TPWD 1956 F-2-R-3 #238: An Inventory and Creel Census of the Fishes of Lake Inks, Texas

STATE Texas PROJECT F-2-R—3 Job B-lK PERIOD June 1955 through January 1955. SEGMENT COMPLETION REPORT FuE ‘by KENNETH C. JURGENS Project Leader TITLE An Inventory and Creel Census of the Fishes of Lake Inks, Texas. OBJECTIVES To determine the relative abundance of species present in Lake Inks; to estimate the total catch; and to obtain data regarding the relative abundance of each species in the total catch. PROCEDURE Inventory 9: Species Regular field trips to Lake Inks were begun in July 1955. On these occasions net and seine collections of specimens were made randomly in all parts of the lake during the study period. The specimens collected were taken through the use of small meshed seines and experimental gill nets, and on one occasion through the use of rotenone. Seine and rotenone specimens, except gizzard shad, were preserved in a lO per cent for“ malin solution for later examination and identification in the laboratory. Netted specimens, on the other hand, were identified, weighed, measured, and examined for their stage of sexual development in the field. The stomachs of game fish found to contain food were removed from the specimens and preserved for later laboratory examination and food analysis. Data was recorded in the field for netted individ« uals of the game species and in some cases for individuals of the forage and rough species. These data formed the basis for estimating the relative abundance of the various species in the total population in Lake Inks. In all, eight net and twelve seine collections were made on each of the monthly field trips with the exception of the trip made in January 1956. During the January trip an area of about two surface acres, with a maximum depth of about ten feet, was treated with rotenone for a complete kill of the fish in that area. This rotenone collection of specimens was substituted for the regular net and seine collections, and the specimens thus collected are lumped together with the netted and seined specimens in the data recorded in Tables I and II. Creel Census To estimate the total catch by species a census of the angler's catch was begun in July 1955. It was found that virtually all the fishermen using the lake could be interviewed by establishing census stations at the three major commercial docks on the lake. The total number of fishermen using the lake on census days were estimated by making cruise counts of fishermen along the shore line of the lake. The census stations were operated throughout July, August, and September. However, the sharp decline in numbers of fishermen after the Labor Day weekend in September soon led to the abandonment of the census stations. From September on, it was necessary to go to the fishermen wherever they were fishing on the lake and interview them on the spot. The cruise count method of estimating the total number of anglers using the lake was continued. In order to obtain an estimate of the average length of fishing trips after Labor Day it was necessary to mark the census cards for each fisherman as either complete or incomplete trips, depending on whether or not the fisherman when inn terviewed was still engaged in fishing or had already quit for the day. The average length of fishing trip was then based on the number of completed trips. Total catch estimates were made for boat and shore fishermen separately and later consolidated. So little trotline fishing took place on Lake Inks that this type of fishing was not included in the total catch data, however, data con~ cerning the success of trotline fishing, based on the sample obtained, have been included. The formula used in estimating the total catch or total yield for the seven month period included in the study by all fishermen using Lake Inks, excluding trotw line fishermen, is as follows: Total yieldz: (a'b°d) ( E-) where a:: the average number of fishermen counted on the lake on all cruise ' counts made during the census period. b‘: the average length of the fishing day, i.e. the length of time in hours from when appreciable numbers of fishermen start fishing until virtually all have stopped fishing for the day. d : the number of days in the census period. f g the total number of fish caught by the fishermen interviewed. ; the total effort in hours by the fishermen interviewed. This formula was derived from: Total yield.: (total fishermen) (average creel) where ( avg. no. of anglers ) (avg. length of) number of days Total fishermen:: counted on all cruises fishing da X in census (length of average fishing tripi period (Total No. fisherm)(Length of)(Total fish can ht b censused men ) Average creel : men censused avg. tri Total hours fished by censused men Total number of fishermen censused and Since Rate of catch 3 Total fish can ht b censused fishermen) Total hours fished by censused fishermen (Total fishermen)(length of) Average creel: censused av . tri (rate of catch) (Total fishermen censused) or Average creel : (length of average trip) (rate of catch). Therefore: Avg. no. men Avg. length