TPWD 1972 F-2-R-19 #1488: Job Completion Report: Productivity Study of the Fishery of the Guadalupe River, Federal Aid Project No. F-2-R-19

--- Page 1 --- t Breen ria al = b JOB COMPLETION REPORT As Required By FEDERAL AID IN FISHERIES RESTORATION ACT TEXAS Federal Aid Project No. F-2-R-19 Region 2-B Fisheries Studies Job No. E-8: Productivity Study of the Fishery of the Guadalupe River Project Leader: D. Wade Butler Assistant Leader: James L. Lasswell Clayton Garrison Executive Director Texas Parks and Wildlife Department Austin, Texas Lonnie I. feters Robert J. Kemp, Director Chief, Inland Fisheries Fish and Wildlife Division August 9, 1973 --- Page 3 --- Job Completion Report State of Texas Project No. F-2-R Name: Region 2-B Fisheries Studies a ——seion enh Fisheries Studies Job No. E-8 Title: Productivity Study of the Fishery of A er tudy of the Fishery of _ the Guadalupe River Period Covered: February 1, 1968 to January 31, 1972 P. S. Objective: To determine production in a Central Texas River. Procedures: This study was initiated in 1968 and during this year, the electrofishing gear was purchased, tested and necessary modification were made. In 1969 potential study sites were electrofished in an effort to determine the maximum efficiency of the electrofishing gear and to check for suitable study sites. Twelve sites were tested during this segment. The sites tested were subjected to a total of 28.45 hours of electrofishing which produced 5,553 fish, representing 14 Species. The data for these collections are presented in Table l. During these tests, valuable electrofishing experience was gained and possibly the best electro- fishing techniques were developed. During the 1970 segment, potential study sites were sampled with the electro- fishing gear and one study site on the San Gabriel River in Williamson County and two study sites on the Guadalupe River in Comal County were chosen. From a litera- ture review of population estimate methods, two methods (Petersen and Schnabel) were determined to be applicable to the needs of this study. During the 1971 segment, no field work was done on this project because the chemical renovation of Lake Lyndon B. Johnson required most of Project F-2-R's time and manpower. However, Federal Aid documents, job progress reports, and other literature pertinent to this job were reviewed during this period. Findings and Discussion: Many obstacles prevented the accomplishment of the project objective. These varied from lack of equipment to lack of manpower to lack of time. This job was terminated in 1972 because it was determined that the construction of weirs, which were necessary for this study, was economically infeasible. Although the project objective was not accomplished, valuable information was obtained. This project progressed as far as the development of devices and techniques which would aid in the accomplishment of its objectives. However, the device (an electrofishing boat) and the development of the techniques necessary for the success- ful use of it are extremely important. This device makes possible the sampling of many areas which cannot be sampled with other sampling devices. It is not selective toward a given fish size and it is only slightly selective toward certain fish species. Since the major accomplishment of this job was the development of the electrofishing boat, an explanation of its design and operation are included in this report. --- Page 4 --- In 1969, 12 sites on four rivers were electrofished. A total of 28.45 hours was spent electrofishing and 5,553 fish were collected. Data concerning each collecting trip made during this period are shown in Table 1. The number of fish caught during night samples exceeds that of daytime samples by approximately 50 per cent for each hour of electrofishing. The water with the lowest conductance (310 micromhos) was the most produc- tive. It is very difficult to successfully electrofish in water with a high conductivity and impossible if the conductivity is exeedingly high. The amperage appears to affect the success of the electrofishing operation. The higher the amperage the greater the tendency of the fish to be “knocked to the bottom". The fish dive directly to the bottom and are difficult for the netters to pick up. The ideal situation is to set the voltage and amperage so that the fish will be stunned and brought to the surface within the electrical field. Note that at 2.5 amperes and 150 volts in, water with