-B Job No. E-6 Experimental Stocking of Largemouth Bass and Threadfin Shad in Ponds in South Texas Assistant Project Leader: John M. Travis J. R. Singleton Executive Director Parks and Wildlife Department Marion Toole g Eugene A. Walker D-J Coordinator Director, Wildlife Services March 8, 1967 --- Page 2 --- ABSTRACT Monthly collections of largemouth bass were continued at three of the four ponds stocked during a previous segment. Work at the fourth pond was termi- nated. As many specimens as possible were collected at each of the ponds during one day's sampling, with a minimum of ten intended. Lengths and weights were recorded for each specimen prior to its release. Pelvic fins were removed from specimens prior to their release so that they might be identified. Right pelvic fins were removed from first generation bass and left fins were removed from second generation fish. Schnabel's equation for population estimates was applied in a mark and recapture program in order that populations might be estimated. These esti- mates at the Hunter and Retzloff ponds varied from the known number of bass originally stocked. Possible explanations for these discrepancies are that the pond owner at Hunter's allowed friends to fish the pond prematurely thus reducing the number of stocked bass, and a suspected near toxic concentration of sulfates at the Retzloff pond prevented offspring from being produced. The Schnabel estimates are thought to be accurate. Best growth, as indicated by monthly length and length-weight frequencies, occurred at the Hunter pond which had the heaviest stocking ratio. This was contrary to expectations. Growth rates at the Kunitz pond, which was lightly stocked, were probably influenced by the high concentration of undesirable fishes competing directly for food. Undesirable species also occurred at the Hunter pond, however. Fishing success was measured as fish per man-hour. Overall, the ponds may be classified as very good, fair, and poor, with Hunter's pond yielding a catch of 1.82 fish/man-hour, Retzloff's 0.68 fish/man-hour, and Kunitz's 0.53 fish/man-hour. Although fishing success occurred in direct order with the stocking ratios, differences in fishing success among the ponds were not in correct proportion to the number of bass stocked per acre. Possible causes for fishing success not being in direct proportion to stocking are the very turbid water at the Kunitz pond and a lack of offspring of stocked bass at the Retzloff pond. During the past three segments, a number of observations have been made concerning the success of such an experiment. Most important of these obser- vations is that a number of uncontrollable variables affect experimental results. Some of those experienced during this segment are: pond quality, water quality, pond location, presence of undesirable fishes, and pond owner- ship. Due to the inability to locate ponds of identical quality and thus limit these variables, it is felt that the experiment should be carried on for additional segments under more controllable conditions. --- Page 3 --- JOB COMPLETION REPORT State of Texas Project No. F-6-R-14 Name: Fishery Investigations - Region 5-B Job No. E~6 Title: Experimental Stocking of Large- mouth Bass and Threadfin Shad _ in Ponds in South Texas Period Covered: _ January 1, 1966 to December 31, 1966 _ Objectives: 1. To determine the stocking ratio presenting the best growth rate for largemouth bass in ponds previously stocked with threadfin shad as forage. 2. To determine the stocking ratio providing the best fishing success in ponds previously stocked with threadfin shad as forage. 