Abundance of Sport Fish in the North Raven River, Alberta, 2005

Transcription

1 Abundance of Sport Fish in the North Raven River, Alberta, 2005 CONSERVATION REPORT SERIES

2 The Alberta Conservation Association is a Delegated Administrative Organization under Alberta s Wildlife Act. CONSERVATION REPORT SERIES 25% Post Consumer Fibre When separated, both the binding and paper in this document are recyclable

3 Abundance of Sport Fish in the North Raven River, Alberta, 2005 Mike Rodtka 1 and Rocklyn Konynenbelt 2 1 Alberta Conservation Association Provincial Building Street Rocky Mountain House, Alberta, Canada T4T 1A3 2 Alberta Sustainable Resource Development Provincial Building Street Rocky Mountain House, Alberta, Canada T4T 1B3

4 Report Editors PETER AKU KELLEY KISSNER Alberta Conservation Association 50 Tuscany Meadows Cres NW #101, 9 Chippewa Rd Calgary, AB T3L 2T9 Sherwood Park, AB T8A 6J7 Conservation Report Series Type Data ISBN printed: ISBN online: Publication No.: T/198 Disclaimer: This document is an independent report prepared by the Alberta Conservation Association. The authors are solely responsible for the interpretations of data and statements made within this report. Reproduction and Availability: This report and its contents may be reproduced in whole, or in part, provided that this title page is included with such reproduction and/or appropriate acknowledgements are provided to the authors and sponsors of this project. Suggested Citation: Rodtka, M., and R. Konynenbelt Abundance of sport fish in the North Raven River, Alberta, Data Report, D , produced by the Alberta Conservation Association, Rocky Mountain House, Alberta, Canada. 20 pp + App. Cover photo credit: David Fairless Digital copies of conservation reports can be obtained from: Alberta Conservation Association #101, 9 Chippewa Rd Sherwood Park, AB T8A 6J7 Toll Free: Tel: (780) Fax: (780) info@ab conservation.com Website: conservation.com i

5 EXECUTIVE SUMMARY The North Raven River (NRR), also know as Stauffer Creek, has long been regarded as one of Alberta s finest trout streams. Located in west central Alberta, Canada, the primary land use in the area is agricultural. By the 1960s it had become apparent that the effects of agricultural and rural development were negatively impacting the stream. The Stauffer Creek Habitat Improvement Program, developed by the Alberta Fish and Wildlife Division in 1973, outlined a plan to initiate habitat protection and improvement, while monitoring changes in the NRR s physical characteristics and fish populations. This monitoring included trout abundance estimation in 1973, 1985, 1995 and 2005 at four study sections along the NRR using electrofishing gear. Our report presents data on trout abundance from the 2005 study, and summarizes past survey data for comparison. We estimated trout abundance via mark recapture surveys at the four study sections previously surveyed using methods comparable to those used in past surveys. Mean brook trout abundance in the upper NRR fluctuated from an estimated low of 37 fish/km (95% CL = 28 51) in 1995 to a high of 193 fish/km (95% CL = ) in Brown trout abundance fluctuated from a low of 124 fish/km (95% CL = ) in 1973 to a high of 744 fish/km (95% CL = ) in Since 1995, brook trout abundance in the NRR appears to have increased, whereas brown trout abundance has decreased. Mean biomass of trout in the study area ranged from an estimated low of 25.4 kg/km (95% CL = ) in 1973 to a high of 86.0 kg/km (95% CL = ) in Brook trout biomass in the upper NRR ranged from an estimated low of 2.2 kg/km (95% CL = ) in 1995 to a high of 7.2 kg/km (95% CL = ) in Brown trout biomass was lowest in 1973 at 20.7 kg/km (95% CL = ) and peaked at 83.8 kg/km (95% CL = ) in Since 1995, brook trout biomass appears to have increased, whereas brown trout biomass appears to have decreased. The size (length) structure of brook trout and brown trout catches varied among survey years. The brook trout catch in 2005 was composed of significantly larger fish than in 1995 (P < ), although condition did not differ between years. The brown trout catch in 2005 was composed of significantly smaller fish than in 1995 (P < ); approximately 50% of the 2005 catch was of fish 100 mm fork length. No clear trend ii

6 in condition of brown trout was apparent since Generally, fish condition tended to decrease with increasing abundance among survey years, and tended to decrease with increasing fish length for both species across years. The most striking trend in the dataset was the general increase in trout biomass which has occurred since riparian habitat conservation and stream improvement initiatives began in the early 1970s. The 2005 survey results indicated that trout abundance and biomass in the upper NRR declined since 1995, but were still well above the lows in abundance and biomass documented in It appears the most recent decline in trout abundance and biomass has been driven by a reduction in brown trout abundance and biomass, which accounts for the greatest proportion of trout biomass in the stream. Evaluation of longterm changes in abundance and biomass of trout in the study area are complicated by a lack of consecutive year trend data. It remains unclear whether changes in abundance and biomass observed in the most recent survey were indicative of a long term trend or were an artifact from limited sampling of a dynamic system. Key words: abundance, biomass, brook trout, brown trout, North Raven River. iii

