s SUMMARY OF AQUATIC STUDIES ON BLUEWATER CREEK, MONTANA (^ Patrick E. Marcuson Fish and Wildlife Biologist i a r"li . I I :: •■: I < Fishery Special Publication Montana Department of Fish and Game Red Lodge , Montana February 1979 Federal Aid to Fish Restoration Project F-20-R Final Report MBit DOCUMENTS COLLECTION sep 1 1 mo MONTANA STATE LIBRARY 930 E Lyndale Ave. Helena, Montana 59801 Montana State Library 3 0864 1006 4079 9 ^ TABLE OF CONTENTS 4, Page ABSTRACT ' \ INTRODUCTION . ] * ] 1 BACKGROUND ...... 1 STUDY AREA . . . . . 2 METHODS 2 FINDINGS ......... 2 Chemical 2 Thermal 5 Fish composition 5 Aquatic plants 5 Aquatic fauna „ 5 Brown trout diets 9 Fecundity and spawning of brown trout 9 Emergence and survival 12 Population abundance of brown trout 12 Sex ratio 15 Fish harvest 15 Age and growth 16 Sediment study summary ... 16 Instream flow recommendations 19 DISCUSSION . . 20 APPENDIX ......... 24 List of Recognizable Insects Collected from Benthic and Drift Samples Collected in Bluewater Creek 25 LITERATURE CITED ......... 26 ABSTRACT Aquatic data collected on Bluewater Creek since 1959 was summarized. Bluewater Creek was a chemically fertile spring creek with optimum water temperatures for wild brown trout. Abundant aquatic plants and a diverse benthic fauna maintained stand- ing crops of benthic organisms of 95 to 310 pounds/acre. Drift organisms moved into brown trout feeding sites at a rate of 24 to 41 organisms/minute. Brown trout diets suggest they were opportunists utilizing seasonally available foods. Brown trout spawning season was from mid-October to the end of November. No Age-I females were mature, but 82% of the Age-IT. and 100% Age-Ill females were mature. The average egg complement was 325 eggs/female. Emergences took 60-70 days and February 1 best describes the birthday of brown trout. Egg mortality was low in clean headwaters and progressively increased as sediment concentrations increased. Browns were 0.6 inches at emergence. The average seasonal biomass of brown trout was 261 pounds/acre in the spring and 264 pounds/acre in the fall. Brown trout larger than 6 inches averaged 159 and 187 pounds/acre in spring and fall, respectively. Catchable-sized brown trout number 16,629 and 3,167 pounds in Bluewater Creek. Densities of catchable-sized fish fluc- tuated least in the area where the majority of trout were harvested. Sex ratio of brown trout was 1:1.3 males to females. Males dominated the Age-V+ fish. Total annual harvest of fish 6 inches and larger was 2,500 taken by 500 persons averaging five fish per trip. Of 4,292 known-age brown trout from 3-year classes, it was found that the 1973 year class lived 3 years, the 1972 year class lived 4 years and the 1969 year class lived to their 7th year. Aging by the scale technique was invalid in Bluewater Creek even though scales appeared typical of brown trout. Growth rates were poor. Fish averaged 8.5 inches at 30 months of age, while Age-7 fish were only 2.3 inches longer. Age-0 fish could be separated by length frequencies. Lengths of known-age trout over- lapped as many as five age groups. Nine years of stream sediment studies showed reduced carrying capacities with increased sediment concentrations. Brown trout were most dramatically suppressed at concentrations over 50 ppm and loads over 40 tons/day. Sediment reductions of 10 to 52% resulted, from three stream improvement projects. Instream flow requests of 6,878, 18,823 and 14,479 acre-feet were made for three stream reaches having average annual flow yields of 8,328, 20,502 and 31,974 acre- feet, respectively. INTRODUCTION Bluewater Creek has been a focal point of aquatic study for years because of accessibility, climate, proximity to two colleges and a university, a self-sustaining trout fishery, land ownership and use patterns, a substantial spring source and chemical fertility. Earliest studies centered on the potential of Bluewater Springs as a water supply for the present Bluewater Springs Trout Hatchery. Specific stream studies began in 1959. This report summarizes aquatic studies of unpublished data and portions of research found in job progress reports, theses and publications. BACKGROUND An investigation of Bluewater Creek was initiated in 1959 to measure effects of sediment, discharge and water temperatures on trout populations, bottom fauna and trout egg incubation. Data from the stream sediment investigation was found in six federal aid documents, D-J Job Progress Reports F-20-R-5 through F-20-R-15, Job Ill-a, Marcuson (1966-197^. Bianchi (1963) reported the effects of sedimentation on egg survival of rainbow and cutthroat trout. Peters (1967) described the influences of sediment on a trout stream from agricultural practices and later (1971) on the effects of sediment control on fish populations. In 1969 Graham and Marcuson started, a study of production of brown trout in Blue- water Creek. This study failed, statistically, but contributed considerable unpub- lished detail regarding composition of brown trout. Two additional studies, a quanti- tative examination of aquatic insects (Zillges, 1971) and a fecundity study (Lockard, 1974) were conducted as supplements to the production study. Recent investigations include data collected to assist in the selection of ade- quate instream discharges necessary for the maintenance of the fishery (Montana Fish and Game Commission, 1976). STUDY AREA Bluewater Creek is an 18-mile spring creek meandering through semi-rough prairie country in south central Montana. It is a tributary to the Clarks Fork of the Yellow- stone River. Figure 1 shows the location of most of the intensive study sites. Physical descriptors are presented in Table 1. Bluewater Creek valley has a semi-arid climate with an annual average precipita- tion of 10 inches. The average frost-free season is from May 19 to September 17. Air temperature extremes are common. Temperatures as high as 108° F and as low as -35° F were recorded,. Salix and Betula occidentalis were abundant woody vegetation types along stream banks