John Hagen1 and Jeremy T. A. Baxter2

Prepared for: BC Ministry of Environment Fisheries Program, East Kootenay Region Cranbrook, BC February 2009

1J. Hagen and Associates, 330 Alward St., Prince George, BC, V2M 2E3 e-mail: hagen_john2@yahoo.ca 2 Mountain Water Research, Box 52, Silverton BC, V0G 2B0 e-mail: Jbaxter@redmtn.ca

2008 Westslope Cutthroat Trout Population Abundance Monitoring of Classified Waters in the East Kootenay Region of British Columbia.

ABSTRACT

The harvest of westslope cutthroat trout from classified waters in the East Kootenay region

of British Columbia is highly restricted. However, angling pressure has increased significantly

on these streams in recent years. This monitoring study was initiated by the British Columbia

Ministry of Environment in response to concern that mortality or injury resulting from catch-

and-release angling may begin to adversely affect westslope cutthroat trout populations and

degrade the angling experience. In August and September, 2008, westslope cutthroat trout

abundance in index sections of the Wigwam River, Michel Creek, and St. Mary River were

assessed using snorkeling surveys. Trout density estimates for the index sections and for the

entire streams were generated from snorkeling counts and mark-recapture estimates of

snorkeling count accuracy made during previous studies, and compared to previous density

estimates where possible. Among study streams, Michel Creek and the lower St. Mary River had

significantly higher estimated densities (per stream kilometer) of trout >300 mm than did the

Wigwam River and upper St. Mary River. In addition to having the highest westslope cutthroat

trout densities, Michel Creek also had the highest estimated densities of large trout >400 mm. In

the Wigwam River, westslope cutthroat trout densities were higher in upstream reaches and

lower in an downstream reach relative to 2001 and 2002, but the overall population size

estimates for fish >300 mm were comparable. In the lower St. Mary River, the mean density of

cutthroat trout >300 mm had more than doubled since the time of lowest recorded densities in

1989 and 1990, but was still significantly lower than the highest recorded density estimate from

1982. Evidence of hooking injury, in the form of facial damage or bruising, could not be reliably

detected in the St. Mary River but was obvious and widespread in the Wigwam River and

especially Michel Creek.

ii

ACKNOWLEDGMENTS

A number of people and organizations dedicated their time and effort to ensure the successful completion of this project. Their help is greatly appreciated. Ministry of Environment Herb Tepper, John Bell, Jeff Burrows, Kevin Heidt, Cary Gaynor Ktunaxa Nation and the St Mary’s Band Additional Help in the Field Scott Decker, Gerry Nellestijn

iii

TABLE OF CONTENTS

ABSTRACT ........................................................................................................................ ii ACKNOWLEDGMENTS ................................................................................................. iii TABLE OF CONTENTS ................................................................................................... iv LIST OF FIGURES ............................................................................................................ v LIST OF TABLES ............................................................................................................. vi LIST OF APPENDICES .................................................................................................... vi INTRODUCTION .............................................................................................................. 1

Background .......................................................................................................................1 Snorkeling counts as a population monitoring tool ..........................................................5

METHODS ......................................................................................................................... 7

Snorkeling surveys ............................................................................................................7 Estimates of westslope cutthroat trout abundance ..........................................................10

RESULTS ......................................................................................................................... 13

Wigwam River ................................................................................................................13 Michel Creek ...................................................................................................................16 St. Mary River .................................................................................................................17 Elk River .........................................................................................................................20 Density comparison ........................................................................................................20 Hooking injury ................................................................................................................21 Other salmonids ..............................................................................................................22

DISCUSSION AND RECOMMENDATIONS ................................................................ 24

Monitoring population status in catch and release fisheries ...........................................24 Contribution of monitoring to management of classified waters ....................................26

REFERENCES ................................................................................................................. 29

iv

LIST OF FIGURES

Figure 1. Map of the East Kootenay region of British Columbia showing locations of the Wigwam River, Michel Creek, and the St. Mary River. ......................................................... 4

Figure 2. Models used to practice size estimation prior to conducting snorkeling surveys.

Visibility to the models was also measured in the lower St. Mary River. ............................ 11 Figure 3. Adult westslope cutthroat trout in the Wigwam River. Where it was impractical to

bring model into a survey section, snorkelers practiced size estimation by observing individual fish together and comparing size estimates. ........................................................ 11

Figure 4. Density estimates for westslope cutthroat trout a) >300 mm and b) >400 mm for

reaches of the Wigwam River. Reaches are left to right in order of furthest upstream to furthest downstream. ............................................................................................................. 15

Figure 5. Density estimates for westslope cutthroat trout >300 mm in index snorkeling

sections of the lower St. Mary River, 1982-2008. ................................................................ 19 Figure 6. Mean calibrated density estimates for westslope cutthroat trout >300 mm among

index snorkeling sections, for streams surveyed during this study in 2008. ......................... 21

v

vi

LIST OF TABLES Table 1. Accuracy of snorkeling counts of adult/subadult trout in streams. ................................. 6 Table 2. Index sections used for snorkeling surveys of westslope cutthroat trout, 2008 .............. 7 Table 3. Westslope cutthroat trout population estimates for index sections of the Wigwam

River, 2001, 2002, and 2008. Sections are in order of furthest upstream to furthest downstream. .......................................................................................................................... 14

Table 4. Population estimates for westslope cutthroat trout in reaches of the Wigwam River

between Desolation and Lodgepole creeks, 2001, 2002, and 2008. Reaches are in order of furthest upstream to furthest downstream. ............................................................................ 14

Table 5. Estimated density of westslope cutthroat trout >300 mm and >400 mm, Michel Creek

2008....................................................................................................................................... 16 Table 6. Counts and population estimates for westslope cutthroat trout in index sections of the

lower St. Mary River, August 2008. ..................................................................................... 17 Table 7. Estimated density of westslope cutthroat trout >300 mm for the lower St. Mary River,

1982-2008. ............................................................................................................................ 18 Table 8. Estimated density of westslope cutthroat trout in the upper St. Mary River, 2008. ..... 20 Table 9. Evidence of hooking injury to westslope cutthroat trout among snorkeling index

sections, 2008. ....................................................................................................................... 22 Table 10. Counts of rainbow trout in index sections snorkelled during 2008. ........................... 23

LIST OF APPENDICES APPENDIX 1. REGION 4 (EAST KOOTENAY) FRESHWATER STREAM REGULATIONS HISTORY APPENDIX 2. EAST KOOTENAY REGION WESTSLOPE CUTTHROAT TROUT SNORKELING SURVEYS, 2008

INTRODUCTION

Background

The westslope cutthroat trout (Oncorhynchus clarki lewisi) is the most northerly distributed

of interior subspecies of cutthroat trout, and is the only interior subspecies of cutthroat trout

naturally occurring in Canada (McPhail 2007). It is native to most of the upper Columbia

drainage system, and also to foothills streams in the South Saskatchewan River basin in

southwestern Alberta (McPhail 2007). Throughout their respective ranges, interior subspecies of

cutthroat trout have experienced dramatic decreases in their distribution and levels of abundance.

In the northwestern United States, westslope cutthroat trout historically utilized lower gradient

mainstem reaches of streams that are now occupied by non-native introduced brook trout and

rainbow trout (Liknes and Graham 1988; McIntyre and Rieman 1995). Now, their distribution is

frequently limited to cold, headwater streams (Rieman and Apperson 1989; Shepard et al. 1997;

Trotter et al. 1999; Trotter et al. 2001). In Alberta, westslope cutthroat trout once occupied the

mainstems of the Bow and Oldman Rivers and their major tributaries downstream far into the

plains. Except in the upper Oldman and Castle River basins, native stocks are now rare

(Mayhood 1999).

Declines in westslope cutthroat trout populations throughout the historic distribution have

been due to several factors, including: habitat loss and degradation; overexploitation;

competition and predation by non-native salmonids; and introgressive hybridization with

introduced rainbow trout (O. mykiss) and Yellowstone cutthroat trout (O. clarki bouvieri)

(Allendorf and Leary 1988; Liknes and Graham 1988; Shepard et al. 1997). Recognizing that

substantial threats to populations in British Columbia exist also, the BC Conservation Data

Centre placed the westslope cutthroat trout on its blue list of threatened species in this province

on June 17, 2001. However, populations in southeastern British Columbia have experienced

much less severe habitat fragmentation and destruction relative to populations in Alberta and the

United States. Except where natural barriers exist or dams built on natural barriers (upper Bull,

Elk Rivers) have been constructed, westslope cutthroat trout populations in the upper Kootenay

River drainage in particular continue to maintain themselves within an interconnected mosaic of

stream habitats ranging from small, high gradient tributaries to lower gradient mainstem reaches.