3. To determine the stocking rate which produces the best combination of growth and yield of largemouth bass in ponds previously stocked with threadfin shad for forage. Procedures: Growth Studies Largemouth bass (Micropterus salmoides) and threadfin shad (Dorosoma petenense) samples were collected monthly at three of the four originally stocked ponds. Experimental use of one pond was terminated and will be discussed later. Bass samples were ordinarily collected by angling with artificial and live baits. Shad and juvenile bass were taken with seines. It was intended that no less than ten bass would be collected during each month, but this figure was not attained at times. Length and weight were recorded for most of the bass specimens. The weight of some young fish taken during hot weather was not measured for fear that this additional handling would impare their survival. Only casual observations on shad growth were made, since their survival was the basic concern. Xield Studies Beginning in September, pond owners were encouraged to fish the ponds. In order to approximate normal harvest conditions, bass weighing 400 grams --- Page 4 --- or more collected by project personnel were also removed from the ponds. To estimate bass population densities, the mark and recapture program was continued. Specimens were recorded as either recaptures or non-recaptures at time of collection. Bass were marked by clipping a pelvic fin flush with the body - right pelvic for first generation (stocked bass) and left pelvic for second generation (progeny). Pond owners were informed of this program and asked to help by recording the number of clipped bass which they removed. The number of man-hours which project personnel spent angling and the number of bass caught were recorded. Pond owners were requested to do like- wise, but none supplied any data. Turbidity and water temperature were recorded each month and water analyses conducted bimonthly. Results and Discussion: Growth Studies Several methods are available for determining the pond having the best growth. The choice depends on the type of growth being measured and the growth criteria. The length-frequency distributions by month given in Figures 1-3 provide a measure of absolute growth in terms of length gain per time interval (slope) and allow separation of generations. These data probably give the best short-term presentation of growth. Linear regression of mean standard length on month was computed for the data from the stocked bass. The regression slopes, b, were: Hunter pond, b = 9.2; Retzloff pond, b = 8.00; and Kunitz pond, b = 3.64. In this measure- ment, b = 0.00 indicates no growth. This method is not entirely valid for measuring rate of growth, since the fingerling bass stocked at Kunitz pond were larger than those stocked at the other ponds and the growth slope is less for smaller (=younger) fishes and the growth slope is not exactly linear. Tentative interpretation of the growth rates indicates that the stocked bass of the Retzloff and Hunter ponds are growing at a similar rate, but the stocked bass of Kunitz pond are growing considerably slower. No tests of significance will be made until completion of the experiment. Figures 4-6 give the scatter diagrams for length and weight. These include both the stocked bass and their progeny and are not useful for comparisons, since no young have been taken at the Retzloff pond. --- Page 5 --- St. length interval 340-349 330-339 320-329 310-319 300-309 290-299 280-289 1 1 270-279 260-269 1 250-259 1 ol 240-249 230-239 220-229 210-219 200-209 190-199 180-189 2 170-179 7 L 160-169 1 150-159 1 140-149 1 130-139 120-129 110-119 100-109 90-99 80-89 70-79 60-69 50-59 40-49 30-39 1 20-29 10-19 0-9 PrRwWePNR fon’ ERO a) FM N DN Pu hb bo Re FW WwW Mure Re i) NENWH PRR Nh ep NS) Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1965 1966 Figure 1 - Length Frequency Distribution for Kunitz Pond --- Page 6 --- St. length interval 340-349 330-339 320-329 310-319 300-309 290-299 280-289 270-279 260-269 Z 250-259 240-249 230-239 220-229 2 3 210-219 1 2 5 200-209 1 190-199 1 180-189 3 4 a3 4 170-179 160-169 4 150-159 140-149 5 130-139 120-129 