Gillespie Lake Stocking Assessment and Reconnaissance 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 Gillespie Lake, also known as Dixie 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 objective of determining the overall effectiveness of past stocking efforts and/or to determine future action in the lake stocking program. Results of the Gillespie 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 providing background and reconnaissance information to further aid in the

management of the lake 1.2 Background Gillespie Lake has never been formally surveyed or assessed and is located approximately 36 km west of Ladysmith. The lake lies in the Coastal Western Hemlock Biogeoclimatic Zone within the South Island Forest District. The lake is situated at an elevation of 810 m in Management Unit 1-04. The surface area is 7.5 ha and the perimeter is 2.2 km. The lake attains a maximum depth of 29.4 m. The lake is sub-alpine in nature and sits in a bench surrounded by partially logged hillsides. The lake has been stocked a total of 6 known times, from 1962 to 1992 (Table 1). An overnight gill net set was conducted on September 16 and 17, 1998, in which 11 rainbow trout were captured. Size ranges were from 10.5 cm to 34.0 cm.

Table 1. Stocking history of Gillespie Lake.

Year Species (Stock) Number Stage Size (g) Mark 1962/01/01 Rainbow Trout (Washington) 90 Yearling 30 --- 1964/01/01 Rainbow Trout (Pennask) 1290 Fry 0.8 --- 1970/01/01 Rainbow Trout (Swalwell) 2000 Fry 1.5 --- 1971/01/01 Rainbow Trout (Swalwell) 2000 Fingerling 3.5 --- 1989/09/07 Rainbow Trout (Dragon) 2000 Fry 0.9 --- 1992/08/11 Rainbow Trout (Tunkwa) 2000 Fry 1.2 ---

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. Gillespie Lake had never been surveyed previously and thus reconnaissance information was recorded (Appendix E), along with the standard temperature/oxygen profiles and fish sampling procedures. 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). A temperature/oxygen profile was obtained using a model 51B YSI meter. Upon locating the deepest part of the lake, the temperature/oxygen profile, as well as the secchi disk reading, was completed. Due to only having 15 meters of YSI cable available, sampling to 29 meters was not possible.

Figure 1. An unofficial bathymetric map of Gillespie 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, whereas the sinking gill net was set to sample a deeper part of the lake (Figure 1). The floating and sinking gill nets were 90 m monofilament experimental gang nets with panels of various mesh size. 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 of all 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. 3.0 Results 3.1 Temperature-Oxygen Profile The layer of water at or above 6 meters is relatively well mixed and has an almost uniform temperature/oxygen profile (Figure 2). The values fluctuate between 15.0oC and 14.7oC for temperature and between 9.1 mg/L and 8.9 mg/L for dissolved oxygen. There is, however, a sharp change in both values at the thermocline at 7.0 meters. The temperature value at 7.0 meters changes to 11.4oC, with a corresponding change in oxygen to 9.8 mg/L. The temperature values continue to decline sharply until 10 meters, where they begin to level off and eventually drop to 4oC at 15 meters. The oxygen levels show a somewhat different trend in that the values rise to a high of 10.8 mg/L at 9 meters. The levels of dissolved oxygen then begin to decrease, finally reaching 8.8 mg/L at 15 meters.

0

2

4

6

8

10

12

14

160 2 4 6 8 10 12 14 16

Dept

h (m

)

Oxygen (mg/L)Temperature (C)

Figure 2. Temperature-oxygen profile of Gillespie Lake on September 18, 2002.

3.2 Netting Data A total of 26 rainbow trout were captured in the two nets set in Gillespie Lake (Table 2). No other fish species were captured. The data from each net set can be seen in Appendix B, and photographs of the catch can be seen in Appendix C. The size range of the rainbow trout varied between 11.5 cm and 36.3 cm. Table 2. Summary of the catch data from the floating and sinking gill nets set in Gillespie

Lake.

Species Sample Size

Size Range (cm)

Ave. K Value

K Value Std. Dev.