of No. days in ( )C )( ) Total yield; counted on cruises fishin da census period X(length of ) (length of average trip) avg. trip X (rate of catch) 01‘ (Avg. no. men ) (Avg. length of)(No. days in ) (Rate of) counted on cruises fishing day census period catch Hence: Total yield a ( aobod) (—5-) LAKE DESCRIPTION Lake Inks is a relatively small reservoir lake of approximately 900 surface acres, containing 16,000 acre feet of water, and is located on the Colorado River in Burnet and Llano Counties, approximately 10 miles west of Burnet. The area of Central Texas in which Inks Lake is located is known as the Llano uplift region. The surrounding county is unique in Texas in that the soils are dem rived from the underlying granite instead of from limestone. The area is marked by the bald tops of granitic intrusions and the terrain of the area is generally rugged. The timber of the area is mostly junipers and cedars on the hills and post oak, blackjack, and mesquite on the more level places. The thin soils of the area are coarse gray or moderately heavy chocolate loams which do not adapt well to agriculture, making the area ranch country. Normal rainfall for this part of Texas should be approximately 30 inches per year but during recent years has been considerably less. Lake Inks itself is a constant level lake. Fluctuations in water level are slight, varying in a downward direction not more than two or three feet for short periods of time. Only on rare occasions does the lake rise above the so called ”normal” level. Because water level fluctuations are slight, submerged aquatic vegetation grows luxuriantly in the lake, providing more than ample cover for the shoreline species of fish. The vegetation at times is a hinderance to anglers, being so thick that most of the shoreline is inaccessible, as are all of the shallow shoal areas. A. There are but three major fishing camps on the lake which have a total of about #5 boats for hire. Another smaller camp is little used by the fishermen coming to the lake. Fortunately approximately one fourth of the shoreline of the lake is included in the Inks Lake State Park. This area is accessible to the general public and during the vacation season is much used by fishermen and campers coming from places all over the state. Much of the shoreline of Inks Lake, in the state park area, is grown up in dense patches of cattails, bulrushes, and saw grass, making the shoreline diffim cult to fish from. Likewise, the lake bottom in this area is mostly a gentle slope much grown over with submerged aquatic plants during the summer and fall seasons. Parrot feather (Myriophyllum ep,) and coontail (Ceratophvllum sp.) are the most an bundant of these plant species. About one fifth of Lake Inks is much like a river in that water coming through the turbines at Buchanan Dam causes a strong and deep current to move through Lake Inks, from the tailmrace of Buchanan Dam to the highway bridge crossing the lake. At a point just downstream from the bridge this current of usually colder water sinks beneath the warmer water of the main lake. Thus, the water from Buchanan Dam to the highway bridge is usually murky and has a strong current while the surface water from the highway bridge to Inks Lake Dam is generally clear. Since the prevailing winds of this part of Texas are southeasterly, most of the lake is not usually subject to violent wave action due to strong winds, making the lake_quite safe for boaters most of the time. FINDINGS Inventory 9f_Species Table I contains a checklist of the fish species found to occur in Lake Inks. In all 66 seine and as net collections were made in addition to a single rotenone collection. During the sevenwmonth study period these collections provided a grand total of u,937 specimens representing 24 species and 10 fish families. The results of these collections are given in Tables II and III. In Table IV is a record of the gonadal development of some of the more regularly collected species. Gonadal development of these species was rated from one to five with No. 1 representing ”ripe”, 2 representing ”nearly ripe”, 3 representing ”sexes distinguishable but gonads not well developed”, a representing ”gonads not developed, sexes not easily distinguishable”, and 5 representing "spent fishmgonads empty". Figure I presents the results of analyses made on the food remains found in the stomachs of 30 channel catfish and 10 white bass. Only four of the largemouth bass collected were-found to contain food in their stomachs. This food had a total volume of lll ml., of which 60.0 ml. was comm posed of the remains of gizzard shad, 50.0 ml. was composed of white crappie, and only 1.0 ml. was composed of sunfish. The single spotted bass stomach found to contain food remains held 28.0 ml. of partly digested giszard shad. Four white crappie stomachs contained a total of 3.6 ml. of food remains. This food included the remains of white crappie, minnows, and insects. Only two bluegill stomachs containing food were examined. The stomachs contained only a trace of unidentifiable insect remains and 0.5 ml. of Diptera