TPWD 1955 F-4-R-2 #138: Creel Census of Benbrook Reservoir

STATE Texas PROJECT NOanfimR~2 Job B-lO PERIOD June 12 1953m0ctober 31a 1955 r __.. . . . a ‘l. l‘ “" a M f ' I _ .l w JOB cowmeébw REPORT BY IEONARD D. LAMB PROJECT LEADER TITLE Creel Census of Benbrook Reservoiro OBJECTIVES To estimate the total catch by species and to obtain data regarding the growth rate and relative abundance of each species in the catcho METHODS on The data used in this report was obtained by inspection of the creels of fishm rmen using Benbrook Reservoiro Census stations were established on the three roads leading into the Reservoir area and were manned by Game and Fish Commission personnel for a total of six days each month. These days were selected to include both weekmend days and week daysu A check was made to determine what the difference in lake use ' would be on week days and week end daysa The results of this check showed that a greater number of people visited the lake on week ends but the percentage of fishermen remained almost constantw Since the lake is so near a large population center where there.is a number of large plants that work night shifts allowing persons to be able to visit the lake at almost any hour, the choice of days had little effect on the resultso The Un 8. Army Corps of Engineers maintained traffic counters on all access roads which gave accurate data as to the number of persons visiting the lake for any given period. Spot checks were run by both Game and Fish Commission and U9 Se Army Engineer personnel to determine the average number of people per car for the traffic over the countersg The creel census stations were set up in such a manner that all persons going overthe counters would be halted by road blockso Those persons who were not fishing were recorded as such and those who had been fishing were required to submit their catch to examination» The fish were measured and recorded in inch length groups on forms devised for that purpose0 The other pertinent data was obtained by questioning the fisherman and included; method of fishing, type of bait, number of hours fished and part of day when fishing was done. The data obtained from actual content with fishermen and count of his catch as expanded to provide the fishing pressure per acre and the total harvesto This expanm sion was made by finding the average number of fish caught per fisherman contacted and 29 multiplying the total number of fishermen to visit the lake, as shown by traffic counters, “y this figure. The same procedure was followed to determine the total hours of fishing is well as to determine the number of each species taken. Since the sampling was done during good days and bad and on week days as well as week ends, it is believed that the calculated totals are reasonably accurate. Calculated data was used in Tables 3 and h, but the data used in all other tables is actual data obtained by a count of the fish taken by the fishermen. In calculatingthese totals it was assumed that the average numbers of fish taken and hours fished by the fishermen contacted would hold true for those not contacted. Each month the totals obtained by actual contact were expanded to cover the total number of of fishermen as represented by the traffic counters. The total number of cars passing the counters was divided by two to account for the fact that the car crossed the counter twice on each trip. Further adjustments were made to account for the percentage of the cars found to be pulling a boat trailer. The final result was then multiplied by the average number of persons per car, as determined by the spot checks to give the total numu ber of persons visiting the lake during that month. The road blocks provided the number of fishermen as well as the number of nonufishermen from which the percentage of fishermen among the total visitors could be determined. This percentage was then taken of the total visitors to give the calculated total fishermen for that month. By this method the calculated totals are: Total Fishermen h71,683 Total Hrs. Fished 1,855,351 Total Fish Caught 637,3tt Av. Fish per Man Hr. .3h3 {STORY OF LAKE The Benbrook Dam is located on the Clear Fork of the Trinity River, 15 river miles above the stream's juncture with the West Fork of the Trinity and about 574 river miles above the mouth of the Trinity. The dam was constructed by the U. S. Corps of Engineers as a dual purpose impoundm ment. Flood control and water conservation are the primary purposes, but recreation and municipal uses are given definite consideration. The dam was closed September 29, 1952 and the impoundment was begun. The lack of rainfall since that date has caused the water level to remain low. The lake was stacked by State and Federal Fish Hatcheries in.May and June of 1953 and was closed to fishing in October of 1953. The lake was opened to fishing on June 1, l95h at which time this