a conductance of 310 micromhos, there were twice as many fish collected per hour of electrofishing time as there was with 3.0 amperes. There were also approximately twice as many fish collected with 150 volts and 2.5 amperes as there was with 150 volts and 4.0 amperes in water having a conductance of 335 micromhos. With the electrofishing unit tested during this period, it appears that settings of 100-150 volts and 2.5-3.0 amperes in waters having a conductance between 300 and 700 micromhos produce the best results. In- sufficient data have been collected to indicate optimum voltage and amperage set- tings for waters with high conductivity (700). Design and Operation of an Electrofishing Boat During 1968 Project F-2 constructed an electrofishing boat to be used as the primary fish sampling device for a-productivity study of a stream fishery. Using trial and error methods and drawing heavily from published literature, the shocker and its operation has been modified so that the end result is an electrical fish sampling tool that works effectively under most stream conditions found in Region 2-B. It has also proven useful in a limited number of reservoir tests. Equipment and Design The two most important components of the shocking equipment are a Model ITII-C Variable Voltage Pulsator designed and manufactured by Coffelt Electronics Company of Denver, Colorado, and a 115-230 volt, 3,000 watt McCulloch alternating-current Mark III generator. These two components can provide output voltages for electro- fishing that can be varied continuously from 0-300 volts D. C., 0-300 volts pulsed D.C., and 0-280 volts A.C., 60 cycles per second. The pulse output from the Cof- felt unit is a square wave voltage with a 50 per cent duty cycle and can be varied from 10-200 pulses per second. The V.V.P. and generator are mounted in a 16 foot, flatbottomed boat equipped with a custom made guardrail around the bow, a 60 gallon live well under the middle seat, remote controls and powered by an 18 horsepower outboard motor (Figure 1). Electrodes for the device are made from 5/8 inch, lead filled, copper tubing. The positive electrode consists of six, 40 inch lengths of tubing connected to an eight foot piece of three inch plastic conduit which is mounted perpendicular to and at the end of a 12 foot section of 2 X 4 by means of a single ten inch carriage bolt and two screendoor springs (Figure 2-Inset 1). This arrangement allows the conduit crossmember to swivel and return to its normal position when rigid objects are encountered during operations. Springs also form the junction between the con- duit and the lengths of tubing so that the electrodes will pass over or around under- --- Page 5 --- aha water debris and return to their normal position. | The base of the boom is attached to the boat by means of a large, loosefitting U-bolt attached to the rear of the front deck. At its mid-point the boom is sup- ported by a stand constructed of 2 X 4 boards in such a manner that the height of the boom can be adjusted (Figure 2-Inset 2). This arrangement makes possible limited adjustments to depth and width of the electrical field by moving the boom in or out and up or down. The negative electrode consists of a single 20 inch piece of tubing suspended from the bow of the boat by means of a harness snap. Size 16 AWG, 600 volt insulated wire is used as the conductor for the electrode circuit. That portion of the circuit located inside the boat is permanently housed in k-inch electrical conduit with outlets at the stern near the V.V.P. and at the rear of the foredeck. The permanent outlets, particularly the forward outlet, should be female twist-lock types to prevent the possibility of crew members being accidentally shocked. The circuit then runs from the forward outlet through an Allen-Bradley, 600 volt A.C - D.C., treadle switch at the bow of the boat to the electrodes. This wiring arrangement allows the circuit to be controlled from both the front and rear of the boat. All components of electrofishing equipment must be connected to a common ground to eliminate any electrical potentials that might exist. This is accomplished by a ground wire that runs from the base of the generator to the side of the boat. (See Figure 3 for a wiring diagram) Night shocking has been found to be roughly twice as productive as day shocking; therefore, a permanent lighting system was mounted on the bow of the boat. It con- sists of two, all weather, floodlight