region 1, nanaimo nanaimo/cowichan planning unit ministry...

Okay Lake Stocking Assessment Report

Region 1, Nanaimo Nanaimo/Cowichan Planning Unit

Ministry of Water, Land and Air Protection

Prepared by:

Laura Cassin Scott Silvestri

2002

1.0 Introduction 1.1 Objective Okay Lake, in the Nanaimo/Cowichan planning unit, was assessed in the fall of 2002 as part of a stocking evaluation of Vancouver Island lakes. These assessments were carried out with the purpose of determining the overall effectiveness of past stocking efforts and/or to determine future actions in the lake stocking program. Results of the Williams Lake evaluation will focus on:

effectiveness of past stocking efforts by evaluating fish abundance and

observing the level of natural recruitment of both stocked and non-stocked fish

effectiveness of past stocking efforts by evaluating the current age structure of the population using fish aging techniques

observations of the presence/absence of non-native fish future considerations for the fish stocking and lake management program

1.2 Background A basic reconnaissance survey of Okay Lake was completed by provincial fisheries staff in 1989. The lake is located northwest of Nanaimo in Weyerhaeuser’s North West Bay Division and lies in the Coastal Western Hemlock Biogeoclimatic Zone within the South Island Forest District. The lake is situated at an elevation of 450 m in management unit 1-05. The surface area is 4.3 ha and the perimeter is 0.8 km. The lake attains a maximum depth of 6.9 m. The lake has been stocked 10 times from 1989 to 2002 (Table 1). Table 1. Stocking history of Okay Lake.

Year Species (Stock) Number Stage Size (g) Mark 1989/08/24 Cutthroat Trout (Taylor) 2000 Fall Fry 2.3 --- 1990/04/25 Cutthroat Trout (Taylor) 1000 Yearling 32.6 --- 1991/10/29 Cutthroat Trout (Taylor) 500 Fingerling 12.7 --- 1993/04/06 Cutthroat Trout (PAQ) 500 Yearling 39.0 --- 1997/05/21 Rainbow Trout (Badger Tunkwa) 1000 Yearling 29.3 --- 1998/05/13 Rainbow Trout (Tzenzaicut) 1000 Yearling 33.6 --- 1999/05/27 Rainbow Trout (BlackWater) 1000 Yearling 41.9 --- 2000/05/10 Rainbow Trout (Tzenzaicut) 1000 Yearling 28.8 --- 2001/05/28 Rainbow Trout (Tzenzaicut) 1000 Yearling 26.1 --- 2002/05/07 Rainbow Trout (Tzenzaicut) 1000 Yearling 28.56 ---

2.0 Methods and Materials The Vancouver Island lakes included in the evaluation were selected because they were previously stocked and needed assessment, or were potential candidates for future stockings. A list of over 45 lakes was compiled, and 18 were selected by the Region 1 Lakes Biologist to be sampled in the fall of 2002. Okay Lake had previous reconnaissance work completed and thus only temperature/oxygen profiles and fish sampling procedures were performed. The lake was assessed by boat, and a Lowrance X65 sounder was used to determine depth measurements. A bathymetric map of the lake was constructed, however, the outline of the lake as well as the position of the contour lines are rough estimates and are only intended to give a general overview of the lake (Figure 1). Upon locating the deepest part of the lake, the temperature/oxygen profile, as well as the secchi disk reading, was completed. The temperature/oxygen profile was obtained using a model 51B YSI meter.

Figure 1. An unofficial bathymetric map of Okay Lake showing the survey site

location and the positions of the floating and sinking gill nets.