larvae. Two stomachs taken from flathead catfish contained a total of 60.0 ml. of food remains. The bulk of this food (h5.0 ml.) was made up of bluegills and the remainder (15.0 ml.) was made up of gizzard shad. Creel Census Table V shows the results of boat fishing on Lake Inks. In it are given the number of successful and unsuccessful boat fishermen, the total fish caught, the rate of catch for successful boat fishermen, for all boat fishermen combined, and the per cent of the total boat fishermen who were not successful. These data are given on a monthly basis for the seven months covered by the creel census. Table VI presents the same data as Table V except that it is for shore fishermen. Table VII gives the results of trotline fishing on a monthly basis showing the total numbers of trotlines, the total fish caught on trotlines, the rate of catch per trotline hour, and the per cent of trotlines catching fish. Table VIII is a breakdown of the total fishermen by month, showing the number of parties and the average number of fishermen per party. It also shows the number of trotlines used by fishermen interviewed. Table IX compares the relative success of the various methods of fishing employed on Lake Inks both in terms of the total numbers of fish taken by each method, and the return per unit of effort in fish per man hour or fish per trotline hour. In Table X are shown the average rates of catch for ten fish species taken by Lake Inks anglers. These averages are given on a monthly basis and an average is given for the entire seven month study period. Necessarily these data are based only on pure catches where only a single species was involved. Table XI shows the relative success in fishing with the various types of baits used by fishermen on Lake Inks. Table XII presents the estimated total yield in numbers of fish for boat and shore fishermen. These estimates are given on a monthly basis and also for the entire creel census period of seven months.. Table XIII is a breakdown of the estimated total catch by species, showing the total number and weight of each species in the sample obtained; and the percent“ age of the total number and total weight of the sampleicatch for each species. In addition the table gives the estimated yield in number and weight for each species taken from the lake during the study period and the estimated number and weight per acre for each species in the estimated total catch. 'No trotline fish, however, are included in these data. ' Table XIV shows the average length in inches for each species in the fishm erman's catch both on a monthly basis and on a study period basis. Table XV presents on a monthly basis the total number of fishermen estimated to have used Lake Inks during the seven months covered by the study. Figures 2 and 3 give a breakdown by species of the total catch for the entire study period and a breakdown by species for the total catch on a monthly basis. The map in Figure H shows the home towns and home counties of the fishers men interviewed during the course of the study. DISCUSSION Inventory of Species Like the other large reservoir lakes in the chain along the Colorado River, west of Austin, Texas, Lake Inks is plagued with a rough fish problem. In this lake, giszard shad comprise a\very large portion of the total fish population. In populam _tion samples taken from the lake, giszard shad made up 16 per cent of the total seine ~sample and over 51 per cent of the combined net and rotenone sample (Tables II and III). Other rough fish species including shortnose garfish, river carpsuckers, and carp, though not so numerous in the total sample, accounted for more than 54 per cent of the weight of the total net sample (Table III). Thus, the combined rough fish species including the gissard shad totaled more than 72 per cent of the weight of the netted specimens taken during the seven months covered by the study (Table III). This is another indication that most of the productivity of the lakes in Central Texas goes into the production of rough fish rather than into the production of game or other desirable fish. The catfishes, which in this part of the country are classed as game species, accounted for another 6 per cent of the total number of netted specimens (Table III). Unlike species classed as rough or undesirable fish, catfishes play a relatively important part in the anglers? catch. To aid in building up the catfish population of Inks Lake, six of the flatm head catfish, taken in gill nets, were given to the Inks Lake Fish Cultural Station, U. S. Department of the Interior. me. Hornbeck, Superintendent of that hatchery, indicated his desire to obtain a spawn of flathead catfish for distribution not only in the large reservoirs of the area, but also in some of the farm ponds in the diam trict served by his hatchery. However, in the event that he is successful in getting these fish to spawn under hatchery conditions, it is expected that the bulk of the spawn will be placed in Lake Inks. It is hoped that propagation of flathead catfish by this hatchery and their subsequent stocking