1 110-119 100-109 90-99 80-89 70-79 60-69 50-59 40-49 30-39 20-29 10-19 0-9 pa WWRNDN rm me WNNEN NN re Nw PENNE PP ro FoONnfRr BR wo Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1965 1966 Figure 2 - Length Frequency Distribution for Retzloff Pond --- Page 7 --- St. length interval 340-349 330-339 320-329 310-319 i 300-309 290-299 280-289 270-279 260-269 250-259 240-249 230-239 1 220-229 210-219 4 200-209 2 3 6 190-199 6 11 13 1 1 180-189 1 10 10 10 2 2 4 1 170-179 3 7 2 3 1 1 160-169 5 3 1 150-159 140-149 1 3 130-139 1 120-129 110-119 100-109 90-99 80-89 70-79 60-69 2 50-59 7 40-49 3 30-39 20-29 10-19 0-9 (Cie ae) FwWaN PuOUwe FAaAW MWn~wn NPRPr hw WNUNH NwWwWeH he Perr i) Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul_Aug Sep Oct Nov Dec 1965 1966 Figure 3 - Length Frequency Distribution for Hunter Pond --- Page 8 --- ES fn oo to Ww PrPenN I Uw — NNO OW wh RUB PRePPrPrPRwWre Pe wR rN co © oo Ne a ee oe oll oe 20 2 1 0 0 V 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 St. Length (mm. ) Figure 4 - Length-weight Frequency Distribution for Kunitz Pond Weights are given in intervals of 20 grams. Standard lengths are given in intervals of 10 millimeters, --- Page 9 --- ion Oo jo) — ~~ Nm Oo NH Ww a fan Ye oe) — rR Nr i) a oO fn Pwr Pree nN Bo (oe) (2) = Ke £ © PR wOeH re 0 ; 0) 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 Figure 5 ~ Length-weight Frequency Distribution for Retzloff Pond Weights are given in intervals of 20 grams. Standard lengths are given in intervals of 10 millimeters. --- Page 10 --- OV i) jo) hr egegs oo oO a _ NFPUDAEH HON Ff NH rFPRARWr rR PWN NF WE Re NWR NS NPRP i ee re jo) jo) PNOAFH £ o_f\ 0 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 St. Length (mm.) Figure 6 - Length-weight Frequency Distribution for Hunter Pond Weights are given in intervals of 20 grams. Standard lengths are given in intervals of 10 millimeters. --- Page 11 --- The stocking specifications of the ponds are given in Table 1. A most alarming observation is that the growth rate of the bass is directly proportional to the rate of stocking. This is diametrically opposite the theoretical model for fish growth which implies that the best growth would occur at the pond with the least competition. Table 1 Stocking Specifications of the Experimental Ponds [Kunitz | Retazloff [O'Brien [7 Hunter | Stocking rate per acre 150 . Surface acres . Total bass stocked It is hardly likely that the model has been reversed. If the experimental design of the job had been such that only the number of bass stocked per acre varied and all other environmental factors were equal (or near equal), the model would have been attained and the magnitude of deviation in growth between stocking rates measured for significance. These results indicate that far greater error (result deviation) was caused by uncontrollable factors than by the intended source of deviation (stocking rate per acre). This is often the case when private ponds are used for experimental purposes. Some of the observed factors influencing growth over which there was no control were: 1. Hunter Pond a. Surface area - Since a two-foot variation in water level doubles or halves the area, a bass per acre rate is almost meaningless. Stocking was done in the summer when the level was down; subse- quent filling nearly doubled the area and halves the stocking ratio. The principle water source was a well which would maintain the level, but the pond owner would not leave the pump running. b. Owner cooperation - The owner allowed friends to fish the pond and did not report the results to project personnel. 