7 ACKNOWLEDGEMENTS We thank Kevin Gardiner, Kevin Fitzsimmons and Donna Rystephanuk (Alberta Conservation Association) and Steve Herman (Alberta Sustainable Resource Development) for assistance with field work. Susan Armitage graciously volunteered her time to assist with field work. Mike Sullivan (Alberta Sustainable Resource Development), Craig Johnson, Calvin McLeod, Garry Scrimgeour (Alberta Conservation Association) and Kevin Fitzsimmons provided input into data analyses. Donna Rystephanuk created study area maps. We sincerely thank area landowners and the numerous individuals and conservation organizations who, through their vision and hard work, have helped make the North Raven River the fishery it is today. iv

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9 TABLE OF CONTENTS EXECUTIVE SUMMARY... ii ACKNOWLEDGEMENTS... iv TABLE OF CONTENTS... v LIST OF FIGURES... vi LIST OF APPENDICES... vii 1.0 INTRODUCTION Study objective STUDY AREA Description MATERIALS AND METHODS Data handling Trout abundance estimation Trout biomass estimation Fish condition and population size structure RESULTS Trout abundance Trout biomass Fish condition and population size structure Summary LITERATURE CITED APPENDICES...21 v

10 LIST OF FIGURES Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Location of the North Raven River (NRR) study area in Alberta, Canada and the four study sections of the NRR assessed in Weighted mean estimate of brook trout abundance derived from markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Weighted mean estimate of brown trout abundance derived from markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Bootstrapped mean trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Bootstrapped mean brook trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Bootstrapped mean brown trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Length frequency distribution of brook trout captured during markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Mean relative weights of three size categories of brook trout captured during mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Length frequency distribution of brown trout captured during markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Figure 10. Mean relative weights of five size categories of brown trout captured during mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and vi

11 LIST OF APPENDICES Appendix 1. Appendix 2. Appendix 3. Appendix 4. Appendix 5. Appendix 6. Appendix 7. Appendix 8. Appendix 9. Appendix 10. Appendix 11. Coordinates of the 2005 upper North Raven River trout abundance estimate sites and habitat measures made at these locations Boundaries of the four study sections on the North Raven River in 1973, 1985 and Original and standardized section identification, reach length, and timing (run) of mark recapture surveys used to generate estimates of trout abundance on the upper North Raven River in 1973, 1985, 1995 and Summary statistics for fork length and weight measurements of brook trout and brown trout from electrofishing catch data combined from four sections of the upper North Raven River in 1973, 1985, 1995 and Number of brook trout and brown trout marked, captured in subsequent passes, and recaptured at four sections of the upper North Raven River in 1973, 1985, 1995 and Estimated brook trout and brown trout biomass at four sections of the upper North Raven River 1973, 1985, 1995, and Weighted mean mark recapture estimates of brook trout and brown trout abundance in the upper North Raven River in 1973, 1985, 1995 and Estimated mean biomass of trout, brook trout and brown trout in the upper North Raven River in 1973, 1985, 1995 and Results of comparisons of ranked relative weights among survey years for two size categories of brook trout and four size categories of brown trout captured in the upper North Raven River in 1973, 1985, 1995 and Summary statistics for fork length and weight measurements of brook trout and brown trout captured via electrofishing of four sections of the upper North Raven River in 1973, 1985, 1995 and Summary statistics for fork length and weight measurements of brook trout and brown trout from electrofishing capture data combined from four sections of the upper North Raven River in 1973, 1985, 1995 and vii

12 Appendix 12. Appendix 13. Appendix 14. Summary statistics for fork length and weight measurements of brook trout and brown trout from electrofishing catch data from four sections of the upper North Raven River in 1973, 1985, 1995 and Relative weights of three size categories of brook trout and five size categories of brown trout from four sections of the North Raven River in 1973, 1985, 1995 and Relative weights of three size categories of brook trout and five size categories of brown trout captured in the North Raven River in 1973, 1985, 1995 and viii

13 1.0 INTRODUCTION The North Raven River (NRR), also known as Stauffer Creek, has long been regarded as one of Albertaʹs finest trout streams, supporting a very popular fishery since the introduction of brown trout (Salmo trutta) and brook trout (Salvelinus fontinalis) in the early 1900s. Not only is the NRR popular among Alberta anglers, but a 1996 angler survey by McLeod and DeRosa (1996) found that anglers from other provinces, the United States, and even Europe visited the NRR. In addition to the economic importance of the fishery, is the inherent natural and aesthetic value of the stream. Given these attributes, the significance of ensuring its long term protection and preservation is evident. The ecological integrity of a stream is largely dependent on adjacent land use practices and land management. Homesteading began in the Stauffer district circa 1905, which led to significant changes in the local landscape. Deterioration of fish habitat and water quality is gradual and often goes unnoticed over time, but by the 1960s it had become apparent that the effects of agricultural and rural development were negatively impacting fish habitat and water quality in the NRR (Cunningham 1964). To support priority habitat conservation initiatives throughout the province, a special trust fund, the ʺBuck For Wildlifeʺ fund, was introduced by the Government of Alberta in 1973 based on the recommendation of the Alberta Fish and Game Association. One dollar from the sale of each angling and hunting licence in Alberta was committed to the fund which was designed to support the maintenance, improvement or development of important fish and wildlife habitat throughout the province. The ʺStauffer Creek Habitat Improvement Programʺ, developed by the Alberta Fish and Wildlife Division, also started in The program outlined a plan to initiate habitat protection and improvement, while monitoring changes in the NRR s physical characteristics and fish populations. Stream corridor fencing to exclude livestock from the riparian area was recommended as the first step toward restoration of stream habitat and the fishery. To date, approximately 70% of the NRR s 34 km length has been fenced. In addition, a variety of other reach specific projects to stabilize the stream s banks and alter channel and flow characteristics have been undertaken. Habitat and fishery data used for program development and evaluation have been collected primarily from the upper half of the river where trout are most abundant (see 1