in the upper half of the stream. Downstream, considerable woody vegetation had been removed for intensive agricultural operations. METHODS This paper incorporates data collected, as part of several specific studies on Bluewater Creek. Particular methodologies can be obtained, by examining documents listed, in the Literature Cited section. Major emphasis involved seasonal collections of brown trout with a 230-volt d-c powered electrofishing unit. Fish were measured for total lengths, weighed, marked by various combinations of fin clips and returned for subsequent recaptures. Permanent marks were applied, to all young-of-the-year brown trout captured, in the 1969, 1972 and 1973 year classes and for a portion of the 1974 year class. Egg densities, scales and otoliths were collected from sacrificed brown trout of known age. Scales were collected in the usual manner and their plastic impressions were magnified, with a Baush and Lomb projector for interpretation. Otolith interpretation was attempted, by examination of fresh specimens and by cross sectioning, polishing and staining preserved otoliths. FINDINGS Chemical Analysis of chemical constituents was performed by technicians at the water quality laboratory at Montana State University and by field, techniques used in the - 2 - i 1 I Town of Fromberg t- Clarks Fork River Station 5 Legend County roads Bluewater Creek BLUEWATER CREEK Carbon County Station 4 -^-Yellowstone River \clarks Fork River Figure 1. Map of Bluewater Creek showing locations of sampling stations. - 3 - Table 1. Descriptive parameters for five stations on Bluewater Creek Stations '^^0 1 2 3 4 5 11 12 13 14 15 11 11 30 26 10 10.5 27.8 23.7 21.4 41.6 25 71 201 263 437 0.8 5.1 18.0 21.1 61.1 8.1 28.1 43.9 46.6 53.2 Mean width (ft.) Gradient (ft. /mile) Discharge (cfs)— M Sediment discharge (ppm)^ 71 201 263 437 1/ Sediment discharge (tons/day)— 2 Drainage area (miles ) 1/ — Average of 8 years of record. 4 - ir various studies. Table 2 lists chemical parameters. As far as is known, Bluewater Creek is more chemically fertile than any other stream in Montana. Thermal Water temperatures for three stations are summarized for 12 years of continuous records in Table 3. With the exception of small amounts of surface runoff, Bluewater Creek derives its water from spring flows which hold a constant temperature of 56° F. Water temperatures change upward or downward depending upon atmospheric conditions and become more variable as the distance from the spring source increases. Ice formation does not occur, regardless of the severity and duration of freezing atmos- pheric conditions, until the water flows at least 10 miles from its spring source. Water near the mouth undergoes the greatest annual temperature fluctuation. Fish Composition Brown trout (Salmo trutta) dominated the fish occupying the upper half of the creek. Browns have been sampled in low numbers in lower stream reaches; however, their distribution was such that they are significant in the stream from headwaters to one-half mile below Station 4. An occasional rainbow trout (Salmo gairdneri) and on one sampling occasion a few kokanee (Oncorhynchus nerka) were sampled near Bluewater Springs Trout Hatchery. These fish were escapees from this rearing station and no natural reproduction was evident. People who have lived along the stream 50 or more years remember when cutthroat trout (Salmo clarki) was the only trout species in Bluewater Creek. Hatchery person- nel recall catching an occasional cutthroat during the 1930' s. The majority of their catch was an equal number of brook trout (Salvelinus fontinalis) and brown trout. No brook trout have been observed since initiation of aquatic research on the creek. The lower half of the stream contained large numbers of suckers and minnows. The following include an approximate ranking of abundance of fish other than trout in Bluewater Creek: longnose dace (Rhinichthys cataractae) , flathead chub (Hybopsis gracilis) , mountain sucker (Catostomus platyrhynchus) , white sucker (Catostomus catostomus) , carp (Cyprinus carpio) , mountain whitef ish (Prospium williamsoni) and shorthead redhorse (Moxo stoma macro lepido turn) . Aquatic Plants The upper half of Bluewater Creek had abundant growths of water cress (Rorippa nasturtium-aquaticum) , Berula erecta and horned pondweed. (Zannichellia) . Nearly all the undisturbed stream banks had some degree of rooted aquatics. Duckweed. (Spirodela and Limna) , Chara, Vaucheria, and unidentified moss and. a leafty liverwort were common. Vegetation existed year-round in the headwaters reaching maximum densities in early summer. Stream velocities, depths and excellent cover for small trout are provided by areas of this vegetation. Cladophora was the only common aquatic plant in the lower portion of stream. Aquatic Fauna Seventy-four benthic samples were collected with a Surber sampler along Blue- water Creek. The average number of organisms per square foot are presented in Table 4. Those forms typical of unpolluted waters were found in the upper stream reaches. As the collections proceeded downstream, the fauna became less diversified and was dominated by diptera and aquatic worms. A list of recognizable species is in the appendix. Based on total wet weights of 19 of the 74 benthic samples, it was estimated that the standing crop of bottom fauna ranged from 95 to 310 pounds per acre. Benthic - 5 - Table 2. Range and mean chemical values at two stations on Bluewater Creek Alkalinity (ppm CaC03) range mean Dissolved oxygen (ppm) range mean 94. - 220 210 7,8 - 10.8 8.7 101 - 252 212. 