2. O'Brien Pond (terminated for experimental use in June) a. Construction - The lake was built by damming a small creek, and in times of heavy rains an entire turnover of water occurs. b. Undesirable fishes - These probably entered from below and above the lake. The lake was treated in November after termination and many smallmouth buffalo were found. --- Page 12 --- =10« c. Owner cooperation - There was no cooperation. Gates to the pond were always locked, and project personnel were denied keys, causing much loss of time. 3. Retzloff Pond a. Water quality - The pond is located in an area rich in sulfur deposits and is fed by an artesian well. Hydrogen sulfide gas is evident at the well and the water has a high concentration of sulfates. Most of the bass collected during the first six months of the job had external ulcers and were in poor condition. No young have been collected, indicating that no spawn occurred or that the young did not survive. No threadfin shad have been col- lected either, and this is also blamed on water quality. b. Proximity to headquarters - The pond is approximately 100 miles from Corpus Christi and this introduces considerable trouble into sampling. 4. Kunitz Pond a. Water quality - The pond is quite turbid (see Table 2) which interferes with proper feeding. b. Aquatic vegetation - Although turbid, there is a tendency for infestation by pond weeds and musk grass which also interferes with feeding. c. Undesirable fishes - The pond contains large numbers of bluegill, white crappie, bullhead, and various sunfishes. Some of these species compete with young bass for food or feed on threadfin shad competing with the adult bass for forage. Results and Discussion: Yield Studies One of the greatest sources of error in the experiment has been the inability to accurately measure the bass populations of the experimental ponds. Past methods of making counts at the termination of the experiment have proven unreliable. In order to estimate the populations, Schnabel's methods have been applied to a mark and recapture program. The formular used was: P = 3 marked fish (unmarked fish + recaptured marked fish) /S7recaptures A monthly record was kept of the bass caught and the number marked. The number of marked bass in the pond at the end of each month, together with those caught, and the number of returns was used to compute total population estimates. These computations are given in Tables 3, 4, and 5. --- Page 13 --- -ll- Table 2 Water Turbidity by Month for Kunitz, Retzloff, and Hunter Ponds as Determined by Secchi Disc Readings in Inches August 1965 September October November December January 1966 February March April May June July August September October November December January 1967 Mean visibility --- Page 14 --- se[dues sjeredss om} YsStj peyazeui-uo YSTy poeyse U Uw SOJEOTPUL - x, S8eOTPUy ~ WN S9JEOTPUT - W 19 69 T 0 T 23g 0 0 sp SON 19 T9 z 0 0) ZAON 19 6S vA 0 j 3290 79 LS Z 0 Zz 129 0 ) dag 0 0) ¥sny (A) GS € re) € eS0Vy €9 (as T T z vATNP 29 IS G 0 9 gATnp €9 9” G T 9 aunp €9 ay ¢ 0 G eS Py G9 9€ G I 9 APH 99 Te L Zz 6 ady 89 0 L G ra IEW L9 LT € ¢ 8 qaa 19 val € I v7 99 uer 69 TL G l 71 23q 49 9 £ Y i ghON TZ C ra I ¢ BAN vial I 0 11 ral 290 T pal | Gg das S27 vZlo zl oo ~ e SaeE eTdwes * SUANISY psyrewW qusney | -ow pC ON ON uot zenby uot e[ndog s,[Teqeuyos Butsg Aq puog z2]TUnNy JoF sseg peyoo sg Jo sajeuTysy uot e[ndog ATYUOW € P1gey --- Page 15 --- -13- eoocoocoOoO COC N ws Oo sotdwes eqeiedss omy YSTJ poyzew-uou YSTy peysew DOT OCODO DODO ONN NN OHS NAON - CODOOMNMNANN MINA HF OUWM eid 6 l ¢ tA ¢ 7 T C 0 6 8 9 S ri suinqey “ON uotjenby uot e[ndog s,Taqeuyog Butsgq Aq puod FJOTZISY TOF sseg psyoojsg Jo sa ,ewTisg_ vote [ndog ALY UOW 7 eTger SOJEOTPUT S9JeOLpuy SOJEIT PUT 4 4 --- Page 16 --- UST} PeyxAeW-vOU SsleoTpuyT = WN UST] payIew soqeoTpuyT - W a ae: = 997 ™” OTSO@ eLT WN T 6) ] 39G WN 7 97 77 ZEEO% O88 WE 0 ¢ GLY I? i LO76T 25 ¢ t €L7 Ov S Se6s8t OFS v7] 6 £67 Gt L SOVLL 9672 9 val 07S Be ¢. 