title
Lake Powell post-impoundment investigations : annual performance report, 1975
author
Array ( [0] => Hepworth, Dale K. [1] => Gustaveson, A. Wayne [2] => Biggins, Richard )
abstract
UDWR Publication Number 76-21
date
1976-01-01
organization
Utah. Division of Wildlife Resources
species
Array ( [0] => Not Specified )
file_path
https://grey-lit.s3.wasabisys.com/lake-powell-post-impoundment-investigations-annual-performance-report-1975.pdf
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https://grey-lit.s3.wasabisys.com/lake-powell-post-impoundment-investigations-annual-performance-report-1975-pdf-1-761x1024.jpg
content
LAKE POWELL POST-IMPOUNDMENT INVESTIGATIONS ANNUAL PERFORMANCE REPORT 1975 PUBLICATION NUMBER 76-21 DingeJl-Johnson Project Number F-28-R-4 Pll.OPERTY OF UTAH W!LDLiFE RESOURCES LIBRAR't. STATE OF UTAH DEPARTMENT OF NATURAL RESOURCES DIVISION OF WILDLIFE RESOURCES John E. Phelps, Director POST-IMPOUNI:MENT INVESTIGA.TIONS Annual PerfOl:m:mce Report 1975 rnle K. Hepworth Project Leader A. Wayne Gustaveson Prqject Biologist Richard Biggins Project Biologist Publication Number 76-21 Dingell-Johnson Project Number F- 28- R-4 Copyright <8> 1976 by the utqh State Division of Wildlife Resources An ~l Opportunity Dtployer John E. Phelps Director T ABLE OF CONTE"ITS Page Job NUJllber: I '1"i tle: Threadfin Shad Study . • • • • • •• 1 Job Number: II Title: Measurement of Fishery Harvest, Pressure I a.nd Success • . • . . . • . . • • . • • •• 1 Job NUJllber: III T1 tle: Index to Annual Fish Population Trends . . . . . . . . . . . . . . • • • 11 Job Number: IV T1 tle: Striped Bass Culture ••• • • 17 Job NUJllber: V Title: Introduction Evaluation of striped Bass . . . . • 31 . . . . . . . . . . . . . . ii LIST OF TABlES Table 1. 2. Total estimated fishing pressure in angler days by aceess area, January through September, 1975 (percent of total pressure is given in parentheses). Fishing pressure was estimated using fishermen per boat factors applied to National Park Service boat counts •••••••••••• Length of mean angler day (hours), February to September, 1975· . . . • • • . • . • . . . . . . . . . . . • • . . . · . • • 3. Number of boats engaged in fishing and nonfishing activities from creel census sample (mean number of fishermen per boat Page 3 4 in parentheses) • • • • • • • • • • • • • • • • • • • • • •• 4 4. Fish harvested per hour by month and access area, March to September, 1975 • • • . • • • • • . . • • • • . • • • • • • 5 5. Fish harvested per hour by species and access area ••• • 6 6. Fish harvested per hour by species and month, M .. rch through September, 1975 • • • • • • • • • • • • • • • • • • • • • • 7 7. Percent species composition of fish harvested by access area. 8 8. Type of terminal gear used by fishermen by percentage . . . 9 9. Percentage of fish harvested using different types of terminal fishing gear, February through September, 1975. • • • • • • • 9 10. Catch rate of various species with different terminal gear, February through September, 1975. • • • • • • • • • • • • •• 10 11. Residence of anglers by percentage, determined for each access area. • . • • • • • • • • • • • • • • • • • • • • • • • • .• 10 iii LIST OF TABLES (Continued) TAble 12. NUlllber of gill nets set and number of fish taken by standardized annual sampling, 1971-1975 (FIN = number Page of fish per net). . • . . . . . • . . • . • • • • . . • . .• l2 13. List of fish collected during spring gill netting on Lake Powell t 1971-1975 • • • . • • • • • • • • • • • • • • • • •• 13 14. C"tch rate and percent of total catch for selected species collected during spring gill netting on Lake Powell, 1971- 1975. • . . . • . • . . . • . • • • . . . . . • . • . • • .. 14 15. Stocking rates of striped bass larvae in rearing ponds, 1975· • • • • • • • • • • • • . • • • • • . • • • • • • • •• 18 16. Striped blISS harvest frolll experimental rearing ponds, 1975.. 20 17. Results from successful culture ponds receiving different stocking rates of striped bass fry, 1974-1975 • • • • • • •• 21 18. Comparison between striped bass fry surviVILl in tempering baskets and fingerling production, 1974-75· •••••••• 25 19. Fingerling production comparing three different sources of striped bass fry, 1974-1975. •••••••••••••••• 29 20. Fingerling produc4on cOlllparing striped bass fry shipped at different ages, 1974-1975. ••••••••••••••••• 29 21. Stomach contents of predaceous fish captured near the govern- ment docks during stocking of striped bass fingerlings, July 16 and 17. 1975. •••••••••••••••••••••• 31 22. Food habits of striped bass age 1+, Lake Powell, 1975. Values based on total nUlllber of stomachs containing food • • • • •• 35 iv LIST OF FIGURES Figure 1. Average number of walleye and largemouth bass captured per gill net in relation to year of capture, Lake Powell • • • • . • • • • • • • • . • • • • • • • • • • 2. Comparison of zooplankton crops and fertilization schedules, 1975. Water 105s expressed as percent of Page • • • • 17 tots.l pond volume per day_ • • • • • • • • • • • • • • • • •• 23 3, 4. Striped bass food habits compared to growth in length, pond *3. 1975. Values expressed as percent by number •• Changes in abundance of predominant zooplankton found in pond #3, 1975 • • . • " •••••••••••••••••• Changes in abundance of predominant zooplankton found in • • • • • • pond #1. 