1

Several populations provide exceptional and unique angling opportunities that contribute

significantly to the economy of the East Kootenay region (Tepper 2008).

Cutthroat trout of all subspecies appear to be extremely vulnerable to overexploitation

(Behnke 1979; McPhee 1966; Rieman and Apperson 1989; McIntyre and Rieman 1995). By the

mid-1980s, stream resident salmonids in the East Kootenay region were recognized to be in

decline, and the older age components of westslope cutthroat trout populations in particular were

thought to be depleted. BC’s Ministry of Environment (MOE) identified that the causes of the

declines had been overly liberal fishing regulations, increased accessibility into major valleys,

and the high catchability of native species (Oliver 1989).

Restrictive regulations appear to be an effective tool for conserving westslope cutthroat trout

stocks, and have been utilized as a primary conservation tool by the Departments of Fish and

Game in Idaho and Montana (Liknes 1984; Rieman and Apperson 1989; McIntyre and Rieman

1995). In British Columbia, Provincial Government biologists made extensive use of restrictive

regulations, including river closures, catch-and-release regulations, and size limitations, to

restore the westslope cutthroat trout fishery throughout its range in the province beginning in the

1980’s and 1990’s (Appendix 1). Currently, westslope cutthroat trout streams in the East

Kootenay region of BC support some of the most economically important recreational fisheries

in the province.

However, fishing pressure for westslope cutthroat trout in British Columbia has increased

dramatically in recent years, partly in response to the rebuilding of stocks, and partly due to the

increasing human population within a day’s drive of the East Kootenay valley (EKAMPC 2003).

Regional biologists, anglers, and angling guides have recognized that the quality of the angling

experience is degrading or is likely to degrade as a result of high fishing pressure on some

streams. As a result, special management of seven streams in the East Kootenay region, the

upper Kootenay, White, Elk, Wigwam, Bull, and St. Mary rivers and Skookumchuck Creek, is

now considered necessary (EKAMPC 2003). Measures to date have included (1) the

classification of these streams as Class II waters requiring a special licence for non-resident

anglers, (2) the setting of angler use targets for three angler categories: residents, guided non-

2

residents, and non-guided non-residents, and (3) the imposition in 2003 of a temporary

moratorium on issuing new guide licences or increasing guide days on these streams (EKAMPC

2003).

Harvest of westslope cutthroat trout has been highly restricted on East Kootenay region

streams (Appendix 1), and reports of good fishing from most areas have suggested that

population abundance is high within classified waters (Tepper 2008). Given that angling

pressure has increased significantly, however, British Columbia’s MOE was concerned that

mortality or injury resulting from catch-and-release angling may begin to adversely affect

westslope cutthroat trout population dynamics. The effects of repeated capture on the survival,

growth, and spawning success of westslope cutthroat trout in British Columbia are unknown.

There are numerous threats to East Kootenay westslope cutthroat trout populations other than

overexploitation, the effects of which MOE was also concerned with. Consequently, during the

summer of 2008 the BC Ministry of Environment initiated this monitoring study of westslope

cutthroat trout in classified waters of the East Kootenay Region, utilizing snorkeling surveys as

the assessment methodology. Index streams to be included in the study during 2008 were the St.

Mary River, the Wigwam River, and Michelle Creek (Figure 1). Historical calibrated snorkeling

count-based abundance estimates are available for index sections on the St. Mary and Wigwam

Rivers, and all three streams receive relatively high angling pressure each season.

3

British Columbia

Figure 1. Map of the East Kootenay region of British Columbia showing locations of the Wigwam River, Michel Creek, and the St. Mary River.

4

Snorkeling counts as a population monitoring tool

Michel Creek and the Wigwam and St. Mary rivers are clear enough by late summer to

permit highly efficient snorkeling surveys as a population abundance monitoring method.

Snorkeling surveys have been used relatively widely to monitor trout abundance in streams

(Northcote and Wilkie 1963; Schill and Griffith 1984; Slaney and Martin 1987; Young and

Hayes 2001; Hagen and Baxter 2005). However, it must not be assumed that all fish present are

seen or counted accurately. Mark-recapture studies employing snorkeling surveys as the

recapture method have been utilized to independently calibrate population estimates derived

from snorkeling counts. There are only a small number of published accounts, but from these it

appears that system-to-system variability can be high, with species differences and the amount of

instream cover being potential variables that can affect the accuracy of diver counts (Slaney and

Martin 1987; Zubik and Fraley 1988; Young and Hayes 2001).

Fortunately, mark-recapture studies have shown that snorkeling efficiency (the proportion of

fish present that are seen by snorkelers) for westslope cutthroat trout is consistently high relative

to other species (Table 1). Slaney and Martin (1987) estimated snorkeling efficiency for

westslope cutthroat trout greater than 20 cm length to be 74% in the St. Mary River despite

underwater visibility of only 3 m (Table 1), while Zubik and Fraley (1988) found that diver

counts in Montana streams were in good agreement with the mark-recapture estimates at

visibility levels ranging from 4-4.6 m. More recently, observer efficiency estimates for diver

counts of westslope cutthroat trout in the Wigwam and Bull Rivers were 79% at 13 m average

visibility (Baxter and Hagen 2003) and 81% at 12 m visibility (Baxter 2004), respectively.

5

Table 1. Accuracy of snorkeling counts of adult/subadult trout in streams.

Species LocationSnorkeling efficiency

Calibration method Source

Visibility (m)

Westslope CT Flathead River, MT 126% mark-recapture Zubik and Fraley (1988) 4-4.6

Westslope CT St. Mary River, BC 74% mark-recapture Slaney and Martin (1987) 3

Westslope CT Wigwam River, BC 79% mark-recapture Baxter and Hagen (2003) 13

Westslope CT Bull River, BC 81% mark-recapture Baxter (2004) 12

Rainbow trout Similkameen River, BC 59% poisoning Northcote and Wilkie (1963) >8

Rainbow trout Salmo River, BC 54% mark-recapture Hagen and Baxter (2005) 11

Brown trout New Zealand 57%-66% mark-recapture Young and Hayes (2001) 7

Brown trout New Zealand 21%-43% mark-recapture Young and Hayes (2001) 10

Differences in behaviour among the species studied may contribute to the variation among

the observer efficiency estimates. When approached by the line of snorkelers, rainbow trout in

the Salmo River fled laterally as the line of divers approached, then burst upstream through it,

behaviour that could affect counting accuracy (Hagen and Baxer 2005). Young and Hayes

(2001) suggested that brown trout in New Zealand rivers react to divers by moving into cover

when it was available, behaviour which appeared to have a significant effect on snorkeling

efficiency. Snorkeling counts were between 57-66% of the mark-recapture estimates at

approximately 7 m horizontal visibility in one of two New Zealand rivers they studied, and 21-

43% in the other at approximately 10 m visibility. The lower levels of accuracy were found in

the system with more instream cover despite a better level of visibility. In contrast, Schill and

Griffith (1984) and Zubik and Fraley (1988) both indicated that westslope cutthroat trout showed

little reaction to the presence of divers, observations that appear to be true for the subspecies in

the east Kootenay region of British Columbia as well (Baxter and Hagen 2003; Baxter 2004).

This behaviour must certainly be a factor in the relatively high levels of observer efficiency

observed for the studied populations across a range of visibility levels. For westslope cutthroat

trout, it is possible that observer efficiency estimates are less system-specific and more precise

generally, and calibration relationships may be suitable for more general application across the

subspecies’ range.

6

7

Westslope cutthroat trout snorkeling efficiency has previously been estimated for both the

lower St. Mary River and the Wigwam River (Table 1). In this study, we make use of existing

snorkeling efficiency estimates to calibrate 2008 snorkeling counts of trout in these two sys

No investigation of snorkeling efficiency has taken place in either Michel Creek or the uppe

Mary River

tems.

r St.

. For these two systems, we utilize in this report a mean snorkeling efficiency

estimate that is based on all of the previous studies of snorkeling efficiency for the species

(Table 1).

METHODS

n

g

crews during the August 18-22 field trip were comprised of both MOE staff and contractors

f.

3per St. Mary R Km 43.5-Pyramid C 10-Sep 3.60 3

Elk R Hosmer Hwy Br.-Hwy Pull Out 18-Sep 4.90 2

Snorkeling surveys

Snorkeling surveys of index sections in the Wigwam River, Michel Creek, and the St. Mary

River were conducted from August 18 to August 22, 2008 (Table 2). Because the upper St.