60TST 870g 8 €T 69S Ez 9 TSOET c6SZ (al BT £19 LT T 68701 LT 0} ja £96 91 L 5106 STEZ Zl 6f VTL 6 2 £699 OS91 rai ST 178 S) t £906 CLE 6 ra BLZI £ 0 GSEBE 0 6) ) BLcl t 0 SEBE 646 ve TT 756 £ t 9S8Z ELOZ Ee Le v8L @) 0) 71 BL Bz 0 82 ais a, 2 i et edog suan joy ponousy peyaewy 1yeney ata “ON _ * ON "ON “ON uoTjenby uot eTNdog s,Teqeuyosg BurTsp kq puog 133UNqH FOjJ sseg payoo Is jo soqyewtT sy vot e[ndog ATYyIuOW G 9TqdeL --- Page 17 --- As these data indicate, a period of six to eight months of marking and re- capturing is required for the population estimates to stabilize and afford an accurate measurement. Since sufficient numbers of offspring have not been marked to allow a true indication of their numbers, only stocked bass have been used for these population estimates. The population estimates obtained for the Retzloff and Hunter ponds varied widely from the number of bass originally stocked (Table 4). The discrepancy indicated for the Retzloff pond is probably due to the short period for which sampling of the recaptures has been successful and may adjust during the next few months. The deficiency of the Hunter pond is probably near correct, since it is known that the pond owner allowed friends to fish the pond prematurely and heavy harvest is suspected. fn order to show the estimated standing crops of stocked bass for each of the ponds, calculated weights were used together with population estimates to approximate pounds of bass per acre (Tables 6, 7, and 8). Examination ot the estimated standing crops for the ponds show Hunter's pond to be the heaviest producer, followed by Retzloff's and Kunitz's. Order of production of the ponds corresponds proportionally to the stocking rates thus far. It is felt that this will alter in the near future, however, since production is believed to be near its maximum at Hunter's now. If this as- sumption is correct, then the desirable stocking ratio, based on production alone, would be between 100 and 150 bass per surface acre. A lower stocking rate than 75 to 100 bass per acre would require approximately two years for maximum procuction, therefore, reducing both the time when catchable fish are available and the number of catchable fish. Fishing success for the three pontis may be rated as very good at Hunter's, fair at Retzloff's,and poor at Kunitz's. These ratings are based on the presumption that one fish per man-hour fishing time is good. Table 9 gives the results of fishing success. Althcugh the best fishing occurred at the more heavily stocked ponds, these successes were not. proportional to the number of bass stocked. While Kunitz's pond, which was stocked at the rate of 50 bass per acre, yielded an overall fishing success of 0.53 fish per man-hour, Retzloff's pond, stocked with 100 bass per acre, yielded only 0.68 fish per man-hour. Obviously, factors other than stocking rates are influencing fishing success. Two probable influences are? water turbidity, and the lack of offspring being produced. The influence of water turbidity on fishing success is pointed out in Figures 7, 8. and 9. It is believed that the turbid condition of the water at Kunitz's pond is responsible for the low fishing success. Correlation analyses will later be used to determine if water turbidity or stocking rates have been the most important facror. The second factor responsible for decreasing fishing success is a lack of offspring being produced by the stocked bass. A high concentration of sulfates in the Retzloff pond ie believed to have prevented the production of oftepring. --- Page 18 --- -16- Table 6 Monthly Estimates of Standing Crop of Stocked Largemouth Bass in Kunitz Pond in 1966 Estimated | Estimated population 104 104 104 104 104 104 104 104 x x x x x x x x 104 x 104 x 10+ * - Calculated from linear regression of mean sample weight on month # - Calculated from Schnabel's mark and recapture method ** - Using 1.1 surface acres --- Page 19 --- =(7- Table 7 Monthly Estimates of Standing Crop of Stocked Largemouth Bass in Retzloff Pond in 1966 ~ Estimated Estimated a. Estimated population | Estimated pounds weight (gm)* | population # __weight (gm) _| per acre ** % - Calculated from linear regression of mean sample weight on month # - Calculated from Schnabel's mark and recapture method ** ~ Using 3.0 surface acres --- Page 20 --- -18- Table 8 Monthly Estimates of Standing Crop of Stocked Largemouth Bass in Hunter Pond in 1966 Estimated Estimated ight_(gm)* | population # 841 744 563 617 569 540 497 473 475 462 466 1. 