1975 •••••••••••••••••••• . ••• • • 28 6. Monthly growth of striped bass at Lake Powell, utah. • • • •• 34 7. Changes in food habits of Lake Powell young-of-the-year striped bass with growth • • • • • • • • • • • • • • • • • •• 36 v ANNUAL PERFORJIMiCE REPORT State UTA H Project No. F-28-R-4 Name Colorado River Drainage Reservoirs and Tailwaters Fisheries Management, Investigations and Surveys. Period Covered: February I, 1975 to December 31, 1975 Job Number: 1. Title: Threadfin Shad Study Objective: To (1) develop, through mid-water trawling and other associated sampling devices, an adequate system for sampling thread fin shad in Lake Powell, (2) to utilize the developed system in determining some thread fin shad population dynamics (population level indices and seasonal characteristics), (3) to evaluate changes in thread fin shad population levels resulting from intro- duction of striped bass (Morone Saxatilis); (4) to collect other pertinent information relating to thread fin shad in LAke Powell (areas of interest may include age and growth, spawning, fecundity, sexual maturity, food preferences, etc.). Accomplishments: Trawling capability of the Steel Clipper was nearly completed. All major equipment (hydraulic winches, pumps, and controls) were installed and made operational. Delays in shipment of the trawl precluded field trial of the entire mechanism and any collection of data on Job Number: thread fin shad, All minor equipment necessary for connecting the trawl to the winch system was obtained or ordered. Field trial and data collection will begin during the next project segment. Title: Measurement of Fishery Harvest, Pressure, and Success Objective: To determine the magnitude and nature of fishing harvest, pressure, and success through creel census. Accomplishments: Project personnel conducted creel census 4-8 days per month at the three major access areas (Wahweap, Bullfrog l38.y, and Hall's Crossing) from March through September. Pressure during , other months was light and did not justify effort involved in a programmed regular creel census. -2- An estimated 126,619 angler days were exerted from January through September 1975 (Table 1). The largest portion of fishing pressure occurred at 'tlRhweap (49.5 percent). Ang;lers at Bullfrog Bay and Hall's Crossing made up 30.1 and 15.8 percent of the pressure, respectively. Angling pressure peaked in May (35,829 angler days) and dropped off to a low in August (6,420 angler days). Length of the average angling day was approXimately 4-5 hours during spring months (TAble 2). Length of the angler day decreased during the summer months to about 3 hours. Number of boats engaged in fishing also changed as the season progressed (Table 3). During March and April, fishing made up the better part of all boating activities. However, during summer months, warm water sports predominated (i.e. swimming, water skiing, etc.). The number of boats engaged in fishing dropped to a low of 11.4 percent in August. -3- TlI,ble 1. Total estimated fishing pressure in angler days by access area, January through September 1975 (percent of total pressure is given in parentheses), Fishing pressure was estimated using fishermen per boat factors applied to National Park Service boat counts. Month January ( 1.3) February ( 3·5) !1arch (11.2) April (22.0) MAY (28.3) June (15·9) July ( 6.2) August ( 5.1) ~eptember ( 6·5) Total (100) 'Nahweap 756 2,237 7,446 l2,l26 18,162 10,468 4,200 3,517 3,744 62,656 (49·5) Bullfrog 482 1,350 3,520 9,111 10,735 6,035 2,187 1,696 2,967 38,083 (30.1) HAll's 390 708 2,664 4,578 5,253 2,920 1,293 1,021 1,198 20,025 ( 15,8) Hite 38 95 554 2,059 1,679 691 197 186 356 5,855 ( 4.6) Total 1,666 4,390 14,184 27,874 35, 829 20,114 7,877 6,420 8,265 l26,619 -4- Table 2. Len gth of mean ' angler day (hours ) , f ebruary to September, 1975. '"ahweap Bullfrog Hall's Mean February 6·50 No Sample No Sample 6·50 '!~rch 4.34 4·90 4.11 4.48 April 4·59 4·54 3·11 4·52 ),lay 6.17 4·58 4.43 5·39 June 3·93 3·13 4.29 3·80 July 3.45 2.69 2·38 2·98 August 3·19 4·53 4.42 3·77 September 3.96 No Sample No Sample 3.96 "~ean 4·79 4.12 4.13 4·51 T"ble 3. Number of boats engaged in fi shing and nonfishing activities from creel census sample (mean number of fishermen per boat in parentheses). Fercent Fi shing Nonfishing Fishing Total M~ rch 295 (J.4) 127 69.9 422 April 411 (2.8) 83 78.4 524 M~.y 748 (3.2) 960 43·8 ,1708 June 457 (2 .7) 1232 27·1 1689 July 134 (2.6) 687 16.3 821 August 103 (2.7) 797 11.4 900 September 62 (2. 4) 249 19·9 311 -5- In all, 2136 interviews representin~ 6312 anglers were conducted during the 1975 creel census. Interviewed fishermen creeled 14,942 fish and fished 27,375 hours for a catch rate of 0.55 fish per hour (1able 4). Bass (0.26 per hour) and crappie (0.24 per hour) were caught at nearly the same rate ( l able 5). Bluegill and channel catfish were taken at a rate of 0.02 fish per hour. while rainbow trout and other species were creeled at rates less than 0.01 per hour. Tqble 4. Fish h~rvested per hour by month and access area, March to September, 1975. '1onth Wahweap Bullfrog nall's Mean "IArch 0.40 0.29 0.23 0.35 April 0·56 0.61 0·39 0·57 Hay 0.65 0.61 0.81 0.67 June 0.45 0·56 0.65 0·53 July 0.47 0·57 0·58 0·52 August 0.15 0.20 0·33 0.22 ~eptember 0.15 No SAmple No Sll.mple 0.15 'lean 0·53 0·51 0.66 0·55 -6- Table 5. Fish harvested per hour by species and access area. Species Wahweap Bullfrog Hall's Mean Bl.ck crappie 0.21 0.27 0·33 0.24 Largemouth bass 0.29 0.19 0·27 0.26 Bluegill 0.02 0.02 0.04 0.02 Chllnnel catfish 0.01 0.03 0.03 0.02 Rllinbow