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HomeMy WebLinkAboutBradley River Salmon Study Program 1997_-$------eesetalwhe!NORTHERN ECOLOGICAL Gude')SERVICES 44 5700 Old Seward Highway,Suite 206 ¢Anchorage,Alaska 99518 *Phone /Fax (907)561-7252 ANNUAL REPORT BRADLEY RIVER SALMON STUDY PROGRAM Prepared for: ALASKA ENERGY AUTHORITY December 1997 ANNUAL REPORT BRADLEY RIVER SALMON STUDY PROGRAM -1997 By John W.Morsell Randall L.Howard and Laurie Daniel Northern Ecological Services Anchorage,Alaska Prepared for Alaska Energy Authority Anchorage,Alaska December 1997 TABLE OF CONTENTS Page INTRODUCTION.wc ccc cccccc ccc cccc nc ccc cece ccc cc cece ccc ecco cscce 1 OBJECTIVES...cccccccccccccccnes we ec eccccce wenee eeeeeeeeeee°eeNDH Dad Wd (©)DSS Study Area ..cece reece esc serves cesscnsescsceresevcsece Study Duration 2...ccccccccccncccnnsnccccccccccccsccees Trap Net Sampling 2...ccc cc cc cc ccenrcccccccccccccccccce Beach Seine Sampling ......icecccccccccces ec ccc eens wceee CarcaSS COUNTS...peewee ere rc esc c ccc vcr cc nserccccccvcccs Fox Farm Creek SurveyS ...crcccccscncnccesccsccccsaseseces Biological Data Management.......cccccsccccccccccnsccecs Population and Escapement Estimation ........eccccccccee Physical Data Collection 2...ccc ccc cece n cece n cans scccece Miscellaneous ObServationS 2...cece cece cence esc nnnncce SAHOOOeWWWRESULTS eeoeseeoeeevneveeeneeesveseeeeeveeeeeeeeeeeeeeveeeeeeneneenveeveeeee Overall Catch wo ccecece ccc c ccc cccncceserncsesnccasesveses Trap Net Index Sampling ...cccccccccncccccnevecscssscescs Pink Salmon ..ccccccccccccavcnvcnnnenensvccccccsces Chum Salmon ...wccwcccnvecccsvccccscccccccscccscsecces Coho Salmon....ccccccccveces emcee errr ence cnccccccce Sockeye SAlMOMN 2...cece eer cc cern veers vecvsesceccccsChinookSalmoncercccccccvvccccssccscsccvccsesscceces DOLly Varden...ccc ccc cccc creer cc ccccccncccncavece Beach Seining ....ccccccccccccccccnvsncccccccccccssssece CALrCASS COUNTS.ccc cree cccccccccsesesevevesescevecesesese Fish Condition cc.cccccvcccccevcccccccsccesccscccccecces Pink Salmon ..cccrccccvccsccccesveresccescesesecees Chum Salmon 2...cc ccwccccccccccevccescccecsccccseecses 10 CONO SALMON .awccccecscnsccseovscceeseccesevsseesecserss 10 Sockeye Salmon ..ccce wcrc cscccccccccccvcccccccscceee 10 Chinook SalMon .ecrccccccsccescceseccceossescccsesesses 10 Stream Life Duration ..ccccccccccccccccccccccccccscceces Ll Pink Salmon ..ccccccccccccccesevesccescccesesecevccses Ll Chum Salmon ...cc ccc r cc ccccvcccesesnccesesscsessee§Ll Chinook Salmon .cccccccscccvcvccevccvvccsscevscceseee ll Spawning Area LOCation.....cccecccccrcccsscccccccsesecee 12 Fox Farm Creek SurveyS ....cccccccrccccccccccccccccecece 12 Population EstimateS .......ccccccccccccccccccccccccccce §12PinkSalmon..cccccvcccsccccvccesesccccevsecsecsesses 12 Chum Salmon....-ccccsccccces emcee ere er cer ccc ccesceecees&§13 Chinook Salmon..ccccccvccccsvccevvccesvccsevesecssecs 13wonnnnnnaooornnn TABLE OF CONTENTS (CONT.) Page Estimates of Total Escapement ......cccccccncnncccansece§14 Pink Salmon ....cece ec r ccc ccc cccccsccccccccccceee§14 Chum Salmon .....ccrccsescccescesce we eee rec cccee wee 14 CONO SALMON ..cwcwccccvecccccesccaessscccecsccccesene 15 Sockeye Salmon ..cccce wcrc cccccccscvcceeecccccceesce 15ChinookSalmon........ccccccccccccccsscccccccsecese§15 Tag Returns From Outside the Study Area ............eeee 15 Physical Data ..........ccceseneee weer cccee ccc c ccc e ese ee =15MiscellaneousObservations........cccccccccsceccescenee 16 DISCUSSION .cccccccccccccccccccccccnancecccccccccccces ee 17 Validity of Abundance Indices and Estimates ............17 Comparison With Prior YearS.....ccsesesssccsceess .19 Pink SalMOn....cccccccnrccccccccssssvessccccesseses 19 Chum Salmon...ccccccccccsvcccecescccccccccseseeee 19 COMO SAlMON...cere ccrcveccccccvrecsceseneccessceser 20 Sockeye Salmon...ccccccsvccvcvssvccscccsceceseseses 20 Chinook Salmon......cwcccnccrccccccccscscccccsesssss 20 ACKNOWLEDGEMENTS ....--cccccccecccccee eoee eevee eeoeoevennveeveeenee 21 REFERENCES ...scceccecee eeovevenvneeeeeeveeveesneanevneneeen en eve eneeeenvneeves 21 ii Table Table Table Table Table Table Table LIST OF TABLES Page Total catch for all sample methods combined.........24 Trap net catch statistics for salmon in the Bradley River...ccc ccc ccc ccc cece ccc cnnsceccereeeeesaD Seine catch summary for pink salmon............222+-26 Carcass count summary -1997....cccccccccccccenecsseldld Comparison of the week of marking with the week of recapture for all recaptured pink salmon.........28 Fox Farm Creek visual SUrVeEYS......ccececscccseseeeead Mark-recapture population estimates for pink salmon -1997......Cece cece wcrc cree ccc cr cccesceeseeee30 iii LIST OF FIGURES Page Figure 1.Lower Bradley River with salmon escapement SCUAY ALEA...ee eee eee e cere c ccc c nrc nc cccessccccsevess SL Figure 2.Bradley River trap net design........ec ccc cece eee -.32 Figure 3.Trap net and seine sites.............eee cece eseee 33 Figure 4.Catch-per-unit-effort for pink salmon by Study week....ccc cere cece vcs scecesesscvescsves eoeee 34 Figure 5.Catch-per-unit-effort for chum salmon by Study week.....cw cece cc cessceccce were ccesccseeee 35 Figure 6.Catch-per-unit-effort for coho salmon by Study week....cccccccccccenececccsesesccccsccesvess 36 Figure 7.cCatch-per-unit-effort for sockeye salmon by Study week.....ccc ce ccc ccc rece rece ence rcccssccesce 37 Figure 8.Catch-per-unit-effort for chinook salmon by Study week....ccccccccccccncncnncnesesessessseseses 38 Figure 9.cCatch-per-unit-effort for Dolly Varden by study week...........weeecere rnc ecccene weer cc sevevee 39 Figure 10.Percent frequency of occurrence of ripe pink salmon by study week.........c ccc c cence ccc cencccce 40 Figure 11.Estimated escapement and trap net catch per hour for pink salmon -1986 through 1997............eoee 41 Figure 12.Trap net catch per hour for chum salmon - 1986 through RS 3°oy 42 Figure 13.Trap net catch per hour for coho salmon - 1986 through 1997..