title
Lake Powell fisheries investigations : 1980 (segment 9) annual report for Colorado River Drainage and Tailwaters Dingell-Johnson Project F-28-R
author
Array ( [0] => Gustaveson, A. Wayne [1] => Pettengill, Thomas D. [2] => Ottenbacher, Michael J. [3] => Johnson, James E. )
abstract
UDWR Publication Number 81-9
date
1981-01-01
organization
Utah. Division of Wildlife Resources
species
Array ( [0] => Not Specified )
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https://grey-lit.s3.wasabisys.com/lake-powell-fisheries-investigations-1980-segment-9-annual-report-for-colorado-river-drainage-and-ta.pdf
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content
. N 4650P6.13: Lak/ 'lifo UTAH O~"':"!TO'" $"~"~("'~ DEC IJ 19BI Lake Powell Fisherie~ SlArl ulRAl1 . Investigations 1980 (Segment 9) Annual Report for Colorado River Drainage and Tailwaters Dingell-Johnson Project F-28-R Utah Division of Wildlife Resources Publication Number 81-9 . • LAKE POWELL FISHERIES INVESTIGATIONS Annual Performance Report January 1980 - December 1980 A. Wayne Gustaveson, Project Leader Thomas D. Pettengill, Project Biologist Michael J. Ottenbacher, Project Biologist James E. Johnson, Fisheries Program Coordinator Publication No. 81-9 Dingell-Johnson Project F-28-R-9 UTAH STATE DIVISION OF WILDLIFE RESOURCES An Equal Opportunity Employer Douglas F. Day Director ABSTRACT Continuing fisheries research with predator and prey species of Lake Powell was summarized for sample year 1980. Threadfin shad, the dominant forage fish, were evident throughout the reservoir; yet, numbers captured by mid-water trawl were at 5-year lows. Sport angling pressure increased approximately 10% from the previous year, and angling catch rates were slightly improved. Sport fish harvested most often were black crappie and largemouth bass, with increasing occurrence of naturally occurring walleye and the recently introduced striped bass. Gill netting to demonstrate game fish population trends showed increasing walleye numbers, while numbers of largemouth bass decreased. Striped bass were caught for the first time at the netting station most distant from the introduction site. Electrofishing surveys suggested a strong year class of largemouth bass was produced in 1980. Black crappie reproduction was also high, even though numbers were less than recorded in 1979. Striped bass reproduced for the second successive year in the Colorado River above Lake Powell. No spawning ·success was detected in the San Juan Arm. The best method of documenting striped bass reproduction was a standardized gill-net survey conducted in the fall . ii TABLE OF CONTENTS LIST OF TABLES . LIST OF FIGURES JOB NUMBER I . THREADFIN SHAD STUDY Methods • • • • • Resul ts and Discussion Recommendations • • • • II . MEASUREMENT OF FISHERY HARVEST, PRESSURE AND SUCCESS Methods • • . • • • Results and Discussion Recommendations • • • • III . INDEX TO ANNUAL FISH POPULATION TRENDS Annual Netting Methods • • • Results and Discussion Recommendations Electrofishing Methods • • • Results and Discussion Recommendat i ons • IV . MONITORING OF STRIPED BASS POPULATION DEVELOPMENT Methods • • • • • • • Results and Discussion Recommendations LITERATURE CITED . . . . . . ." iii iv vi 1 1 1 8 9 9 9 14 16 16 16 16 21 22 22 22 26 27 27 27 31 35 Table 1. 2 . 3. 4. 5 . 6 . 