8.0 - 10.4 PH range Total hardness (ppm CaCOo) range mean Conductivity (Umhos) range mean Silica (ppm) range mean Phosphate (P) Sodium (Na+) Potassium (K ) Sulfate (S04=) Nitrogen (N03_N) Chloride (ppm) Fluoride (ppm) 7.6 - 8, 280 - 750 451 721 - 938 825 8 ,2 - 12.4 11.2 .01 5.52 1.96 25.8 .312 2.20 1.12 6.6 480 - 1,050 850 812 1 122 2,650 8 0 - 12 12. ,4 .02 8 12 ,87 2 .42 70 .8 .409 2 .45 1 .19 ^ Table 3. Monthly mean maximum, minimum and mean temperature (F. ) in Bluewater Creek for 12 years of record at 3 stations Stations 1 2 4 min. mean max. min. mean max. min. mean max. January 49 51 52 46 48 50 36 38 40 February 50 51 53 46 49 51 40 42 45 March 51 52 54 46 50 54 42 44 47 April 51 54 56 49 53 57 46 50 53 May 53 55 58 51 56 60 52 61 69 June 53 56 59 54 58 62 53 59 65 July 54 57 59 53 58 63 59 64 68 August 55 57 59 52 57 63 59 62 65 September 53 55 57 50 54 59 54 56 58 October 52 53 55 49 52 55 45 50 53 November 51 52 53 48 50 52 41 43 44 December 49 50 52 46 i 48 50 38 40 41 Table 4. Number of benthic invertebrates per square foot collected at five stations on Bluewater Creek Numb ar Per Square Foot Classification Stations 1 2 3 4 5 Amphipoda 1 1 0 0 0 Oligochaeta 1 1 29 170 29 Ephemeroptera 54 52 116 41 17 Plecoptera 28 29 38 3 1 Coleoptera 28 21 1 1 1 Tricoptera 175 122 27 14 6 Diptera 44 18 12 12 136 Mollusca 6 44 2 2 0 Others 2 3 0 4 3 Totals 339 291 225 247 193 ! W> fauna was the lowest during late October and November and highest during March and April. Zillges (1971) collected 15 day and 15 night drift samples at Stations 2 and 5. Over four times more drift occurred at night. May flies, primarily Baetis parvus, were the major drifting form at Station 5. Station 2 also had large numbers of drifting May flies (Ephemerella inermis and Baecis) . Stone flies (Isoperla spp.), Chironomids and Simulium also consistuted major drifting forms in Bluewater Creek; however, stone flies were a minor item at Station 5. Table 5 is an abbreviated presentation of Zillges findings on drift forms. My calculations of Zillges data revealed that the average number of aquatic insects drifting by Station 2 was 41 per minute compared to 24 per minute at Station 5. The orders in Table 5 are listed by magnitude for both stations combined; however, variability between sites was common. The only organism collected in larger numbers downstream was the caddis fly (Hydropsyche sp.). Certain aquatic organisms like dragonflies and scuds were readily observed in upper Bluewater Creek, but rarely captured and quantified. These forms are typical of aquatic plant communities, undercut banks and debris habitats. In a similar stream in Minnesota, Waters (1965) found that the scud (Gamma rus limnaeus) was a primary drift species. Gammarus was commonly observed in Bluewater and in brown trout stomachs, but was never captured in 30 drift samples and only rarely captured in benthic collections. Brown Trout Diets Stomach contents were examined for numerous brown trout taken during different seasons. It appears that these fish were opportunists, taking a variety of food organisms. Their intake paralleled seasonal sources. Trout eggs were common food for brown trout during spawning season, juvenile trout were consumed during the emergence period, terrestrial insects dominated during summer and early fall and aquatic forms were consumed on a regular basis . Food does not appear to be limiting to fish in Bluewater except possibly for the months of October and November. These months revealed the lowest numbers of available aquatic forms, terrestrial items were rare and sexual aggressiveness of brown trout precluded eating or searching out food. During the spawning season, stomachs often contain burrowing benthic organisms and trout eggs not commonly observed during other seasons. Those forms dislodged from the substrate during redd construction were typically small organisms of insignifi- cant weight. Shrimp (Gammarus) were found in stomach contents, but to a lesser degree than the more available May flies, stone flies and caddis flies. Fecundity and Spawning of Brown Trout Spawning activity became evident by mid-October and most brown trout discharged sexual products by the end of November. The peak spawning activity occurred the second week of November. Samples of fish from December through January revealed an occasional yearling as small as 3.5 inches. This causes speculation that some spawn- ing occurred later than the end of November. With mean water temperatures of 53 F in October, 52° F in November, 50° F in December and 51° F in January at Station 1, it seemed reasonable that the spawning period could be very lengthy. However, no normal adult females were found with sexual products during December through February collections. Temperature patterns of the upper two stations during the spawning season are presented in Figure 2. In 1974 Lockard compared fecundity of female brown trout with stream fertility in 17 Montana streams. Fish from Bluewater Creek, the most chemically fertile of the waters studied, were least fecund. Lockard resolved that chemical fertility of streams is generally related to age at sexual maturity and fecundity of brown trout except in fish from Bluewater Creek. His findings were similar to McFadden, Cooper - 9 - I I-1 o o M +J u a> i a) CD M 4-1 W Figure 2, 56 T 55 -■ 54 53 ■- 52 ■■ 51 ■■ 50 49 48 47 Spawning Peak of Spawning Activity Spawning Ends Station 1 10 15 20 October 25 30 1 10 15 20 November 25 30 Mean daily temperatures averaged over 5 years of record for the months of October and November at 2 stations on Bluewater Creek. t ( c Table 5. Numbers and volumes (cc) of insects from drift samples on Bluewater Creek Classification Day Drift 2 5 ^tat ions Night Drift 2 5 Vt Dominate Species Ephemeroptera Unid. pupae Diptera Plecoptera Trichoptera Coleoptera Odonata 45.1 (t) 51.5 (t) 121.8 40.3 595.9 (2.7) 384.8 (0.6) 117.9 44.0 34.8 56.6 47.9 63.4 (t) (t) (t) (t) 11.0 1.0 156.6 4.5 (t) (t) (1.0) (t) 12.2 9.8 34.9 54.1 (t) (t) (0.2, (0.3) 16.7 1.9 44.3 5.1 (t) (t) (t) (t) .. m - 1.5 " ■ " (0.2) 241.6 161.1 997.5 555.4 (t) (t) (3.9) (1.2) Baetis parvus Ephemerella inermis Chironomidae Simulium arcticum Isoperla spp. Hydropsyche sp, Optioservus ovalis Helichus striatus Ophiogomphus Totals - Volumes in parenthesis - t = trace. 