@eees#ses eeoeeeoeesee#stssst ec eeeenseensrese#enteneeees 43 Figure 14.Trap net catch per hour for sockeye salmon - 1986 through tS):y A 44 Figure 15.Trap net catch per hour for chinook salmon - 1986 through 1997.......ccc wee ec ee wc ec cee ccc eee cene 45 iv LIST OF APPENDICES Appendix A.Catch records Appendix A-1.Pink salmon catch records. Appendix A-2.Chum salmon catch records. Appendix A-3.Coho salmon catch records. Appendix A-4.Sockeye salmon catch records. Appendix A-5.Chinook salmon catch records. Appendix A-6.Dolly Varden catch records. Appendix B.Fishing effort summary for each net by week during 1997 Bradley River sampling. Appendix C.Physical Data. INTRODUCTION The Federal Energy Regulatory Commission (FERC)license granted to the Alaska Power Authority (now Alaska Energy Authority)for the Bradley Lake Hydroelectric Project (Project No.8221)stipulated that a plan be developed and implemented to monitor the abundance of salmon in the Bradley River.Studies per the approved monitoring plan (Alaska Power Authority 1986a)were conducted from 1986 through 1995 with the intent of providing a yearly index of salmon abundance during both the pre-operational and post- operational periods to allow an appraisal of project impacts to salmon resources of the Bradley River.Additionally,a study of salmon attraction to the powerhouse discharge (tailrace)was initiated in 1992 and completed in 1993.The results of these studies are reported in annual reports for the above years.A summary of the study results from 1986-1995 is included in the 1995 Final Report (Alaska Energy Authority 1995). Submittal of the 1995 Final Report constituted completion of the required fisheries monitoring per the FERC license.However,the Alaska Energy Authority elected to continue the salmon escapement monitoring program for an additional three years to provide a longer period of record and better establish salmon population trends in the Bradley River during the operational regime.This report presents the results of the second year of investigation under the extended study program. Operation of the Bradley Lake Hydroelectric Project began in the fall of 1991,consequently 1992 was the first full year of project operation.However,operational flows were in effect during the summer of 1991 while the reservoir was filling.Therefore,1997 was the seventh year of the study to examine the salmon resources under the operational flow regime. The salmon resources of the Bradley River have been documented in considerable detail through a series of studies beginning with early permit-related investigations (USFWS 1982;Woodward-Clyde Consultants 1983,1984;Northern Technical Services 1985)and continuing with the 1986-1995 FERC mandated monitoring program. The Bradley River is a turbid stream of glacial origin, consequently fish cannot normally be visually detected.Various active and passive sampling techniques have been utilized to gain insight into fish populations.The results of these studies have indicated that pink salmon (Oncorhynchus gorbuscha)is the principal salmon species using the river for spawning,although smaller numbers of chum (0.keta),coho (0.kisutch),sockeye (0. Nerka)and chinook (0.tshawytscha)also utilize the river. Potential spawning habitat is limited to a short segment of the river due to high gradient and coarse substrate at the upstream end and silty tideflats at the lower end. Pink salmon were identified early in the permit process as the key evaluation species,consequently all study efforts have emphasized this species. OBJECTIVES The primary objectives of the 1997 field effort were to: -Continue monitoring the escapement of salmon to the Bradley River to extend the period of record and provide a better indication of trends in salmon reproduction under'the regulated flow regime. -Continue the general assessment of the habitat value of the river under the operational flow regime as compared to the pre-operational flow regime -Gain additional insight into the effects on fish populations as flows are fine-tuned closer to allowable minimums 2 -Maximize the amount of biological information obtained from the study by thoroughly analyzing the data. METHODS Study methodology was essentially identical to that used in the FERC monitoring program from 1986-1996 so that catch and population data would be comparable.The study period was shortened from 9 weeks to 8 weeks under the extended study program starting in 1996 to reduce costs while still encompassing the full pink salmon spawning period. Study Area The primary study area consisted of an approximately 2,300-m (7,500-ft)stream segment extending from the downstream end of Riffle Reach to waterfalls above the upstream end of Bear Island Slough (Figure 1).The study area encompasses almost all of the known spawning habitat in the Bradley River system. One study site was located outside of the primary study area.Fox Farm Creek,a small clear-water tributary to the Bradley River at RM 2.5 was monitored for salmon escapement (Figure 1). Study Duration The study was conducted over an 8 week period from July 22 through September 11.The general timing of the study was originally selected to coincide with the duration and timing of the pink salmon run,based on the results of the earlier studies and confirmed in recent years. Under the normal schedule of sampling,the field crew traveled to the site on Monday evening of each calendar week and intensive sampling took place on Tuesday,Wednesday and Thursday. 