creel census was begun. FINDINGS Table 1 shows the fishing success as represented by data collected by actual contact with the fishermen and it may be noted that the month of June 1954 was the best fishing month with January 1955 as the poorest. The fact that the month of June 1955 was the first month of fishing since the closing of the lake in October 1953 may be cone sidered responsible for the unusually high catch as well as the heavy fishing pressure. The high degree of success during this month is also marked since 64% of all fishermen were successful as compared to a high of 35% during the other months and a low of 7.06% 1 January 1955. Table 2 presents the monthly variation in species taken by fishermen and here the intensity of the fishing pressure during June 195M is apparent. The catch of this month made up about h5% of the total catch for the entire 17 months period while the bass catch for June 195% composed 83% of the total bass catch. The base were able to dominate the catch in only two months of the entire period. They made up 77.97% Of the catch in June 195M and 59.38% in November. in examination of figure 1 will show that except for the months of June and November, 195M, the brunt of the fishing pressure was taken by the sunfish and bullheads with white crappie increasing in the last three months. The monthly variation in average weight for the fish taken from Lake Benbrook is presented in Table 3 and closely corresponds to the variations in standard length groups shown in Figures 2, 3, and M. The larger fish of each species appear to have been rather heavily harvested during the first month the Lake was open to fishing. Five months were required to raise the average weight of the bass caught above the .Bh lbs. of the first month. Only four of the seventeen months offered an average weight for bass greater than that of the opening month. Sunfish exceeded the Opening month average weight in only one month while the crappie averaged 1.69 lbs. in June 195% and had attained an average of .65 lbs. by October 1955. The crappie average in June 195t was based on only six fish which is not large enough sample to give good results. The channel catfish did not appear in good numbers in the catch at any time and averaged .53 lbs. in June l95h and after disappearing from the catch until May 1955 attained an average weight of 1.53 lbs. and 1.28 lbs. in May and June 1955 respectively. The bull- heads however were unable to exceed the .h8 lbs. average of June 1954. In Table A the monthly variations in fishing precaure per acre of water are hown. This is calculated from creel census data and is based on the results obtained by the nee of information furnished by the automatic traffic counters. The average acreage represents the average for the month. The catch per acre in both numbers and pounds is very high but when the monthly variations are noted it becomes apparent that the majority of the harvest was completed during the first month the lake was open to fishing. This month provided hh% of the total number and 71% of the total pounds that were produced during the entire 17 months. The pounds of fish per manehour of fishing is not good since the month of June 1954 produced the high mark with .38 lbs. and the entire 17 months only produced .2 lbs. per manmhour of fishing. The data in Table 5 is based on the actual data expanded by the information given by the U. S. Corps of Engineers traffic counters and presents the calculated total harvest in number, percent? and weight of each species in the catch. The bass catch provided H9.7l% of the total number of fish caught and 80.lh% of the total weight. Sunfish furnished 30.37% of the total number but afforded only 7.h1% of the total weight. Table 6 shows the comparative success of the various fishing methods used on Benbrook Lake and is based on the data obtained from contact with the fishermen. Stille fishing accounted for 83.h1% of the total fish caught and usually produced the greatest catch per manehour fished. The comparative data on number of fish caught on various baits shows that in June 195% more fish were caught on artificial lures than any other (t2.28%) but in July 1954 combinations of live baits produced 61.32% of the total catch. The catch for no remaining fifteen months of the creel census was dominated by minnows and worms with worms accounting for the majority of the catch. (Table 7) The stocking of Benbrook Lake by both State and Federal Hatcheries is presented in Table 8a The initial stocking was made in May and June of 1953 following the closure of the dam in September of 19520 The stream had been almost dry above the dam before closure and few fish were Present when the stocking was maden The only stocking in 1954 was wade ‘by the Eagle Mountain State Fish Hatchery and consisted of 109,000 bass from 6 inches to 9 inches in lengtho This stocking was made about