in the Inks Lake Reservoir will be an aid in the reduction of the rough fish population. White bass, though not abundantly taken in either seines or nets, are ape parently quite numberous in Lake Inks. This assumption is based on the effort made by many fishermen to take this species from tailrace waters below Buchanan Dam. Ate tempts made to determine the extent of spawning success during the study period had little success. Only two small specimens were taken in seine collections during the seven months the lake was studied (Table II). However, 56 specimens were netted during the same period and these accounted for more than 5 per cent of the total weight of the net samples, though they accounted for only 2 per cent of the total number taken in nets (Table III). Regardless of the small numbers of white bass taken in seine and net samples, the species accounted for more than 31 per cent of the total anglers“ catch of those fishermen who were interviewed during the creel census (Table XIII). Many of the white bass caught by anglers were relatively small, indicating a good spawn during the preceding spawning season. It appears as if the bulk of the white bass population remains in that stretch of water just below Buchanan Dam, where there is generally a strong current. This area, for obvious reasons,lhas not been extensively seined although nets set in the area have produced white_bass. Though Lake Inks is reputed to produce a great many largemouth bass of ”lune ker” size, this species did not appear in large numbers in either the seining, netting or rotenone samples taken from the lake. For that matter, they did not appear in very large numbers in the total angler‘s catch as sampled by the creel census. Regardless of this, largemouth bass are much sought after by anglers who come from many parts of the state. Even though the largemouth bass has not showed up in numbers in either the population samples or in the creel census, compared to Lake Travis, Lake Inks yielded l.5 more largemouth bass per acre in the seven months covered by the creel census than Lake Travis did in an entire year. (See Table XIII and Completion Report for Job ems, Project Fm2~Rm2). Two species of spotted bass were found to occur in Lake Inks. These were the so called Kentucky spotted bass, M. unctulatus, and the Texas spotted bass, M. treculi. Combined these species accounted for less then I per cent of the total netted specimens and less than 1 per cent of the seined specimens. (Table II and III). The sunfishes of Lake Inks include six species as shown in Table I. These species, combined, make up a numerous portion of the total fish population as evim danced by the fact that they accounted for nearly 36 per cent of the seined specimens and 25 per cent of the netted specimens taken during the study (Tables II and III). 0f the sunfish species the two most important are the bluegills and the redears (L. macrochirus and L. microlOphus). Unlike some of the other lakes in the chain along the Colorado River, Lake Inks apparently has a relatively large populam tion of redear sunfish. This species, however, provided only a small portion of the total anglers? catch, being overshadowed to a very great extent by the bluegill. The smaller forage fishes include only two cyprinid species, or minnows; two darters,and two topminnows. Combined, these species accounted for uu.2s per cent of the total seined specimens (Table II). The great bulk of these specimens were blacktail or spottail shiners, N. venustus. The paucity of small forage species is probably accounted for in the age of this lake, in the lack of tributary streams, and in the large numbers of sunfish. Creel Census The study of Inks Lake fishing under the present segment extended, as did the inventory of species, from July I955 through January 1956. During the seven months, the oracle of 39h boat fishermen and 690 shore fishermen were examined by 8. ' Game and Fish Commission personnel. In addition, the catch from 3h trotlines was also examined. In all, boat fishermen took 50h fish, shore fishermen took 1,28h fish, and 122 fish were taken on trotlines, for a grand total of 1,910 fish in the total sampled catch of the fishermen interviewed during the course of the study (Tables V, VI, and VII). Based on data recorded during the interviews, it was determined that host fishermen had an average rate of catch of O.h5 fish per man hour, or a fish every 2.2 hours. Similarly, shore fishermen caught fish at an average rate of 0.79 fish per man hour, or one fish every 1.3 hours. Trotlines, as would be expected, caught fish at the slowest average rate with 0.28 fish per trotline hour, or a fish every 3.6 hours. The average creels for boat and shore fishermen were 1.2 and 1.9 fish per fishermen per trip respectively (Tables V, VI, and VII). Lake Inks fishermen, on the average, fish for relatively short periods of time. The average length of fishing trip for both boat and shore fishermen was ap~ proximately 2 hours in duration (Tables V and VI). This is prObably explained in that the greater number of fishermen who fish on Lake