Mary River experienced poor viewing conditions on August 22, one of the two index sections i

this reach was re-done on September 10. A section of the Elk River was also snorkelled on

September 18 to assess the feasibility of conducting future surveys in that system. Snorkelin

provided by Mountain Water Research, while September surveys were done by MOE staf

Table 2. Index sections used for snorkeling surveys of westslope cutthroat trout, 2008

Stream Section Date of surveyDistance

surveyed (km)Number of snorkelers

Wigwam R Cattleguard to Fenster C 19-Aug 5.75 2Wigwam R Fenster C to canyon 18-Aug 3.50 2Wigwam R Canyon to Bighorn C 18-Aug 6.50 2Wigwam R Bighorn C to km 42 19-Aug 3.60 3Wigwam R Km 42 to km 36.5 19-Aug 5.10 3Michel C Upper: below Andy Good C 20-Aug 4.00 1Michel C Mid: Bridge to CPR Junction 20-Aug 4.60 2Michel C Lower:1st-2nd HWY bridge 20-Aug 4.80 2Lower St. Mary R Perry C to CPR trestle 21-Aug 3.00 6Lower St. Mary R McPhee bridge to Mission 21-Aug 2.85 6Upper St. Mary R Km 43.5-Pyramid C 22-Aug 3.60 3

pper St. Mary R Pyramid C-Redding C Bridge 22-Aug 3.25UUp

r

the Elk River, Michel Creek, and

the upper St. Mary River were surveyed for the first time.

h

re

y estimating the mean number of 5 m lanes required to cover

the usable width of the stream.

lane

of the snorkelers would walk around the

constriction or drift through behind the others.

their

described elsewhere for organizing snorkelers into lanes, such as marked ropes (Northcote and

Index sections surveyed during previous studies were those in the lower St. Mary River

(Table 2: Slaney and Martin 1987; Oliver 1990; Westover 1994) and those in the Wigwam Rive

(Baxter and Hagen 2003). The index sections established in

The snorkeling methodology described by Hagen and Baxter (2005) was followed wit

minor modifications. One to six snorkelers were utilized to survey index sections. In the

Wigwam River, Michel Creek, and the upper St. Mary River, the entire width of the stream

suitable for trout of >200 mm was surveyed (a survey directed at juvenile fish <200 mm, who a

much more likely to inhabit shallow water unsuitable for downstream drifting, and frequently

exhibit daytime concealment behaviour, was considered to be not feasible). Crew size for each

survey was determined by visuall

Under conditions of good underwater visibility, the “lane” for each snorkeler was 5 m wide

and consisted of the water in front of him and extending 5 m toward shore. Snorkelers in lanes

meeting in the middle of the stream were positioned back to back. When the usable wetted width

of the stream exceeded the total lane width, one or more of the snorkelers would extend his lane

width and look both ways. In areas where the usable width was substantially less than the

width, the number of lanes was reduced and one

To minimize the potential for overcounting, snorkelers only counted fish that were in

lane as the line of snorkelers passed by, but frequent communication was still required to

determine if duplication in counts had occurred. During the implementation of this study we

used previously established methods (Hagen and Baxter 2005) where crew members staggered

their starts in each new habitat unit to account for faster mid-channel velocities, and slowed or

increased their swimming speed where possible to keep the line of snorkelers organized. The

importance of these steps was emphasized repeatedly during the study. We considered methods

8

Wilkie 1963) or PVC pipes (Schill and Griffith 1984), but we considered these impractical given

the length of sections we wished to survey and the turbulent nature of Kootenay region streams.

In stream sections where viewing conditions made fish identification marginal at distances

of 5 m, snorkelers adjusted their position in the lane by moving slightly towards the shore. The

survey of water in front of them was then expanded to include the portion of their lane that

remained outside of their position. This modification of the study protocol ensured that fish

could be identified across the full width of the lane. Snorkelers under these conditions conducted

the survey through the water at a slower rate wherever possible, to permit looking in both

directions.

In the lower St. Mary River, where the width of the stream frequently exceeded 30 m, the

approximate wetted width surveyed by six snorkelers, methods similar to Slaney and Martin

(1987) were employed. Six snorkelers were organized into shore, near-shore, and mid-channel

lanes on each side of the river. The protocol of Slaney and Martin (1987) was modified whereby

snorkelers surveyed 5 m lanes rather than 3 m lanes. The reasons for this were threefold. First,

under the existing visibility conditions snorkelers felt they could adequately count trout in 5 m

lanes, following the methods described above. Second, two 5 m lanes along each bank

encompassed the majority of quality holding water for trout >200 mm at most locations, meaning

extrapolation of the shore and near-shore counts was unnecessary. Finally, the sampling fraction

of the total stream width was increased by approximately 67%, meaning that uncertainty

resulting from the extrapolation of offshore lane counts to unsurveyed parts of the stream was

reduced. The unsurveyed, mid-channel portion of the stream was visually estimated periodically

during the surveys of the two lower St. Mary River stream sections.

All observed fish were identified by species. Westslope cutthroat trout (and rainbow trout,

if present) were classified into one of four size categories: <200 mm, 200-300 mm, 300-400 mm,

and >400 mm. Snorkelers also recorded whether observed fish exhibited injury or scarring from

previous hooking, which typically appeared as bruising of the maxilla and lower jaw, a torn or

missing maxilla, eye injuries (missing or bloodied), and broken-off flies protruding from the

fish’s mouth.

9

Size estimation was practised on models suspended in the water column at the survey start

point on each survey date until no misclassification occurred (Figure 2). If access to the reach

was difficult and the models could not be brought in, snorkelers practised size estimation by

observing fish together and comparing estimates (Figure 3). Horizontal underwater visibility

was recorded two times during each survey by measuring the distance at which a white, 10 cm

by 18 cm dive notebook was no longer identifiable. In the St. Mary River, visibility was also

measure using the models instead of a notebook (Figure 2), to permit a comparison with previous

surveys (Slaney and Martin 1987).

Estimates of westslope cutthroat trout abundance

In this study we were particularly interested in estimating the relative abundance of

westslope cutthroat trout >300 mm, which facilitates comparisons with past surveys and is the

best index of the adult population size. For comparative purposes, analysis of snorkeling count

data in the Wigwam and lower St. Mary rivers utilized previously established methods (Slaney

and Martin 1987; Baxter and Hagen 2003).

Following Baxter and Hagen (2003), the Wigwam River was stratified into three reaches

above Lodgepole Creek: upper (Desolation Creek to Fenster Creek), middle (Fenster Creek to

Bighorn Creek), and lower (Bighorn Creek to Lodgepole Creek). A portion of each reach was

sampled over one or two days (Table 2). The westslope cutthroat trout density estimates from

the sampled lengths were first calibrated using the snorkeling efficiency estimate of 78% (SE =

4.3%) derived from mark-recapture study of Baxter and Hagen (2003; for fish >300 mm), then

applied to the reach as a whole to estimate the population sizes of cutthroat trout >300 mm and

>400 mm. Limits of 95% confidence for the reach density estimates (and population estimates)

were estimated by inserting 95% confidence limits for the snorkeling efficiency estimate into the

above calculation. However, it should be noted that the confidence intervals are underestimates

because two of the three reaches were subsampled, and replication within the reach was

insufficient to account for spatial variation in densities. Mean cutthroat trout density for the

Wigwam system was estimated as the total population estimate divided by the total stream length

between Desolation and Lodgepole creeks.

10

Figure 2. Models used to practice size estimation prior to conducting snorkeling surveys.

Visibility to the models was also measured in the lower St. Mary River.

Figure 3. Adult westslope cutthroat trout in the Wigwam River. Where it was impractical to

bring models into a survey section, snorkelers practiced size estimation by observing individual fish together and comparing size estimates.

11

For the two index sections in the lower St. Mary River (Table 2), counts from the two mid-

channel lanes were expanded to account for unsurveyed, off-shore areas of the river (Slaney and

Martin 1987). The necessary expansion factor was calculated based on measurements of stream

width for the index sections made during previous surveys (Westover 1994), with visual

estimates of the unsurveyed stream width made during this study (see above) used for

corroboration. The expansion factor was calculated by first subtracting 20 m (for four lanes of

shore and near-shore snorkelers) from the mean width of the river in the index section, to

estimate the mean width of mid-channel habitat, then dividing this value by the 10 m made up by

the two mid-channel lanes. Expanded mid-channel counts were combined with unadjusted shore

and near-shore counts into the total expanded count. To calculate the population estimate for the

index section, the total expanded count was factored together with the estimated mean snorkeling

efficiency of 74% (Slaney and Martin 1987). Limits of 95% confidence for the population

estimates were based on corresponding limits of confidence for the snorkeling efficiency

estimate, which we derived from replicate expanded counts and mark-recapture population

estimates (Slaney and Martin 1987) using the method of Monte Carlo simulation (Haddon 2001).