11 - and Anderson (1965) where in Pennsylvania brown trout from infertile waters had a smaller proportion of mature fish per age class and a smaller weight of eggs than comparable fish fr^.a fertile waters. Lockard concluded that "Bluewater Creek fish attained sexual maturity much earlier than fish from less fertile streams; however, these fish from the chemically most fertile stream had the poorest growth rates of all the fish studied." Since aging fish in Bluewater Creek by the scale technique was not reliable, I felt that Lockard may have underestimated the age of some of the small females in the creek. To test Lockard ' s findings I sacrificed 200 known-age females of the 1974 year class as I's in 1975, II ' s in 1976 and Ill's in 1977. I found no Age-I females mature, but did note a small number of mature males. Females of Age-II were 82% mature and all Age III females were found to be mature. Table 6 presents egg complements of Age-II and III females from known-age brown trout at two stations. The 187. immature Age-II females were typically smaller fish. Emergence and Survival February 1 was considered the birthdate for brown trout in Bluewater Creek. Based on electrofishing, redd excavation and egg development in plastic vials, it was found that the earliest emergers escaped the gravels in early January and most were out by early February at Station 1 r,nd by mid-February at Station 2. The average water temperature at Station 1 was 52° F during incubation period; however, water temperatures were 5° F cooler 6 inches within the substrate. It took an average of 60 days to emergence. At Station 2, the average water temperature during incubation was 48 F and 43° F around the eggs. Average time to emergence was 72 days. Bianchi (1963) experimented with survival of eggs of rainbow and cutthroat trout placed in artificial redds at five stations along Bluewater Creek. Egg mortalities for rainbow trout were 67, 92, 97 , 99 and 997» for Stations 1-5, respectively, and 43, 94, 98, 100 and 877= for cutthroat trout eggs from Stations 1-5. In 1969 sediment control measures had reduced sediment loads by 32% at Station 2 and 52% at Station 3. Juvenile brown trout were noted farther downstream than previously observed; however, egg survival experiments were not repeated. It was assumed that egg survival was considerably improved at Stations 2 and 3. Juvenile browns averaged .6 inches at emergence. By mid -March the average length of both early and late emergers was 2.1 inches. Population Abundance of Brown Trout To best describe the population of brown trout in Bluewater Creek, I averaged 28 population estimates collected at three stations over all seasons for 6 years - 1969 to 1975. These average standing crops were further grouped to include fish above and below 6 inches (Table 7). Figures for fish less than 6 inches do not include the most prolific size group of newly emerged juveniles during spring sampling periods. These juveniles are represented 7 months later in fall samples (Table 7). An accumulation of 2,000 juvenile brown trout are required to increase the biomass by 1 pound. An average acre of brown trout water in Bluewater Creek contains 76,781 juveniles or 38 pounds. The above estimate was based on 929 reproducing size fish per acre, 1.3:1 ratio of females to males, an average egg complement of 325 eggs per female and an egg to emergence survival rate of 45%. Not counting the juvenile population each spring, the average spring standing crop of all brown trout was 223 pounds/acre compared to 264 pounds/acre average for fall. If 38 pounds/acre was a realistic estimate of juveniles, then the spring and - 12 - w c Table 6. Egg complement of Age II and III females from 119 known-age brown trout at Station 1 and 2, Bluewater Creek STATION 1 Age Group STATION 2 Age Group II III II III Mean egg count Range of eggs counted Number of females Mean length of females Length range of females Mean weight of females Weight range of females 218 319 329 436 52-412 72-713 162-534 82-839 38 44 17 20 7.9 8.2 9.3 9.3 6.3-9 3 5.8-10 .5 7.8-11 .4 6.6-12.2 .17 .22 .31 .32 .09- 30 .06-. 54 .16-. 52 .10-. 68 13 - Table 7. Brown trout abundance of Bluewater Creek averaged over 6 years, 1969- 1975 ^ Less Than 6 Inches— 1/ 6 Inches and Larger Number/acre (spring).?/ Number/acre (fall) Pounds/acre (spring).?/ Pounds/acre (fall) Number/1,000 feet Pounds/1,000 feet Yearly number/acre Yearly pounds/acre Number/mile Pounds /mile 3/ Number/ stream- Pounds /stream 2,298 2,398 64 77 603 19 2,319 69 3,184 100 39,791 1,254 917 937 159 187 253 48 929 175 1,336 253 16,629 3,167 1/ fish. Standard deviations were considerably higher than for 6 inch and larger 2/ - Spring numbers do not include juveniles - only yearling and older fish under 6 inches. ^ 3/ Based on 65,988 feet of brown trout waters, - 14 - fall biomasses were about equal. The catchable-sized fish over 6 inches contributed 159 pounds/acre in the spring and 187 pounds/acre average in the fall. The condition factor (CF = W/LJ x 10 ) of yearling and older brown trout progres- sively increased downstream from 34.6 to 37.1. The condition of these fish was slightly higher in the fall (35.7) than in the spring (35.4). Vincent (1977) reported condition factors in the mid-40 ' s for brown trout in the Madison River. The number and weight of catchable 6-inch and larger brown trout in Bluewater Creek was calculated at 16,629 fish and 3,167 pounds (Table 7). Examination of numbers of 6-inch and larger fish occurring each season at each station divulged a range of 548 to 1,521 fish per acre. A comparison of catchable-sized fish/acre at Station 1 disclosed a low population density of 373 in the spring and 549 in the fall of 1973. Other than this density change of 176 fish/acre, the population of 6-inch and larger fish remained close to 480 fish/acre. An electrofishing section between Stations 1 and 2 had a low of 1,020 catchable fish/acre to a high of 1,521 fish/acre. This 501 density fluctuation was separated by 4 years and reflected a low spring density and a high fall density. The mean density of catchable-sized brown trout in this area was 1,176 fish/acre. This sam- pling area was on private land where no fishing was allowed. The 6-year