Sex Ratio (M:F)

Rainbow Trout 26 11.5-36.3 1.181 0.084 10:16 Figure 3 shows the length-frequency distribution, by age, of all rainbow trout captured. Good distribution of fish through all age classes is shown for Gillespie Lake. The largest numbers of fish seen are in the 3+ age class with 12 individuals captured. 5 fish of age 2+ and 7 fish of age 4+ were also captured in the two gill net sets. 1 fish was captured in both the 1+ and 6+ age classes with no individuals captured in the 5+ age class.

0

1

2

3

4

10 11 12 13 14 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 1+ (N=1)

RB 2+ (N=5)

RB 3+ (N=12)

RB 4+ (N=7)

RB 6+ (N=1)

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

fall of 2002.

Figure 4 displays the length/weight relationship and the average condition factor for the rainbow trout captured in Gillespie Lake. The weight of the sampled population increases according to the formula W = 6.6208e0.1272L where W represents weight in grams and L represents length in centimeters. The equation also has a closeness of fit or R2 value equal to 0.9584 and a calculated average condition factor of 1.181 with a standard deviation of 0.084.

y = 6.6208e0.1272x

R2 = 0.9584Ave K = 1.181

0

100

200

300

400

500

600

700

800

10.0 15.0 20.0 25.0 30.0 35.0 40.0

Length (cm)

Wei

ght (

g)

Rainbow trout

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

2002. Angling (fly fishing ) during the lake reconnaissance on September 11, 2002, yielded a catch of 11 rainbow trout (8 fish between 28-32 cm fork length and 3 fish between 35-45 cm fork length). An ant hatch was occurring at the time and many fish were rising. 3.3 Presence/Absence of Non-Native Species No non-native species were observed in Gillespie Lake. The presence of only rainbow trout in the gill nets set in Gillespie Lake suggests that they are the only species present in the lake. BC Fisheries databases state that coho salmon are also present in this lake, however, no indication of coho was found in the two net sets. The presence of coho salmon in Gillespie Lake is also unlikely due to several large obstructions on the outlet stream that enters into Shaw Creek.

4.0 Discussion 4.1 Temperature-Oxygen Profile The temperature-oxygen profile for Gillespie Lake shows conditions suitable for fish health and development. The lake appears well mixed in the upper layers, leading to

normal temperature and oxygen levels throughout all depths. This, along with the depth of the lake, suggests few summer or winter fish kills, thus leading to high survival rates of fish between seasons. 4.2 Netting Data The data from the net sets show a normal length frequency distribution by age of rainbow trout in a lake environment. The low number of age 1+ fish is typically seen as trout do not usually enter the lake from nearby streams until the age of 2+. The low number of 2+ fish in comparison to 3+ fish is unusual, however, differences in reproduction rates between year classes often occurs. Age 2+ parr may also remain in the streams if conditions are favourable. The length at age comparison between year classes shows significant overlap, not uncommon in high elevation lakes. The growing season of these lakes is typically shortened, thus separation between age classes is not as distinct. The length-weight relationship for Gillespie Lake rainbow trout appears normal, with an average condition factor of 1.182. The condition factor, along with the fact that the lake has not been stocked since 1992, shows that the lake is sustaining a fish population adequate for its size and type. The normal condition factor also demonstrates that natural recruitment levels are high enough to sustain the limited fishery that occurs. 4.3 Netting Data in Relation to Stocking History As there has been no stocking of Gillespie Lake since 1992, all fish captured were derived from natural reproduction. The oldest fish was aged at 6 + years thus suggesting a brood year of 1996 and not one of hatchery origin. 5.0 Conclusion The current stock assessment of Gillespie Lake shows a healthy population of rainbow trout, and lake conditions that are favourable for fish. Natural recruitment appears to be at an equilibrated level where the condition factor is normal for rainbow trout. In fact, the fishery in Gillespie Lake is quite good, with many fish in the nets larger than 30 cm, and some taken during angling efforts larger than 40 cm. It should be noted that the lake has restricted access due to a gate across the road 4.8 km from the lake. This fact suggests that if entry remains restricted, natural recruitment is likely able to sustain the limited fishery that occurs here. However, if access is improved, (i.e. gate removed, or alternate road improved) fishing pressure is likely to increase thus potentially reducing the quality of the fishery.