Two gill nets, one sinking and one floating, were set in the lake overnight. The gill net sites were selected with the intention of sampling areas with evenly spaced contour lines on a bathymetric map. The floating gill net was set with the intent of covering more shoal area, where as the sinking gill net was set to sample a deeper part of the lake (Figure 1). The floating and sinking gill nets were 90m monofilament experimental gang nets of varying panel sizes. Both nets were anchored with the smallest mesh size panel nearest to shore and extended into the lake. Sampling of the gill net catch consisted of recording length (cm), weight (g), sex, maturity, and stomach contents of all fish captured. In addition, scale samples were taken from a representative sample of rainbow trout captured and mounted on slides. Columbia Environmental Consulting Ltd. aged the scales by counting the number of annuli that represent different growing seasons. Printed copies of each scale sampled can be seen in Appendix D. The ages of the fish that were not scale sampled were determined using a length-at-age comparison utilizing the known age data. 3.0 Results 3.1 Temperature-Oxygen Profile Okay Lake is a relatively shallow lake, less than 7 meters deep, with large shoal and flooded marsh areas all around the lake (Figure 1). The temperature-oxygen profile shows a lake that is well mixed from the surface to the bottom. Surface water temperatures are slightly warmer than subsurface water at 6.5 oC. Temperature values below the surface range from 6.1 oC at 1 m to 5.9 oC at the 6.5 m depth. Oxygen values remain constant at 11.8 mg/L for all depths.

0

1

2

3

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5

6

70 2 4 6 8 10 12 14

Dep

th (m

)

Oxygen (mg/L)Temperature (C)

Figure 2. Temperature-oxygen profile of Okay Lake.

3.2 Netting Data A total of 131 fish were captured in the two nets set in Okay Lake (Table 2). The results of the catch data can be seen in Appendix B and photographs of the catch can be seen in

Appendix C. The size distribution of rainbow trout in Okay Lake varied between 18.1 cm and 37.4 cm. The sex ratio between males and females was 57:70.

Table 2. Summary of catch from the floating and sinking gill nets set in Okay Lake.

Species Sample Size

Size Range (cm)

Ave. K Value

K Value Std. Dev.

Sex Ratio (M:F)

Rainbow Trout 127 18.1 - 37.4 1.083 0.060 57:70

Cutthroat/Rainbow Trout Hybrids 4 20.9 - 27.3 1.079 0.037 4:0

Figure 3 shows the length-frequency distribution, by age, of all the rainbow trout and hybrids captured in Okay Lake. The age distribution appears normal, with only a small amount of overlap between some age classes. The largest number of fish captured (n=106) were seen in the 2+ age class. No fish of age 1+ were captured, while 19 age 3+ and 2 age 4+ rainbow trout were sampled. Only 4 cutthroat/rainbow trout hybrids were captured, of which 3 belong to the 2+ age class and 1 to the 3+ age class. The length at age data appears normal with a good distribution of sizes for each age class.

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15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Length (cm)

# of

Fis

h

RB 2+ (N=106)RB 3+ (N=19)RB 4+ (N=2)CT/RB 2+ (N=3)CT/RB 3+ (N=1)

Figure 3. Length-frequency distribution by age for rainbow trout in Okay Lake

in the fall of 2002.

Figure 4 displays the length/weight relationship and the average condition factor for both the rainbow trout and cutthroat/rainbow trout hybrids captured in Okay Lake. The weight of the sampled population of rainbow trout and cutthroat/rainbow trout hybrids increase according to the formulas W = 7.807e0.1211L and W = 8.4299e0.1189L where W represents weight in grams and L represents length in centimeters. The equations also have a

closeness of fit or R2 value equal to 0.9746 and 0.9907 respectively. The calculated average condition factor for Okay Lake rainbow trout and cutthroat/rainbow trout hybrids was 1.083 and 1.079.

Rainbow Trouty = 7.807e0.1211x

R2 = 0.9746Ave. K = 1.083

Cutthroat/Rainbow Trout Hybridy = 8.4299e0.1189x

R2 = 0.9907Ave. K = 1.079

0

100

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500

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15 20 25 30 35 40

Length (cm)

Wei

ght (

g)

Cutthroat/Rainbow Trout Hybrid(N=4)Rainbow Trout (N=127)

Figure 4. Length-weight relationship of rainbow trout in Okay Lake in the fall of

2002.