mean number of 6-inch aud larger fish at Station 2 was 1,129 fish/ acre. The density of these fish ranged from 584 to 1,285 fish. The low 584 fish/ acre occurred in the fall of 1970. The next lowest population estimate of 6-inch plus fish per acre was 788 in the spring of 1975. The typical fluctuation of catchable- sized fish, disregarding the two extremes above, was within 150 fish of the 1,129 fish/ acre mean. This portion of the brown trout fishery received the majority of the angling pressure on Bluewater Creek. Sex Ratio Yearling and older brown trout are easily sexed by the curvature of the anal fin method described by Gruchy and Vladykov (1968). The method was found valid in Blue- water Creek. Sexes of 8,600 fish collected at Stations 1 and 2 kindled a ratio of 1.3 females per male. Sex ratio of 819 known-age brown trout was dominated, by females through Age Group IV. Among fish V and older, males surpassed females 3 to 1. Fish Harvest Creel census designed to produce total harvest estimates was never conducted on Bluewater Creek. Total harvest of fish was estimated by combining results of random creel checks, observations of fishermen by hatchery and management personnel and discussions with landowners. The vast majority of the fishing pressure occurred on state owned land near the hatchery. No fishermen were ever observed or reported by landowners along lower reaches of Bluewater. Several areas under private ownership were essentially closed, to fishing. Bluewater Creek was open year-long and received fishermen mostly from the Bridger- Fromberg area. Most fishing occurred during the spring and fall. The area had a reputation for abundant rattlesnakes which discouraged fishing during the hottest season. The majority of the fishermen were retired persons. The Bluewater area averaged one car per day with a 1.5 fisherman per car average. They caught an average of five fish per trip over 6 inches in length. Considerably more fish less than 6 inches were captured, but were returned voluntarily for larger fish. Total annual harvest was estimated at 2,500 fish over 6 inches in length. - 15 - With the exception of a few hatchery reared rainbow trout, the anglers harvested wild brown trout. Age and Growth Aging brown trout by the scale method was performed by Peters (1971) for Blue- water fish. He found, no significant differences of growth rates between stations which were subjected to increased degrees of sediment loads. Peters assigned overall lengths to the last annulus as follows: Age I - 3.9 inches, II - 6.6, III - 9.7; older fish scales were not readable. Graham and I also reviewed scales from brown trout in Bluewater Creek and arrived at growth interpretations (unpublished), but both of us agreed, that we were influenced by length frequency and that scale interpretation was not self-evident. As a part of an attempted production study, we permanently marked juveniles of the 1969, 1972 and. 1973 year classes and recorded progress of these fish at each recap- ture until none remained in the population. Data collected from three mark and. recapture sections has been combined with three year classes (Figures 3 and 4). A total of 4,292 juveniles of the 1969, 1972 and 1973 year classes were marked in early September. Emerging fish were not marked until 7 months of age to lessen chances of mortality and for ease of handling and better recruitment to electrofish- ing gear for population estimates. An unexplained decline in both length and weight occurred between Age II fish captured in the fall and Age III fish captured the following spring. A similar decline occurred between Age IV and Age V fish. It was obvious that such declines were impossible for specific individuals, but the possi- bility of sampling smaller individuals within a population could be real. This exemplified the disadvantage of using marks other than those identifying individuals. The last individuals of the 1969 year class were captured in mid-September 1975 as VI' s. Only three marked fish of the 197 2 year class were captured in October of 1976 as Age Group IV and of 1,294 juveniles ol the 1973 year class only 22 were recap- tured beyond Age II; the last three were captured, at 44 months of age. No explain- able reasons were evident to account for the loss of the 1972 and 1973 year classes. Examination of Figures 3 and 4 show not only poor growth of fish, but a large degree of overlap of sizes among age groups. For example, the smallest Age IV fish falls within the size ranges of every age group to Age I. Only Age 0 fish separated, from the others in a length-frequency distribution. Growth of known-age fish in the fall was Age 0-3.6 inches, I - 7.0, II - 8.5, III - 8.5, IV - 9.3, V - no fall fish and IV - 10.8 inches and Age 0 - .03 pounds, I - .14, II - .22, III - .24, IV - .32, V - no fall fish and VI - .52 pounds. Except for the first 30 months of age, the brown trout living 6 years only grew 2.3 inches and .30 pounds. Fall to spring sampling revealed little overwinter growth despite water temperatures in the low 50 's for most of the trout producing water. Following spawning season, fish in Bluewater Creek tend to become snakey in appearance and remain so until early spring. I'm sure a production study would reveal negative values during a portion of this period. When scales were examined from fish of known-age, I was able to achieve the following interpretation of readable scales: 100% - Age 0, 63% - I, 59% - II, 36% - III, 10% - IV and 0% on all older fish. Otoliths from numerous known-age fish were examined as fresh, stained, cut and polished specimens without meaningful results. The only reliable aging technique for brown trout in Bluewater Creek appears to be known-age measurements of individually identifiable fish. Sediment Study Summary The first 6 /~=»rs (1961-1966) of the stream sediment investigation involved - 16 - \ ^1 I 10 o a a 00 C Age III Age IV {— — l 24 30 36 42 48 54 60 Age in Months and Age Group Age V Age VI 66 72 78 84 Figure 3. Age and growth in length of known-age brown trout of three year classes averaged for three sections, Bluewater Creek, CO' I 1.10 T 1.00 ■■ Age III Age IV „{ — .