Mean density for the lower St. Mary River was estimated as the total population estimate divided

by the total surveyed length, for both sections combined.

For Michel Creek and the upper St. Mary River, mean cutthroat trout densities >300 mm

were estimated based on the total population estimate from the survey sections (Table 2) that had

been adjusted by a generalized snorkeling efficiency estimate. The generalized snorkeling

efficiency estimate was derived from the four westslope cutthroat trout studies in which

snorkeling efficiency had been estimated previously (Table 1), and was high and relatively

imprecise (90%, SE = 24%) due to the obvious overcounting in Zubik and Fraley (1988). Limits

of 95% confidence for the study section density estimates (and population estimates) were

estimated using 95% confidence limits for the snorkeling efficiency estimate. Westslope

cutthroat trout density estimates were not calculated for the Elk River survey because snorkelers

felt 7-8 snorkelers would be required (only 2 were utilized; Table 2).

12

RESULTS

Wigwam River

Underwater visibility during 2008 snorkeling in the Wigwam River ranged from 10.1-12.0

m, averaging 11.4 m over all sections (Appendix 2). Visibility was more variable in these

sections (10.4-15.0 m) during the mark-recapture study of 2001, and slightly higher on average

(13.0 m; Baxter and Hagen 2003). We considered the visibility conditions to be excellent

(Figure 3), and therefore utilized the 2001 snorkeling efficiency estimate of 79% (Table 1) to

expand counts of trout in the Wigwam River (Appendix 2) into population estimates.

For the purpose of direct comparison with results from previous work, we calculated

population estimates for the index sections (Table 3), and for the three reaches in the upper

Wigwam system between Desolation and Lodgepole Creeks (Table 4) that had been previously

identified (Baxter and Hagen 2003). Population estimates for snorkeling survey sections

upstream of Bighorn Creek were in most cases higher in 2008 than in either 2001 or 2002. In

contrast, population estimates for sections downstream of Bighorn Creek were lower in 2008

(Table 3). When compared with upstream reaches in 2008, the Bighorn Creek to Lodgepole

Creek reach still had the highest densities of westslope cutthroat trout >300 mm and >400 mm

(Table 4), but a shift in fish densities favouring upstream reaches appears to have occurred since

2001/2002 (Figure 4).

Overall, the estimated westslope cutthroat trout population size for the 42.1 km of the

Wigwam River between Desolation and Lodgepole creeks was 701 >300 mm and 189 >400 mm

(note: latter estimate is included in the former). These estimates are comparable to previous

estimates of 796 and 175 for 2001 and 611 and 171 for 2002, for trout >300 mm and >400 mm,

respectively. Estimated mean densities for the entire section between Desolation and Lodgepole

creeks were 16.7 trout >300 mm and 4.5 trout >400 mm/km. The proportion of fish >400 mm in

this part of the watershed in 2008 was estimated to be 27%, comparable to estimates of 22% and

28% for 2001 and 2002, respectively (Baxter and Hagen 2003).

13

Table 3. Westslope cutthroat trout population estimates for index sections of the Wigwam River, 2001, 2002, and 2008. Sections are in order of furthest upstream to furthest downstream.

length >300 mm >400 mmSection Year (km) count N LCL UCL count N LCL UCLHenry's to Fenster C* 2001 7.5 na na

2002 35 44 40 49 12 15 14 172008 53 67 61 75 18 23 21 25

Fenster C to canyon 2001 3.8 48 61 55 67 11 14 13 152002 28 35 32 39 7 9 8 102008 64 81 74 90 14 18 16 20

Canyon to Bighorn C 2001 6.5 na na2002 45 57 52 63 10 13 12 142008 59 75 68 83 19 24 22 27

Bighorn C to km 42 2001 3.6 74 94 85 104 24 30 28 342002 76 96 88 107 17 22 20 242008 60 76 69 84 15 19 17 21

Km 42 to km 36.5 2001 5.1 147 186 169 207 23 29 26 322002 130 165 150 183 41 52 47 582008 101 128 116 142 22 28 25 31

* Note: an expansion factor of 1.3 was factored with 2008 counts to make section lengths equivalent

Table 4. Population estimates for westslope cutthroat trout in reaches of the Wigwam River between Desolation and Lodgepole creeks, 2001, 2002, and 2008. Reaches are in order of furthest upstream to furthest downstream.

2001 2002 2008 2001 2002 2008 2001 2002 2008Total reach length (km) 17.4 10 14.7Distance surveyed (km) 3.5 17.4 5.8 3.8 10 10 8.7 8.7 8.7Count >300 mm 26 62 53.0172 48 73 123 221 206 161Count >400 mm 6 20 18 11 17 33 47 58 37Expanded count >300 mm 33 78 67 61 92 156 280 261 204Expanded count >400 mm 8 25 23 14 22 42 59 73 47Density >300 mm 9.4 4.5 11.6 16.0 9.2 15.6 32.2 30.0 23.4Density >400 mm 2.2 1.5 3.9 3.7 2.2 4.2 6.8 8.4 5.4N >300 mm 164 78 201 160 92 156 473 441 344N >400 mm 38 25 68 37 22 42 101 124 79

Desolation-Fenster Fenster-Bighorn Bighorn-Lodgepole

14

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Desolation-Fenster Fenster-Bighorn Bighorn-Lodgepole

Trou

t >30

0 m

m/k

m

200120022008

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Desolation-Fenster Fenster-Bighorn Bighorn-Lodgepole

Reach

Trou

t >40

0 m

m/k

m

200120022008

a)

b)

Figure 4. Density estimates for westslope cutthroat trout a) >300 mm/km and b) >400 mm/km for reaches of the Wigwam River. Reaches are left to right in order of furthest upstream to furthest downstream. Error bars denote confidence intervals for mean density within index sections - replication within reaches was insufficient to to allow the incorporation of spatial variation in densities.

15

Michel Creek

The highly productive nature of Michel Creek probably influenced water clarity during

surveys, as underwater visibility averaged only 5.8 m (SE = 0.72 m) among stream sections

(Table 2). Michel Creek is however a very small stream without extensive deepwater areas, and

snorkelers therefore felt that visibility was adequate for snorkeling surveys.

Westslope cutthroat trout abundance, which we estimated from the count data (Appendix 2)

and the generalized snorkeling efficiency estimate (see Methods) of 90%, was exceptionally high

given Michel Creek’s small size. Among the three sampling sections, the density of westslope

cutthroat trout >300 mm ranged from 25-65 trout/km and averaged 46 trout/km, while the

density of trout >400 mm ranged from 5-29 trout/km and averaged 16 trout/km (Table 5). This

indicates that an impressive 37% of trout >300 mm were in the >400 mm size category. For both

size categories the highest densities were found in the middle section surveyed, located a

relatively short distance upstream of the easternmost Highway 3 crossing. This section also

appeared to have significantly greater angler use relative to upstream and downstream sections

that were surveyed.

Based on the mean density estimates from the three sites, and a map-based estimate of the

total stream length between Andy Good Creek and the Elk River of 36.7 km, total population

sizes in Michel Creek were roughly 1704 and 611 for westslope cutthroat trout >300 mm and

>400 mm, respectively (Table 5).

Table 5. Estimated density of westslope cutthroat trout >300 mm and >400 mm per km, Michel Creek 2008.

DistanceSurveyed section surveyed Density LCL UCL Density LCL UCLUpper: below Andy Good C 4.0 25 5.0Mid: Bridge to CPR Junction 4.6 65 29Lower:1st-2nd Hwy bridge 4.8 49 16Overall 13.4 46 22 71 17 11 35

Total stream length below Andy Good C (km) 36.7Population estimate N 1704 807 2602 611 400 1291

Westslope cutthroat trout >300 mm Westslope cutthroat trout >400 mm

16

St. Mary River

Based on previous stream width measurements for the two lower St. Mary River index

sections (Westover 1994), the mean unsurveyed width of mid-channel habitat was estimated to

be 12 m for the upper section (Perry Creek to the CPR trestle) and 16 m for the lower section

(McPhee Bridge to Mission). Mid-channel lane counts (Appendix 2) were expanded based on

these estimates, and the total expanded count for each section was factored together with the

74% snorkeling efficiency estimate (Slaney and Martin 1987) to generate population estimates

for size categories >200 mm (Table 6).