3 Trap Net Sampling Trap nets were again used as a primary sampling technique as in the 1986-1996 efforts.The standard project trap nets as redesigned in 1990 (see Alaska Energy Authority 1990)were designed to fish in water as shallow as 0.5 m and proved to work well at selected deeper sites in the river.Net design is illustrated in Figure 2. These nets were made from 6.35 cm (2.5 inch)stretch mesh nylon. Net wings were attached to the main frame of the net in various configurations depending on the location of the net in the river. The 6 trap net sites established in 1991 for the operational flow regime were utilized again in 1997 (Figure 3).There was no indication that significant stream channel changes had occurred since the 1991 season,consequently the conditions at each net location effectively duplicated the conditions present during the 1991 through 1996 studies.Some of the nets were accessible by boat and some were only accessible by foot. During each typical weekly sampling period,the trap nets in the primary study area were set Tuesday morning and fished until Thursday morning for a total of approximately 48 hours,after which they were removed from the water until the following week.During normal operations,each net was checked every 4 hours during the daytime and then allowed to fish overnight.Some variation in the typical sampling regime occurred because of the difficulty accessing nets during extreme high tides.Sampling times were delayed by 1-2 hours during those days when unusually high tides coincided with scheduled sampling times. During normal operating procedures,fish were removed from the nets at each check,identified to species,measured,and salmon species were tagged using sequentially numbered Floy spaghetti tags. Larger Dolly Varden were marked by punching a hole in the upper lobe of the caudal fin.Sex and spawning condition were recorded 4 for all salmon.Spawning condition codes were as follows: Code Condition 1 Fresh,non-spawning coloration, silvery 2 Spawning coloration,not ripe 3 Ripe,eggs or milt readily stripped 4 Spawned out 5 Visible deterioration 6 Dead Because of the large number of pink salmon in 1997,field crews were overwhelmed by the number of fish in the nets at times during the peak of the run.Under these circumstances,salmon were simply counted and recaptured fish were recorded. Beach Seine Sampling Beach seining was used as a supplemental sampling method.Seine sites are indicated on Figure 3.Sites Sl and S3 were seined consistently during most weeks.In most cases two hauls were made at each site.The seine utilized was 100 ft.long by 6 ft.deep, constructed of 2.5 in.stretch mesh netting.Captured fish were processed in a manner similar to that described for the trap net sampling. Carcass Counts All salmon carcasses observed within the study area were counted and tags were noted. Fox Farm Creek Surveys Visual surveys of fish present in Fox Farm Creek,a clear tributary to the Bradley River (Figure 1),were conducted once during each sample week.Observers walked the entire habitable length of the 5 creek at lower tide levels and recorded the numbers of fish present for each species of salmon and the numbers of fish showing visible project tags. Biological Data Management Data from field data books were entered into a computer spreadsheet (Quattro Pro)using an IBM compatible microcomputer.Printouts from the spreadsheets were checked by field personnel against the field notebooks.The spreadsheets were edited,correcting any observed errors.Graphs were prepared using the Quattro Pro program. Population and Escapement Estimation The principal methods used for estimating populations were the same as those used in past years to assure comparability of data. Population estimates based on trap net catches were calculated for the primary species of salmon present during each sample week using the Peterson mark and recapture model,as modified by Chapman (Ricker 1975).The following assumptions were used in constructing the model: 1.Salmon numbers remained constant during the 3-day sample period. 2.All fish marked during the previous 2 sample weeks were still present in the study area. 3.Fish marked 3 or more weeks prior to the sample week were no longer present in the study area. 4.Marked and unmarked fish were equally susceptible to capture. In addition,mark and recapture population estimates were calculated based on selected seine catches and carcass counts. Physical Data Collection Air temperature,water temperature,turbidity,and stream stage were recorded daily at the field camp (Figure 1)on those days that the study crew was in the field.Turbidity was measured in the field using an HF Instruments Model DRT15 nephelometric turbidity meter.Stream stage was measured using a staff gage.The gage measurements were strictly relative and were not tied to any datun. Miscellaneous Observations Wildlife presence and other events of ecological interest were noted as they occurred. RESULTS Overall Catch Overall catch for all methods combined is summarized by week in Table 1.Complete catch records for all fish are presented in Appendix A. As in past years,all five species of Pacific salmon indigenous to Alaska were captured in the Bradley River.Pink salmon were very abundant with a total catch of 5744 fish.Substantial numbers of chum (166 fish),coho (66 fish),sockeye (180 fish),and chinook (190 fish)salmon also were caught.In addition,325 Dolly Varden (Salvelinus malma)were collected. Trap Net Index Sampling Trap nets were the primary sampling technique and proved to be effective at catching adult salmon.The sampling effort for the 6 index nets was uniform throughout the study period.Trap net fishing times for each net and week are summarized in Appendix B. Pink Salmon Pink salmon catch and catch-per-hour for each week are presented in Table 2 and weekly catch-per-hour is summarized in Figure 4. The catch-per-hour increased gradually during weeks 1 through 4 then peaked dramatically in Week 5 (August 19-21).Substantial numbers of fish were present in Weeks 6 and 7 followed by a rapid decline in Week 8.The maximum catch rate was reached in Week 5 at 5.9 fish per hour (Table 2). Chum Salmon Chum salmon catch was highest during the mid-July to early August period then declined precipitously in mid-August (Table 2 and Figure 5).The maximum catch rate occurred during the second week of the study at 0.16 fish per hour (Table 2). Coho Salmon Coho salmon (Table 2 and Figure 6)were first seen in the study