receptacles with yellow, 100 watt, 115-125 volt bulbs to reduce light reflection from the water and to inhibit insect attraction. Numerous types of commercially manufactured dipnets were used in conjunction with the electrofishing operation. They were too weak to withstand the weight of the large number of fish that were often netted. Much stronger dipnets were obtained from a private source through Project F-9-R personnel and have been found to be very adequate for electrofishing. Miscellaneous Equipment Two pieces of auxilliary equipment are a volt-ohm meter and a portable conduc- tivity meter. There are many junctions and splices necessary in the wiring system of the electrofishing boat and each is a potential trouble spot for shorts. Occa- sional malfunctions of the V.V.P., the generator and the footswitch are also en- countered and with a volt-ohm meter, these malfunctions can usually be located rapid- ly and repaired in the field with a minimum of time lost. Without the volt-ohm meter, the simplest short may take hours to locate and repair. —_—————————— lgasic design of the positive electrode was patterned after the electrode arrangement of a device built by Mr. Billy D. Cooper. --- Page 6 --- The degree of electrofishing success depends primarily on the conductivity of the water in which it is used; therefore, a portable conductivity meter is very useful to determine roughly how efficient the shocker will work in an area. Operation A minimum of three men are needed to operate the electrofishing equipment effi- ciently and a fourth man, although not absolutely necessary, is a definite asset to the operation. One man positioned in the rear controls the boat and the master con- trols on the V.V.P. and generator. Two men are positioned at the bow and it is the job of one of these to operate the footswitch which controls the circuit to the electrodes. He and the second man are also primary netters. The fourth man, when used, is a utility man. He is positioned immediately behind the foredeck and in front of the livewell. He acts as a secondary netter, empties the dipnets of the primary netters and is relief man for the primary netters. Best results have been obtained when the boat is driven slowly (about trolling speed or less) upstream in a zig-zag pattern from bank to bank with the circuit to the electrodes being alternately broken and reestablished on approximately 10 second intervals by the footswitch operator. When the switch is depressed, fish in the field are immobilized; and those on the weak outer perimeter of the field are driven upstream by the zig-zag pattern. When the circuit is interrupted, some fish will attempt to turn back and are collected when the circuit is reestablished. This method has proven very successful for narrow streams. In wide streams many fish can elude the field and escape downstream. But good success can be obtained by using the zig-zag method from one bank to midstream and back to the bank and then repeating the procedure on the opposite side on the return trip downstream. In many instances those fish that run upstream just in front of the electrical field can be herded into gravel bars, log jams, dead-end sloughs and other natural barriers. When this can be accomplished large numbers of fish may be stunned at one time. In unusually fast moving water, upstream movement of the boat has been found undesirable, because fish are swept away by the current as soon as they are stunned. Allowing the boat to free-float with the current using the outboard only to keep the boat aligned has been found to be the most productive method for swift water. Limiting Factors Some factors that adversely affect the efficiency of the electrofishing boat are: high water-conductivity, extreme turbidity and deep water. Conductivities in excess of 1,000 microhms/cm. severely limit the intensity of the electrical field and may inhibit the electrofishing operation entirely. Turbidity does not limit the effectiveness of the machine itself, but rather inhibits the visability of the netters. Many fish that are stunned cannot be seen and consequently are not netted. Maximum depth-penetration of the electrical field appears to be 6-8 feet, but this will vary with water conductivity. In waters where the field fails to penetrate to the bottom, fish have been consistently observed escaping under the field. From tests conducted over a two-year period, optimum conditions for peak effi- ciency of this unit seems to be a clear (6-8 ft. secchi), shallow (6-8 feet deep), stream which exhibits a conductivity between 300-700 micromhos with operations con- ducted at night, but adequate results have been obtained under all stream conditions, --- Page 7 --- TABLE 1 SUMMARY OF ELECTROFISHING OPERATIONS 4 vo we 13) u 3 Ga (0) co) n & a no na =| x u (7 no vd oa 1S) oO fc)) ot U4 UH is] Vv =} ft ¢ fy 3 1?) 