14 summaries in Cunningham 1964; Shirvell 1972; Kraft and Shirvell 1975; Antoniuk 1976; Rhude and Kraft 1987; Brown and Stanislawski 1995; R.L. & L. 1995). The majority of funds for the fencing, other physical improvements, and project monitoring which have occurred along the NRR have been obtained through the Buck For Wildlife fund, which was administered by the Alberta Fish and Wildlife Division from program inception until Administration of the fund was delegated to the Alberta Conservation Association in In 2005, the Alberta Conservation Association (ACA), in partnership with Alberta Sustainable Resource Development (ASRD), reassessed sport fish abundance in the upper NRR at reaches originally surveyed in 1973 (Kraft and Shirvell 1975) and again in 1985 (Rhude and Kraft 1987) and 1995 (Brown and Stanislawski 1995). The survey sections included a reach in which the stream corridor was not fenced until the mid 1990s, and three other sections which were fenced in the 1970s. These sections were used to monitor trout abundance in the stream and evaluate the effectiveness of stream corridor fencing for enhancement of trout populations (Brown and Stanislawski 1995). 1.1 Study objective The main objective of this study was to estimate brook trout and brown trout abundance (absolute, density, biomass), fish condition and population size structure at the four previously identified study sections in the NRR using methods comparable to those used in previous surveys in 1973, 1985 and 1995, and to compare results of this study to those of the earlier studies. 2

15 2.0 STUDY AREA 2.1 Description Located in west central Alberta, Canada, approximately 80 km southwest of Red Deer, the NRR is a second order stream that drains an area of approximately 145 km 2 (Figure 1). The river arises from two groundwater sources with a combined discharge of ~0.35 m 3 /sec. Numerous other springs enter the river within its first 1.5 km. At normal flow level (absence of significant precipitation), the NRR carries a total mean discharge of approximately 1.25 m 3 /s at its mouth. The stream has a mean gradient of 1.7 m/km (0.17%), and flows into the Raven River at N and W. Average stream width is 9 m. The flow regime in the upper half of the stream remains very stable year round due to its ground water source, and approximately one fourth of the NRR, from its source downstream, remains ice free throughout winter. In addition to brook trout and brown trout, fish species documented in the NRR include brook stickleback (Culea inconstans), burbot (Lota lota), lake chub (Couesius plumbeus), longnose dace (Rhinichthys cataractae), longnose sucker (Catostomas catostomas), mountain whitefish (Prospium williamsoni), northern pike (Esox lucius), trout perch (Percopsis omiscomaycus), spoonhead sculpin (Cottus ricei) and white sucker (Catostomas commersoni) (Brown and Stanislawski 1995, Rodtka and Konynenbelt unpubl. data). The NRR watershed is situated in a transition zone between the Parkland and Boreal Forest natural regions. Remnant patches of aspen and willow surrounded by productive agricultural lands and underlain by black soils are characteristic of the Parkland Natural Region, whereas deciduous, mixedwood, and coniferous forests interspersed by wetlands characterize the Boreal Forest Natural Region (Natural Regions Committee 2006). The foremost land use in the area is agriculture; primarily livestock grazing, secondarily hay and feed grain production. 3

16 Figure 1. Location of the North Raven River (NRR) study area in Alberta, Canada and the four study sections (in red) of the NRR assessed in

17 3.0 MATERIALS AND METHODS 3.1 Data handling We obtained biological information (i.e., species, length, weight) collected during past surveys in 1973, 1985 and 1995 from the original datasheets housed in ASRD s (Rocky Mountain House office) fisheries files and arranged to have these data entered into Microsoft Excel spreadsheets by a data processing service. Raw length weight data were plotted, and visually assessed for outliers. We checked outliers against the original datasheets for accuracy and corrected (n = 15) or removed them (n = 27) from the dataset. As a result of this process, sample sizes used in our analyses may not correspond exactly to those reported in previous summaries of these data. We obtained past survey section length, location, survey timing and mark recapture data from Brown and Stanislawski s (1995) summary report. Data collected in 2005 were entered into the Alberta Fisheries Management Information System database maintained by Alberta Sustainable Resource Development, Project ID Coordinates of the 2005 section boundaries and general habitat characteristics of each section are contained in Appendix Trout abundance estimation We used mark recapture methods to estimate trout abundance at four sections of the NRR upstream of the Highway 54 crossing. Mark recapture estimates of trout abundance have previously been made at three (1973) or four (1985, 1995) sections of the NRR upstream of the Highway 54 crossing. Sections 3 and 4 are subsections of Kraft and Shirvell s (1975) lowermost section (Appendix 2). Boat mounted electrofishing gear was used to capture fish, except during our survey of Section 1 in 2005, when shallow water conditions necessitated use of a backpack electrofisher. Section identification and length, and survey timing varied among years (Appendix 3). During marking runs fish were anesthetized, weighed, and trout with a fork length (FL) > 99 mm were given a fin clip unique to the section. Measurement and precision of fish weights varied among survey years. During the 1973 survey, weights were preferentially obtained from larger trout. Precision of weight measurements was to the nearest 1 g (1995 survey), 5 g (1985 and 2005 surveys) or 10 g (1973 survey). 5