November 27, 19540 The 1955 stocking was made by both State and Federal Hatcheries and included yellowbelly sunfish in addition to the species originally stocked with the exception of black crappie which have not appeared in the catch of experimental nets of the biologistso DISCUSSIONS AND CGNCLUSIONS The percentage of fishermen who-caught at least one fish remained fairly constant except for June195h when the high of 6&006% was reached and January and February when 7°06% and 1ho82% respectively were the low percentages for the periodo This lack of snow case is somewhat due to the fact that the closed season together with the volume of news- paper publicity given the lake during the period when it was closed to fishing caused many people to fish in this lake who were not experienced anglers and who for this reason were unable to catch any fisho The catch was dominated by largemouth bass during the month of June 195M when 77°79% of the total catch was composed of this species, Table 29 November of that year was the only other month when bass predominated the catcho The predominance of bass in the catch for June was sufficient to give that species first place with 42098% of the total catch while sunfish and bullheads make up 31,77% and 2102h% respectivelyo This domination by base was due to the heavy stocking of that species in May and June 1953 'hen 3703325 bass fingerlings were stocked in the lakeo _ The monthly variation in average weight for the various species taken from Benbrook Lake show that the largemouth bass averaged cahw lbso during June 195%, Table 30 These fish were believed to be those stocked or spawned in the lake during the previous spring with the exception of a few fish taken that were obviously present in the stream before impoundmenta These older fish were few since the low rainfall during the previous three years had allowed the stream to dry up into a few potholes that were so small and shallow that they supported only a limited populations The average weight of this species remained below that of the first month; with the exception of Nevember 1954 and February 1955, until the following June when the average weight reached 085 poundsa August and September provided average weights lol8 and 1001 pounds respectivelyo The monthly average weights of sunfish and bullheads did not exceed the weight of June 195% except for sunfish in December when an average weight of 019 lbso was reachedo The harvest of these species is far below the optimum and the lack of larger individuals in the catch indicates that the danger of overcrowding is presenta The streams that form the "watershed of this lake were well known for their production of large sunfish in the years past but the recent drought has eliminated the habitat that formerly existedo This has resulted in a population of small sunfish in the limited, shallow pools that are left in these streams, and with each rain that produces stream flow these small specimens are added to the population of the lake resulting in a still further reduction of the average size of the sunfish presento The data shown in Figure 2 indicates that the small sunfish bear the bulk of the ishing pressure for that species since 5h% of the total catch fell in the 3"-and M” standard length groupSs The 5” length group provided 32% leaving only 14 % to be made up of the sizes that are usually considered to be above averageo . 5. The bullhead harvest (fig. 3) is made up, largely, of the smaller fish since 68% of the total catch was in the 3” to 6” standard length group. Lake Benbrook suffered from drastic changes in water level, Table t , as the 912 acre average in June 195M had steadily decreased until only 501 acres remained in February 1955. Rainfall increased in 1955 however and the water rose rather steadily until the basin contained 1,275 acres in OctOber 1955. This change in water level during the first nine months forced the fish to concentrate themselves and their feeding into smaller areas and increased the pressure on the food supply. This should have increased the take of fish per manwhour of fishing but such was not the case. The abnormally high yield in both number and pounds per acre during June 195M had apparently reduced the population of bass until that species was not crowded to the point where their food supply became critical. The crowded conditions that prevailed during the winter and spring of 1953~5h had either prevented a spawn of bass or had resulted in the young being eaten soon after hatching since seining operations in all parts of the lake failed to produce young base. This was in direct opposition to the condition in the spring of 1953 when minnow seine drags in any shallow area of the lake produced an abundance of small base. The minnow seine did not produce an appreciable number of any forage species at this time to further indicate a crowded condition with regard to