7 . LIST OF TABLES Adult and y- o-y threadfin shad trawl tow at Wahweap , Bullfrog Powell, 1980 ••••••••• captured/ standard and Hi te , Lake Sport fishery catch rates (fish/angler hour) by species and lake area, Lake Powell, April -June 1980 • . . . . . . . . . . . . · . · · · · . Species composition as percent of the total recorded creel for anglers interviewed a t Wahweap, April - September 1980 · . · · · · . · Species composition as percent of the total recorded creel for anglers interviewed at Bullfrog , Hall ' s Crossing and Hite, April-September 1980 • . . . . · · Catch rate (fish/net day) during annual gill netting, Lake Powell, March 1980 • · · · · · Percent of total sample occurring in each category of the visceral fat index for walleye collected by gill netting during March 1980, Lake Powell . . . . . • . . . . . . · · · Percent of total sample occurr ing in each category of the visceral fat index for largemouth bass collected by gill netting during March 1980, Lake Powell • • • • . • 8. Comparison of catch rates (fish/net day) fo r spring and fall gil l netting at Lake Powell, 1980 9. 10 . 11 . Number of fish caught/hour of electrofishing at Lake Powell during August 1980 • • • • • • • Comparison of three spawning aggregations of striped bass in Lake Powell , April-June 1980 Compa r ison of gill-net catch rates in naturally reproducing striped bass fisheries . • . • • . • iv Page 7 · · · · 13 · · · · 15 · · · · 15 · · · · 17 20 20 21 24 28 30 LIST OF TABLES (continued) Table Page 12 . Seasonal occurrence of food items in striped bass stomachs collected during 1980. Percent occurrence of food items based on number of stomachs containing food • • • v 32 • Figure 1- 2 . 3 . 4. 5 . 6 . 7. 8 . 9 . LIST OF FIGURES Mean numbe r of young- of-the - year shad captured / trawl haul a t Wahweap · Mean number of young- of-the - year shad captured/ trawl haul at Bullfrog Mean number of young- of-the-year shad captured / trawl haul at Rite Mean number of adult shad captured/t rawl haul at Bullfrog . · · · · · · · Indices of total recreational boa t use and angling pressure, Lake Powell , 1965- 80 · Catch rates (fish/angler hour) for largemouth bass , black crappie and all s pecies during the months of Apri I - June 1965- 80 , Lake Powell · Catch rates ( fish /ne t day) fo r largemouth bass and walleye from annual nett ing, 1971-80 , Lake Powell . . . . . . . · · · · · · · . . . . . . Map of Lake Powell showi ng annual netting sites (dots), electrofishing transects (c ircles ) and lake areas . . . . . · · · · · · · . . . . . . · Mean number of young-of- the- year largemouth bass and black crappie collected /hour of electro- fishing during August-September 1977-80, Lake Powell . . . . . . . . . . . . . . . . . . . 10 . Seasonal occurrence of food items in striped bass s tomachs collected during 1980 . Percent occurrence of food items based on number of 2 3 4 · · · · 6 · · · · 10 · · · · 12 · · · · 18 · · · · 23 25 stomachs containing food • • • • • • • • • • • • • • ., 33 vi Methods THREADFIN SHAD STUDY JOB I Monthly mid-water trawl collections were taken from June through October at Wahweap and Bullfrog, and from July through Octobe r at Hite. The sampling methods used were reported in Gustaveson et al. 1980. Results and Discussion A comparison of young-of-the-year (y-o-y ) shad caught in 1980 with catches made in 1977 and 1978 indicated low production for threadfin shad in Lake Powell (Figures 1, 2 and 3). A possible explanation for the low catches was that