1. L. 2 wd ae 2.4 2s 2% 2. 3. 3.% A * - Calculated from linear regression of mean sample weight on month # - Calculated from Schnabel's mark and recapture method we - Using 3.4 surface acres --- Page 21 --- a] Ox Table 9 Fishing Success in Fish per Man-hour for Kunitz, Retzloff and Hunter Ponds Kunitz | Retzloff ~ Hunter No. No. Fish per. fish man-hrs.__man-hr. No. No. Fish per fish man-hrs. man-hr. No. Fish per fish man-hrs. man-hr. 10 3.00 3.033 LO 1.00 10.00 6 4.75 16 6.75 2.37 28 7.50 3.73 12 6.25 16 12.50 1.28 28 3.00 9.33 LO 14.50 7 8.50 0.82 56 9.00 4.00 8 12.00 10 7.50 1.33 tl 15.00 0.73 4 14.00 0 3.00 0.00 0 6.00 0.00 8 16.25 3 11.42 0.26 LZ 4.50 2.67 12 13.00 3 L3..50 0.22 15 4.75 3.16 9 7.30 5 15.50 0.32 19 3.59 5643 il 14.83 3 13.00 0.23 it 3.50 3.14 6 4.50 5 13.33 0.38 18 7.00 2.57 9 23.00 9 7.50 1.20 13 9.00 1.44 1 30.83 LL 17,42 0.63 18 17.42 1.03 0 13.50 4 3.75 1.07 12 10.58 1.13 5 9.00 10 9.00 1.11 ll 7233 1.50 2 2.00 6 16.00 0.38 12 9.30 1.26 1 9.75 3 10.50 0.28 8 10.50 0.76 2 5.00 3 11.00 0.27 3 17.50 0.28 106 200.46 124 183.17 --- Page 22 --- SOyuout Ut sBulpear TYIIAS e@ 8 6 6 o9 © @ e & e eo > & @ a a es ® o N °o 8 5», © 8 82 #@ %® @ ® jo) ie] puog ziTuny ye sBurpesy TYyI9eg YIIM sssoong BuTYsT| Jo uostiedwog - / 2INBTyq ee 9961 S961 dag AON 399) «d8g° Bay [np oun AeM ddy apy aeq oe 35g AON 1990 deg Bny Se aera WS ey 4 ~ r | / SSuULpeai Tyo.e¢ sso00ns BuTyusSTyY -=— wn ANoYy-UeU/YSTT = ssaoons Surysty --- Page 23 --- -21- SayoUuT UT SsBuUTpedsI TyI09¢S puog JJoTZ139y Je sBuLpeaey TyI.eg YIM ss9d0ng . — — 2961 seq. ACN 390 deg any [nr une Aew ady iy BuUTUsST4y Jo UoSsStAedwog ~ Qg dsanBTy S967 Geq uer oq AON 199 deg sny SSuTpedt TYyoDeC ssaoons Surystq’ ~"7 inoy-ueu/ystTy - sss0ons Buryust¥ --- Page 24 --- 222 - S9YdUT UT s8uUTpeaz TYyd0a0 wy N O€ ° ° oo na eee oaman cs 2 puog 291UnY Je ssuTpeay TYyI.eg YITM sseoong BSuTYSTy Jo uostaeduoy ~ 6 aunty 9961 6961 qd A0N 390 deg 3ny [ne ung Seq ady xeq qag uep oeq AoN 190 dag Sny ~~ ieee ae emcee | k,n I ca nt 4 is sSuLpeer Tyo0eg { ‘\ sseoons Sutustym—-= / \ / \ a “A / \ \ / \ \\ ; \, / \ ‘ ¥ \ NN 4 \ 4 \ \ a’ \ ‘ / ‘ ! i . \ / ly \ / \ iy \ / \ I \ \/ \ / \ e j { \ / } , 7 \ / \ , of \ 1 \ \/ ) \ 7 0 wn t Anoy-uew/YstTy - ssaoons Butrysty Oo ~ lon) --- Page 25 --- ne) Go If this is true, then the number of bass per acre is less than it should be, thus accounting for the low fishing success. Discussion and Recommendations: Upon reviewing the work completed during the first three segments, several observations have been made concerning the success of the experiment. The most important observation is that many uncontrollable variables were encountered. Such variables as pond quality, water supply, water quality, pond location, and pond ownership have proven detrimental to the experiment. It is felt that these uncontrollable factors have influenced results as much or more than the experimental design, thus reducing faith in any conclusions which might have been reached. Due to the presence of these variables, it is felt that the experiment should be carried on for at least two additional segments under more controlled conditions. Acknowledgement : Special recognition is made of Project Leader John C. Barron. His advice and help with the analysis and presentation of data have been very valuable in contributing to the experiment. Prepared by John M. Travis Approved by O/CEPCOD A _ Asst. Project Leader ' Coordinator Date March 8, 1967 Ernest G. Simmons Regional Supervisor