3.3 Presence/Absence of Non-Native Species The presence of both rainbow trout and cutthroat/rainbow trout hybrids in the gill nets set in Okay Lake suggests they are the only two species present in the lake. The BC Fisheries database states that both rainbow trout and cutthroat trout are present in the lake. No pure strain of cutthroat trout was noted in the gill net data during this sampling period. It should be noted that cutthroat were stocked historically, but haven’t been added since 1993. The lake is not accessible to anadromous salmonids. 4.0 Discussion 4.1 Temperature-Oxygen Profile The temperature-oxygen profile for Okay Lake shows both temperature and dissolved oxygen levels ideally suited for fish development. Temperature values were fairly cold, however given the time of year it is not unexpected. The nearly uniform levels through all depths for temperature and oxygen show a lake that is well mixed with no presence of a thermocline. Oxygen values are consistent at all depths suggesting that mixing is occurring from the surface down to the bottom. Temperature values show minor

fluctuations, but it is likely due from daytime heating. Small shallow lakes are typically very productive and thus ideally suited for the growth of most trout species. High water temperature levels can, however, cause problems if values are in excess of 20oC. Okay Lake is at a high enough elevation and is likely deep enough where temperature values are not likely to reach or exceed this critical level. Conversely, temperature values during winter periods are not likely low enough to cause extreme ice formation and/or oxygen depletion. 4.2 Netting Data The dominant age class in Okay Lake appears to be fish in the 2+ age class. This is likely a result of the stocking that occurred here in the spring. The drastic decline in the number of fish present in older age classes maybe partly due to the fishery on this lake. Another explanation is overcrowding, as the results from the gill nets show a lake that is overpopulated. The small overlap between age classes maybe the result of improper aging or incorrect ages inferred for those fish that were not scaled. The presence of a few hybrid fish suggest that some natural recruitment does occur, however it likely occurs when conditions are optimum. Spawning area is also extremely limited thus large amounts of natural recruitment are not possible in this lake without habitat modifications. The absence of juveniles from the gill net data supports the notion of little to no natural reproduction in Okay Lake. The length-weight relationships for both the rainbow trout and the cutthroat/rainbow trout hybrids appear normal with equations that are represented by good R2 values. The mean condition factors of 1.083 and 1.079 are normal for these two species on Vancouver Island. The presence of a large sample size, especially of small fish (<25 cm), from the gill nets set in Okay Lake suggests that the lake maybe over populated. 4.3 Netting Data in Relation to Stocking History Stocking of Okay Lake has occurred annually since 1997, however no fish have been marked, thus verifying them as hatchery fish is difficult. Most fish sampled are likely from hatchery origin as natural recruitment seldom occurs as seen from the absence of juveniles in the gill net data. 4.4 Fish Health A matter of concern in Okay Lake fish is the presence of what appears to be yellow grub, an encysted parasitic fluke. The larval form of the fluke is released from snails and travels through the water column where it penetrates the skin of fish and embeds beneath, usually at the base of fins. The grub does no serious harm to fish, but if infection is heavy, the flesh is unsuitable for human consumption. The presence of these cysts was seen on all fish sampled from the gill nets, and in some cases infection was extremely prevalent

(Appendix C, Picture # 13). Little can be done about the infection, since no known efforts have resulted in the removal of the parasitic fluke larvae. 5.0 Conclusion The overall assessment of Okay Lake indicates good conditions for a healthy fishery. The level of natural recruitment in the lake appears extremely limited, however it is likely that annual stocking efforts have resulted in large numbers of trout in the lake. The gill net data shows a large portion of the fish less than 25 cm, thus suggesting the lake is overpopulated. The amount of use of Okay Lake by anglers is also unknown and maybe fairly low due to the restricted access by Weyerhaeuser. Road access is quite good to Okay Lake, but is fairly overgrown, suggesting limited use. The health concern, as a result of the parasitic flukes, may also reduce the angling pressure. 6.0 Recommendations The recommendations by the Regional Lakes Biologist is the scaling down of stocking from 1000 rainbow yearlings stocked annually to 500 rainbow yearlings stocked in even years. This would reduce the amount of competition for food, thus resulting in a higher number of larger fish. The resulting scale back would likely result in only minor changes to angler success rates as Okay Lake in only four hactares in size. If fishing pressure increases, the stocking program for this lake may have to be altered, thus it is recommended that fishing pressure be monitored to ensure a good quality fishery at Okay Lake. By reducing the stocking rate in Okay Lake, a reduction in parasitic infections may also occur. It is likely that overcrowding causes proliferation of the fluke, resulting in higher infection rates.