threadfin shad were not evenly distributed in the reservoir. The uneven distribution may have been partly in response to spawning habitat. Threadfin shad begin spawning about mid-May when surface tempera- tures reach 21 C. Shad spawn at the surface, randomly distributing their eggs on any floating object . Shad seek out areas where terrestrial vegetation is partially submerged or where streams have carried in drifting debris. They seem to prefer rafts of driftwood and floating debris but will also spawn around marinas on the boats, docks and cables, in the absence of preferred habitat. Since 1979, shad have not been observed spawning in the Bullfrog or Wahweap marinas. Spawning mats placed in the Bullfro g Marina in May 1 ~ ra J: ... cu 0- "C ra -= en -0 ... cu ..c E ~ z c ra cu ~ 2 2400 2000 1600 1200 800 • 400 ~ ~ 1978 • "" 1977 • \ , , , , \ 1976 , , , , \ 1979 & 1980 a .J ,. 7" .. · .. · ...... • .. ....... .. .... ; :,r,-mmar i • • June July Aug. Sep. Oct. Months Figure 1. Mean number of young- of- the- yea r shad captu r ed / trawl haul at Wahweap. '5 ca J: 2800 2400 2000 ... 1600 ~ " ca .c: (f) -o ... 1200 0 :t: 0. 8. a: w 0 .7 ... J " z 0 .6 c t a: 0 .5 w a. 0 .4 :t: (/ ) II. . 0 .3 0 .2 0. 1 i' ..... ... I \ I \ I \ I \ I \ I \ I \ I \ I \ I ... . \ ,; ,. . .. - L A R G E M O U T H B A S S .. .. .. . B L A C K C R A P P IE - - A L L S P E C IE S i • • • • • • \ .. " ' , , \ , .... -- -. ' ; : ' . , " .... ' " : " ' " , r- _ _ ' " ... . . . , ~ , I ' " ... ... ' , I '- - _ / : . . . ' I : '". , " .' " .' " " " ... .. " , " . ' " .' ' . I : ".. . , " .. , "If· - .. .. .. .. .. ~ J : , 1 9 6 5 1 9 6 6 1 9 6 7 1 9 6 8 1 9 6 9 1 9 7 0 19 71 19 72 19 73 19 74 1 9 7 5 1 9 7 6 1 9 7 7 1 9 7 8 1 9 7 9 1 9 8 0 Y E A R F ig u re 6 . C at ch ra te s (f is h /a n g le r h r) fo r la rg em o u th b as s , b la ck c ra p p ie an d a ll sp e c ie s d u ri n g th e m on th s o f A p ri l- Ju n e , 1 9 6 5 -8 0 , L ak e P o w el l. I- ' N 13 Table 2. Sport fishery catch rates (fish/angler hour) by species and lake area, Lake Powell , April - June 1980 . Spec ies Largemouth bass Black c r appie Channel 1 0 . 08 0 . 31 Lake Areaa 2 3 4 5 6 7 Meano 0 . 19 0 . 19 0 . 15 0 . 18 0 . 1l 0 . 26 0 . 16 0 . 10 0 . 66 0 . 27 0 . 15 0 . 07 0 . 37 0 . 27 catfi sh t C 0 . 03 t 0 . 01 0 .01 0 . 01 0 . 02 0 . 01 Bluegill t t 0 . 01 0 . 01 t 0 . 00 0 . 03 0 . 01 Rainbow trout t 0 . 00 t 0 . 00 t 0 . 00 0.00 t Walleye 0 . 02 0 . 03 0 . 02 0 .01 t 0 . 00 0 . 04 0 . 02 Striped bass 0 . 02 t t t t 0 . 00 t t All species 0 . 43 0 . 36 0 . 89 0 . 45 0 . 35 0 .19 0 . 72 0.47 aSee Figure 8 fo r map of lake areas: 1 . Glen Canyon Dam to Gunsight Butte . 2 . Gunsight Butte to Rainbow Marina . 3 . Rainbow Marina to Rincon. 4 . Rincon to Tapestry Wall . 5. Tapestry Wall to Hite . 6 . Above Hite . 7 . San Juan Arm. bMean = total fish divided by total anglers hours . Ct = less than 0 . 01 fish/angle r hour . 14 Catch rates for striped bass were relatively low during the c ensus months. However, the best fishing for striped bass occurred during the late summer which was not included in the census period. Striped bass comprised the ma j ority of the harvest for anglers in the Wahweap area du ring August and September (Table 3) . Striped bass also accounted for about 17% of the harvest in August at the Bullfrog-HaIl's area (Table 4 ) . Little additional information was gained from questionnaires distributed at launching ramps. Less than 5% of the survey forms were returned. Recommendations Creel census should be conducted April through September in 1981. Methods should be consistent with those used in 1980. Total lengths should be recorded and scales obtained from cree led striped bass to assess the contribution of each year class to the harvest. These data would provide a baseline for comparison with future years when naturally reproducing striped bass enter the creel. 