the carniverous species. The total production shown in Table 5 was calculated on the basis of data pros vided by the automatic traffic counters regarding the total number of fishermen visiting the Lake each month. The average number of fish in each size group found in the creels of the fishermen was expanded by the calculated number of fishermen to give the totals 158d in this table. The average lengths and weights along with the percentage of number and weight remain constant with the fisherman. These totals show that three species provided almost the entire production of the lake with largemouth bass carrying the major portion of the load. The 316,833 bass averaged 9.35 inches in standard length and .86 pounds in weight for the entire 17 months period and constituted M9.71% of the total number and 80.1h% of the total weight. The 193,585 sunfish averaged n.83 inches in standard length and .13 pounds in weight to make up 30.37% of the total number and 7.hl% of the total weight. Bullheads numbered 111,126 and averaged 6.23 inches standard length and .29 pounds in weight for l7.t3% of the total number and 9.h7% of the total weight. The other three species in the catch were in such small numbers that they appear to be negligible. The black crappie did not appear in either the creel checks or the netting operations involved in the inventory job that was carried on at the same time as the creel census. This was not expected since 23,650 of this species were stocked in the lake in 1953. The analysis of the various fishing methods revealed that after September 195M only stillfishing and casting were used to any extent and only stillfishing continued to be productive. (Table 6). The favored method of fishing during the month of June 1954 a was stillfishing but trolling produced the best catch per manmhour. Trolling however soon failed to produce and stillfishing became the accepted method with a few fishermen continuing to cast with comparative poor results; Artificial lures proved to be the most effective bait during June 195% when approximately 78% of the total catch was largemouth base but that condition lasted only during that month (Table 7). The percentage of fish caught on lures fell from us.28% in June to 2.19% in July and never exceeded lu.05% thereafter. Combinations of live baits proved to be the most productive in July producing ’l.32% of the total catch but the bulk of the catch after July was made by minnows and worms with worms accounting for the majorityg This may be attributed to the fact that can cept fOr dhne and November 195M the entire catch was predominately sunfish and bullheads. These species are readily taken on both worms and minnows with worms being most readily accepted and least expensive to use. The initial stocking of Benbrook Lake was made with the assumption that reasonably lormal rainfall would occur. This was not the case, however, and the 9hO surface acre area at the time of the initial stocking was reduced to 912 surface ares by June 195h when the lake was opened to fishing and this creel census was begun. The initial stocking of 5e8,575 fish amounted to 583.6 fish per surface acre of which 393.9 were largemouth bass. This stocking was in addition to the fish already present in the lake, some of which had spawned during the spring and early summer. The usual stocking of bass in waters that do not contain fish is 150 per acre when stocked alone or 100 per acre in combination with other species. This apparent overstocking was further complicated by the lack of rainfall and the closing of the lake to fishing. RECOMMENDATIONS 1. The results of this study have indicated a need for further study and it is recommended that a similar study be considered within the next four years to check on changes thatnaur occur in the fishing success and pressure. 2. It is further recommended that the policy of closing lakes to fishing during the first year after closure be examined closely to determine if the lake benefits from such closure. - 3. The need for an increased harvest of sunfish and bullheads is quite apparent and further study of this problem is suggested. a. The possible introduction of flathead catfish as a control on the small bullhead and sunfish population is offered as a possible aid in solving that and the ough fish problem. \ SUMMARY 1. Benbrook Lake is located on the Clear Fork of the Trinity River near Fort Worth, Texas. It is a flood control and water conservation impoundment constructed by the U. S. Corps of Engineers and completed September 29, 1952. 