area during Week 3 with catch rate increasing to a peak in early September.The highest catch rate occurred during Week 7. Sockeye Salmon Sockeye salmon were present in the Bradley River during most of the study period (Table 2 and Figure 7).The number of fish gradually increased during August reaching a peak in late August and early September. Chinook Salmon Chinook salmon were present in significant numbers during Week 1 and declined rapidly,thereafter (Table 2 and Figure 8).Chinooks were the most abundant salmon species during Week 1 with a catch of 0.46 fish per hour. Dolly Varden Dolly Varden were collected in trap nets during all weeks of the study with greatest abundance occurring in early September (Table 2 and Figure 9). Beach Seining Beach seine catch data are summarized for pink salmon in Table 3. A total of 812 pink salmon were caught by the beach seine in 1997, of which 60 were fish that had been tagged previously.Small numbers of the other salmon species as well as Dolly Varden were also caught in the seine. Carcass Counts The results of carcass counts are presented in Table 4.During the course of the 1997 study,806 pink salmon carcasses,17 chum salmon carcasses,47 chinook salmon carcasses,9 sockeye salmon carcasses, and 2 coho salmon carcasses were observed in the study area. Fish Condition Pink Salmon The condition codes for all measured salmon are presented in Appendix A-1.Condition 3,"ripe",is indicative of spawning condition and was the least subjective of the condition codes since it depended on the actual presence of eggs or milt.Figure 10 shows the percent frequency of occurrence of Condition 3 fish for both male and female pink salmon.By early August,most male pink salmon present in the study area were ripe.The percent frequency of ripe females increased gradually,reached a peak of ripeness in Week 5 of the study (August 18-21),and decreased thereafter with no ripe females left in the study area during Week 8.As has been 9 the case in most prior years,male sexual maturity preceded the peak of female sexual maturity by about two weeks. Chum Salmon During the first week of the study in mid-July,97 percent of the males and 77 percent of the females were ripe.During Week 2,90 percent of the males and 73 percent of the females were ripe. After Week 2 few chum salmon were left in the river.It is likely that chums were at the peak of spawning at the time that the study started. Coho Salmon Coho salmon were first observed in the Bradley River on August 6, however no ripe fish were seen until the last week of the study when two ripe males were observed.No ripe females were observed during the study period.The peak of coho spawning likely occurred well after the end of the study period in late September or early October. Sockeye Salmon Small numbers of sockeyes were caught in the Bradley River starting in Week 3 (early August)and continuing throughout the entire study period.Percentages of ripe fish in Weeks 3 through 8 were 50,43, 74,73,53,and 75,respectively,suggesting that spawning occurred over a prolonged period from mid-August to early September. Chinook salmon During the first week of the study 87 percent of the chinooks caught were ripe and during the second week 83 percent were ripe. The number of chinooks present in the river decreased rapidly after Week 2.Most spawning probably occurred early in the study period during the last two weeks of July. 10 Stream Life Duration Pink Salmon Table 5 provides information on the tagging history of all pink salmon recaptured in trap nets.As has been the case in past years,most of the prior-weeks recaptures for any given week were fish that had been marked in the previous 2 weeks,suggesting an average stream life duration of about 2 weeks.However,several fish spent a longer time in fresh water.One male pink salmon was tagged on July 22 and recaptured on August 27 for a total stream life duration of at least 37 days,the longest freshwater duration ever recorded in the Bradley River.Three other fish remained in the river for minimum periods of 28-31 days,including one female. In spite of these exceptional fish,the 1997 pink salmon run was generally quite abrupt with most fish entering the study area during the extreme high tides on August 17-23 (Figure 4)and spawning quickly thereafter.Very few pink salmon remained alive after September 7. Chum Salmon Since the 1997 study began near the peak of chum salmon spawning, the information does not provide much insight into stream life duration for this species.Of 42 recaptured fish,none were recaptured more than 10 days after the marking date. Chinook Salmon The timing of the study period did not include the early part of the chinook salmon run;consequently,stream life duration cannot be accurately determined.Eleven chinook salmon were recaptured in 1997 after Week 1,most of which had been tagged in Week 1 and recaptured in Week 2.One fish was recaptured in Week 3 that had been tagged 14 days earlier. 11 Spawning Area Location The unusually high turbidity during most of the 1997 study period prevented detailed visual observations of spawning fish.General observations suggested that spawning locations were similar to prior years except that the large populations of pink and chinook salmon may have caused some expansion into marginal areas.In contrast to prior years,pink salmon were observed spawning in lower Riffle Reach,downstream from the gravel bar (Figure 3). Changes in the channel configuration have occurred in this area and the habitat may be more suitable than in the past.Chinook salmon were observed spawning in new areas in the south channel at Riffle Reach and in the reach adjacent to Bear Island. During Week 8,water clarity dramatically improved due to rainfall and reduced release of water from the Bradley Lake dam.MTwenty- two sockeye salmon were observed spawning in upper Tree Bar Reach (Figure 3)in the same area used by pink salmon.Coho salmon were observed schooled in deep areas and had apparently not