Appendix Appendix A – Temperature-Oxygen Profile Locality: Okay LakeDate: November 4, 2002Bottom Depth 6.9 mSecchi Depth > 6.9 mWeather: Sunny, few clouds, cool and calm

Depth (m) O2 (mg/L) Temperature (oC)

Surface 11.8 6.51.0 11.8 6.12.0 11.8 6.03.0 11.8 6.04.0 11.8 6.05.0 11.8 6.06.0 11.8 5.96.5 11.8 5.9

Appendix B – Net Set Information and Catch Record Floating Gill Net

Netting record keyLM - left maxillaryRM - right maxillaryAD - adiposeNO - not markedR - ripe

SP - spent

IMM - immatureMG - maturingMT - mature

SMB - small mouth bass

RB - rainbow troutCT - cutthroat troutDV - Dolly VardenEBT - eastern brook troutFine Organic Substrate

5.1

Time Lifted : 10:05

Max. Depth Along Net (m) :

0.5Fine Organic Substrate

5.1

Shallow End Depth (m) :Shallow End Substrate :

Floating Gill Net04-Nov-02

15:1505-Nov-02

Deep End Depth (m) :Deep End Substrate :

ParameterDate Set :Time Set :Date Lifted :

Sample Number Species Fork Length (cm) Weight (g) Sex Maturity Mark Age Type Bottom Organisms Plankton Terrestrial Fish Volume Comments

1 RB 37.4 571 F MG No Scale Caddis and Casing Copepods 1/2 Parasitic Encysted Worms2 RB 27.8 208 M MG No Scale Digested Matter Copepods 1/4 Parasitic Encysted Worms3 RB 28.3 273 F MG No Scale Water Boatman 1/4 Parasitic Encysted Worms4 RB 25.4 172 F MG No Scale Copepods 1/8 Parasitic Encysted Worms5 RB 25.5 169 M IMM No Copepods Unident. Insect 1/4 Parasitic Encysted Worms6 RB 24.4 146 M IMM No Copepods 1/8 Parasitic Encysted Worms7 RB 24.6 153 F IMM No Scale Copepods 1/4 Parasitic Encysted Worms8 RB 22.7 138 M MG No Caddis and Casing 1/4 Parasitic Encysted Worms9 RB 22.7 128 M MG No Copepods 1/8 Parasitic Encysted Worms10 RB 23.9 150 F IMM No Copepods Unident. Insect 1/4 Parasitic Encysted Worms11 RB 22.8 107 F IMM No Scale Empty Parasitic Encysted Worms12 RB 22.6 134 F MG No Copepods 1/8 Parasitic Encysted Worms13 RB 20.3 91 M IMM No Empty Parasitic Encysted Worms

14 RB 21.1 107 M IMM NoDaphnia,

Copepods 1/8 Parasitic Encysted Worms15 RB 20.5 90 F IMM No Empty Parasitic Encysted Worms16 RB 21.3 100 M IMM No Daphnia <1/8 Parasitic Encysted Worms17 RB 20.0 92 M MG No Empty Parasitic Encysted Worms18 RB 21.1 97 F IMM No Empty Parasitic Encysted Worms19 RB 20.7 89 F IMM No Daphnia <1/8 Parasitic Encysted Worms20 RB 20.5 91 F IMM No Daphnia 1/8 Parasitic Encysted Worms21 RB 20.3 85 M IMM No Scale Daphnia 1/8 Parasitic Encysted Worms22 RB 20.6 91 M IMM No Daphnia <1/8 Parasitic Encysted Worms