Inks are either campers or peo» ple who own or use the large number of lake houses along the shore of the lake. Few people who fish this lake during the summer season come fishing just for the day and then return home that evening. Thus, a large number of short trips are made on the lake by people who fish for an hour or so and then go back to the cabin or camp to rest or get out of the sun, with the intention of going fishing again later on in the day. It should again be mentioned that the summer season, when large numbers of fishermen are on the lake, comes to a rather abrupt close at the end of the Labor Day weekend. This, coupled with the opening of the dove hunting season about the middle of September, drastically reduces the numbers of fishermen on Lake Inks during the fall season. This is further complicated with the opening of the duck and deer seasons. The reduction in numbers of fishermen on Lake Inks is graphically illustrated bin Tables V, VI, VII, and XII. During the winter season, the peeple who fish on the lake are for the most part those who live close by and fish until they get cold and go home. Generally speaking, wintertime fishermen do not stay on the lake for very long at a time. Tables V, VI, and VII indicate that persons coming to Lake Inks to fish have a little better than even chance to catch fish, regardless of the fishing mew thod employed. 0n the whole, it can be said that Lake Inks fishermen are successful in catching at least one fish per trip. In addition, it can be said that fishing parties on Lake Inks are generally small, consisting of not more than two persons in each party (Table VIII). The most successful method of fishing, whether hat fishing or shore fishing, at least in terms of numbers of fish caught per hour of fishing, was stillfishing (Table IX) and the most successful type of bait to use was live bait (Table XI). The old standbys, minnows and worms, were by far the most successful baits used. Casting, the method used by most bass fishermen, was moderately successful during the period covered by this report. Casting from the shore, at least during the study period, outmproduced casting from a boat as a means of catching fish (Table IX). This might be explained in the numbers of fishermen who fished near the tailrace of Buchanan Dam for white bass. Their success in catching white bass in tailrace waters on feathered jigs probably accounts for the higher rate of catch for shore fishermen using casting as a method of fishing. 9. The results as shown for fly fishermen are high but only a few fish are involved and these data are not felt to be sufficient to be of significance (Table IX.). V1y fishing is the least popular of the fishing techniques used on Lake Inks. Similarly, so few fish were taken trolling that no significance can be attached to the results as shown for this method except to say that the method was apparently not used on Lake Inks after September 1955. Trotline fishing on the other hand, took a relatively large portion of the catfish in the sampled creels at an average rate of catch of 0.3 fish per trotline hour (Table IX). As is to be expected in most warm water lakes which contain a sunfish pepulation, this group of Species accounted for the largest portion of the total catch. They were taken at the average rate of l.h fish per man hour by boat fishermen and 1.6 fish per man hour by persons fishing from the bank. Together, the sunfishes comprised more than #2 per cent of the total catch by all fishermen fishing Lake Inks(Tab1es X and XIII). The average sizes of the various species included in the sunfish group range from 5 inches to 5.7 inches in total length (Table XIV), and it is estimated that 15,t82 sunfish, weighing a total of 2,388 lbs. were harvested from Lake Inks. This is a per acre yield of 17.2 sunfish weighing 2.7 lbs. from each of the 900 acres of Lake Inks (Table XIII). The most abundantly harvested single species other than sunfish was the white base. This fish accounted for nearly 32 percent of the total fish in the sampled creels (Table XIII). Shore fishermen took white bass at an average rate of 1.1 fish per man hour and persons fishing from boats took them at the rate of 0.? fish per man hour (Table X). The average total length for white bass over the seven month period was 11.4 inches while the greatest average total length for any given month was for January when the average white bass caught measured lh.7 inches (Table XIV). It is estimated that fishermen catching this species harvested 11,286 fish weighing 6,793 lbs. The per acre yield for white bass is estimated at 12.5 fish weighing 7.6 lbs. (Table XIII). Channel catfish, the next most abundantly taken species, made up approximately 11 per cent of the total anglers catch (Table XIII) and were caught at an average rate of 0.6 fish per man hour of fishing by both boat and shore fishermen alike (Table X). Like the white bass, channel catfish were most intensively fished for in the swift waters near the tailrace of Buchanan Dam. Here the fishermen fished mostly from the banks, casting their baited lines