18 We estimated trout (> 99 mm FL) abundance using mark recapture data and Chapman s modification of the Lincoln Petersen estimator when greater than six recaptures were obtained. We assumed fish movement between sections was minimal; only 3% (n = 4) of recaptures in 2005 were of fish first marked in another section. We modeled uncertainty in Lincoln Petersen estimates using the random number generation function in Microsoft Excel to simulate 10,000 replicate recapture events from the binomial distribution (Alberta Fisheries Management Data Standards Committee 2006), with distribution parameters based on recapture information obtained from the section. In sections where less than six recaptures were obtained, but where the species still comprised greater than 1% of the total catch of trout, we estimated trout abundance by correcting mean single pass electrofishing catch data by mean sampling efficiency. We calculated mean sampling efficiency estimates for each species using available mark recapture data from all sections within a survey year and modeled uncertainty in estimated sampling efficiency using the beta distribution (Paul et al. 2005) to simulate 10,000 sampling efficiencies using the random number generation function in JMP statistical software. We calculated empirical confidence limits (95% CL) from the simulation data following Haddon (2001). We used measured sampling efficiency (i.e., the number of recaptured fish divided by the number of marked fish returned to the reach in the first electrofishing run; Peterson et al. 2004) when calculating parameters for both the binomial and beta distributions. When reporting estimates of abundance by survey year we used the weighted mean of individual section abundance estimates with section length as the weighting factor. 3.3 Trout biomass estimation We calculated brook trout and brown trout biomass (kg fish/km stream) for each section as the product of simulated fish abundance and non parametric bootstrapped mean fish weight (10,000 bootstraps), and standardized the final proportions (i.e., probability densities) to range between 0 and 1 (Haddon 2001). We calculated empirical confidence limits from the simulation data following Haddon (2001). Where unavailable, we estimated fish weights using the regression equation describing the linear relationship between log10 transformed length and weight data (catch from all sections combined) for each species in a survey year (r 2 = ; Appendix 4). The high proportion of estimated weights in the 1973 survey (53%) and rounding of fish 6

19 weight to the nearest 10 g resulted in an underestimation of uncertainty in mean biomass estimates relative to subsequent surveys. When reporting estimates of biomass by survey year we used the weighted mean of individual section biomass estimates with section length as the weighting factor. Trout density and biomass were not calculated by area because stream width data were unavailable for some surveys. 3.4 Fish condition and population size structure We used relative weight (Wr; Murphy et al. 1991) to compare fish condition among years. Relative weight is considered an indicator of general fish health and has been associated with body composition and gross energy content (Blackwell et al. 2000). Relative weight was calculated as: Wr = W/Ws x 100 where Ws is the length specific standard weight predicted by weight length regression constructed to represent the species as a whole (Murphy et al. 1991). We used Hyatt and Hubert s (2001) standard weight equation for brook trout (120+ mm) and Milewski and Brown s (1994) equation for lotic brown trout (140+ mm). For our calculation of Wr (which is based upon total length, TL), a FL to TL conversion ratio of 1:1.05 was used for both species based on comparative measurements of 97 brook trout ( mm FL) and 321 brown trout ( mm FL) in the 2005 catch. We detected significant differences in Wr among size categories of brook trout and brown trout within survey years (Rodtka and Konynenbelt, unpubl. data) so we reported Wr data using length categories (Gabelhouse s 1984 length categorization system) according to the recommendation of Murphy et al. (1991) and Blackwell et al. (2000). Gabelhouse s (1984) categories are defined as percentage lengths of the all tackle world record for the species; the Stock size category is considered the minimum size category to provide recreational value to anglers (Gabelhouse 1984). Minimum TL of the Stock, Quality and Preferred categories for brook trout was 160, 287 and 361 mm respectively (Gabelhouse 1984). Minimum total length of the Stock, Quality, Preferred, Memorable and Trophy categories for brown trout was 198, 356, 445, 584 and 732 mm, respectively (Gabelhouse 1984). Minimum TL of brook trout and brown trout included in the < Stock category presented in our analyses were based on the 7