—~_^— ^_ ■!_.. -}_ _ ^_ 36 42 48 54 60 Age V Age In Months and Age Group Figure 4. Age and growth in weight of known-age brown trout of three year classes for three sections, Bluewater Creek. ( ( comparisons of fish species abundance and distribution with suspended sediment con- centrations, discharge and water temperature. Sediment loads which are a measure of sediment concentrations and discharge averaged 0.7 tons per day in the headwaters and progressively increased to a mean of 75.8 tons per day near the mouth. As a result of irrigation withdrawals and warmed return flows, lower reaches of Bluewater Creek underwent wide ranges of temperature fluctuations. Brown trout numbers decreased progressively downstream as the aquatic environment deteriorated. The first 6 years of study documented the detrimental effects of sediment on trout. The nature of the study was then altered to evaluate major factors causing sedi- mentation in Bluewater Creek and take corrective steps to reduce this silt load. Three improvement projects were undertaken in the spring of 1966. A pipeline was installed to control erosion from a waste water ditch. Several hundred feet of eroded stream bank were lined with rock and as a part of the fishing access program, approximately 100 acres involving % mile of stream were fenced to restrict access by cattle. Continued evaluation of the silt content in Bluewater Creek suggested that the improvements were effective in reducing silt loads. The average sediment load figured on 48 months of data collected prior to improvements was 6 tons per day at the sampling station immediately downstream from the improvements (Station 2). The average load at this station was reduced to 4.1 tons per day based on 28 months of record after improvements. This represents a 3270 reduction of sediment load. At Station 3, a 52% reduction occurred and at Station 4, suspended sediments were reduced 44% - calculated, over the 28 months of record. Response of the fishery to the improved water quality was obvious to the inves- tigator, but did, not statistically show a significant response. Lack of statistical response might be explainable when one considers natural fluctuations of various year classes. Apparently many years and many year classes are needed to accurately assess responses of a population to subtle changes in the environment (see discussion, also Hunt, 1966 and Chapman, 1965). This investigator noted that following reduc- tions of sediment loads, there were juvenile brown trout farther downstream than previously observed, and that large brown trout were more abundant at Station 4 than previously noted (Marcuson, 1967). A positive response of brown trout to sediment reductions was with the percent- age ratio of total weight of trout to rough fish of 39:61 before (1963) compared to 78:22 after (1968) stream improvements. Six miles farther downstream (Station 4) the trout: rough fish ratio was 12:88 before compared to 51:49 after improvements. The stream sediment investigation was completed in 1970. Observations and subse- quent measurements indicated additional discharge of approximately 6 cfs after 1970. This additional flow was due to additional flows collected for hatchery operation. Sediment loads responded upward with these flow increases and from intensified agri- cultural operations upstream. Increased loads, however, do not appear to be anywhere near the magnitude common prior to the improvement projects. Stream sediment problems can be effectively reduced; however, land use changes often diminish or negate the results over time. Earlier discussion on sediment find- ings alluded to the precent reduction based on 28 months after stream improvements. Suspended sediment monitoring was discontinued in 1970, 52 months after improvements. By this time, Station 2 had a 20% suspended sediment reduction, Station 3 had a 107» reduction and Station 4 had a 14% reduction compared to reductions of 32, 52 and 44% C after 28 months at Stations 2, 3 and 4, respectively. Instream Flow Recommendations Due to irrigation practices and type of agriculture along Bluewater Creek, three - 19 - reaches were picked to best characterize flow regimes. These three reaches (upper, middle and lower Bluewater) are described in unpublished form (Marcuson, 1976) on file at the State 'c Montana, Department of Fish and Game office in Billings. The 9-year mean monthly discharge was 11 cfs, 28 cfs and 44 cfs for the upper, middle and lower sections, respectively. Discharge at the middle section averaged 34 cfs at the time this report was compiled, due to additional discharge from Blue- water Springs Trout Hatchery. Historic flow measurements were measured, over the 9-year period at the five sediment stations and reflected existing agricultural use. Bluewater Creek has special need for flow maintenance in that it is one of the few rich prairie spring creeks. It is also a focal point of activity for wildlife, livestock, recreation and human occupation in this semiarid area. The recommended flows presented in Table 8 are considered necessary for maintenance of the fishery and allows for additional water for future agricultural expansion. Major consideration was for adequate flows in the upper and middle trout produc- ing sections. The upper section has little opportunities for intensifying agricul- tural operations. The request of 9.5 cfs is 1.5 cfs less than mean flows. The middle section requires 26 cfs to minimize sediment deposition and. is 8 cfs less than the new (since 1970) mean discharge. The mean monthly flow in lower Bluewater for 9 years of record was 44 cfs, thus 24 cfs or 55% of the annual discharge is available for future agricultural expansion in the area where enlarging the agricul- tural base is most feasible. DISCUSSION A good trout fishery is the result of a combination of many ecological features. Adequate water precedes all needs, thus instream flow