23 RB 20.1 92 M MG NoDaphnia,

Copepods 1/8 Parasitic Encysted Worms24 RB 20.3 85 F IMM No Copepods 1/4 Parasitic Encysted Worms25 RB 20.7 91 M IMM No Copepods Unident. Insect 1/4 Parasitic Encysted Worms26 RB 21.6 104 F IMM No Empty Parasitic Encysted Worms

27 RB 20.1 93 M MG NoDaphnia,

Copepods <1/8 Parasitic Encysted Worms28 RB 20.6 97 F IMM No Caddis Casing 1/8 Parasitic Encysted Worms29 RB 19.2 81 M IMM No Empty Parasitic Encysted Worms

30 RB 19.7 86 F IMM No ScaleDaphnia,

Copepods 1/8 Parasitic Encysted Worms31 RB 18.9 73 F IMM No Scale Daphnia <1/8 Parasitic Encysted Worms

Fish Characteristics Stomach Contents

Appendix B – Net Set Information and Catch Record Continued Sinking Gill Net

Netting record key



Sinking Gill Net04-Nov-02

15:2305-Nov-02

Fine Organic Substrate6.5

Time Lifted : 11:35



5.6



RB - rainbow troutCT - cutthroat troutDV - Dolly VardenEBT - eastern brook trout R - ripe

SP - spent


LM - left maxillaryRM - right maxillaryAD - adiposeNO - not marked


1 RB 32.8 372 F MG No Scale Clams, Plant Matter Copepods 1/2 Parasitic Encysted Worms2 RB 33.0 410 M MG No Scale Clams Copepods 1/2 Parasitic Encysted Worms3 RB 28.7 261 F MG No 1/4 Parasitic Encysted Worms4 RB 29.5 275 F MG No Scale 1/8 Parasitic Encysted Worms5 RB 27.2 220 M MG No 1/4 Parasitic Encysted Worms6 RB 28.0 232 F MG No 1/4 Parasitic Encysted Worms7 RB 28.4 247 F IMM No 1/4 Parasitic Encysted Worms8 RB 25.9 226 F MG No Clams Copepods 1/2 Parasitic Encysted Worms9 RB 26.5 215 F MG No 1/4 Parasitic Encysted Worms10 RB 26.1 204 M MG No 1/8 Parasitic Encysted Worms11 RB 25.7 195 M MG No 1/4 Parasitic Encysted Worms12 RB 29.1 252 M MG No 1/2 Parasitic Encysted Worms13 RB 27.7 231 F MG No 1/8 Parasitic Encysted Worms14 RB 25.5 161 F MG No Scale <1/8 Parasitic Encysted Worms15 RB 24.5 156 F IMM No 1/8 Parasitic Encysted Worms16 RB 24.1 155 M MG No 1/8 Parasitic Encysted Worms17 RB 24.4 144 F MG No 1/8 Parasitic Encysted Worms18 RB 23.7 147 F MG No <1/8 Parasitic Encysted Worms19 RB 23.4 148 F IMM No Scale 1/4 Parasitic Encysted Worms20 RB 22.1 125 M MG No 1/4 Parasitic Encysted Worms21 RB 22.7 135 F MG No Empty Parasitic Encysted Worms22 RB 24.0 149 M MG No 1/4 Parasitic Encysted Worms23 RB 23.0 129 M MG No 1/4 Parasitic Encysted Worms24 RB 23.3 134 F MG No 1/4 Parasitic Encysted Worms25 RB 22.3 116 F IMM No 1/4 Parasitic Encysted Worms26 RB 21.6 114 M MG No 1/4 Parasitic Encysted Worms27 RB 22.3 119 F MG No 1/8 Parasitic Encysted Worms28 RB 22.0 114 F IMM No 1/4 Parasitic Encysted Worms29 RB 21.4 108 M MG No 1/4 Parasitic Encysted Worms30 RB 22.1 123 M MG No 1/8 Parasitic Encysted Worms31 RB 20.2 96 M MG No 1/8 Parasitic Encysted Worms32 RB 20.4 95 F MG No 1/8 Parasitic Encysted Worms33 RB 20.2 89 F IMM No 1/8 Parasitic Encysted Worms34 RB 20.1 86 F IMM No Scale 1/8 Parasitic Encysted Worms35 RB 20.4 92 M IMM No Empty Parasitic Encysted Worms36 RB 20.3 93 F IMM No 1/4 Parasitic Encysted Worms37 RB 21.3 102 M MG No 1/8 Parasitic Encysted Worms38 RB 20.7 96 F IMM No 1/8 Parasitic Encysted Worms39 RB 20.2 89 F IMM No Empty Parasitic Encysted Worms40 RB 21.2 98 M IMM No 1/8 Parasitic Encysted Worms41 RB 21.2 96 F IMM No 1/8 Parasitic Encysted Worms