6.0 Recommendations Stocking of Gillespie Lake is not recommended by the Regional Lake Biologist at this time. Natural recruitment levels appear high enough to sustain the fishery, however access and fishing pressure need to be monitored in order to maintain the quality of the fishery in Gillespie Lake.

Appendix Appendix A – Temperature-Oxygen Profile Locality: Gillespie LakeDate: September 18, 2002Bottom Depth: 18.9 mSecchi Depth: 11.1 mWeather: 100 % overcast, cool

Depth (m) O2 (mg/L) Temperature (oC)Surface 9.1 14.9

1.0 9.0 15.02.0 9.0 15.03.0 8.9 15.04.0 9.1 14.85.0 8.9 14.86.0 9.1 14.77.0 9.8 11.48.0 10.3 8.99.0 10.8 7.1

10.0 10.6 6.011.0 10.2 5.312.0 9.8 4.913.0 9.5 4.714.0 9.1 4.315.0 8.8 4.0

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

Netting record key

? - unknown

BNH - brown bullheadDeep End Depth (m) :Deep End Substrate :

ParameterDate Set :Time Set :Date Lifted :

Floating Gill Net11-Sep-02

14:5012-Sep-02

Fine Organic Substrate8.5

Time Lifted : 10:55

Max. Depth Along Net (m) :

0.4Fine Organic Substrate

8.5

Shallow End Depth (m) :Shallow End Substrate :

SMB - small mouth bass

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

CO - coho salmonGBT - german brown trout

PM - pumpkinseed sunfishKO - kokanee

R - ripeSP - spent

IMM - immatureMG - maturingMT - mature

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

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

1 RB 35.0 440 F MG No 6+ Scale Winged Ants Full2 RB 36.3 510 F MG No 4+ Scale Winged Ants, Hymenoptera Sp. Full3 RB 32.6 402 F MG No 4+ Scale Winged Ants, Leaf Hopper Full4 RB 33.0 413 F MG No 4+ Scale Winged Ants Full5 RB 31.4 346 F MG No 4+ Scale Winged Ants Full6 RB 27.2 224 M MG No 4+ Scale Winged Ants, Grasshopper Full7 RB 25.8 187 M MG No 3+ Scale Winged Ants Full8 RB 22.3 142 M MG No 3+ Scale Winged Ants, Hymenoptera sp. Full9 RB 24.2 160 F MG No 3+ Scale Winged Ants Full10 RB 27.3 220 F MG No 4+ Scale Winged Ants, Beetles Full11 RB 22.6 151 M MG No 3+ Scale Winged Ants Full12 RB 21.0 121 M MG No 2+ Scale Winged Ants Full13 RB 24.4 160 F MG No 3+ Scale Winged Ants, Dragonfly Full14 RB 21.5 123 M MG No 3+ Scale Winged Ants Full15 RB 20.2 98 F MG No 3+ Scale Winged Ants Full16 RB 19.6 96 M MG No 3+ Scale Winged Ants Full17 RB 20.1 97 F MG No 3+ Scale Winged Ants Full18 RB 16.6 58 F MG No 3+ Scale Winged Ants Full19 RB 16.8 60 M MG No 3+ Scale Winged Ants Full20 RB 11.5 20 M MG No 2+ Scale Winged Ants Full

Fish Characteristics Stomach Contents

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

Netting record key

? - unknown

BNH - brown bullheadDeep End Depth (m) :Deep End Substrate :

ParameterDate Set :Time Set :Date Lifted :

Floating Gill Net11-Sep-02

15:2012-Sep-02

Fine Organic Substrate11.5

Time Lifted : 11:30

Max. Depth Along Net (m) :

0.3Fine Organic Substrate

10.3

Shallow End Depth (m) :Shallow End Substrate :

SMB - small mouth bass

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

CO - coho salmonGBT - german brown trout

PM - pumpkinseed sunfishKO - kokanee

R - ripeSP - spent

IMM - immatureMG - maturingMT - mature

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

Sample

Number Species Fork Length (cm) Weight (g) Sex Maturity Mark Age Type Bottom Organisms Plankton Terrestrial Fish Volume Comments1 RB 35.4 514 F MG No 4+ Scale Winged Ants Full2 RB 21.5 113 F IMM No 3+ Scale Winged Ants, Wasp Full3 RB 18.3 76 M MG No 2+ Scale Winged Ants Full4 RB 14.2 35 F IMM No 2+ Scale Winged Ants Full5 RB 13.8 31 F IMM No 2+ Scale Winged Ants Full6 RB 11.8 18 F IMM No 1+ Scale Dragonfly Nymphs Full

Fish Characteristics Stomach Contents

Appendix C – Photos

Picture 1. Gillespie Lake looking north from center of lake. Partially logged hillside.