begun to spawn. Fox Farm Creek Surveys Fox Farm Creek was used by small numbers of pink salmon during the mid-August to early September period and chum salmon in late July and early August (Table 6).Maximum number of pink and chum salmon observed was 29 and 4,respectively.Flow was low in the creek for most of the study period until the last week when flow increased substantially as a result of rainfall. Population Estimates Pink Salmon Weekly population estimates for pink salmon based on trap net 12 recaptures using the same mark and recapture techniques employed in the 1986-1996 studies are presented in the first part of Table 7.Weekly population estimates ranged from a low of about 4600 fish in Week 8 to a high of 23700 in Week 7.The Week 7 estimate is considered to be inflated because of the rapid mortality occurring at that time;fish tagged more than one week prior to Week 7 were likely dead and,thus,no longer available for recapture.The estimates for Weeks 3 through 6 are thought to be reasonably reliable.Significant numbers of fish were also present in Week 2,however the single recapture for that week is insufficient for estimating purposes. Population estimates also were calculated from selected seine hauls in Weeks 2 through 7 and from weekly carcass counts in weeks 5 through 8 (Table 7).Agreement is quite good for the estimates calculated from the various recapture methods. Chum Salmon A mark-recapture population estimate was calculated for chum salmon in Weeks 2 and 3 as follows: Week Total Catch Tags Out Recaps.Pop.Est.95%Limits 2 47 34 4 336 150-840 3 44 68 6 444 220-970 Chinook Salmon A single estimate for Week 2 provides some insight into numbers of chinook salmon: Week Total Catch Tags Out Recaps.Pop.Est.95%Limits 2 43 98 6 622 309-1361 13 Estimates of Total Escapement Pink Salmon An estimate of the total escapement can be calculated from the weekly trap net population estimates for pink salmon using the method of Pirtle and McCurdy (1980).With this method the weekly trap net estimates are summed and divided by a stream life factor of 2.5.Since there is no population estimate for Week 1,the population was assumed to be equal to 10 times the total catch for the week,which is a highly conservative estimate of the actual numbers of fish present.The seine recapture estimate is utilized for Week 2 since there was no trap net estimate for that week. Based on the above methodology,total escapement for pink salmon in the Bradley River in 1997 is estimated at about 32,500 fish. Another approach to escapement estimation is based on a comparison of the overall trap net catch-per-hour in 1997 compared to previous years.The year 1993 was used for comparison purposes because it is an odd year with a high salmon population and the escapement estimate for that year is considered to be reasonably accurate. Adjusting the 1993 escapement estimate to reflect the proportional difference in 1997 catch rate yields an estimated 1997 escapement of about 45,700 pink salmon.The relative accuracy of these various escapement estimates is examined below in the Discussion section. Chum Salmon The net catch of chum salmon in 1997 was 166 fish of which 25 percent were recaptures of fish caught previously.The mark- recapture estimates for Weeks 2 and 3 indicated that the number of chum salmon present in the river at that time probably fell into the range of 150-970 fish.An estimated total escapement of around 500 fish is reasonable,based on the 1997 catch statistics. 14 Coho Salmon The study ended early in the coho run,therefore escapement cannot be estimated.The total net catch was 66 cohos,of which 2 percent were recaptures. Sockeye Salmon A total of 180 sockeye salmon were caught during the study,of which 12 percent were recaptures.A conservative estimate of the number of sockeyes present in the Bradley River,based on observations during the 1997 season,is 300-500 fish. Chinook Salmon Combining untagged captures with untagged carcasses results ina total of 182 individual chinook salmon that were handled during the study period.This represents the minimum number of fish present. The mark-recapture population estimate for Week 2 described above suggested that about 600 chinooks were present in the river at that time.A conservative estimate of the total escapement of chinooks in 1997 is 300-700. Tag Returns From Outside the Study Area No tag returns from outside the study area were reported to the Alaska Department of Fish and Game or the Alaska Energy Authority in 1997. Physical Data Air and water temperature,turbidity,and relative water level data are presented in Appendix C.Temperature data were usually collected in mid-afternoon and,thus,are approximately representative of daily maximums.Water temperature showed 15 relatively little variation,ranging from 9.4 to 13.9 degrees C. Water temperatures were generally quite warm compared to other years.Turbidity was consistently high for the first 7 weeks of the study mostly ranging from 83 to 120 NTU.Low precipitation during most of the study period contributed to generally dry conditions in the Bradley River drainage.Nearly all the water in the lower Bradley River from mid-summer to early September was contributed by release from the fishwater bypass at the Bradley Lake dam and,thus,contained high glacial sediment load.Heavy precipitation during the September 6-8 period increased the availability of water in the watershed.Release of water from the reservoir was shut off during the last week of the study causing turbidity to decrease dramatically (3.8 NTU on September 10). River water level was very stable during the first 7 weeks of the study period varying less than 2 inches.Precipitation prior to the last week of the study caused level to rise substantially at that time. Miscellaneous Observations Bears No bears were seen by the field crew during the study.However the presence of tracks,scat,and partially eaten salmon indicated that bears were present along the river throughout most of