20 minimum length of fish used for development of the standard equation for the species (120 and 140 mm TL for brook trout and brown trout, respectively). To compare size structure and fish condition data among years we used Analysis of Variance (ANOVA) on ranked data where n 5. Many of these data were not normally distributed but performing an ANOVA on data ranks is asymptotically equivalent to using the non parametric Kruskal Wallis test (Neumann and Allen 2007). We used Tukey s Honestly Significant Differences (HSD) test when making multiple post hoc comparisons. In all cases, statistical significance was evaluated at P 0.05 and statistical tests were two tailed. Reduced alpha levels (P = 0.05/n, where n = number of pairwise comparisons) were used to correct for experiment wise error rate when comparing Wr within size categories among years. Our comparison of trout abundance, biomass, condition and population size structure between the stream sections surveyed in 1973 and the subsections surveyed in subsequent years, assumes fish were distributed uniformly within the larger reach in This assumption is only partially supported by comparison of abundance (Appendix 5) and biomass (Appendix 6) data from sections 3 and 4 from subsequent surveys and needs to be considered when interpreting our results. 4.0 RESULTS 4.1 Trout abundance Mean brook trout abundance in the upper NRR ranged from an estimated low of 37 fish/km (95% CL = 28 51) in 1995 to a high of 193 fish/km (95% CL = ) in 1985 (Figure 2). Mean brown trout abundance fluctuated from a low of 124 fish/km (95% CL = ) in 1973 to a high of 744 fish/km (95% CL = ) in 1985 (Figure 3). Both species were most abundant in Since 1995, brook trout abundance appears to have increased, whereas brown trout abundance has decreased. Estimates of brook trout and brown trout abundance summarized by section and year are presented in Appendices 5 and 7, respectively. 8

21 Figure 2. Weighted mean estimate of brook trout abundance derived from markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Error bars denote 95% confidence intervals. Figure 3. Weighted mean estimate of brown trout abundance derived from markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Error bars denote 95% confidence intervals. 9

22 4.2 Trout biomass Mean biomass of trout (i.e., brook and brown trout) in the study area ranged from an estimated low of 25.4 kg/km (95% CL = ) in 1973 to a high of 86.0 kg/km (95% CL = ) in 1995 (Figure 4). Mean trout biomass in 2005 appears to have declined from the high observed in A substantial increase in brown trout biomass was evident since the survey began in Based on the 95% confidence limits around the means, both the 1973 and 1985 biomass estimates were relatively precise. However, uncertainty in the 1973 estimate was likely underestimated (see methods), whereas the high precision of the 1985 estimate can largely be attributed to the relatively narrow distribution of fish weights in that year s brown trout catch (Appendix 4). Figure 4. Bootstrapped mean trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Error bars denote 95% confidence intervals. Brook trout biomass in the upper NRR ranged from an estimated low of 2.2 kg/km (95% CL = ) in 1995 to a high of 7.2 kg/km (95% CL = ) in 1985 (Figure 5). The proportion of total trout biomass composed of brook trout declined from nearly 19% in 1973 to 8% in 2005 (Appendix 8). This decline was likely due to the substantial gain in brown trout biomass observed in the upper NRR since 1973 (Figure 6). Brown trout biomass was at its lowest at 20.7 kg/km (95% CL = ) in 1973 and peaked at 83.8 kg/km (95% CL = ) in Since 1995, brown trout biomass appears to 10

23 have declined to a level similar to that observed in Estimates of trout biomass summarized by section and year are presented in Appendices 6 and 8, respectively. Figure 5. Bootstrapped mean brook trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Error bars denote 95% confidence intervals. Figure 6. Bootstrapped mean brown trout biomass derived from mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Error bars denote 95% confidence intervals. 11

24 4.3 Fish condition and population size structure Brook trout in the 1973 catch were significantly larger than fish in the 1985 and 2005 catches, and fish in the 1995 catch were significantly smaller than fish in the 1985 and 2005 catches (F3, 3243 = , P = <0.0001; Figure 7). Quality Preferred size brook trout (i.e., trout 287 mm but < 361 mm) were rarely captured in any survey (n = 2 5). Within survey years, brook trout condition generally decreased with increasing fish length, although results varied (Figure 8). Brook trout in the < Stock and Stock Quality size categories were in significantly better condition in 2005 than those captured during the 1973 and 1985 surveys. Results of comparisons of Wr among years are summarized in Appendix 9. The size distribution of the brown trout catch varied considerably among surveys. The 1973 and 2005 length distributions were positively skewed with approximately 50% of the brown trout catch consisting of fish 100 mm FL, resulting in a catch composed of significantly smaller fish than in 1985 and 1995 (F3, 8232 = , P = <0.0001; Figure 9). Within size categories, brown trout condition in the 1985 catch was the lowest or significantly lower than condition of fish in the catch for most other survey years (Figure 10; Appendix 9). Reduced condition of fish in the 1985 catch may be a result of increased competition for forage, because brown trout abundance in 1985 was relatively high. Furthermore, condition of fish in the 1973 and 2005 catches, when brown trout abundance was relatively low, were typically significantly higher than in other survey years (Appendix 9). A general pattern of decreasing brown trout condition with increasing fork length within survey years was apparent, although the trend was less consistent than that observed for brook trout. Summary statistics on population size structure of trout by section and year are presented in Appendices 10 and 11, respectively. Summary statistics on population size structure for only those trout used in mark recapture and biomass estimates (i.e., fish > 99 mm FL) are presented by section and year in Appendices 12 and 4, respectively. Summary statistics for trout Wr by section and year are presented in Appendices 13 and 14, respectively. 12