15 Table 3. Species composition as percent of the total recorded creel for anglers interviewed at Wahweap, April-September 1980. Species Apr May Jun Jul Aug Sep Largemouth bass 32.0 24 .9 50.3 20 .0 15.0 0.0 Rainbow trout 0.1 0.5 0 . 0 0 . 0 0.0 0 . 0 Channel catfish 0.0 7.8 5.4 15.0 10.0 0.0 Black c rappie 66 .6 49.6 20.5 0.0 0.0 0.0 Bluegill 0 .3 4.4 2.2 49.0 12.5 0.0 Walleye 0 .9 9.3 17.3 11.0 5.0 16.7 Striped bass 0.1 3.2 4.3 5.0 57.5 83.3 Other 0.0 0.2 0.0 0 .0 0 . 0 0.0 Table 4. Species composition as percent of the total recorded creel for anglers interviewed at Bullfrog, Hall's Crossing and Hite, April-September 1980. Species Apr May Jun Jul Aug Sep Largemouth bass 28 . 1 44.0 38.9 59.4 4. 3 34. 0 Rainbow trout 0.0 0 .1 0 . 0 0.0 0 . 0 0 . 0 Channel catfish 0.1 2.9 15.0 0.0 78. 3 7. 0 Black crappie 70 . 8 46 . 5 23 .3 0 . 0 0 . 0 12 .0 Bluegill 0 . 7 3.7 5.6 0 . 0 0 .0 47. 0 \'lalleye 0 ·3 2.6 14.3 37 . 5 0. 0 0 . 0 St riped bass 0.0 0.2 3 · 0 3·1 17. 4 0 . 0 Other 0.0 0 .1 0. 0 0.0 0.0 0 . 0 Methods INDEX TO ANNUAL FISH POPULATION TRENDS JOB III Annual Netting Methods used for the standardized gill netting in the spring are described in Gustaveson et al. 1980. Sampling in 1980 was carried out at four stations during the first weeks in March employing 30 net days/station. Gill netting was also conducted in November at the standard Padre Bay and Good Hope Bay stations and at an area near the San Juan station. Sampling effort in the fall at the Padre Bay and Good Hope stations was 20 net days (over a 2-day period) at each location. The fall sampling at the San Juan consisted of 14 net days of effort. A selected sample of walleye and largemouth bass collected during the spring sampling was used to quantify fish condition according to the visceral fat index (VFI) used by the Utah Division of Wildlife Resources. Results and Discussion A total of 735 fish was collected in 120 net days during the annual netting in March 1980 (Table 5). As in the past, the majority of the catch consisted of walleye (60%) and largemouth bass (26% ) . The overall catch rates for bass and walleye also followed the same trends as in the past (Figure 7 ) . The average catch rate of largemouth bass decreased to 1.6 fish/net day (down 11% from 1979 ) . Other species collected during the spring sampling were only occasionally caught and showed no changes 16 17 ~ atch rate (fish/net day) during annual gill netting, Lake 'owell, March 1980. ,ie .sh :fish h ,ut :s head .ke Padre San Bay Juan Rincon 0.2 1.9 1.5 4.8 1.2 3.8 t b 0.1 0.0 0.0 0.0 0.0 0.0 t t t 0.6 0.5 0.4 0 . 2 t 0.0 t t t 0.0 0 . 0 t t 0.0 0.0 0.0 t 0.0 0.0 0.0 5.7 4.1 6.0 Good Hope Bay 2.8 4.7 0.0 t 0.0 0.3 0.6 0.1 0.0 t 0. 1 t 8 .8 . fish divided by total net days. t han 0 . 1 fish/net day. Totala 1.6 3.7 t t t 0.4 0·3 t t t t t 6.1 % of Catch 25.9 59 . 7 0 . 5 0.1 0.4 5. 7 5.2 1.0 0 . 3 0. 5 0.5 0.1 >
geography
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