out into the swift water and, after letting their bait settle to the bottom, tighteline fished until a channel catfish took the bait. The most frequently used and most successful baits used in fishing for channel catfish were shad giszards and shed entrails or cut shed, and at times frozen shrimp. This type of still fishing, especially in the swift tailrace waters, provides almost unexcelled sport for the fishermen who have learned to use this technique. The channel catfish caught averaged 13.7 inches in total length for the seven months of study period, however, in November the catfish averaged somewhat longer at 16.4 inches in total length (Table XIV). In all, an estimated 3,825 channel catfish weighing 3,916 pounds were taken by boat and shore fishermen during the census period. This was a per acre yield of b.37 fish or H.35 pounds of channel catfish harvested from each acre of Lake Inks (Table XIII). It needs to be again pointed out however, that these estimates do not include the fish taken on trotlines and that the yield of channel catfish is expected to be much higher than these calculated esm timates indicate. Largemouth bass were the fourth most abundantly taken fish from Lake Inks, accounting for more than 6 per cent of the total catch in the oracle of the fishere men interviewed (Table XIII). However, so many hours were spent in fishing for this species that the average rates of catch for largemouth bass are relatively low. Boat ishermen took them at the rate of 0.3 fish per man hour and shore fishermen took them at the rate of 0.2 fish per man hour (Table X). The average total length for largemouth bass was small, being only 11.8 inches during the seven months of the JO. creel census. Surprisingly, the greatest average total length for this species was for the month of July when the average bass caught measured 16.5 inches (Table XIV). It is estimated that 2,252 largemouth bass, weighing 2,h39 1bs., were taken from the lake during the study period by anglers. This was a per acre yield of 2.5 fish weighs ing 2.71 lbs. (Table XIII). The only other game fish species taken in relatively large numbers was the white crappie, comprising approximately 5 per cent of the total anglersi catch, and was caught at the rate of l.h and 0.5 fish per man hour by boat and shore fishermen respectively (Table X). The average total length for'these fish.was small, being only 7.3 inches in total length over the seven month study period (Table XIV). In all, an estimated 1,766 crappie, weighing 308 lbs. were taken from the waters of Lake Inks, for a per acre yield of 1.9 fish or c.3u lbs. (Table XIII). All other Species of fish caught by Lake Inks anglers during the creel cane one were taken in relatively small numbers and are not treated separately in this report. It is of interest, however, that doughbait fishermen harvested approximately 850 suckers, carp, and smallmouth buffalo from the lake and these fish weighed approxm imately 3,670 lbs. (Table XIII). Since the period covered by this report is relatively short, extending for only seven months, no attempt has been made here to state which are the best times of year to fish for any of the species normally sought after by fishermen. Any ate tempt to do so would certainly be complicated by the sudden drop in fishing pressure during the fall season. The limited amount of data in the sample after September does not lend itself to the formation of what could be considered valid conclusions. However, Figures 2 and 3 show the monthly breakdown of the total anglers‘ catch in the sampled creels, giving the percentage of the total catch made up by each of the species represented. These data are included only for information purposes and are not intended as the basis for any concrete conclusions. Based on the data recorded during the interviews with persons fishing on Lake Inks, it is estimated_that a total of 35,898 fish were harvested during the period from July 1955 through January 1956. This estimated total anglers? catch is broken down on a monthly basis in Table XII. As is shown in the Table, no fish were taken by boat fishermen during the months of November, December, or January. It is recognised that there is a possibility some boat fishermen, not included in the same _ple caught fish, but it is felt that these fish were negligible in number and would (not materially increase the estimated total yield for the seven month period of the creel census. In Table XIII, the estimated total catch for the seven month period is broken down by species. In addition, the calculated weight of the total catch for each species is also given. These weights were based on the sample Obtained by cene sus personnel. The estimated total catch of 35,898 fish weighed approximately 19,882 lbs. for a total per acre yield of 39.89 fish weighing 22.09 lbs. The estimated number of man days spent in fishing on Lake Inks during the study period was 8,668 man days for boat fishermen and 12,772 man days for shore fishm ermen. This was a grand total of 2l,hh0 fishing trips made on the lake during the seven months (Table XV).