25 Figure 7. Length frequency distribution of brook trout captured during markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and

26 Figure 8. Mean (± SE) relative weights (Wr) of three size categories of brook trout captured during mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and

27 Figure 9. Length frequency distribution of brown trout captured during markrecapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and

28 Figure 10. Mean (± SE) relative weights (Wr) of five size categories of brown trout captured during mark recapture surveys at four sections of the upper North Raven River in 1973, 1985, 1995 and Summary Results of the 2005 survey indicated that trout abundance and biomass in the upper NRR have declined since the last survey in 1995, but remain well above the low abundance and biomass documented in The most recent decline has likely been driven by a reduction in brown trout abundance and biomass, which accounts for the greatest proportion of trout biomass in the stream. Brook trout abundance and biomass in the upper NRR actually appears to have increased since 1995, although this observation requires qualification. The 2005 survey of Section 1, which contains primarily brook trout, was restricted to the upper third of the reach. Deep silt and shallow water conditions made effective sampling of the lower portion of the reach impossible. This sampling problem may have biased results because the upper portion of the reach also appeared to contain the best habitat. However, an increase in brook trout abundance was also observed in Section 2 suggesting the increase may be real. The size composition of catches of both brook trout and brown trout differed significantly and varied among survey years. General trends of decreasing fish condition with increasing abundance among survey years and decreasing condition with increasing fish length within survey years were observed. 16

29 Evaluation of long term changes in abundance and biomass of trout in the study area was complicated by a lack of consecutive year trend data. Considerable empirical evidence for natural fluctuations in fish populations exist and it cannot be stated unequivocally that the changes in trout abundance and biomass observed in recent surveys are indicative of any longer term trend or simply an artifact resulting from limited sampling of a dynamic system. However, trout abundance and biomass in the upper NRR has consistently remained above record lows documented in 1973 when habitat protection and restoration within the drainage began in earnest. 17

30 5.0 LITERATURE CITED Alberta Fisheries Management Data Standards Committee Angler surveys in Alberta recommended standards. Alberta Sustainable Resource Development, Fish and Wildlife Division, and Alberta Conservation Association. Edmonton, Alberta. 42 pp. + App. Antoniuk, T North Raven River habitat evaluation (Sec W5), Alberta Recreation, Parks and Wildlife, Fish and Wildlife Division, Rocky Mountain House, Alberta. 22 pp. Blackwell, B., M. Brown, and D. Willis Relative weight (Wr) status and current use in fisheries assessment and management. Reviews in Fisheries Science 8: Brown, R., and S. Stanislawski Assessment of the trout population in the North Raven River after two decades of habitat enhancement. Department of Environmental Protection, Natural Resources Service, Fish and Wildlife Division, Rocky Mountain House, Alberta. 32 pp. + App. Cunningham, E.B Population survey of Stauffer Creek, Report prepared for Alberta Fish and Wildlife Division, Rocky Mountain House, Alberta. 5 pp. Gabelhouse, D A length categorization system to assess fish stocks. North American Journal of Fisheries Management 4: Haddon, M Modeling and quantitative methods in fisheries. Chapman & Hall/CRC, Washington, D.C. 386 pp. Hyatt, M., and W. Hubert Proposed standard weight equations for brook trout. North American Journal of Fisheries Management 21:

31 Kraft, M.E., and C. Shirvell Survey of the habitat and fish population in the North Raven River. Alberta Recreation, Parks and Wildlife, Fish and Wildlife Division, Rocky Mountain House, Alberta. 54 pp. + App. McLeod, C.R., and D.C. DeRosa An evaluation of angler use and harvest on the North Raven River, May to August, 1986 and Alberta Environmental Protection, Natural Resources Service, Fish and Wildlife, Rocky Mountain House, Alberta. 60 pp. + App. Milewski, C., and M. Brown Proposed standard weight (Ws) equation and length categorization standards for stream dwelling brown trout (Salmo trutta). Journal of Freshwater Ecology 9: Murphy, B.R., D.W. Willis, and T. A. Springer The relative weight index in fisheries management: status and needs. Fisheries 16: Natural Regions Committee Natural regions and subregions of Alberta. Compiled by D.J. Downing and W.W. Pettapiece, Government of Alberta, Publication No. T/852, Edmonton, Alberta. 176 pp. + App. Neumann, R.M., and M.S. Allen Size structure. Pages In: C.S. Guy and M.L. Brown, editors. Analysis and interpretation of freshwater fisheries data. American Fisheries Society, Bethesda, Maryland. 961 pp. Paul, A.J., C.G.S. Dormer, and C. Greenway Effect of a severe flood on the cutthroat trout population of Silvester Creek, Alberta draft. University of Calgary, Calgary, Alberta. 25 pp. Peterson, J., R. Thurow, and J. Guzevich An evaluation of multipass electrofishing for estimating the abundance of stream dwelling salmonids. Transactions of the American Fisheries Society 133: Rhude, L.A., and M.E. Kraft The effect of habitat enhancement upon the trout population and physical characteristics of the North Raven River from 1973 to 19