the study period and were actively consuming salmon.Tracks of a sow and cub were observed at Fox Farm Creek in early August. Eagles The eagle nest downstream from Net 4 which was constructed in 1996 was in use again in 1997 and two young were present in early August.At least one young bald eagle successfully fledged and was observed out of the nest on September 4.Adult and immature bald eagles were commonly observed along the Bradley River throughout the study period.Heavy eagle use of the lower river occurred 16 during the peak of the pink salmon run.Ten eagles were observed near Fox Farm on August 7 and more than 20 eagles were seen between Fish Camp and Fox Farm on September 9. River Otters A river otter was observed in the upper study area on July 31 and otter signs were observed on numerous other occasions including tracks at Fox Farm Creek.Otters invaded a trap net and ate several salmon during the week of August 5. Common Mergansers A family of mergansers was observed at various locations on the Bradley River during the latter part of the study period.Eight mutilated juvenile chinook salmon were observed on the shoreline on September 10.These salmon had most likely been regurgitated by a merganser.The very clear water during the last study week probably allowed the mergansers to prey heavily on young salmon. Other Observations A coyote was observed near the eagle nest on July 28.Selected birds observed during the study period included belted kingfisher, semipalmated plover,sharp-shinned hawk,greater yellowlegs,spruce grouse,tundra swan,and water ouzel. DISCUSSION Validity of Abundance Indices and Estimates The potential difficulties with the use of mark and recapture population estimates under the circumstances in the Bradley River are discussed in detail in the 1986 study report (Alaska Power Authority 1986b).The analysis of marking net vs.recapture net presented in the 1989 study report (Northern Ecological Services 17 1989)indicates that pink salmon move widely throughout the study area prior to actual spawning and provides some assurance that the assumption that tagged fish are randomly distributed is not grossly violated.It should be noted that all of the "capture"methods were biased in favor of specific components of the pink salmon population.The trap nets sampled fish that were actively moving within the river and tended to catch more males than females. Seining in the latter part of the study period sampled fish that were actively spawning and usually included a more equal sex distribution than the trap net fish. Because of the small number of recaptures in some weeks,population estimates should be viewed very carefully and statistical confidence limits shouldbe taken into consideration.In addition, the run was quite abrupt in 1997;most fish entered the stream in Week 5 and spawned quickly thereafter.The rapid influx followed by rapid mortality significantly violated the assumption of a closed population which is required for accurate mark-recapture estimates.It is important to note that trap net,seine,and carcass count estimates for Weeks 3-7 are relatively consistent. It is felt that the estimates are probably reasonably reflective of numbers of fish in the river at that time. Reliability of estimates of overall season escapement depends on the accuracy of weekly estimates as well as stream life duration. Overall catch-per-hour of pink salmon for the 1997 study period was the highest ever recorded for the 12 years of study.But the escapement estimate of about 32,500 fish was the third highest recorded.Clearly,either catch-per-unit-effort does not always provide an exact index of overall escapement,or escapement estimates are subject to substantial error.Most likely,there are factors that affect the consistency and accuracy of both methods. Nevertheless,it can be concluded with certainty that the pink salmon abundance in 1997 was among the highest recorded since the study began in 1986.An estimate of 30,000-40,000 fish is reasonable based on both the 1997 calculations and prior year 18 estimates. Comparison With Prior Years Pink Salmon Figure 11 compares the overall catch-per-hour and estimated total escapements for the years 1986 through 1997.Escapement in 1997 was clearly very high,ranking in the same general range as 1989 and 1995,the two highest prior years.The trend of high odd year escapements was continued in 1997 and demonstrates good survival of progeny from pink salmon that spawned in 1995. Wild pink salmon returns to Kachemak Bay streams were generally good as is typical of odd numbered years;Humpy Creek,the largest pink salmon producer in Kachemak Bay,had an estimated escapement of 78,000 fish which is considered a good odd-year run (L. Hammarstrom,ADF&G,personal communication).Numbers of pink Salmon observed in the Bradley River were consistent with area- wide trends. Chum Salmon The catch rate for chum salmon in the Bradley River in 1997 was intermediate compared to past years (Figure 12).Estimated chum salmon escapements have varied from 50 fish to 1600 fish since 1986 with 3 years having escapements of greater than 500 fish.The approximately 400-500 fish present in 1997 is somewhat above average for post-project years.Chum salmon returns to Lower Cook Inlet streams have been generally low for the last several years. Escapement to Humpy Creek was poor in 1997 (L.Hammarstrom,ADF&G, personal communication).The relatively low number of chums in the Bradley River in 1997 was consistent with area trends. 