Table 6. Counts and population estimates for westslope cutthroat trout in index sections of the lower St. Mary River, August 2008.

<200 mm 200-300 300-400 >400Perry C to CPR trestleShore and near-shore 20 43 58 22Center lanes 1 7 9 1Expanded center lanes 2 16 20 2Expanded count 22 59 78 24Expanded count*1.35 na 79 105 33N >200 217 LCL: 178 UCL: 277N >300 138 LCL: 113 UCL: 176

McPhee bridge to MissionShore and near-shore 28 47 65 14Center lanes 1 1 2 1Expanded center lanes 3 3 5 3Expanded count 31 50 70 17Expanded count*1.35 na 67 95 22N >200 184 LCL: 151 UCL: 235N >300 117 LCL: 96 UCL: 150

Westslope cutthroat trout

It should be noted that underwater visibility in the lower St. Mary River averaged 5.2 m

during surveys on August 21, and 4.2 m when measured to models (Figure 3). This exceeds the

visibility estimate of 3 m for Slaney and Martin (1987), but in the earlier study snorkelers

compensated for lower visibility by counting in narrower (3 m) lanes. In our study, the two

shore and near-shore lanes, in which counts were not expanded, accounted for the majority of

17

westslope cutthroat trout seen in all size categories (Table 6), suggesting that the distribution of

the six lanes across the stream width was optimal.

Westslope cutthroat trout density estimates for the lower St. Mary River are available for

several years in the 1982-1994 period (Table 7, Figure 5). Westslope cutthroat trout appear to

have recovered significantly from low abundance in the late 1980s/early 1990s (Oliver 1990;

Westover 1994), but the very high density estimate for 1982 also suggests that the carrying

capacity of the lower St. Mary River may be much higher than indicated by the current trout

density. It should be noted that density estimates for 1982 and 1989 (Table 7, Figure 5) were

based on sampling data from seven and six index sections, respectively (Oliver 1990), and may

not be directly comparable to the 1984, 1990, and 1994 estimates based on the same index

sections used in this study. However, given that the 1989 survey based on six index sections

appears to be corroborated by the estimate for the following year, which employed the same two

index sections used in our study, it appears likely that 1982 westslope cutthroat trout densities in

the lower St. Mary River were significantly greater than current population levels.

Table 7. Estimated density of westslope cutthroat trout >300 mm for the lower St. Mary River, 1982-2008.

Density nYear (trout >300 mm/km) (snorkeling sections) Source1982 77 7 Table 7, Oliver (1990)1984 45 1 Table 6 (Slaney and Martin 1987)1989 20 6 Table 8, Oliver (1990)1990 17 2 Westover, 19941994 32 2 Westover, 19952008 44 2 This study

The total length of the lower St. Mary River was estimated in Oliver (1990) to be 54.1 km.

Extrapolating the 2008 density estimate of 44 westslope cutthroat trout >300 mm/km to this

entire distance gives an estimate of 2,360 for the total population size. This may not be entirely

reasonable, given that only two index sections were sampled.

18

0

20

40

60

80

100

120

1982 1984 1989 1990 1994 2008

Trou

t >30

0 m

m/k

m

Figure 5. Density estimates for westslope cutthroat trout >300 mm in index snorkeling sections of the lower St. Mary River, 1982-2008. Error bars denote confidence intervals for mean density within index sections - replication in most years was insufficient to allow the incorporation of spatial variation in densities within the reach.

By August 22, 2008, the upper St. Mary River appeared to have risen significantly as a

result of heavy rain over the preceding 48 hours. Flows were so swift that snorkelers had a

relatively brief time to identify fish at any one location, and fish themselves appeared to have

shifted their positions, often into lower visibility areas of heavy cover. Snorkelers conducted

surveys of two index sections (Appendix 2), but did not consider their counts to be reliable. As a

result, snorkeling counts in one of the index sections were re-done on September 11 under good

viewing conditions (underwater visibility = 16.7 m). Counts of trout were significantly higher

than on August 22 (Appendix 2), confirming our notion that the earlier counts should be

disregarded. Densities of westslope cutthroat trout >300 mm in the upper St. Mary River index

section were 13.6 fish/km (Table 8). Sampling from other locations is required before density

estimates can be used to estimate the size of the westslope cutthroat trout population of the upper

St. Mary River.

19

Trout >400 mm made up 20% and 22% of the total estimated populations of cutthroat >300

mm in the upper and lower St. Mary River index sections, respectively. This is a slightly lower

proportion of larger fish than seen in the Wigwam River and Michel Creek (27% and 37%,

respectively).

Table 8. Estimated density of westslope cutthroat trout in the upper St. Mary River, 2008.

200-300 mm 300-400 mm >400 mm >300 mmMean density 21 11 2.8 14UCL 44 23 5.9 6.4LCL 14 7.1 1.8 21

Westslope cutthroat trout

Elk River

The snorkeling survey of the Elk River on September 18 was conducted to assess the

feasibility of future surveys. Visibility observed during the survey (7.7 m) was probably the

minimum necessary for snorkeling surveys in 5 m lanes. Seven to eight snorkelers may be

required to adequately survey this relatively large river, however. Although density estimates for

the Elk River cannot be made, unadjusted counts from the feasibility swim suggest a very high

density of westslope cutthroat trout, and of very large cutthroat trout, in this system. Two

snorkelers surveyed 4.9 km of the Elk River and counted 192 westslope cutthroat trout >300

mm, of which an impressive 56% were >400 mm (Appendix 2).

Density comparison

Comparing the streams surveyed in 2008 reveals sharp contrast in the density estimates for

westslope cutthroat trout >300 mm. The upper St. Mary and Wigwam rivers are significantly

less productive for westslope cutthroat trout than are Michel Creek and the lower St. Mary River

(Figure 6). The very small size of Michel Creek (it was wadable at any point along its length

during the August survey) suggests that the density of catchable trout is even more exceptional.

Although density estimates for the Elk River cannot reasonably be made, the unexpanded

number of fish counted on the feasibility survey, which at 39 trout >300 mm/km is comparable

to estimated densities for the lower St. Mary River and Michel Creek, suggest that fish

abundance in this system is significantly greater than in the other streams surveyed.

20

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Lower St. Mary Upper St. Mary Wigwam aboveLodgepole C

Michel belowAndy Good C

Trou

t >30

0 m

m/k

m

Figure 6. Mean calibrated density estimates for westslope cutthroat trout >300 mm among index snorkeling sections, for streams surveyed during this study in 2008. Note that error bars denote confidence intervals for mean density within index sections, and that uncertainty for density estimates in the upper St. Mary River and Michel Creek are inflated due to the lack of snorkeling efficiency studies on these systems (see Methods).

Hooking injury

Visual estimates of hooking injury are by nature underestimates – hooking injury can occur

on one or both sides of the face, and scarring or bruising on the unseen side of a trout will be

missed. There is a further, more important limitation of the data. Unfortunately, estimates of

hooking injury cannot be compared very well among systems. In the St. Mary River, most fish

could not be assessed for hooking injury because of the water depth – most fish were seen from

above, or at a distance when seen from the side, so inspections of the side of the fish’s face for

scarring or bruising were usually not possible. In the Wigwam River and Michel Creek,

however, hooking injury, which included bruising of maxillae and lower jaws, torn or missing

maxillae, eye injuries (missing or bloodied), and broken-off flies protruding from mouths, could

be easily seen and was obviously widespread. Evidence of hooking injury in the Wigwam River,

for westslope cutthroat trout >300 mm, ranged from a low of 15% in the Canyon-to-Bighorn

Creek section, for trout 300-400 mm, to a high of 66% for trout 300-400 mm in the Fenster

21

Creek-Canyon section (Table 9). Evidence of hooking injury was significantly greater in Michel

Creek, and for fish >300 mm ranged from a low of 40% for trout of 300-400 mm in the upper

section below Andy Good Creek to a remarkable high of 94% for trout >400 mm in the middle

section upstream of Highway 3 (Table 9). Although not quantified, hooking damage observed in

Michel Creek was frequently more severe, as well, and some fish appeared unlikely to survive

their injuries (e.g. broken or dislocated lower jaws).

Table 9. Evidence of hooking injury to westslope cutthroat trout among snorkeling index sections, 2008.