32 1985. Alberta Forestry, Lands and Wildlife, Fish and Wildlife Division, Rocky Mountain House, Alberta. 50 pp. + App. R.L. & L. Environmental Services Ltd North Raven River habitat measurement project. R.L. & L. Report No. 459F, prepared for Alberta Environmental Protection, Natural Resources Service, Fish and Wildlife Services, Rocky Mountain House, Alberta. 37 pp. + App. Shirvell, C.S Survey of Stauffer Creek and habitat program. Alberta Department of Lands and Forests, Fish and Wildlife Division, Red Deer, Alberta. 88 pp. + App. 20

33 6.0 APPENDICES Appendix 1. Universal Transverse Mercator (UTM) coordinates (NAD 83, reference meridian 117) of the 2005 upper North Raven River trout abundance estimate sites and habitat measures made at these locations. UTM Start UTM End Section Easting Northing Easting Northing Wetted width Maximum depth n Mean a ± SD Range n Mean a ± SD Range ± ± ± ± ± ± ± ± a Measured 15 June 6 July 2005 (high water conditions immediately following abundance estimates precluded earlier measurement). Wetted width (nearest cm) was measured at transects spaced at 50 m intervals. Maximum depth (nearest cm) between transects was measured using a graduated wading rod. 21

34 Appendix 2. Boundaries of the four study sections on the North Raven River in 1973, 1985 and In the 2005 analysis, data from section 3 in the 1973 study were not included, and sections 3 1 and 3 2 from the 1985 and 1995 surveys were referred to as sections 3 and 4, respectively. 22

35 Appendix 3. Original and standardized section identification, reach length, and timing (run) of mark recapture surveys used to generate estimates of trout abundance on the upper North Raven River in 1973, 1985, 1995 and Year Section reference in original report 2005 standardized section reference Length Run (km) Marking Recapture May 2 May May 2 May and May 3 4 May April 30 May May 1 May May 2 May May 3 May April 25 May April 26 May April 27 May April 28 May NA May 20 May 27 NA May 4 May 12 NA May 5 May 11 NA May 6 May 13 NA not applicable 23

36 Appendix 4. Summary statistics for fork length and weight measurements of brook trout (BKTR) and brown trout (BNTR)(> 99 mm fork length) from electrofishing catch data combined from four sections of the upper North Raven River in 1973, 1985, 1995 and Linear regression equations of log10 transformed length and weight values and goodness of fit of the models are also presented. Fork Length (mm) Weight (g) Length weight regression equation Year Species Mean (± SD) n Mean (± SD) n Y = αx + b r a BKTR 145 ± BNTR 195 ± ± x ± x b BKTR 139 ± ± x BNTR 178 ± ± x c BKTR 161 ± ± x BNTR 232 ± ± x b BKTR 149 ± ± x BNTR 204 ± ± x a 10 g precision, b 5 g precision, c 1 g precision. 24

37 Appendix 5. Number of brook trout and brown trout (> 99 mm fork length) marked (M), captured in subsequent passes (C), and recaptured (R) at four sections of the upper North Raven River in 1973, 1985, 1995 and Associated capture probabilities (P), mark recapture estimates of abundance (N) and fish/km are also presented. Brook trout Brown trout Year Section M C R P N (± 95% CL) Fish/km (± 95% CL) M C R P N (± 95% CL) Fish/km (±95% CL) ( ) 804 ( ) (62 87) 77 (65 92) ( ) 232 ( ) ( ) 144 ( ) 3 and (20 44) 3 (2 5) ,062 (838 1,381) 120 (95 157) ( ) 561 ( ) (20 332) 89 (21 349) ( ) 409 ( ) ,967 (1,756 2,219) 1,320 (1,178 1,489) (64 401) 80 (32 203) (851 1,129) 493 ( ) ,994 (1,808 2,208) 856 ( ) (69 128) 94 (73 135) (12 56) 26 (13 59) (79 205) 86 (53 137) (632 1,207) 572 ( ) (21 47) 15 (11 24) ,069 (987 1,158) 540 ( ) ( ) 350 ( ) (73 200) 391 ( ) (16 60) 103 (55 207) ( ) 214 ( ) (559 1,259) 388 ( ) (3 49) 8 (2 30) ( ) 196 ( ) ( ) 243 ( ) 25

38 Appendix 6. Estimated brook trout and brown trout (> 99 mm fork length) biomass (kg/km) at four sections of the upper North Raven River 1973, 1985, 1995, and Range provided in parentheses denotes the 95% confidence limits around the estimate. Brook trout Brown trout Year Section kg kg/km kg kg/km ( ) ( ) 3 and ( ) 28.8 ( ) 9.4 ( ) 0.3 ( ) 7.5 ( ) 42.5 ( ) ( ) 7.9 ( ) 12.4 ( ) 25.3 ( ) ( ) 14.8 ( ) 4.7 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 3.9 ( ) 8.8 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 13.5 ( ) 0.8 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 5.0 ( ) 72.8 ( ) 53.0 ( ) 94.4 ( ) 9.2 ( ) ( ) 98.6 ( ) 76.2 ( ) 2.9 ( ) 75.1 ( ) 43.9 ( ) 48.9 ( ) 26