trout *t t t t Others t t t t Ul Species 0·53 0·51 0.66 0·55 *t = less than 0.01 fish per hour On a monthly basis. bass fishing was best in July (T"ble 6). C~tch rates for bass remained high from March through July (0.25 - 0.35 fish per hour), but dropped off sharply in August and September (less than 0.10 fish per hour). Crappie fishing was best in April and May (about 0.30 fish per hour), but was poor during the remainder of the year (less than 0.14 fish per hour). Bluegill and channel catfish were taken in limi ted numbers, but July and August were best for both species. Bass were the predominant species harvested from the reservoir (48.4 percent. Table 8) with crappie a close second (44.1 percent). Crappie comprised a larger portion of the total creel at Bullfrog (52.1 percent) and Hall's Crossing (48.7 percent), than at Wahweap (39.8 percent). Bass made up 54.7 percent of the catch at Wahweap where most fishing pressure occurred (49.5 percent, Table 1). T ab le 6 . F is h h ar v es te d p e r h o u r b y s p e c ie s a m m o n th , M ar ch th ro u g h S ep te m b er , 19 7. 5. H ou rs B la ck L ar g em o u th C h an n el R ai nb ow "' o n th F is h ed C ra p p ie B as s B lu e g il l C at fi .s h T ro u t M '.r c h 41 81 0 .0 9 0. 2. 5 * t t t A p ri l 51 80 0 ·3 0 0 .2 5 0 .0 2 t t M ~ y 10 76 1 0 ·3 7 0 .2 7 0 .0 3 0 .0 1 t Ju n e 45 17 0 .1 4 0 ·3 2 0 .0 3 0 .0 4 t Ju ly 10 12 0. 0. 5 0 ·3 5 0 .0 4 0 .0 8 -0 - A u ~ s t 1 0 0 4 0 .0 2 0 .1 0 0 .0 4 0 .0 6 t ~ e p t e m b e r 61 9 0 .0 1 0 .0 9 0 .0 2 0 .0 3 -0 - To tA l 2 7 2 7 4 0 .2 4 0 .2 8 0 .0 2 0 .0 2 t * t = l e s s th an 0 .0 1 f is h p er h o u r. O th er S p ec ie s -0 - -0 - t t t t t t T o ta l 0· 3. 5 0. ,5 8 0 .6 7 0 ·5 3 0. ,5 2 0 .2 2 0. 1. 5 0· 5. 5 I -- 0 I -8- T.ble 7. Percent species composition of fish harvested by access area. Species Wahweap Bullfrog Hall's Total Blnck crappie 39·8 52.1 48·7 44.1 Largemouth bass 54.7 37·7 40.7 48.4 Bluegill 3·3 4.6 5·8 4.1 Channel catfish 1.8 5·4 4.7 3·1 Rainbow trout 0·3 t t t Other species t t t t *t = less than 0.1 percent Lures were the favored fishing gear (Table 8). Of all parties interviewed, 53.0 percent used lures exclusively, 24.8 percent used live bait, and 20.2 percent tried a combination of the two. Lures were the preferred gear each month except August and September when live bait pre- dominated. Percent of fish cree led by different methods (Table 9) followed nearly the same ratio as the gear use figures. Most fish caught were taken by lures (54.3 percent), followed by a combination of bait and lures (22.9 percent), and live bait (21.2 percent). Certain species were caught more readily on specific types of gear (Table 9 and 10). Crappie were caught at a rate of 0.37 fish per hour on lures (77.3 percent of all crappie harvested) and only 0.04 fish per hour on live bait. Total numbers of bass caught were split about equally between live bait (34.2 percent) and lures . (37.7 percent), but catch rates were higher with live bait (0.36 fish per hour) compared to lures (0.20 fish per hour). -9- T.ble 8. Type of terminal gear used by fishermen by percentage. Month Live Bait Other Bait Lures Bai t an::! Lures February 50.0 0.0 50.0 0.0 March 27·5 1.0 46.4 25·1 April 28.6 0.7 49.1 21·5 May 14.8 1.8 63.3 20.0 June 28.4 1.6 54.2 15·8 July 38.9 6.1 42.0 13·0 Au~st 40.0 7.4 28.4 24.2 September 42.1 3·5 24.6 29.8 Total 24.8 2.0 53.0 20.2 Table 9. Percentage of fish harvested using different types of terminal fishing gear, February through September, 1975. Species Live Bait Other bait Lures Bai t an::! lure s Black crappie 4.0 1.1 77.3 17.6 LiI1rgemouth bass 34.2 1.0 37.7 27.1 Bluegill 27·7 9.2 35·7 27·5 Channel catfish 58·5 5.4 10·9 25·3 Rainbow trout 21.9 12 ·5 53.1 12.4 Other species 0.0 5·9 82.4 11.8 Combined 21.2 1·5 54·3 27·9 -10~ TILble 10. CILtch rILte of VlLrious species with different terminILl gear, February through September, 1975. Species Live blLit Other bait Lures Bai t and Lures BlILck crappie 0.04 0.24 0·)7 0.18 LILrgemouth blLss 0.)6 0.2) 0.20 0.)0 Bluegill 0.02 0.19 0.02 0.0) Ch~.nnel cILtfish 0.04 0.08 t 0.02 RILinbow trout t 0.01 t t Others 0.00 t t t *t = indicILtes rILte less than 0.01 Although most of lAke Powell is wi thin the state of Utah, the JlllLjori ty of ILnglers were from other states (TILble 11). Anglers ILt Wahw9!Lp were JlllLinly from Arizona (85.) percent). At Bullfrog, UtlLh residents comprised 4).) peroent of the total, while ILnglers from ColorlLdo numbered 47.6 percent. Hall's Crossing was used mlLinly by ColorlLdo ILnglers ()).8 percent), with approximately equlLl use by Utah (25.9 percent) ILnd New Mexico anglers (19.1 percent). TILble 11. Residence of anglers by percentage, determined for each access area. 1 2 State WILhweILp Bullfrog Hall's Utah 4.9 4).) 25·9 ArizonIL 85·) 1.2 8.2 California 5·2 ).9 7·5 ColorlLdo ],.1 47.6 )).8 New Mexico 1.9 0.4 19·1 Other states 1.6 ).7 '·5 1 WILhweILp totals include interviews taken from FebruILry through September, 1975. 