Appendix B – Net Set Information and Catch Record Continued Sinking Gill Net Continued

Netting record key




15:2305-Nov-02


Time Lifted : 11:35



5.6




SP - spent




42 RB 20.1 85 F IMM No 1/8 Parasitic Encysted Worms43 RB 19.9 89 F IMM No <1/8 Parasitic Encysted Worms44 RB 20.9 107 F IMM No 1/8 Parasitic Encysted Worms45 RB 20.6 80 F IMM No <1/8 Parasitic Encysted Worms46 RB 20.0 86 F IMM No 1/8 Parasitic Encysted Worms47 RB 21.0 101 F IMM No 1/2 Parasitic Encysted Worms48 RB 20.6 100 F IMM No <1/8 Parasitic Encysted Worms49 RB 21.5 102 M MG No 1/4 Parasitic Encysted Worms50 RB 18.9 79 F IMM No Scale 1/8 Parasitic Encysted Worms51 RB 20.3 90 M IMM No 1/4 Parasitic Encysted Worms52 RB 19.4 80 F IMM No 1/8 Parasitic Encysted Worms53 RB 19.3 81 M MG No 1/8 Parasitic Encysted Worms54 RB 19.2 81 F IMM No 1/8 Parasitic Encysted Worms55 RB 20.8 93 F IMM No 1/4 Parasitic Encysted Worms56 RB 19.9 85 F IMM No 1/8 Parasitic Encysted Worms57 RB 21.3 101 F IMM No 1/4 Parasitic Encysted Worms58 RB 19.8 87 M MG No 1/8 Parasitic Encysted Worms59 RB 20.4 91 F MG No 1/4 Parasitic Encysted Worms60 RB 20.7 102 M MG No <1/8 Parasitic Encysted Worms61 RB 19.5 89 M IMM No 1/8 Parasitic Encysted Worms62 RB 18.6 73 F IMM No 1/8 Parasitic Encysted Worms63 RB 19.4 81 M MG No 1/4 Parasitic Encysted Worms64 RB 21.0 93 M MG No Empty Parasitic Encysted Worms65 RB 20.0 86 M IMM No 1/8 Parasitic Encysted Worms66 RB 19.4 80 M IMM No 1/8 Parasitic Encysted Worms67 RB 21.1 94 F IMM No 1/4 Parasitic Encysted Worms68 RB 20.2 86 F IMM No 1/8 Parasitic Encysted Worms69 RB 20.8 91 F IMM No Empty Parasitic Encysted Worms70 RB 20.0 88 M IMM No 1/4 Parasitic Encysted Worms71 RB 20.1 89 F IMM No 1/8 Parasitic Encysted Worms72 RB 20.5 98 M IMM No 1/8 Parasitic Encysted Worms73 RB 21.6 98 M IMM No 1/8 Parasitic Encysted Worms74 RB 19.8 87 F IMM No Empty Parasitic Encysted Worms75 RB 19.3 83 F IMM No Empty Parasitic Encysted Worms76 RB 20.3 89 F IMM No 1/8 Parasitic Encysted Worms77 RB 19.7 80 F IMM No 1/8 Parasitic Encysted Worms78 RB 19.6 87 M MG No <1/8 Parasitic Encysted Worms79 RB 19.6 81 F IMM No <1/8 Parasitic Encysted Worms80 RB 20.5 94 M IMM No Daphnia 1/8 Parasitic Encysted Worms81 RB 19.1 76 M IMM No Empty Parasitic Encysted Worms