Stream Surveyed section <200 mm 200-300 mm 300-400 mm >400 mmWigwam R Cattleguard to Fenster C - 25% 44% 50%Wigwam R Fenster C to canyon 0% 29% 66% 64%Wigwam R Canyon to Bighorn C 3% 8% 15% 26%Wigwam R Bighorn C to km 42 0% 5% 31% 53%Wigwam R Km 42 to km 36.5 0% 16% 41% 50%Michel C Upper: below Andy Good C - 41% 40% 67%Michel C Mid: Bridge to CPR Junction 54% 76% 92% 94%Michel C Lower:1st-2nd HWY bridge - 24% 46% 66%St. Mary R Perry C to CPR bridge - 6% 3% 17%St. Mary R McPhee bridge to Mission - 2% 15% 13%St. Mary R Above Pyramid C - 0% 9% 0%St. Mary R Pyramid C-Redding C Bridge - 0% 0% 0%St. Mary R Km 43.5-Pyramid C - - - -

Evidence of hooking injury

Other salmonids

The only sections surveyed where non-native rainbow trout were not observed were the

upper St. Mary River and the Elk River (Table 10). Rainbow trout were present in low numbers

in the Wigwam River and Michel Creek. A total of nine rainbow trout (across all size

categories) were observed in the Wigwam River. Juveniles <200 mm were not seen, and all but

one were seen downstream of the Bighorn Creek confluence. Twenty-two rainbow trout were

counted in Michel Creek, including two juveniles of <200 mm. The majority of rainbow trout

were observed in the middle section upstream of Highway 3. Rainbow trout were observed in

the lower St. Mary River (Table 10), but their relative abundance was probably underestimated

significantly. Similar to the survey of hooking injury, most fish were seen from above, or at a

22

distance when seen from the side, and differentiating cutthroat and rainbow trout was frequently

not possible.

Table 10. Counts of rainbow trout in index sections snorkelled during 2008.

Stream Section Date <200 200-300 300-400 >400Wigwam R Cattleguard to Fenster C 18-Aug 0 0 0 0Wigwam R Fenster C to canyon 18-Aug 0 0 0 0Wigwam R Canyon to Bighorn C 19-Aug 0 1 0 0Wigwam R Ram C to km 42 19-Aug 0 1 1 0Wigwam R Km 42 to km 36.5 19-Aug 0 1 2 3Michel C Upper: below Andy Good C 20-Aug 1 0 0 0Michel C Mid: Bridge to CPR junction 20-Aug 0 17 2 0Michel C Lower:1st-2nd Hwy bridge 20-Aug 1 0 1 0St. Mary R Perry C to CPR trestle 21-Aug 1 0 1 0St. Mary R McPhee bridge to Mission 21-Aug 0 1 6 4St. Mary R Km 43.5-Pyramid C 22-Aug 0 0 0 0St. Mary R Pyramid C-Redding C Bridge 22-Aug 0 0 0 0St. Mary R Km 43.5-Pyramid C 10-Sep 0 0 0 0Elk R Hosmer Hwy Br-Hwy Pull Out 18-Sep 0 0 0 0

Rainbow trout size category (mm)

Hundreds of bull trout spawners were present in the Wigwam River, the most important bull

trout spawning tributary for Koocanusa Reservoir. Counts were not attempted because of their

potential to distract snorkelers from westslope cutthroat trout counts and injury assessment.

Mountain whitefish were also present in low numbers in the Wigwam River (Appendix 2).

Hundreds of mountain whitefish were present in the lower St. Mary River, and counts were

not attempted. Four adult bull trout were observed in the lower St. Mary index sections, as were

nine eastern brook trout. Six bull trout >300 mm were seen in the upper St. Mary index section,

and a single eastern brook trout was seen during the previous survey of the same section made

under poor viewing conditions (Appendix 2). Mountain whitefish were not present in the upper

St. Mary index sections.

Juvenile and adult mountain whitefish were both highly abundant in Michel Creek

(Appendix 2). A total of 27 bull trout, mostly of adult size, were observed, but only in the lower

and middle sections. A total of 24 eastern brook trout, including juveniles and adults, were also

counted in Michel Creek. These were observed only in the upper section below Andy Good

Creek.

23

Mountain whitefish were very abundant in the Elk River, and over 2,000 were estimated to

have been observed in the two lanes surveyed. A total of 22 bull trout were observed by the two

snorkelers, with 11 being large fish >500 mm in length.

DISCUSSION AND RECOMMENDATIONS

Monitoring population status in catch and release fisheries

The capture and release of westslope cutthroat trout by anglers has obvious physical effects

to fish, as evidenced by facial bruising and injury observed during this study. Additionally, not

all fish survive capture and release, with typical salmonid hooking mortality being 3-5%

(Marnell et al. 1970; Schisler and Bergesen 1996). Cutthroat trout in popular streams may be

caught many times during a season. For example, a 1981 study on a 4.5 km section of the

Yellowstone River reported that cutthroat trout were caught an average of 9.7 times during the

angling season (Schill et al. 1986). In another example, a 400 mm, radio-tagged male cutthroat

trout in the Wigwam River was caught three times by the same angler over a period of three days

(Baxter and Hagen 2003). When considered over the entire season, therefore, the mortality rate

due to hooking may be substantially higher than just 3-5%.

There is strong evidence to suggest that westslope cutthroat trout in the lower St. Mary

River are doing better in a popular catch-and release fishery than they were in the late 1980s,

when a harvest of two fish >300 mm was permitted (Figure 5, Appendix 1). However, is there a

point at which the effect of catch-and-release fisheries becomes significant for the population

dynamics of a system? Ultimately, negative effects on fish growth, fecundity, and survival from

a catch-and-release fishery will become problematic when they result in a declining population.

Monitoring of population abundance, therefore, is important for evaluating the cumulative

effects of catch-and-release management on trout population dynamics. Monitoring is of course

also important for evaluating the long-term effects of other threats to westslope cutthroat trout

populations, including habitat loss and degradation, and competition and introgressive

hybridization with introduced rainbow trout.

24

The foresight of previous workers in establishing methods for population monitoring in

index sections of East Kootenay region streams has allowed us to compare current westslope

cutthroat trout population density estimates to estimates from as long ago as 1982 (Figure 5).

For these indices of abundance to be sensitive to changes in westslope cutthroat trout population

status, population density estimates must be reliable (relatively precise). Mark-recapture studies

of snorkeling efficiency on the lower St. Mary River (Slaney and Martin 1987) and on the

Wigwam River (Baxter and Hagen 2003) have indicated that population abundance in index

sections can indeed be estimated with reasonable precision, and provide the basis for our

population estimation methods for these two systems. However, estimates of the accuracy and

precision of snorkeling counts in the upper St. Mary River and Michel Creek, the other stream

sections surveyed during this study, have not been made, resulting in inflated levels of

uncertainty for population density estimates (Figure 6). We recommend, therefore, that mark-

recapture estimation of snorkeling efficiency take place within these systems during the next

round of population monitoring. Marking of fish captured by angling should take place in the

two weeks prior to the scheduled survey date, and be limited to a defined, middle portion of the

index section that is significantly shorter than the total section length (to allow for limited

movement between marking and subsequent snorkeling survey for marks).

Monitoring of the same index sections in each year reduces variability in the index

associated with spatial variation in fish density. To be able to monitor shifts in abundance from

one stream section to another, however, which may occur even under stable levels of total

abundance (as appears to have happened in the Wigwam River from 2001-2002 to 2008; Figure

4), more than one index section is required per stream. Three to four sections spaced

systematically along the reach of interest should probably be a minimum goal. In future,

therefore, we recommend that two to three additional sampling sections be established in the

upper St. Mary River to better characterize population distribution and abundance. Two, three

kilometre-long sections could be surveyed by each three-person crew, meaning that snorkeling

surveys of the reach could be completed in a single day. Additional sites in the lower St. Mary

River may also be warranted. The important series of density estimates utilizing the same two

sections used during our study, however, argues for retaining the current index section within

any expanded sampling program.

25

For the purpose of future monitoring of westslope cutthroat trout population status, we also

recommend that monitoring methods and an abundance baseline be established as soon as

possible for other classified waters in the region: upper Kootenay River, White River,

Skookumchuck Creek, and the Elk River. A mark-recapture study of snorkeling efficiency and

westslope cutthroat trout abundance has been completed already for the Bull River (Baxter

2004).