2 Bullfrog ILnd HILll's totals include interviews taken from March through August, 1975. Job Number: A creel censUS computer program was completed and tested. The program was used to partially analyze -11- 1975 creel census data. Computer analysis will also allow comparisons to be made of all creel data collected since 1970. Data has been coded and needs only to be punched and run. A report describing trends in fishing harvest, pressure, and success since impoundment will be written and published separately. III Ti tle: Index to Annual Fish Population Trends Objective: To use gill netting and electro-fishing as indices of ~ame fish population trends. Accompli shments: St..ndardized sampling was conducted during March at four stAtions on Lake Powell (Padre Bay. Cha Canyon, Rincon, and Red Canyon). ",en experimental diving gill nets with varyin~ mesh panels (1, It, 2, and 3 inch bar mesh) were fished for three consecutive days at each station. Nets were set perpendicular to the shoreline over similar rock and rubble habitat. Annual netting has been conducted since 1971. Although ten nets fished for three days per station each year was the preferred schedule, net loss and poor weather conditions reduced the sample size in some years. A total of 961 fish (8.0 per net) were taken in 1975 ( Table 12). The highest catch rate occurred in 1972 (10.1 fish per net). The lowest catch rate per net (4.0) occurred in 1971 when 49 net sets in Padre Bay and Rpd Canyon yielded 196 fish. Sixteen species . were captured during the five years of sampling (Table 13). Largemouth bass, walleye. carp, crappie, and channel catfish were the dominant species taken. Bluegill and green sunfish were important in the catch during some years. Largemouth bass dominated the catch each year (56.1 percent of the total sample, Table 14). Bass comprised as much as 63.4 percent of the fish taken in 1974 and made up greater than 50.0 percent of the sample every year except 1971 when they totaled 41.3 percent of the catch. Catch rates for largemouth bass ranged from 1.65 per net in 1971 to 5.82 per net in 1972. Walleye were second in 'abundance, making up 26.8 percent of the total in the 1975 sample ( Table 14). Walleye catch rate per net has varied from a low of 0.29 in 1971 to a high of 2.15 in 1975. T9 b1 e 1 2 . ~ u m b e r o f g il l n et s se t an d nu m be r o f fi sh t ak en b y st an d ar d iz ed a nn ua l sa m pl in g. 1 97 1- 19 75 (F /~ = n um be r o f fi sh pe r n e t. ). 19 71 12 72 12 73 12 Z 4 N o . No . N o. N o. N o. N o. N o. N o. N o. 1n .2 N o. S tA ti o n Ne ts F is h F IN N et s F is h F IN N et s F is h F IN Ne ts F is h F lr. N et s F is h p .d re B a.y 18 54 3 .0 22 28 1 1 2 .7 30 12 8 4 .3 30 21 1 7 .0 30 20 0 R ed C 8n yo n 31 14 2 4 .6 24 19 1 8 .0 )0 10 5 3 ·5 30 15 4 5 ·1 30 24 8 Ch A C ~ n y o n 24 23 0 9 .6 )0 16 5 5 ·5 30 21 2 7 .1 30 27 6 R in co n 24 25 2 1 0 ·5 )0 13 9 4. 6 30 18 2 6 .1 30 23 7 T o ta l 49 19 6 4 .0 94 95 4 1 0 .1 12 0 53 9 4 .5 12 0 75 9 6 .3 12 0 96 1 F LN 6 .7 8 ·3 9 .2 7 ·9 8 .0 I ~ I Table 13. List of fish collected during spring gill netting on Lake Powell, 1971-1975. Common name Scientific name Thr8lldfin shad RAinbow trout Brown trout Carp Boneytail chub Colorado squawfish 'tlhi te sucker Flannelmouth sucker H\lI!Ipback sucker BlBck bullhead Yellow bullhead Channel catfish Green sunfish Bluegill Largemouth bass BIRck crappie 1,I .. lleye DorosoMR petenense Sallno gairdneri Sallno trutta Cyprinus carpio ptychocheilus lucius catostomus commersoni Catostomus latipinnis Xyrauchen texanus Ictalurus melas Ictalurus natali s Ictalurus punctatus Lepomis cyanellus Lepomi s IIIIlcrochirus Micropterus sallnoides Pomoxis nigromaculatus Stizostedion vitre\ll!l vitre\ll!l -13- T ob Ie 1 4 . C A tc h ra te a nd p er ce n t o f to ta l ca tc h f o r se le ct ed sp ec ie s co ll ec te d d u ri n g s p ri n g g il l n e tt in g on L A ke P ow el l, 19 71 -1 97 5. 19 71 19 72 l ~ m 12 Z4 12 Z! 1 C at ch P er ce n t C .t ch P er ce n t C at ch P er ce n t C at ch P er ce n t C at ch P er ce n t :: ~ c i e s ra te o f ca tc h ra te o f ca tc h ra te o f ca tc h ra te o f ca tc h ra te o f ca tc h L. r! re ll lo ut h bA ss 1 .6 5 4 1 .) 5· 82 57 .4 2 .7 1 6 2 .) 4. 01 6 ). 4 4 .4 9 56 .1 -"0 11 e ye 0 .2 9 7. 1 1. 12 1 1 .0 0. 41 9 ·4 1 ·0 9 1 7 .) 2 .1 5 2 6 .8 B lo ck c ra p p ie 0. 12 ). 1 0. 67 6 .6 0 .2 7 6 .1 0 .2 7 4 .2 0 .) 6 4 ·5 B lu e g il l 0 .l 2 ). 1 0· 52 5 ·1 0. 06 1 .) 0. 05 0 .8 0 .0 4 0 ·5 G re en su n fi sh 0. 10 2 ·5 0. 16 1 .6 0· 09 2 .1 0 .1 ) 2 .0 0. 06 0 .7 C h .n n el c a tf is h 0. 12 ). 1 0 .4 ) 4. 2 0. 20 4 .6 0 .1 4 2 .) 0. 25 ). 1 C .r p 1 .1 4 28 .6 0. 79 7. 8 0 .) 2 7 .) 0 .) 4 5 ·4 0 .) 6 4 .4 F lo nn el m ou th su ck er 0 .1 8 4 .6 0. 28 2 ·7 0. 11 2 ·5 0. 17 2 .6 0. 08 0 ·9 ~ l l sp ec ie s 4 .0 4 10 .1 2 4 .1 7 6 .) ) 8 .0 1 I f -lS- Yearly ratios of mean number of bass and walleye caught per net tested among sampling stations was not statis- tically independent by Chi square analysis (t:I. = .OS). ~onindependence indicated that gill nets captured bass and walleye in the same relative porportions at each individual station every year. When' numbers were up or down at any one netting site, the catch rate changed porportionally at the other stations. Nonindepimdence indicated that data among sampling stations could be combined and averaged for individual years. Linear regression calculations were made to compare data among years (Figure 1). Regression analysis of bass catch rate to year sampled was used to determine if bass populations were increasing or decreasing. The regression line (Y = 3.391 + O.l42X) had a positive slope (b = 0.142), but the slope was not significantly different from b = 0 (t testc(.OS). Data was, thus, insufficient to confirm an increasing or decreasing trend in bass numbers, but suggested fluctuations around a constant level. Linear regression of walleye catch rate over the five year study (Y = -0.298 + 0.428X) showed a positive slope (b = 0.428) Significantly different from b = 0 (t = 7).79,0<= 0.001). Numbers of walleye as measured by gill nets .. thus, Significantly increased at the four sample sites since 1971. Other species were captured in too few nUlllbers to be treated in the above manner. An electro-fishing boat was tested on Lake Powell in the fall of 1975. The boat, a 26 by 8 foot pontoon boat, was rigged with an electro-fishing system designed by Mr. Joseph Coffelt, Coffelt Electronics Co., Inc. The system utilized DC current and a VVP uni t which produced a pulsed current over four electrodes. The system worked well and the VVP unit was ordered for purchase. Electro-fishing will be incorporated into a regular sampling program pending arrival and installation of all necessary equipment. -16- E-< g;] WALLEYE p:; r..< 3 p... r..< Y ~ = -0.298 + 0.428 X H H ..: • ~ 2 ~ 0 p:; r..< ~ 1 ~ z ..: ~ 1971 1972 1973 1974 1975 YEAR OF CAPTURE LARGEMOUTH BASS Y • 3.39 + 0.142 X • • • • • 1971 1972 1973 1975 YEAR OF CAPTURE Figure 1. Average number of walleye and largemouth bass captured per gill net in relation to year of capture, Lake Powell. Job NUlIlber: Objective: -17- T1 tle: Striped Bass Culture To evaluate variables affecting survival and growth of pond cultured striped bass and to develop techniques for rearing of larval striped bass to fingerling size. Accomplishments: Three shipments of striped bass fry were received and stocked in culture ponds in late May. 1975 (Table 15). Two sh~pm~nts were from California and one from North Carolina. Culture ponds were fertilized with alfalfa hay at the rate of 650 lbs per surface acre prior to receiving fry. Stocking different rates of striped bass was evaluated by varying the rate among ponds (ponds received 20, 35, or 50 thousand fry per acre-ft). Fry were held in seran tempering baskets until six days of age and then released into the culture ponds. Sur- vival of fry in tempering baskets was poor in ponds '1, #2, and #6 and excellent in ponds #3, 14, and '5. High mortali ty was attributed to fungus infections, sudden exposure of fry to intense light, adverse wind and wave action, and plankton blooms dominated by organisms too large to serve as food. T .b le 1 5 . ~ t o c k i n g ra te s o f st ri p e d b as s la rv a e i n r e a ri n g po nd s, 1 9 7 5 . A ge A ge S u rv iv al fi sh p er To ta l D at e R ec ei ve d R el ea se d in T em pe ri ng Po nd S o u rc e a c re -f t fr y R ec ei ve d (d ay s) (d ay s) B as k et 1 - R CR I. 5 0 ,0 0 0 5 3 ,0 0 0 5 -2 0 -7 5 4 n o t re le a se d po or b " . Ca ro li n a 5 0 ,0 0 0 53 ,0 00 5 -2 2 -7 5 2 n o t re le as ed po or c Co l. 50 ,0 00 5 3 .0 0 0 5 -2 8 -7 5 5 6 po or 2 C. l. 5 0 ,0 0 0 5 3 ,0 0 0 5 -2 0 -7 5 4 6 po or 3 Cd . 2 0 ,0 0 0 1 4 2 ,0 0 0 5 -2 0 -7 5 4 6 e x c e ll e n t 4 "< . C ar o li n a 2 0 ,0 0 0 1 2 3 ,0 0 0 5 -2 2 -7 5 2 6 e x c e ll e n t 5 K . Ca ro li n a 3 5 ,0 0 0 72 0, 00 0 5 -2 2 -7 5 2 6 e x c e ll e n t 6 Ca l. 3 5 ,0 0 0 75 0, 00 0 5 -2 8 -7 5 5 6 po or - Th re e at te m p ts w er e m ad e a t te m p er in g fr y i n po nd #1 b ef o re su rv iv in g f ry w er e re le as ed in to th e po nd . , I--' (Xl , -19- Fingerlings Here harvested-July IS-20th, at an age of 57-62 days. A total of 100,678 fingerlings were produced for a mean survival of 5.5 percent (Table 16). Ponds #1, #2, and #6 failed to produce any fish. Ponds #3, #4, and #5 produced considerable numbers of fingerlings. Pond #3 was particularly successful, . producing 67,955 fish with an overall survival of 47.9 percent. Results obtained from different stocking rates of striped bass fry during 1974-1975 are given in Table 17. Data was difficult to interpret because of lack of control over numerous variables influencing survival besides stocking rates. The best information was prob- ably obtained from pond #1 in 1974 and pond #3 in 1975 . Excellent fingerling production was obtained in both ponds, and survival was probably least influenced by uncontrolled variables. Pond #1 was stocked at the lOHer rate (83,333 per acre) and had a high percent survival (58.8 percent) and total production (44,080 fingerling per acre). An increased stocking rate in pond #3 (142,000 per acre) may have increased fingerling production (67,955 per acre) and also resulted in reduced survival (47.9 percent). In either case, actual stocking rates probably did not deviate far from an optimum level. Field observation would suggest that production capacity of pond #3 was at a maximum. Even if supplemental food had been provided, space for additional fish was limited. Crowding was obvious with the smaller fish in pond #3 apparently restricted to shallow, less desirable areas of the pond by haras- sment from larger fish. Although data available on stocking rates is still limited, 140,000 fry per acre (20,000 per acre-ft in pond #3) was believed to be a satisfactory figure. Further refinement of stocking rates may not be immediately necessary, especially in view of the difficulty and error in estimating actual numbers of fry. I !. b le 1 6 . S tr ip e d b .. ss h .. rv e st f ro m e x p er im en ta l rM ri n g p o n d s, 19 75 . T o ta l T o ta l 'tl e ig h t M e . . n i f T o ta l II l! F ry # F ry P er fi n g e rl in g fi n g e rl in g fi n g e rl in g Po nd l! R el ea se d k r e p ro d u ce d ( K g) p er K g p ro d u ce d 1 53 ,0 00 13 2, 50 0 2 53 ,0 00 13 2, 50 0 3 14 2, 00 0 14 2, 00 0 14 1. 