4 Wy v ao n ina) a o Oman fs) uo a u 3) 4 oo S&S Oo oD u is] On 3) go OD o. ° 3 6 O DO Ke 4 a fs) go v oO ra cS a ') O rm) 4 > sal BG io) n i) © U GT VU 2 a Yr bE 09D ON 0 oO Ss) 3) aS) 4 8 @ 8 < My > 2) 9 oO wo 7) co) fe) m4 CO) o vo wo cv) & n O. u b Hu 39 @w@ ww @g b ¢ bow rm) q¢ -<¢ .«¢ w a oe 4 oF) 7) qc 9p BGO HY OO a » OO aS) a) > bead wa Bb wv oo Ww ws s Ss 4 3 o@ S52 0 #£ B & § a 5 & Ba sess B s § 9 a a oe Oo oF SOF S 2 vn a HB a oO a OD A & A | a a 4/2 D Llano Kimble 1.75 400 150 3 LS 1 - 34 - 16 10 7- - - - 31 60 159 69 4/2 N Llano Kimble 1.25 400 150 3 15 - 6 122 - 9 30 9 34 - - - 36 49 268 69 4/3 D Maynard Kimble 1.5 450 150 3 10. —s- - - - - - - -2 - - ~ 44 186 232 69 Creek 4/3 N Maynard Kimble 1.5 450 150 3 10) = - - - = - - 1 - - - 38 292 331 69 Creek 4/28 D Guadalupe Comal 2.5 310150 3 20 - 4 35 6 6 305 - -- - - 2 15 43, 416 69 4/28 D Guadalupe Comal 1.0 310 150 3 20, = - 34. 14 - 207 - -- 1 - 2 20 278 69 4/28 N Guadalupe Comal 1.5 310150 3 20, = - 8 295 4 4 433 - - 2 - - - 12 50 808 69 5/6 N Guadalupe Comal 1.3 310150 3 20 - - 38 13° =«21 276 - -- - - 1 - - 329 69 5/12 D Lampasas Lampasas -66 550100 4 20 - 3 31 - - 6 - 154 - - = 27 14 ~=100 69 5/12 N Lampasas Lampasas 1.0 550100 4 20 - U1 29 - 8 5 - «7 - 1 - 12 19 92 69 5/13 D Lampasas Lampasas -5 975 75 3 20 |- - - - - ~ - l- - - - 2 - 3 69 5/13 D Lampasas Lampasas -66 550125 4 20 - - = - i - - 3 1 6 - - ll 91 113 69 5/19 D Guadalupe Comal 1.5 310150 2.5 20 - 20 25 - - 630 - 17 - - 3 4 37 727 69 5/19 N Guadalupe Comal 1.5 310150 3 20. - 27 275 - + 198 - -1l - 1 - - 29 531 --- Page 8 --- pe & fo\8} ord ea uy ° a0) wv > ise] is] (=) a 6/6 OD 69 5/6 D 69 9/23 N 69 9/24 D 69 12/16 D 69 12/16 N 69 12/17 D 69 River System Guadalupe Guadalupe Guadalupe Guadalupe Guadalupe Guadalupe Guadalupe County Comal Comal Kerr Kerr Comal Comal Comal TOTAL Generation Time (Hours) No wm Re Go Wo 1.00 2.0 1.0 1.0 28.45 w Conductance (micromhos) re oO 310 390 335 335 335 335 w =Voltage e o 150 140 150 150 175 150 Ww Amperage {ee) 2.5 TABLE SUMMARY OF ELECT Pulses/second i) jo) iD) i=) 15 20 16 14 20 Spotted Gar * (Cont.) ISHING OPERATIONS ua ise} ie) vo n ° G 60 ue) i= iso) ° & a n 2 54 ll 29 - 72 - 146 - 45 ll 33 - 89 103 1386 w Trout 13 53 River Carpsucker —y (oe) 42 Gray Redhorse Sucker a uw ee) 11 16 14 110 24 2444 Spotted Sucker 19 Carp 30 Channel Catfish — ~ 37 Bullhead Catfish 6 Flathead Catfish a d Bass © Spotte re 19 \ Largemouth Bass — i) 262 Sunfish 139 52 24 19 1145 Total bo ~ i=) 105 86 217 181 115 9553 --- Page 9 --- POSITIV:. BKLECTHGDES LIGHTING SYSTE: NEGATIVL ELECTRODE FOOTSWITCH CuNDUIT LIVE WaLL GoNERATOR - ELECTRICAL PLUGS - STEERING GEAR VARIABLE VOLTAGE PULSATOR OUTBOARD 7,0TOR FIGURE 1 - TOP VIEW OF ELECTROFISHING BOaT WITH COMPONENTS --- Page 10 --- DOOR SPRING a 2" CARRIAGE BOLT BOOM : j \ ZZ E , SPRING 7 c | Z ELECTRODE i oil | INSET 1\, SPRING ARRANGEMEN'\ FOR POSITIVE ELECTRODES INSET 2 - ADJUSTABLE BOOM STAND Figure 2 - ELECTROFISHING BOAT - SIDE VIEW --- Page 11 --- POSITIVE ELECTRODES NEGATIVE ELECTRODE FOOT SWITCH GROUND WIRE GENERATOR TO LIGHTING __ SYSTEM | PULSATOR Figure 3 - DIAGRAM OF HLECTROFPISYING BOAT CIRCUITS --- Page 12 --- -10- both day and night, so long as stream conductivity remained below 1000 micromhos/cm. Safety As with all high voltage devices, safety procedures should be followed when working with electrofishing equipment. The following list of precautions should be included as part of each electrofishing operation: 1. Approved lifejackets, rubber gloves and non-conductive foot wear should be worn by all crew members. 2. All crew memebers should have a thorough knowledge of electrofishing operation. 3. All electrical circuits should be checked for shorts before operating. 4. Make sure all electrical wires are out of the way. 5. Use dipnets with non-conductive handles. 6. Have fire extinguisher and first aid kit and know how to use them. 7. Never work for long periods. Take frequent rest breaks. Prepared by: James L. Lasswell . Approved by: Asst. Project Leader Date: August 9, 1973 , R. L. Bounds Region II Inland Fisheries Director