requests are essential to Blue- ^ water's fishery. Secondly, trout need water of good quality. The chemical fertility of Bluewater Creek was well established; its major deterent to quality water was silt pollution from agricultural practices. The sediment study fortified knowledge of the detrimental effects of sediment to trout and. also established, that suspended sediments could be effectively reduced even in highly erodable country. It was also learned that an improved stream will need continued surveillance to retain a new improved status. With Bluewater Creek, improved water quality opened, the door for new agricultural developments and subsequently new sediment sources. The possibility of new contamination is always a threat and will have to be contended with on a case- by-case basis. Besides treating sources of sediment, I feel the most effective means of maintaining quality water is through good land management techniques, efficient water use and. maintaining good stream bank vegetative cover. Stream bank cover provides an effective sediment filter, trapping rich silts where vegetative matter quickly establishes. Numerous researchers documented, reduced carrying capacity of trout in lotic waters because of high sediment concentrations (Sanders and Smith, 1965; Herbert, et al., 1961; Condone and Kelly, 1961; Doudoroff, 1957; Hynes, 1960 and Wallen, 1957). Unfortunately, the quantity of sediment capable of harming an environment has never been firmly established for various fish species. The contention of this author is that sediment acted as the agent responsible for the demise of cutthroat trout and indirectly for the brook trout in Bluewater Creek. Brown trout in Bluewater Creek were found in far fewer numbers where sediment sustained high concentration levels. Like most fish these brown trout tolerated extremely high sediment discharge for short periods of time without noticeable harm. Populations of brown trout in Bluewater Creek were greatly diminished at concentra- tions over 50 ppm and loads over 40 tons per day. - 20 - ( C1 Table 8. Recommended flows for three sections of Bluewater Creek ___»««___«»___. 2/ Sept. Oct. Nov. Dec, Total- Upper cfs 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 AF 584 528 584 565 584 565 584 584 565 584 565 584 6,878 ( 8,328) Middle-'cfs 26 26 26 26 26 26 26 26 26 26 26 26 AF 1,599 1,444 1,599 1,547 1,599 1,547 1,599 1,599 1,547 1,599 1,547 1,599 18,823 (20,502) i S3 Lower cfs 20 20 20 20 20 20 20 20 20 20 20 20 AF 1,230 1,111 1,230 1,190 1,230 1,190 1,230 1,230 1,190 1,230 1,190 1,230 14,479 (31,974) - Does not include additional 6 cfs since 1970. 2/ - Number in parentheses is the 9-year average annual yield, It was the feeling of researchers on Bluewater Creek that the amount of sediment settling on the streambed. over time was closely related to numbers, age structure, species composition and biomass of fish populations. For sediment standards, it would be beneficial to quantify sediment loads with deposition rates. Meaningful standards would consider silt deposition during incubation periods of trout eggs. Fishermen using Bluewater Creek seem satisfied with fishing. Brown trout have been harvested at a rate of 2,500 fish by 500 anglers since 1970. Most of this harvest was from a stretch of accessible stream less than 1 mile in length (Station 2) out of 12.5 miles of brown trout water. This particular site maintained the highest number of catchable sized fish, the largest mean sized fish and the most stable density of fish 6 inches and longer among the sampling sites. Densities of 6-inch and larger brown trout fluctuated more from the 6-year mean density in areas where little or no angling occurred. Regulations of ten fish daily and a season open 365 days per year were generous and with low fishing pressure appeared to be grossly underutilizing this resource. It is my opinion that a spring stream as rich as Bluewater Creek and with opti- mum water temperatures for trout growth, should yield considerably more large fish. An acre of trout water produced an average 929 fish over 6 inches in length (175 pounds) per acre, but the mean length of brown trout only reached 10.8 inches, .52 pounds as 6-year-old fish, 9.2 inches, .30 pounds as 5-year olds and smaller. The creek produced some large individuals (largest trout was 22.1 inches, 3,75 pounds), but some year classes died before they reached 9 inches and .25 pounds. The loss of 2 year classes^' eliminated 4 and 5-year old brown trout from Bluewater Creek in 1975. This loss occurred in areas of no fishing as well as areas with fishing. I do not know whether losses of year classes are common phenomenons in wild fisheries or an unusual event; however, fluctuations in population density are com- monly reported. McFadden (1961, 1967) and Hunt (1966) reported numerical variations and differing biomass contributions of numerous year classes in the same stream sections. It seems reasonable that these fluctuations in density are expected and that management interpretations based on short-term population changes should be carefully scrutinized. Aquatic organisms in Bluewater Creek were more diversified than that found in brown trout diets. Besides diversity of food organisms, large numbers of aquatic organisms commonly utilized as brown trout food were readily available. Drifting foods also appeared readily available. Waters (1965) noted that quantitative relationships between drift rates and population density on the stream bottom have not been determined. He noted, that drift forms may originate 50-60 meters upstream and. that physical nature of the stream, upstream from the drift site, influenced drift composition and density. In Bluewater Creek the major aquatic foods consumed by brown trout were organ- isms typical of the drift community. For the most productive trout water, there were 40 organisms per minute entering the feeding stations downstream from riffles. It appeared that aquatic food was more than adequate to feed, fish in Bluewater Creek not counting allochthonous