0 4 8 2 67 ,9 55 4 12 3, 00 0 11 1, 81 8 1 3 .6 37 5 5, 11 4 5 72 0, 00 0 23 2, 25 8 8 5 ·7 )2 2 27 ,6 09 6 75 0, 00 0 18 4, 61 5 T o t. l 1, 84 1, 00 0 24 0. 4 41 8 10 0, 67 8 L en g th (m m ) 55 61 60 56 P e rc e n t S u rv iV ll l 0 .0 0 .0 4 7 ·9 4 .2 3 ·8 0 .0 5 ·5 ~ o I -21- TAble 17. Results from successful culture ponds receiTing different stocking rates of striped bass fry, 1974-75. YeAr Pond 1975 5 1974 6 1974 4 1975 3 1974 3 1975 4 1974 1 Number fr:l stocked roduction r Acre r Ac-F t r Acre 232,25B 35,000 3·B B.906 171.000 2B,461 7·B 9,184 150,000 27,117 9·0 13,682 142,000 20.000 47·9 67.955 125,000 18,512 6.4 8,385 111.81B 20,000 4.2 4,649 83,333 2B,571 SB.B 44,OBO During 1974 and 1975 volume was used as a standard unit in determining fertilization and stocking rates. Values were expressed in terms of acre-ft. Experimentation in 1975 required that plankton production be held relatively constant among ponds. Pond #1-4 were fertilized at a constant rate (650 lbs per acre-ft) in hopes of achiev- ing this. Ponds #5 and ;6 were fertilized at a lower rate because of a lack of fertilizer. Results are shown in Figure 2. Plankton production was not held constant. No relationship was apparent between fertiliza- tion in terms of acre-ft and plankton production. However, when comparisons were made between the amount of fertilizer applied per surface acre and plankton production, a relationship was evident. Ponds that received greater amounts of fertilizer per surface acre, generally had higher mean standing crops of zooplankton . Plankton CDOPS were even more predictable when water seepage from each pond was considered (Figure 2). Ponds with moderate fertilization per surface acre had relatively high standing crops of zooplankton if the rate of water loss was low. It was evident that productivity, in this case, was more closely associated with surface area than total water volume. FERTILIZATION BY UNIT VVLUV£ 600 · +> 4-, I OJ • " <.l cu LWO · " OJ P. · UJ .0 rI 200 · Pond : 1 2 3 MEAN STANDING CROP OF ZOOPLANKTON " OJ +> ..-I 1 600 rI " OJ o. 1200 ~::: ~ 800 cu OJ z 400 Pond: 1 2 % Survi va l: 0 0 FERTILIZATION BY 4000 · OJ " <.l 3000 cu · " OJ 2000 o. UJ ,0 1000 rI · Pond : 1 \vater loss : 2 . 4 2 7 .1 3 47 . 9 UNIT AREA 3 2 .1 4 4 4 . 2 4 9 . 3 _ I n organic o Cr gani c 5 6 c::J Nauplii copepods ~ Ad u l t copepods _ Ro t ifers 5 3 . 8 -I 5 0. 6 I 6 0 I n organic Organ i c 6 5. 6 Figure 2. Comparison of zooplankton crops and fertilization schedules, 1975. Water loss expressed as percent of total pond volume per day. -23- Best fingerlin~ production during 1975 occurred in the pond with the highest fertilization rate (pond #3, Figure 2). Although ponds ,1-4 received an initial 650 Ibs of alfalfa hay per acre-ft, pond #3 received the greatest amount in terms of surface acres (4,600 Ibs). Field observations, as well as quantative plankton analysis, indicated that pond *3 had a distinctly richer plankton bloom than any other pond. It is recommended that initial fertilization rates near 4,600 Ibs per surface acre of alfalfa hay be further evaluated. High survival in pond #3 during 1975 provided an opportunity to periodically sample fish during the culture period and determine food habits. A dip net or small seine was used to collect 10-20 striped bass at weekly intervals. In general, food habits changed from smaller to larger items as striped bass increased in length (Figure 3). Rotifers, the smallest organisms available, were found in stomachs during the first two weeks after fry introduction, but were later avoided. Rotifers were never used to a great extent, but may ha ve been important at the time fry started to feed, befo·re any stomachs were collected. Nauplii copepods, the next larger organism, were also utilized by fry during the first month, but were unimportant after striped bass obtained about 30 mm total length. utiliz- ation of adult copepods started when fry were about 12 days old and gradually increased in impo~tance until they made up 100 percent of the diet. Although size of adult copepods was not measured, it was evident that striped bass selected larger individuals as the culture period progressed. During mid-June, zooplankton numbers began to decline (Figure 4) and striped bass converted to feeding on benthic chironomids (Figure 3). After supplementary fertilization, zooplankton numbers again increased, and striped bass reverted back to utilizing adult copepods. Benthic organisms apparently acted as a food reserve when plankton became limited. 100 80 60 20 0 ----- Rot i fers Naupli i copepods - •• - Adult cope pods • ••••••••• Chironom1d l arvae ••• - ... - Chi ronomi d pupae Age (days) 22 29 36 43 , , I 50 56 , I . _ .. _ ......... 10 • r, • • I , : " .-, .. 20 • • • • I • • I -' . - • • ............ • . . . • I • . ". ..• , .. . . .. <. 