2. The lake was stocked with 548,575 fish in May and June, 1953 and closed to fishing October 1, of that year. 3. The fishing season was opened June 1, 195M at which time the creel census was begun with census stations operating on the three access roads. These stations were manned by Game and Fish personnel a total of six days each month with these days so dise tributed as to include both week days and weekeends and good weather and bad to give an adequate sample of fishing conditions. a. Road blocks were set up at these census stations which were so located as to stop all cars leaving the lake. These cars were required to pass over automatic traffic counters maintained by the U. S. Corps of Engineers and gave the total number of cars using the lake area. This data was used to expand the data that was obtained by the creel census stations during the six days per month they were in operation to give total productions. 5. The fishing during the month of June 195% was largely for bass with stille ishing as the most popular method but trolling producing the greatest number of fish per manehour and artificial lures accounting for the greatest number of fish. This cone dition changed rather rapidly and except focNovember 1954, base were exceeded in the catch by either sunfish or bullheads. The favored fishing method continued to be stille 7, ”ishing with casting a poor second and minnows and worms becoming the most productive baits 6. The average weights of the fish taken from Benbrook Lake indicated that occa.sional catch of a fish that was present in the stream at the time of impoundment The average weights during the succeeding months was generally below that of the opening month To The loss of water due to lack of rainfall reduced the average a.creage from 912 in June 195% to 501 by February 1955 The increase in rainfall during l955 increased the acrea ge to 1,275 acres by October 19556 The harvest of fish per acre and pounds per acre was very high for the first month but declined rather steadily until the lake started to increase in volume when‘the decrease in production became less pronounced. 8a The calculated tota.l production indicates that bass, sunfish, a.nd bullheads carry the load with white crappie beginning to show an increase during the latter months of the census period Because of the heavy predominance of bass in the first month of the census that species accounts for 49 71% of the total number and 80. lh% of the total weight mo Hmawe Ho nwmwwom mcooemm mm waeuemaoaem 6% Uses oowwmodwm wees weucnoow beam Queew neomomc Mane He mer so Ooaowme wwc Hmmmo WHmWMEmo wmeomod ow bww eHmWeHamo mooeammwsw mneoemmwsw dbmfioommmwow Hodmw Wamfi domoooemmwzH Wemw\gmo meg Hodmw aoemw omsmwd Wemfiowemo moowm moon Wamfimm moose Wamwma monommmwsw mefiwam awareness Weaveuaeo moon gon bomcmd mmwamaaee Ooaoweu Zodeedmn veneesmn mem mmoomuw newcomuw zmuow beeww Sew 955w MSH% bcmomd mewdmadme Ooaoame Hoabb Hm Wm Hoe sea was Hem Haw wH mummo Ham ems mom mma ewe mmo meo use Ham Ham steam mw HOH was mmw man wmm see «me mme Her acmmm ammo www mom mma was mmw Hem emo mew mew same swam Here men mew mmo WW4 Hecmmm anew H.mmo ammm may aow mam H mew Homer -maw wmw rue ewe mmo mac H.mme new: name ommm Heme wem mo: Hoe Hmm mH em: mom ewe mmmo mane mmwm Home rmwm ewe meo mwcmom new; Lama rwmm Pew mom Ham “ewe gene name .wrw meoom macaw mm.mq wm.44 mmrmm worse mw.ma e om H: mm wmaom mo.ow mm.mw mo.e~ mm,H: wmum: wmomm weoeo weiem HQUHm mo mweowmm Bower hcomawmm: .chw . bcmomd moweaadmu Ocdocmw Zedesdee beoeBUmw mmoome%anmm Wmdwsmww zmeow wwHHH gee home moww bom5md mmwdmsceu Oododmu BOHme b. E; meme Zoo a was some Hm He.mm wm womw mm wo.we we woomm ma meowm w Heowm aw weomw we wooaw wm womw em Hmcmw we mime we are Wm Hm.mm wm some #4 Hm.aw so wo.me wcpw: rwowm wcmwp mmowwmw 20 a pm: Hwowe we noomo Hma mm.mw m4 renew re magma wm wmoo: m: ma.mo we wwomw me warm: Hoe wwowe era wa.4w wmm spawn. Hem .+mgw: we mo.oo mew emcee Hoe .+woew aw w4.HH and mo wswwwemmm 20¢ a wow m.mo wo H:.mo mm wwnmw wm Hmoww mm :H.aw we He.em Ha wHowm we wmamm we Hoimw ewe meoma woe wwoew wmm :m.mw are Wm.wm mo wwoww ems wo.mm mm wegrm we Hoamw Hcmww NH.mr 2e oumwwwm Zoo I‘OO‘N F-F‘Ch a stem wewo Heawe .mm mama mama wmomw wQHO ow amdwwmw 2o. {DWI-'3 LUI-JJ—T' \O‘F‘l—J wm a woe rwm wrao were new new worm omH owe same are omuw 2o. HO HMi—JH we H.0m Hoor Howe woom ngr “we owe owm .9ww new EOU¢SH% <muwmewoo H5 mweowmm amass fines weodnoow Hme mm mwoeo 6% oummH Qabmom weds» meme H» mer so Oneodmu ch memo Hedmwm smmH acwmm lO . Table 3. Monthly variations in Average Weights of Species Taken from Benbrook Lake as Shown by Creel Census Date, June 1, l95h to October 31, 1955. W Month German Carp Channel Bullhead Largemouth - Catfish Catfish Black Bass Sunfish Crappie 19st June .53 .us .8t .18 1.69 July I .l3 .72 .15 .08 August .19 .62 .13 .10 September .15 .20 .69 .16 October .17 .78 .10 November - .27 1.11 .15 December -.hl .Tl .l9 1955 January .MS .68 .lO ebruary .A6 1.27 .13 .18 March 2.01 .22 .72 .15 r.2e April 1.25 .21 .78 .12 .M2 May 2.t1 1.53 .22 .80 .15 .35 June 1.28 .17 .85 .10 .39 July .26 .75 .12 August 1.08 .38 .22 1.18 .11 .3h September .23 1.01 .10 .31 October .36 .36 .71 .11 .65 17 MONTH 1.63 .90 .29 .86 .13 .e0 AVERAGE