foods available from spring to fall. Where water chemistry, temperature, habitat, food, etc. appeared ideal for trout production, the trout population was high, fish harvest was low yet growth was - All permanently marked members of the 1972 and 1973 year classes from three sampling sections were no longer sampled nor were their unmarked cohorts recognized. - 22 - J ^gy poor. It appears that a spatial problem might well exist. Chapman (1962) suggested that spatial limitations act as density regulators in coho, forcing less aggressive fish to emigrate. He also found that feeding of coho in excess did not alter hold- ing capacity of st'°aij aquaria. Since it appeared that food was not limiting, I felt that crowding of fish in Bluewater Creek had lessened growth potential. Manipulating seasons and catches at low fishing intensities will not allow ade- quate population reductions to see if there would be a positive growth response. Assuming that harvest rate remained nearly constant, then additional population reductions by more controllable means would best test the growth/density hypothesis. In the event more research be undertaken on Bluewater Creek, I would urge manipulat- ing population size of brown trout and if positive responses are not realized, then I would attempt manipulation of the genetic pool by introducing new stocks of brown trout. 23 APPENDIX 9 List of Recognizable Insects Collected from Benthic and Drift Samples Collected in Bluewater Creek Coleoptera Agabus sp. Bidessus af finis Deronectes griseostriatus Dineutus sp. Elmidae Enochrus sp. Gyrinus bifarius Haliplus strigatus Haliplus borealis Helichus striatus Hydroporus sp. Laceophilus maculosus Optioservus ovalis Peltodytes callosus Tropisternus sp. Diptera Cecidomyiidae Chironomidae Dicranota sp. Dixa sp. Empididae Euparyphus sp. Fannia sp. Heme rod romiinae Hexatoma sp. Lispoides aequifrons Pericoma sp. Phaenicia sericata Simulium arcticum Sphaerophoria sp. Tetanocera sp. Tipula sp. Ephemeroptera Bertis parvus Choroterpes albiannulata Ephemerella inermis Heptagenia elegantula Tricorythodes minutus Odonata Ophiogomphus sp. Plecoptera Acroneuria sp. Isogenus sp. Isoperla spp. Kathroperla sp. Nemoura sp. Trichoptera Brachycentrus sp. Hydropsyche sp. Ochrotrichia sp. Rhyacophila acropedes 25 LITERATURE CITED Bianchi, D. R. 1963. The effects of sedimentation on egg survival of rainbow trout and cutthroat trout. MS thesis. Mont. State Univ., Bozeman, Mont. 28 pp. Chapman, D. W. 1965. Net production of juvenile coho salmon in three Oregon streams. Trans. Amer. Fish. Soc. 94(1): 40-52. 1962. Agressive behavior in juvenile coho salmon as a cause of emigration. J. Fish Res. Bd. Canada 19: 1, 047- 1,080. Condone, A. J. and D. W. Kelley. 1961. The influences of inorganic sediment on the aquatic lift of streams. Calif. Fish and Game, 47(2): 189-228. Doudoroff, P. 1957. Water quality requirements of fishes and the effects of toxic substances, pp. 403-430* In the Physiology of Fishes. Vol. II (Ed. M. E. Brown) Academic Press., N. Y. 526 pp. Gruchys C. G. and V. D. Vladykov. 1968. Sexual dimorphism in anal fin of brown trout, Salmo trutta, and close relatives. J. Fish Res. Bd. Canada 25(4)- 813-815. Herbert, D. W. M. , J. S. Alabaster, M. C. Dart, and R. Lloyd. 1961. The effect of china clay wastes on trout streams. Int. J. Air Wat. Poll., 5(1): 56-74. Hunt, R. L. 1966. Production and angler harvest of wild brook trout in Lawrence Creek, Wisconsin. Wisconsin Conservation Dept. Technical Bulletin, No. 35. 52 pp. Hynes, H. B. N. 1960. The biology of polluted water. The Univ. Press, Liverpool. 366 pp. Lockard, L. L. 1974. Some environmental influences on egg production in brown trout (Salmo trutta) from Montana streams. MS thesis. Mont. State Univ., Bozeman, Mont. 28 pp. Marcuson, P. E. 1966. Stream sediment investigation. Mont. Dept. of Fish and Game, Job Progress Rpt. F-20-R-10, Job H-a, mult. 6 pp. 1966. Stream sediment investigation,, Mont. Dept. of Fish and Game, Job Progress Rpt. F-20-R-11, Job Il-a, mult. 7 pp. 1967. Stream sediment investigation. Mont. Dept. of Fish and Game. Job Progress Rpt. F-20-R-12, Job Il-a, mult. 9 pp. 1968. Stream sediment investigation. Mont. Dept. of Fish and Game, Job Progress Rpt. F-20-R-13s Job n-a, mult. 10 pp. 1969. Stream sediment investigation. Mont. Dept. of Fish and Game, Job Progress Rpt. F-20-R-14, Job Il-a, mult. 8 pp. 1970. Stream sediment investigation. Mont. Dept. of Fish and Game, Job Progress Rpt. F-20-R-15, Job n-a, mult. 7 pp. - 26 c McFadden, J. T. 1961. A population study of the brook trout, Salvelinus fontinalis. Wildl. Monogr., No. 7. McFadden, J. T., F I. Cooper and J. K. Anderson. 1965. Some effects of environ- ment on egg production in brown trout (Salmo trutta) . Limn, and Ocean. 10(1): 88-95. 1967. Numerical changes and population regulation in brook trout, Salvelinus fontinalis. J. Fish. Res. Bd. Canada 24(7): 1,425-1,459. Mont. Fish and Game Commission. 1976. Application for reservation of water in the Yellowstone River basin. Helena, Mont. 300 pp. Peters, J. C. 1967. Effects on a trout stream of sediment from agricultural practices. J. Wildl. Mgmt. 31(4): 805-812. 1971. Effects of sediment control on fish populations. Ph. D thesis Colo. State Univ., Fort Collins, Colo. 86 pp. Sanders, J. W. , and M. W. Smith. 1965. Changes in a stream population of trout associated with increased silt. J. Fish Res. Bd. Canada 22(2): 395-404. Vincent, E. R. 1977. Madison River temperature study. Mont. Dept. of Fish and Game, Job Progress Rpt. F-9-R-25, Job H-a, mult. 10 pp. Wallen, I. E. 1951. The direct effect of turbidity on fishes. Bull. Oklahoma Agric. Mech. College, Stillwater. Oklahoma Arts and Science Studies. Biol. Ser. 2, 48(2): 1-27. Waters, T. F. 1965. Interpretation of invertebrate drift in streams. Ecology 46(3): 327-333. Zillges, G. F. Jr. 1971. The aquatic insects of Bluewater Creek, Montana, above and below an area of intensive agriculture. MS thesis. Mont. State Univ., Bozeman, Mont. 29 pp. - 27 „ o o O u 0 i- r n < , S3 d o S e to L ■mmI w "A