Appendix B – Net Set Information and Catch Record Continued Sinking Gill Net Continued

Netting record key




15:2305-Nov-02


Time Lifted : 11:35



5.6




SP - spent




82 RB 21.2 93 M IMM No <1/8 Parasitic Encysted Worms83 RB 20.4 94 F IMM No 1/8 Parasitic Encysted Worms84 RB 18.1 62 M IMM No Scale <1/8 Parasitic Encysted Worms85 RB 20.3 90 M IMM No 1/8 Parasitic Encysted Worms86 RB 20.3 89 M IMM No 1/8 Parasitic Encysted Worms87 RB 21.2 107 F IMM No 1/8 Parasitic Encysted Worms88 RB 21.5 102 M MG No 1/8 Parasitic Encysted Worms89 RB 19.7 88 M MG No 1/8 Parasitic Encysted Worms

90 RB 23.2 140 F MG NoNewt/

Salamander 3/4 Parasitic Encysted Worms91 RB 19.7 81 M IMM No Daphnia <1/8 Parasitic Encysted Worms92 RB 20.0 91 M MG No 1/4 Parasitic Encysted Worms93 RB 20.5 84 M IMM No <1/8 Parasitic Encysted Worms94 RB 21.0 97 M MG No <1/8 Parasitic Encysted Worms95 RB 19.8 84 F IMM No Empty Parasitic Encysted Worms96 RB 18.6 71 F IMM No Daphnia 1/8 Parasitic Encysted Worms

1 CT/RB hybrid 27.3 216 M MG No 1/8 Parasitic Encysted Worms2 CT/RB hybrid 22.3 125 M MG No 1/4 Parasitic Encysted Worms3 CT/RB hybrid 20.9 99 M IMM No 1/8 Parasitic Encysted Worms4 CT/RB hybrid 23.2 130 M MG No 1/8 Parasitic Encysted Worms


Appendix C – Photos

Picture 1. Okay lake looking northeast from the center of the lake.

Picture 2. Okay Lake looking east from the center of the lake.

Picture 3. Okay Lake looking southwest from boat launch.

Picture 4. Okay Lake looking west southwest from boat launch.

Picture 5. Okay Lake looking west from boat launch.

Picture 6. Okay Lake looking west from center of the lake.

Picture 7. Looking west towards lake from the lake outlet. Note large flooded marsh area.

Picture 8. Outlet channel 100 m upstream of lake outlet. Note presence of cobble.

Picture 9. Outlet channel 100 m upstream of lake. Note presence of logs and cobble.

Picture 10. Okay Lake floating gill net catch.

Picture 11. Okay Lake sinking gill net catch.

Picture 12. Okay Lake sinking gill net catch close-up.

Picture 13. Photo showing heavy infection of parasitic flukes inside the body cavity.

Picture 14. Comparison of rainbow trout and cutthroat/rainbow trout hybrids in Okay

Lake. Note the presence of red hyoid slash. Fish also possessed vomer teeth.

Picture 15. Close-up of cutthroat/rainbow trout hybrids of Okay Lake.

Appendix D – Scale Readings

Scale Sample #1 – Sinking gill net RB 18.9cm 79g age 2+



Scale Sample #9 – Floating gill net RB 20.3cm 85g age 3+




Scale Sample #16 - Floating gill net RB 27.8cm 208g regenerated scales

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