19 Coho Salmon Study timing in 1997,as well as in previous years,has prevented estimates of coho salmon escapement and meaningful comparisons are difficult.The 1997 trap net catch rate was the third lowest since the beginning of the study program in 1986 and probably reflects a low population (Figure 13).The 1997 spawners were probably the result of eggs spawned in 1993 and/or 1994.The 1993 run was very small and the 1997 returns may reflect the low number of spawners in 1993.Coho salmon returns to south-central Alaska streams were generally poor in 1997 (L.Hammarstrom,ADF&G,personal communication),consequently the below average return to the Bradley River is consistent with area trends. Sockeye Salmon The number of sockeyes caught in 1997 was one of the highest since the Bradley River salmon escapement study program began in 1986 (Figure 14).Sockeye salmon were observed spawning in the same areas and at the same time as the pink salmon.Evidence continues to mount that the river supports a small run of sockeyes that has become established in the last ten years.Survival appears favorable under the regulated flow regime. Chinook Salmon The catch-per-hour for chinook salmon in 1997 was,by far,the highest since the beginning of the study (Figure 15).Since the study period begins during the latter part of the chinook spawning period,it is likely that the overall catch rate underestimates the relative abundance of chinooks.Success of chinook salmon under the regulated flow regime appears to be very good based on the 1995 through 1997 returns.All spawners returning to the Bradley River in 1997 were likely spawned and reared under regulated flows. 20 ACKNOWLEDGEMENTS We would like to thank the Homer Electric Association Bradley Lake Hydroelectric Project field staff for their cooperation and logistical support of the field crew during the course of the field study.Special thanks go to field technician Laurie Daniel.Ms. Daniel is to be congratulated for conducting the field work in a safe,efficient,and professional manner under conditions that were not always favorable. REFERENCES Alaska Power Authority,1986a.Salmon monitoring plan for Federal Energy Regulatory Commission Project No.P-8221-000.Prepared by Stone and Webster Engineering Corp.,Anchorage,Ak. ,1986b.Bradley River salmon escapement monitoring report for 1986.Prepared by Dames &Moore under contract to Bechtel Civil &Minerals,Inc.for the Alaska Power Authority,Bradley Lake Hydroelectric Project.Anchorage,Ak. ,1987.Bradley River salmon escapement monitoring report for 1987.Prepared by Dames &Moore under contract to Bechtel Civil &Minerals,Inc.for the Alaska Power Authority,Bradley Lake Hydroelectric Project.Anchorage,Ak. ,1988.Bradley River salmon escapement monitoring report for 1988.Prepared by Dames &Moore under contract to Bechtel Civil &Minerals,Inc.for the Alaska Power Authority,Bradley Lake Hydroelectric Project.Anchorage,Ak. Alaska Energy Authority,1989.Bradley River salmon escapement monitoring study-1989.Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage, Alaska 21 ,1990.Bradley River salmon escapement monitoring study- 1990.Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage,Alaska ,1991.Bradley River salmon escapement monitoring study- 1991.Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage,Alaska ,1992.Bradley River salmon escapement monitoring and tailrace attraction studies-1992.Prepared by Northern Ecological Services for the Alaska Energy Authority, Anchorage,Alaska ,1993.Bradley River salmon escapement monitoring and tailrace attraction studies-1993.Prepared by Northern Ecological Services for the Alaska Energy Authority, Anchorage,Alaska ,1994.Bradley River salmon escapement monitoring and salmon rearing studies-1994.Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage,Alaska ,1995.Final Report -Bradley River salmon study program. Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage,Alaska ,1996.Annual Report -Bradley River salmon study program. Prepared by Northern Ecological Services for the Alaska Energy Authority,Anchorage,Alaska Hammarstrom,Lee (Alaska Dept.of Fish &Game),1997.Personal communication with John Morsell,Northern Ecological Services. Northern Technical Services,Inc.,1985.1985 salmon escapement survey report.Prepared for the Alaska Power Authority, Anchorage,Ak. 22 Pirtle,R.B.and M.L.McCurdy,1980.Prince William Sound general districts 1976 pink and chum salmon aerial and ground escapement surveys and consequent brood year egg deposition and pre-emergent fry index programs.Alaska Dept.of Fish & Game Technical Data Report No.51. Ricker,W.E.,1975.Computation and interpretation of biological statistics of fish populations.Bull.Fish.Res.Board Can. 191.383 pp. Fish and Wildlife Service,1982.Appendix B:Bradley Lake Hydroelectric Project,Homer,Alaska.Final coordination report.USFWS Western Alaska Ecological Services,Anchorage, Alaska.131 pp.In:U.S.Army Corps of Engineers,1982. Bradley lake Hydroelectric Project,Alaska.Final Environmental Impact Statement.Alaska District,U.S.Army Corps of Engineers. Woodward Clyde Consultants,1983.Bradley River instream flow studies.Prepared for the Alaska Power Authority,Anchorage, Ak.77 pp. Woodward Clyde Consultants,1984.Report on salmon fry sampling in the Bradley River.Prepared for the Alaska Power Authority,Anchorage,Ak.6 pp. 23 TABLE 1.TOTAL CATCH FOR ALL SAMPLE METHODS COMBINED -1997 WEEK DATES PINK CHUM COHO SOCKEYE CHINOOK DOLLY NO.SALMON SALMON SALMON SALMON SALMON VARDEN 1 JUL 22-24 141 40 0 1 135 33 2 JUL 29-31 252 49 ce)e)45 15 3 AUG 5-7 673 49 1 14 8 39 4 AUG 12-14 953 19 1 21 0 30 5 AUG 19-21 2113 4 6 31 fe)46 6 AUG 26-28 685 2 14 60 2 34 7 SEP 2-4 902 1 28 37 fe)56 8 SEP 9-11 25 2 16 16 0 72 TOTAL 5744 166 66 180 190 325 24 SZTABLE 2.TRAP NET CATCH STATISTICS FOR SALMON IN THE BRADLEY RIVER-1997. SAMPLING WEEK 1 2 3 4 5 6 7 8 TOTAL SPECIES CATCH CPH CATCH CPH CATCH CPH CATCH CPH CATCH CPH CATCH CPH CATCH CPH CATCH CPH CATCH CPH PINK 129 0.45 212 0.72 588 2.00 TB 2.69 1811 5.90 685 2.35 704 2.43 23 0.09 4932 2118 CHUM 40 0.14 47 0.16 44 0.15 13 0.04 4 0.01 2 0.01 1 0.00 2 0.01 153 0.066 COHO 0 0.00 0 0.00 1 0.00 1 0.00 6 0.02 14 0.05 22 0.08 16 0.06 60 0.026 SOCKEYE 1 0.00 0 0.00 14 0.05 21 0.07 31 0.10 60 0.21 36 0.12 16 0.06 179 0.077 CHINOOK 130 0.46 43 0.15 7 0.02 0 0.00 0 0.00 2 0,01 0 0.00 0 0.00 182 0.078 TABLE 3.SEINE CATCH SUMMARY FOR PINK SALMON -1997 DATE UNTAGGED TAGGED TOTAL 07/24 8 4 12 07/29 37 3 40 08/05 83 2 85 08/12 161 14 175 08/19 276 