30 40 Total l ength (mm ) 50 60 Fi gure 3 . Stri ped bass food habits compa red t o grow t h in l ength, pond #3 , 1975 . Va l ues expressed as percent by number . -24- -25- It was evident from data collected in 1974 and 1975 that fingerling production was related to the success of initially introducing striped bass fry (Table 18). Successful ponds, (ponds producing substantial numbers of fingerlings) always resulted when survival in tempering b~skets was rated good-excellent. Invariably, pond production was poor if fry did not do well in the baskets. Survival of fry for the first 24-48 hours after stocking was probably the most important factor in determining overall fingerling production in 1974 and 1975. Restocking tempering baskets in which fry do not do well with new fry would be the best way of insur- ing that all ponds receive successful fry introductions. This could be done in the future, if multiple shipments of fry can be arranged. Table 18. Comparison between striped bass fry survival in tempering baskets and fingerling production, 1974-75. Survival in tempering basket poor - fair good - excellent Number ponds 5 7 Successful ponds a 7 Percent survival to fingerling 0.0 Zooplankton abundance in culture ponds in 1975 showed a possible relationship to fry survival and fingerling production. Plankton populations were monitored every fourth day from the time ponds were filled to the time of harvest. Occurrence of zooplankton in pond iJ which had the highest percent survival and greatest production is represented in Figure 4. At the time of fry intro- duction, the plankton community was dominated by small organisms. Larger organisms developed later and in the same sequence that occurred in the diet. In contrast, the plankton development in pond #1 was considerably different (Fi~e 5). Fry were introduced shortly after the plankton bloom had reached its peak. Greater numbers of large adult organisms were present and three attempts at i~troducing fry were unsuccessful. Timing of plankton blooms with fry introductions was possibly of major importance. Stocking fry at a time well before zooplankton numbers peaked, not only assured numerous quanti ties of small organisms ' that were potential food and minimum numbers of large organisms that might compete for food, space, and possibly be predaceous, but also allowed more comp~ete utilization of the entire plankton bloom. 6000 5000 4000 3000 2000 1:000 500 - - - Rotifers --.- Fish stocked I -\ I \ I \ , \ : \ I \ I __ I I I , , I 1 11ay \ Nauplii copepods Adult copepods \ \ Supplemental ferti lization I \ ~ I \_.. . . • • I • • \/\. ')c. I ,/ .. - .. June • • July Figure 4. Changes in abundance of predominant zooplankton found in pond #3 , 1975. -26- 6000 jOOO 4000 lOOO 2000 1000 500 - .. - ....... .......... Fish stocked II I Rotifers Nauplii copepods Adult copepods Cladocerans Supplemental fertilization I , " " , , , , , . . , : . • • • • • • • • • • • • • • • ~ .. • ., I . • ., / "" " /'- . . / '\ '/' ./ ...... ,. - .. 1/ , .... May • • • • • • June •••• " July Figure 5. Changes i n a b undance of pre dominant zooplankton found in pond # 1, 1975, -27- -28- Pond 16, which wa s unsuccessful, also had a plankton bloom dominated by large organisms when fry were stocked. All successful ponds had plankton blooms oonsisting mainly of small organisms at the time of fry introductiDn. Pond 12 apparently had a desirable plankton population when fry were stocked, but samples of the fry indicated that nearly 100 percent were infected with fungus. Results were not conclusive, but possible relationships between fry survival and quality of zooplankton deserves future attention. A number of precautions might also help improve survival of fry during the initial stages of int.,lIddction. Best results were obtained when fry shipments arrived in the evening and were stocked at night. This minimized sudden exposure of sensitive fry to bright light. Ex- tremes in temperature, wind, and wave action were also avoided at night, allOwing more favorable conditions for adjustment. Construction of windbreaks and covers for seran baskets might also reduce detrimental effects of intense light and wave action. Utili&ation of more baskets could enhance fry survival by reducing density of fry in anyone basket. Fingerling production for 1974 and 1975 was also compared to source of fry and age when shipped (Table 19 and 20). Fry received from California had the most widely variable results. Out of five attempts, California fry were only successful in two ponds. The two successful ponds, however, were exceptionally productive. East coast shipments were successful in five out of seven attempts, but generally less productive. A similar trend was evident for age when shipped. C.lifornia fry were shipped when 3-5 days old, while east coast fry were shipped at 2 days of age. With only limited data on source of fry and age when shipped, no positive conclusions could be drawn. TAble 19. Fingerling production comparing three different sources of striped bass fry, 1974-1975. Fingerling production iI in successful ~nds iI Ponds* Successful MeAn iI Source stocked ~nds (%) % Survival per Acre C .. lifornia 5 2 ( 40.0) 49·8 61,133 North CArolina 2 2 (100.0) 3·9 7,791 Vir~nia 4 2 ( 50.0) 7·9 11,160 ·one successful ~nd , not included above, was stocked wi th a Dlixed source from North Carolina and Virginia. TobIe 20. Fingerling production comparing striped bass fry shipped at different ages, 1974-1975. Fingerling production Ae:e at iI in successful ~nds receipt If Ponds Successful Mean If (days) stocked ponds (%l % Survival per acre 2 7 5 ( 7]..4) 5·3 9,017 3-4 4 2 ( 50.0) 49·8 61,133 5 1 a ( a ) -29- -31- Job Number: v Title: Evaluation of Striped Bass Introduction Objective: To evaluate the success of the striped bass introduction into Lake Powell, both biologically and as a sport fishery. Accomplishments: An estimated total of 94,878 fingerling striped bass were stocked in Lake Powell during July 15-20th, 1975. All introductions were made at boat ramps in Wahweap Bay. During the first 2 days of stocking, fingerlings were