Westslope cutthroat trout appear to be uniquely well suited to snorkeling surveys, and

snorkeling count accuracy has routinely been high in past studies (Table 1). However, even with

population monitoring, annual stochastic variation in abundance may mask important changes in

the population status, and significant declines in abundance may need to occur before managers

become aware that a problem exists. It may be possible to acquire some advance indication that

population dynamics have changed from biological sampling (scales, maturity status, size,

fecundity). The data can either form a baseline for future comparisons, or be compared with

similar data collected already during past sampling. For example, back-calculated length-at-age

estimates from scale samples, as well as estimates of age and size of first maturity, exist for

Wigwam River cutthroat trout in 2001 (Baxter and Hagen 2003). Such sampling would ideally

be combined with the tagging of fish prior to snorkeling surveys in the future, in which mark-

recapture estimates of snorkeling efficiency could be acquired along with counts of trout.

Contribution of monitoring to management of classified waters

Obviously, if a population is in decline because of overexploitation, or negative population

growth rate caused by a catch-and-release fishery, the associated fishery will degrade in quality

over time. However, in the case where cutthroat trout abundance has not declined, but fish are

repeatedly captured and released during the season, does the fishery degrade because of reduced

catchability of the fish? We assume there is a relationship between the number of times a fish

has been caught and its future catchability, but are unaware of whether such relationships have

been documented.

26

For classified waters of the East Kootenay region, monitoring data may provide

complimentary information that helps interpret quality-of-experience information provided by

river guardian creel survey reports, counterfoil data from classified waters licences sold in 2005

and 2006, and angling guide reports (Tepper 2008). Monitoring data from 2008 can be useful

already in considering questions raised in the 2008 status report for angler use on East Kootenay

classified waters (Tepper 2008).

The perception of resident anglers, guides, and non-resident anglers alike is that the

Wigwam River is very crowded, and the trend suggested by angler interviews is toward a lower

quality angling experience (Tepper 2008). Based on classified waters licence counterfoil data,

1,103 and 1,084 non-resident angler days were spent on the Wigwam River in 2005 and 2006,

respectively, which exceed the target allocation (EKAMPC 2003) by roughly 230%. The recent

trend in catch-per-unit-effort (CPUE) is downward, which has raised concerns that the westslope

cutthroat trout population may have been impacted by heavy angling pressure (Tepper 2008).

Results from the 2008 monitoring study can provide some indication of whether impacts

have occurred. First, evidence of hooking injury is obvious and widespread among westslope

cutthroat trout in the Wigwam River (Table 9). Second, although trout abundance appears to

have shifted towards upstream areas relative to 2001 and 2002 (Figure 4), overall the population

does not appear to have declined compared to 2001/2002 (see Results). It is encouraging that

high angling pressure does not appear to have caused a population decline. However, this also

supports the notion that the catchability of fish has declined instead, and the fishery may be

degrading as a result of crowded conditions.

Michel Creek is also perceived to be crowded, but this perception is primarily held by local

resident anglers (Tepper 2008). Recently, the large majority of anglers using the system have

been non-residents. All anglers in 2008 considered the fishery to be a high or excellent quality

angling experience, and the CPUE was a very high 1.7 fish/hour, which is only slightly down

from the peak of 2.0 fish/hour recorded for 2006 (Tepper 2008).

27

Michel Creek is truly a special stream. Results from our study indicate a remarkable density

of westslope cutthroat trout (Figure 6) and of large fish >400 mm. Given that the stream also is

highly accessible, and has wadable flows, it would be a shame to see it degraded due to

overcrowding. Although this very high density of trout supports a high CPUE, evidence of

hooking injury was more extensive than even the Wigwam River (Table 9). In our view, this

supports the perception of the local resident anglers that angling pressure is too high, and special

management actions may be warranted.

On the lower St. Mary River, CPUE has dropped from a peak of 1.8 fish/hour in 2005 to less

than half this (0.8 fish/hour) in 2008 (Tepper 2008). However, 79% of anglers considered the

stream to be ‘not at all crowded.’ Guided days have actually been decreasing on this system

since a peak in 2004.

The comparison of the 2008 mean density estimate for the lower St. Mary River to estimates

for previous years has suggested that abundance has been significantly higher in the past (see

Results), with the 1982 density estimate almost double that of 2008 (Figure 5). It appears,

therefore, that reduced abundance of westslope cutthroat trout in the lower St. Mary River, and

not reduced catchability, may be behind recent declines in CPUE. If the system is indeed

uncrowded, population declines appear unlikely to be related to the catch-and-release fishery,

and some other factor is probably at work.

28

REFERENCES

Allendorf, F. W., and R. F. Leary. 1988. Conservation and distribution of genetic variation in a

polytypic species, the cutthroat trout. Conservation Biology 2:170184. Baxter, J. S., and Hagen, J. 2003. Population size, reproductive biology, and habitat use of

westslope cutthroat trout (Oncorhynchus clarki lewisi) in the Wigwam River watershed. Consultant report prepared for BC Ministry of Water, Land, and Air Protection and BC Ministry of Sustainable Resource Management, Nelson, BC, and Tembec Industries Inc, Cranbrook, BC.

Baxter, J. S. 2004. Westslope cutthroat trout studies in the upper Bull River: preliminary

surveys conducted in Fall 2003. BC Hydro, Castlegar, BC. Benhke, R.J. 1979. The native trouts of the genus Salmo of western North America. Report to

the U.S. Fish and Wildlife Service, Denver Colorado. East Kootenay Angling Management Plan Committee. 2003. Status report: East Kootenay

angling management plan. Report prepared for BC Ministry of Water, Land, and Air Protection, Nelson, BC.

Hagen, J. and J. S. Baxter. 2005. Accuracy of diver counts of fluvial rainbow trout relative to

horizontal underwater visibility. North American Journal of Fisheries Management 25:1367-1377.

Haddon, M. 2001. Modeling and Quantitative Methods in Fisheries. Chapman and Hall/CRC,

Florida. Liknes, G. A. 1984. The present status and distribution of the westslope cutthroat trout (Salmo

clarki lewisi) east and west of the Continental Divide in Montana. Montana Dept. of Fish, Wildlife, and Parks, Helena.

Liknes, G. A., and P. J. Graham. 1988. Westlope cutthroat trout in Montana: Life history, status

and management. American Fisheries Society Symposium 4:53-60. MacPhee, C. 1966. Influence of differential angling mortality and stream gradient on fish

abundance in a trout-sculpin biotope. Trans. Am. Fish. Soc. 95:381-387. Marnell, L. F., and D. Hunsaker. 1970. Hooking mortality of lure-caught cutthroat trout (Salmo

clarki) in relation to water temperature, fatigue and reproductive maturity of released fish. Transactions of the American Fisheries Society 99:684-688.

Mayhood, D. W. 1999. Provisional evaluation of the status of westslope cutthroat trout in

Canada. Proceedings of the Biology and Management of Species and Habitats at Risk, Kamploops, B.C.

29

McIntyre, J. D., and B. E. Rieman. 1995. Westslope cutthroat trout. Pages 1-15 in M. K. Young, editor. Conservation assessment for inland cutthroat trout. U.S. Forest Service General Technical Report RM-256.

McPhail, J. D. 2007. The Freshwater Fishes of British Columbia. University of Alberta Press,

Edmonton, AB. Northcote, T. G., and D. W. Wilkie. 1963. Underwater census of stream fish populations.

Transactions of the American Fisheries Society 92:146-151. Oliver, G.G. 1989. A management strategy for stream resident salmonid fisheries in the

Kootenay Region. BC Ministry of Environment, Fisheries Branch, Cranbrook. Oliver, G.G. 1990. Investigations on the status of westslope cutthroat trout (Oncorhynchus

clarki lewisi) in the lower St. Mary River (1980-89). BC Ministry of Environment, Fisheries Branch, Cranbrook.

Rieman, B.E., and K.A. Apperson. 1989. Status and analysis of salmonid fisheries: westslope

cutthroat trout synopsis and analysis of fishery information. Idaho Department of Fish and Game, Boise. Job Performance Report, Project F-73-R-11, Subproject II, Job 1.

Shepard, B. B., B. Sanborn, L. Ulmer, and D. D. Lee. 1997. Status and risk of extinction for

westslope cutthroat trout in the Upper Missouri River Basin, Montana. North American Journal of Fisheries Management 17:1158-1172.

Schill, D. J. and J. S. Griffith. 1984. Use of underwater observations to estimate cutthroat trout

abundance in the Yellowstone River. North American Journal of Fisheries Management 4:479-487.

Schill, D. J., J.S. Griffith, R.E. Gresswell. 1986. Hooking Mortality of Cutthroat Trout (Salmo

clarki bouveri) in a catch and release segment of Yellowstone River in Yellowstone National Park, Wyoming, U.S.A. North American Journal of Fisheries Management 6(2):226-232.