39 Appendix 7. Weighted mean mark recapture estimates of brook trout and brown trout (> 99 mm fork length) abundance (fish/km) in the upper North Raven River in 1973, 1985, 1995 and Estimates are based on mark recapture data combined from four sections of the river. Range provided in parentheses denotes the 95% confidence limits around the estimate. Brook trout Brown trout Year Fish/km Fish/km ( ) ( ) (28 51) (64 138) 124 ( ) 744 ( ) 409 ( ) 274 ( ) Appendix 8. Estimated mean biomass (kg/km) of trout, brook trout and brown trout (> 99 mm fork length) in the upper North Raven River in 1973, 1985, 1995 and Estimates are based on mark recapture data combined from four sections of the river. Range provided in parentheses denotes the 95% confidence limits around the estimate. Trout Brook trout Brown trout Year kg/km kg/km kg/km ( ) 4.7 ( ) 20.7 ( ) ( ) 7.2 ( ) 64.9 ( ) ( ) 2.2 ( ) 83.8 ( ) ( ) 4.7 ( ) 54.4 ( ) 27

40 Appendix 9. Results of Tukey s HSD multiple comparisons of ranked relative weights (Wr) among survey years for two size categories of brook trout and four size categories of brown trout captured in the upper North Raven River in 1973, 1985, 1995 and Letters are used to denote significant differences among years; years with the same letter within a size category are not significantly different. Brook Trout Brown Trout ANOVA < Stock Stock Quality < Stock Stock Quality Quality Preferred Preferred Memorable Error df ,970 2, F P < < < < B C A A A A 1985 B B B B C B 1995 A B B C C B B A 2005 A A A A A B A 28

41 Appendix 10. Summary statistics for fork length and weight measurements of brook trout (BKTR) and brown trout (BNTR) captured via electrofishing of four sections of the upper North Raven River in 1973, 1985, 1995 and Fork Length (mm) Weight (g) Year Species Section Mean (± SD) Range n Mean (± SD) Range n 1973 a BKTR ± ± ± ± and ± ± BNTR ± ± ± ± and ± ± b BKTR ± ± ± ± ± ± NA 1 50 NA 1 BNTR ± ± ± , ± ,940 1, ± ± , ± , ± ,445 1, c BKTR 1 90 ± ± ± ± ± ± ± ± BNTR 1 99 ± ± , ± ± , ± ± , ± ± , b BKTR ± ± ± ± ± ± BNTR 1 85 ± ± ± ± , ± ± , ± ± , a 10 g precision, b 5 g precision, c 1 g precision; NA not applicable. 29

42 Appendix 11. Summary statistics for fork length and weight measurements of brook trout (BKTR) and brown trout (BNTR) from electrofishing capture data combined from four sections of the upper North Raven River in 1973, 1985, 1995 and Fork length (mm) Weight (g) Year Species Mean (± SD) Range n Mean (± SD) Range n 1973 a BKTR 127 ± , ± BNTR 145 ± , ± , b BKTR 116 ± , ± BNTR 160 ± , ± ,940 2, c BKTR 105 ± ± BNTR 195 ± , ± ,020 1, b BKTR 121 ± ± BNTR 147 ± , ± ,145 1,348 a 10 g precision, b 5 g precision, c 1 g precision. 30

43 Appendix 12. Summary statistics for fork length and weight measurements of brook trout (BKTR) and brown trout (BNTR) (> 99 mm fork length) from electrofishing catch data from four sections of the upper North Raven River in 1973, 1985, 1995 and Fork Length (mm) Weight (g) Year Species Section Mean (± SD) n Mean (± SD) n 1973 a BKTR ± ± ± ± and ± ± BNTR ± ± ± ± and ± ± b BKTR ± ± ± ± ± ± BNTR ± ± ± ± ± ± ± ± c BKTR ± ± ± ± ± ± ± ± 19 4 BNTR ± ± ± ± ± ± ± ± b BKTR ± ± ± ± ± ± BNTR ± ± ± ± ± ± ± ± a 10 g precision, b 5 g precision, c 1 g precision. 31

44 Appendix 13. Relative weights (Wr) of three size categories of brook trout (BKTR) and five size categories of brown trout (BNTR) from four sections of the North Raven River in 1973, 1985, 1995 and < Stock Wr Stock Quality Wr Quality Preferred Wr Preferred Memorable Wr Memorable Trophy Wr Year Species Section Mean ± SD Range n Mean ± SD Range n Mean ± SD Range n Mean ± SD Range N Mean ± SD Range n 1973 a BKTR 1 89 ± ± ± ± ± and 4 70 NA ± BNTR 1 90 ± ± NA 92 NA ± ± ± NA NA 1 3 and ± ± ± ± b BKTR 1 83 ± ± ± ± ± ± ± NA 1 BNTR 1 95 ± ± ± ± ± ± NA ± ± ± ± ± ± ± ± c BKTR 1 97 ± ± ± ± ± ± ± ± BNTR 1 91 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± b BKTR 1 93 ± ± ± ± ± ± BNTR 1 92 ± ± ± ± ± ± ± ± ± NA ± ± ± ± ± a10 g precision, b 5 g precision, c 1 g precision; NA - not applicable. 32