released at the government boat ramp. Four 100 ft experi- mental gill nets (each with four panels of 1, It, 2 and 3 inch mesh) were fished at the release site to evaluate the extent of predation on the newly released striped bass . The number of predator fish caught in the nets was low and only four stomachs were found to contain striped bass (Table 21). Soon after release, striped bass fingerlings oriented themselves, formed schools, and moved away from the boat ramp. It was apparent that in- creasing numbers of predator fish were being attracted to the ramp area as stocking progressed. Sunfish were particularly abundant and thought to be attracted by the large number of aquatic insects present in the transported water from the culture ponds. To reduce attraction and possible predation on striped bass, other boat ramps in the area were also utilized. Table 21. Stomach contents of predaceous fish captured near the government docks during stocking of striped bass fingerlings, July 16 and 17, 1975. Stomachs containing 1/ Striped bass 1/ stomachs striped bass ~r stomach S~cies examined number percent mean range Largemouth Bass 10 3 33·3 1.0 0-7 Green Sunfish 2 1 50.0 1.0 0-2 Black Cra ppie 2 0 0.0 0.0 Channel Catfish 4 0 0.0 0.0 Growth of striped bass in Lake Powell was rapid (Figure 6). Fish stocked in July, 1974 averaged 282 mm (11.1 in) total length and weighed 303 g (0.67 Ib) by December. Little growth occurred during winter and spring, but resumed again in June. Scale analysis showed distinct annulus for- mation in early June. By the end of their second summer, striped bass averaged 410 mm (16.4 in) -32- total length and had a mean weight of 831 g (1.82 Ib). Growth of striped bass stocked in 1975 was rapid from July through September (Figure 6). Fish captured from October through December were not as large as the previous year. but the difference might have been caused by sampling bias from the use of smaller mesh gill nets. Food habits of striped bass during their first summer in Lake Powell are described in Figure 7. Dipteran larvae and pupae (Heleidae and Chironomidae) dominated the diet shortly after stocking. Thread fin shad began to enter the diet when striped bass reached about 90 mm (3.5 in) total length. By the time striped bass were 130 mm (5.1 in) long, fish made up the entire diet (72 percent thread fin shad and 28 percent unidentified). Threadfin shad continued to dominate the diet of striped bass during their second year of life (Table 22). Crayfish were the only other identifiable food item found. 4 0 0 ~ ~ 3 0 0 ~ 8 0 Z W ..< ..< 2 0 0 ~ 8 0 8 I 1 0 0 6 2 1 1 O c t N ov D ec 7 4 SA M PL E S IZ E (n ) 23 0 0 0 1 1 5 5 1 3 1 6 1 4 4 ~? 2! 2 4 4 3 6 1 1 1 9 7 4 Y e a r C la ss 1 9 7 5 Y e a r C la ss -, Ja n F eb M ar A p r M ay Ju n J u l A ug S ep O c t N ov D ec 7 5 M ON TH F ig u re 6 . M o n th ly g ro w th o f s tr ip e d b a ss a t L ak e P o w e ll , U ta h . ~ I -34- Fish .... ~.Chironomid larvae and pupae _ •••• Heleid larvae and pupae 100 80 60 40 20 60 70 80 90 100 110 120 130 14 0 TOTAL LENGTH (mm) Figure 7. Changes in fo od habits of Lake Powell, young-of- the-year striped bass with growth. T ~ b l e 2 2 . Fo od h a b it s o f st ri p ed b as s ag e 1+ , lA ke P o w el l. 19 75 . V al ue s ba se d on to ta l nu m be r o f st om ac hs c o n ta in in g f oo d oJ< Su m m er F a ll W in te r ~ ( n =1 72 ~ by ~ by ~ ( n =1 2l ~ by % by J (n =4 2 ~ by % by It em D cc . V ol . N o. O cc . V ol . N o. D ec _ V ol . N o. C r. y fi sh 6 .0 8 .0 2 .0 -- F is h 9 4 .0 9 2 .0 9 8 .0 1 0 0 .0 1 0 0 .0 1 0 0 .0 1 0 0 .0 1 0 0 .0 1 0 0 .0 T hr ea d f i n S h" d 7 7 .0 8 1 .0 9 0 .0 83 .0 87 .0 8 3 .0 1 0 0 .0 9 9 ·5 9 3 ·0 Un id e n ti fi e d 2 5 ·0 1 1 .0 8 .0 4 2 .0 1 3 .0 1 7 .0 25 ·0 0 ·5 7 .0 * N o te : 1 5 st o m a ch s o f 4 8 e xa m in e d w e re e n p ty . I W V I I Returns of striped bass were largely restricted to '""hweap and '"arm Creek bays. All fish collected in gill nets were from these locations. Nith the exception of two fish, all known striped bass taken by anglers were also within 10 miles of the dam. The exceptions occurred in late fall of 1975 when one report was confirmed of a striped bass being caught near Last Chance (25 miles up lake) and another from near Rainbow (45 miles up lake). It is recommended that stocking be expanded in 1976 to upper reservoir areas to better distribute striped bass populations. A potential mass marking technique was also partially evaluated on 200 striped bass fingerlings (60 mm mean len~th ) . Fish were sprayed with orange flourescent pigment at 90-100 Ibs pressure with a compressed air gun held at a distance of 18 in. Fish were after- -36- wards placed in " seran ba s ket located in pond #1. Thirteen mortalities (6.5 percent) occurred within 24 hours. The remaining 187 fish were released in the pond. After 18 days the pond was drained and 184 fish were recovered. Avera ge length had increased to 91 mm. All fish were then preserved and a sample checked for mark retention. All fish inspected were marked. This technique showed promise, but more work is needed to determine the longevity of the mark before using the method in a research project. No further work is planned along these lines, unless a distinct need to makk striped bass becomes apparent from project work.
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Content: 59bd4bdfdfb23078084a405f59936ad6763c50aa | Abstract: d0dd8330b221ce0a2aa16ac55bf35fbd1f6029ba