Schisler, G. J. and E. P. Bergersen. 1996. Post-release hooking mortality of rainbow trout caught

on scented artificial baits. North American Journal of Fisheries Management 16(3):570-578. Slaney, P. A. and A. D. Martin. 1987. Accuracy of underwater census of trout populations in a

large stream in British Columbia. North American Journal of Fisheries Management 7:117-122.

Tepper, H. 2008. 2008 status report on angler use for the seven classified waters in Region 4.

BC Ministry of Environment, Fisheries Program, East Kootenay Region, Cranbrook, BC. Trotter, P.C., B. McMillan, N. Gayeski, P. Spruell, and R. Berkley. 1999. Genetic and

phenotypic catalog of native resident trout of the interior Columbia River Basin -

30

31

Populations of the upper Yakima River basin. Report to Bonneville Power Administration, Contract No. 98AP07901, Project No. 9802600.

Trotter, P.C., B. McMillan, N. Gayeski, P. Spruell, and M.K. Cook. 2001. Genetic and

phenotypic catalog of native resident trout of the interior Columbia River Basin - Populations in the Wenatchee, Entiat, Lake Chelan, and Methow River drainages. Report to Bonneville Power Administration, Contract No. 00004575, Project No. 199802600.

Westover, B. 1994. Memorandum to file: St. Mary River Swim. BC Ministry of Environment,

Cranbrook, BC. Young, R. G., and J. W. Hayes. 2001. Assessing the accuracy of drift-dive estimates of brown

trout (Salmo trutta) abundance in two New Zealand Rivers: a mark-resighting study. New Zealand Journal of Marine and Freshwater Research 35:269-275.

Zubik, R. J., and J. J. Fraley. 1988. Comparison of snorkel and mark-recapture estimates for

trout populations in large streams. North American Journal of Fisheries Management 8:58-62.

APPENDIX 1. REGION 4 (EAST KOOTENAY) FRESHWATER STREAM REGULATIONS HISTORY General Stream Regulation History: (only changes to regulations are noted) General Regs prior to 1981

• Aggregate trout/char over 50cm fork length (Daily=2, Possession=6) • Aggregate trout/char other (Daily=8, Possession=24)

General Regs 1980/1981

• Aggregate trout/char over 50cm fork length (Daily=2, Possession=4) • Aggregate trout/char other (Daily=8, Possession=16) • WCT in streams and lakes(Daily=4, Possession=4)

General Regs 1984/1985

• WCT in streams (Daily=2, Possession=4) • Trout/char closure in all streams of Region 4 except Columbia River and Kootenay River

below White River confluence from Nov 1 to June 14. General Regs 1985/1986

• Aggregate trout/char over 50cm fork length (Daily=1, Possession=2) • Aggregate trout/char over 30cm in streams (Daily=2, Possession=4) • Aggregate trout/char in streams (Daily=4, Possession=8)

General Regs 1994-1996

• Trout/char release in streams, Nov 1 to March 31

General Regs 1996/1997 • No fishing in any stream in Region 4 from April 1 to June 14 • Single hook in all streams of Region 4, all year

General Regs 1997/1998 • 1 bull trout

General Regs 1999/2000

• Single barbless hooks restriction for all streams in the East Kootenay area of Region 4 General Regs 2003/2004

• Single barbless hook restriction for all streams in Region 4 (and province), all year General Regs 2005/2006

• 7 streams are classified as Class II waters in Region 4: Bull, Elk, Kootenay (upstream of White), Skookumchuck, St. Mary, White and Wigwam

32

33

Stream Specific Regulation History: Wigwam River

• Prior to 1981/1983=general regs • 1981/1982 to 1985/1986=angling closure • 1985/1986=Fly fishing only above and including Bighorn Creek; bait ban from June 15

to October 31; no trout/char under 30cm may be harvested. • 1988/1989=trout/char release above and including Bighorn Creek • 1994-1996=other parts, trout/char daily quota of 2 (none under 30cm); single hook and

bait ban all parts below Bighorn Creek all year, June 15 - Oct 31 • 1996/1997=trout/char release all parts • 1998/1999=No fishing above Bighorn Creek from Sept 16 to Oct 31; fly fishing only all

parts • 2002/2003=no fishing upstream of km 42 Forest Rec Site from Sept 1 to Oct 31

Michel Creek (included in Elk River tributary regs prior to 1998/1999)

• Prior to 1983/1984=general regs with angling closure from Oct 1 to June 15 • 1984/1985=bait ban, June15 to Oct 31 • 1985/1986=no fishing from Sept 15 to Oct 31; no trout/char under 30cm; Bull trout quota

of 1. • 1996/1997=trout/char release all year • Stand alone listing in regulations starting in 1998/1999 to present; above hwy 3=trout

char release and bait ban, June 15 to Oct 31; below hwy 3=trout/char daily quota of 1 and bait ban, June 15 to Oct 31

Prepared by K. D. Heidt, BC Ministry of Environment, Fisheries Program, East Kootenay Region, Cranbrook, BC, January 2008.

APPENDIX 2. EAST KOOTENAY REGION WESTSLOPE CUTTHROAT TROUT SNORKELING SURVEYS, 2008

Other

Stream Section Date CrewStart WP (UTM)

End WP (UTM)

Distance (km)

<200 mm

200-300

300-400

>400 <200 200-300

300-400

>400BT MW EB

Visibility (m)

Visibility to models

Wigwam R Fenster C to canyon 18-Aug JTB,GN 652987; 5443276

651595; 5445592

3.50 2 21 50 14 0 0 0 0 >100 11 0 11 -

Wigwam R Canyon to Ram C 18-Aug SD,KG,JH 651595; 5445592

648629; 5449806

6.50 40 36 40 19 0 1 0 0 >100 0 0 12 -

Wigwam R Cattleguard to Fenster C 19-Aug JTB,GN 655229; 5439243

652987; 5443276

5.75 0 12 27 14 0 0 0 0 >100 0 0 10.1 -

Wigwam R Ram C to km 42 19-Aug SD,KG,JH 648629; 5449806

647374; 5451978

3.60 24 37 45 15 0 1 1 0 >100 2 0 12 -

Wigwam R Km 42 to km 36.5 19-Aug SD,KG,JH 647374; 5451978

649326; 5455898

5.10 65 86 79 22 0 1 2 3 >100 0 0 12 -

Michel C Upper: below Andy C 20-Aug JH 667333; 5488234

664435; 5490085

4.00 514 235 73 18 1 0 0 0 0 50-450 mm: 139

16<200, 7 200+, 1 300+

4.5 -

Michel C Mid: Bridge to CPR Junction 20-Aug JTB,GN 659475; 5496634

659931; 5500537

4.60 147 391 149 119 0 17 2 0 14 458 - 5.8 -

Michel C Lower:1st -2nd Hwy bridge 20-Aug SD,KG 660065; 5504598

656919; 5507346

4.80 121 210 143 70 1 0 1 0 13 adults >CT biomass

0 7 -

St. Mary R Perry C to CPR trestle 21-Aug JTB,JB,SD,KG,JH,GN 580814; 5494777

583192; 5494435

3.00 20 43 58 22 0 0 0 0 3 adults >>100 3 5.2 4.2

Center lanes: 3.00 1 7 9 1 1 0 1 0 >>100St. Mary R McPhee bridge to Mission 21-Aug JTB,JB,SD,KG,JH,GN 586849;

5492818588403; 5493237

2.85 28 47 65 14 0 1 6 4 1 adult >>100 6 5.2 4.2

Center lanes: 2.85 1 1 2 1 0 0 0 0 >>100St. Mary R Km 43.5-Pyramid C 22-Aug JB,SD,JH 545721;

5504378547297; 5501866

3.60 6 15 22 4 0 0 0 0 2<400 mm, 2>400 mm

0 0 7.5 -

St. Mary R Pyramid C-Redding C Bridge 22-Aug JTB,KG,GN 547297; 5501866

548438; 5500114

3.25 3 31 22 9 0 0 0 0 3 adults 0 1 5.8 -

St. Mary R Km 43.5-Pyramid C 10-Sep JB,KH,HT 545721; 5504378

547297; 5501866

3.60 8 68 35 9 0 0 0 0 1@300+, 2@400+, 3@500+

0 0 16.7 -

Elk R Hosmer Hwy Br.-Hwy Pull Ou18-Sep HT,KH 646771; 5494642

644476; 5491326

4.90 4 47 84 108 0 0 0 3@200+, 3@300+, 5@400+, 11@500+

2000+ estimate

0 7.7 -

Rainbow troutWestslope cutthroat trout