26 302 09/02 187 11 198 TOTALS 752 60 812 26 TABLE 4.CARCASS COUNT SUMMARY 1997 SPECIES DATE UNTAGGED TAGGED TOTAL PINK SALMON 08/05 3 0 3 08/06 1 2 3 08/07 2 0 2 08/11 2 1 3 08/13 11 8 19 08/14 13 8 21 08/18 5 1 6 08/19 52 1 53 08/20 35 7 42 08/21 25 10 35 08/26 221 22 243 08/27 48 6 54 08/28 40 3 43 09/02 150 3 153 09/03 39 4 43 09/04 50 6 56 09/08 0 1 1 09/09 15 2 i7 09/10 8 1 9 720 _86 806 CHUM SALMON 07/30 1 0 1 08/05 1 1 2 08/06 1 1 2 08/07 4 0 4 08/13 2 2 4 08/14 3 ]3 08/20 1 0 1 13 4 17 CHINOOK SALMON 07/22 1 t')1 07/23 0 1 1 07/24 2 1 3 07/29 4 2 6 07/30 6 2 8 07/31 6 2 8 08/05 4 [')4 08/06 5 1 6 08/07 1 1 2 08/11 1 1 2 08/12 1 0 1 08/13 1 1 2 08/14 1 0 1 08/18 0 1 1 09/10 1 i]1 34 13 a7 SOCKEYE SALMON 08/18 1 0 i 08/27 0 1 1 09/02 0 1 1 09/03 0 2 2 09/04 2 0 2 09/09 0 1 1 09/10 0 1 1 3 6 9 COHO SALMON 08/26 1 0 1 09/02 1 0 1 2 0 2 27, TABLE 5.COMPARISON OF THE WEEK OF MARKING WITH THE WEEK OF RECAPTURE FOR ALL PINK SALMON TRAP NET RECAPTURES- 1997 RECAPTURE MARKING WEEK WEEK 1 2 3 4 5 6 7 8 TOTAL 1 8 8 2 1 14 15 3 6 18 36 60 4 0 6 57 34 97 3 3 11 15 103 71 203 6 1 1 O 11 64 21 98 7 0 QO 0 0 0 34 30 64 8 0 0 0 0 0 0 2 0 2 TOTAL RECAPS.19 50 108 148 135 55 32 0 547 TOTAL TAGS OUT 120 216 572 680 856 318 216 6 2984 YoRECAPTURED -16%23%19%22%16%17%15%0% 28 TABLE 6:FOX FARM CREEK VISUAL SURVEYS-1997 DATE SPECIES TOTALLIVE LIVEW/TAGS TOTALDEAD DEAD W/TAGS JUL 24 NO FISH 0 JUL30 CHUM 4 0 0 0 AUG07 CHUM 3 1 0 0 AUG 13.CHUM 2 0 0 0 PINK 28 3 1 0 AUG 27 PINK 8 0 2 0 SEP 04 PINK 1 0 0 0 SEP 09 PINK 11 1 0 0 29 O€TABLE 7.MARK-RECAPTURE POPULATION ESTIMATES FOR PINK SALMON-1997 WEEK TOTALCATCH TAGSOUT RECAPS -95%R +95%R POP.EST.-95%N +95%N (Past 2-wks)_(R)(N)RECAPTUREVIA TRAP NET 1 129 0 0 ----- 2 212 120 1 -.--- 3 588 336 24 15.4 35.6 7940 12103 5423 4 778 788 63 49.2 80.6 9604 12234-7532 5 1811 1252 118 98.5 141.3 19079 22809»«15955 6 685 1536 75 59.8 94.0 13873 17342 --:11099 7 704 1174 34 23.5 47.5 23668 33811. =S «17080 8 25 534 2 0.2 72 4637 11592 1696 RECAPTURE VIA SEINE 2 40 120 3 0.6 8.8 1240 3101 506 3 85 336 2 0.2 7.2 9661 24152 3534 4 175 788 14 17 23.5 9258 15961 5668 5 302 1252 24 15.4 35.6 15186 23150 +=10373 7 198 1174 11 5.4 19.7 19485 36535.«11296 RECAPTURE VIA CARCASS COUNTS 4 (8/11-8/14)43 788 17 9.9 27.2 1929 3185 1231 5 (8/18-8/21)136 1252 19 11.5 29.6 8583 13733 5610 6 (8/26-8/28)340 1536 31 21 44 16379 23824 «=:11647 7 (9/02-9/04)252 1174 13 6.9 22.3 21234 =37630 =S:12759 8 (9/08-9/10)27 534 4 1 10.2 2996 7490 1338 BEAR ISLANO os esSiegBLOUGHTs PEA ETSweeeesove :\TREE BAR HOOLIGAN \ SLOUGH REACH FISH STUDY CAM ae Dt We nnCoeeatita teosePITPsAPEESEREERSPRLE EsPsALTEEISEIERTESEESTEPCRENASoeSEPALSETAeR,aoa eed tan RIFFLE REACH FOX FARM CREEK 2.0 etc.»RIVER MLES ©feet 500 SCALE FIGURE 1 LOWER BRADLEY RIVER WITH | SALMON ESCAPEMENT STUDY AREA 31 ce12” 12" END VIEW Showing offset throat BOTTOM Float Line Open Top 4' SIDE VIEW 4'Figure 2 Bradley River Trap Net Design (As Modified in 1990) o 35, >Vain xr. " 1 Key Rm 50 Trap Nets <7 Seine Sites 3 tttas S5 V2_7h =Figure 3. Scale in Feet Trap Net vocations.andeineSites 33 CATCHPERHOURPINK SALMON -1997 JULY 4H AUGUST SEPT Figure 4. 4.§ STUDY WEEK 1 -T Catch-per-unit-effort for pink salmon by study week. 34 CATCHPERHOURCHUM SALMON -1997 _{JULY |AUGUST 1 SEPT STUDY WEEK Figure 5.Catch-per-unit-effort for chum salmon by study week. 35 CATCHPERHOURCOHO SALMON -1997 JULY AUGUST SEPT Figure 6. STUDY WEEK Catch-per-unit-effort for coho salmon by study week. 36 CATCHPERHOURSOCKEYE SALMON-1997 0.2571 |JULY AUGUST SEPT 0.2- 0.15- 0.15 0.05- Figure 7.Catch-per-unit-effort for sockeye salmon by study week. 4 T 5 J STUDY WEEK 37 CATCHPERHOURCHINOOK SALMON -1997 JULY 4H AUGUST SEPT Figure 8. 1.2 +3 +4 6 STUDY WEEK Catch-per-unit-effort for chinook salmon by study week. 38 CATCHPERHOURDOLLY VARDEN -1997 JULY 4H AUGUST 12)mUvpar0.25- 0.2- 0.15- 0.17 Figure 9. STUDY WEEK Catch-per-unit-effort for Dolly Varden by study week. 39 PERCENTFREQUENCYPINK SALMON RIPE MALES AND FEMALES JULY AUGUST SEPT 100- STUDY WEEK MSN MALES FEMALES Figure 10.Percent frequency of occurrence of ripe pink salmon bystudyweek. 40 EST.ESCAPEMENT &CATCH/HR.-1986-1997 PINK SALMON YNOH Y3d HOLVO rT. Fe) .) DCO 0000000006000 0006000 GOIOOOKI0G0000000000000000000000000 OormnN3 3 As = -_ " a g LU i com : zh @ g Lu A\ em |4;\YUMUDA aT| ] !ji JJ Lf8$$¢88&@&22*® ° (spuesnouL)LNAWAdVOS3 G3LVAILSS 1986 1987 1988 1989 1990 1991 STUDY YEAR ISN CATCH PER HOUR [ES]EST.ESCAPEMENT Estimated escapement and trap net catch-per-hour for pink salmon -1986 through 1997. Figure 11. 41 TRAP NET CATCH/HOUR-1986 THROUGH 1997 CHUM SALMON REGULATED FLOW 7A "pp fffiZLyMG Sf, " VAI A LEK OD YY BR RR RT aR ERR RE RR RRRRRAROS 0.35 0.255 0.25 YNOH 3d HOLYD 0.175 STUDY YEAR Trap net catch-per-hour for chum salmon -1986 through 1997. Figure 12. 42 TRAP NET CATCH/HOUR-1986 THROUGH 1997 COHO SALMON WYByoe aaa YNOH Yad HOLVD STUDY YEAR Figure 13.Trap net catch-per-hour for coho salmon -1986 through 1997. 43 TRAP NET CATCH/HOUR-1986 THROUGH 1997 SOCKEYE SALMON REGULATED FLOW LRa - | HEBER eae CORSEee 0.125 0.08-4 0.04- 0.02 YNOHYadHOLVS STUDY YEAR Trap net catch per-hour for sockeye salmon -1986through1997. Figure 14. 44 CATCHPERHOURTRAP NET CATCH/HOUR-1986 THROUGH 1997 CHINOOK SALMON 0.08 0.077 0.06 REGULATED FLOW 0.05- 0.045 0.03 0.02- 0.015 Figure 15. 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 STUDY YEAR Trap net catch-per-hour for chinook salmon -1986 through 1997. 45 LIST OF APPENDICES Appendix A.Catch records Appendix A-1.Pink salmon catch records. Appendix A-2.Chum salmon catch records. Appendix A-3.Coho salmon catch records. Appendix A-4.Sockeye salmon catch records. Appendix A-5.Chinook salmon catch records. Appendix A-6.Dolly Varden catch records. Appendix B.Fishing effort summary for each net by week during 1997 Bradley River sampling. Appendix C.Physical Data. (PLEASE NOTE:Data appendices are not included with this volume. Appendix materials can be obtained from Northern Ecological Services or Alaska Energy Authority)