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

Picture 3. Gillespie Lake looking south from center of the lake.

Picture 4. Gillespie Lake looking west from center of the lake.

Picture 5. Gillespie Lake looking southwest from road. Marsh at north end of the lake.

Picture 6. Gillespie Lake looking west at boat launch from the narrow gap separating the two parts of the lake.

Picture 7. Gillespie Lake looking southeast from boat launch to the narrow gap

separating the two parts of the lake.

Picture 8. Gillespie Lake floating gill net catch.

Picture 9. Gillespie Lake sinking gill net catch.

Appendix D – Scale Readings

Scale Sample #1 – Sinking gill net RB 11.8cm 18g age 1+

Scale Sample #2 – Sinking gill net RB 13.8cm 31g age 2+

Scale Sample #3 – Sinking gill net RB 14.2cm 35g age 2+

Scale Sample #4 – Sinking gill net RB 18.3cm 76g age 2+

Scale Sample #5 – Sinking gill net RB 21.5cm 113g age 3+

Scale Sample #6 – Sinking gill net RB 35.4cm 514g age 4+

Scale Sample #7 – Floating gill net RB 11.5cm 20g age 2+

Scale Sample #8 – Floating gill net RB 16.8cm 60g age 3+

Scale Sample #9 – Floating gill net RB 16.6cm 58g age 3+

Scale Sample #10 – Floating gill net RB 20.1cm 97g age 3+

Scale Sample #11 – Floating gill net RB 19.6cm 96g age 3+

Scale Sample #12 – Floating gill net RB 20.2cm 98g age 3+

Scale Sample #13 – Floating gill net RB 21.5cm 123g age 3+

Scale Sample #14 – Floating gill net RB 24.4cm 160g age 3+

Scale Sample #15 – Floating gill net RB 21.0cm 121g age 2+

Scale Sample #16 – Floating gill net RB 22.6cm 151g age 3+

Scale Sample #17 – Floating gill net RB 27.3cm 220g age 4+

Scale Sample #18 – Floating gill net RB 22.5cm 142g age 3+

Scale Sample #19 – Floating gill net RB 25.8cm 187g age 3+

Scale Sample #20 – Floating gill net RB 27.2cm 224g age 4+

Scale Sample #21 – Floating gill net RB 31.4cm 346g age 4+

Scale Sample #22 – Floating gill net RB 33.0cm 413g age 4+

Scale Sample #23 – Floating gill net RB 32.6cm 402g age 4+

Scale Sample #24 – Floating gill net RB 36.3cm 510g age 4+

Scale Sample #25 – Floating gill net RB 35.0cm 440g age 6+

Appendix E – Reconnaissance Information Location Location: approximately 36 km west of Ladysmith Elevation: 810 m UTM: 10U 399793E 5425869N Management Unit: 01-04 NTS Map: 092C16 1:20K Map: 092C.099 Watershed Code: 920-257700-96000-49000 Waterbody Identifier: 00378COWN Drainage: Gillespie Lake – unnamed stream – Shaw Creek – Cowichan Lake Physical Data Surface Area: 7.5 ha Perimeter: 2.2 km Max Depth: 29.4 m Secchi Disc Depth: 11.1 m Terrain Features Immediate Shoreline: Approximately 40% of the shoreline is exposed bedrock with sheer faces and some bedrock outcroppings. The remaining shoreline largely consists of marshy areas around the main lake along with two almost separate backwatered marshy bays. In the areas where there are not sheer bedrock walls the substrate consists of organic fines. Gravel was observed in the narrowing between the main lake and the boat launch bay. Fallen submerged trees are also prevalent along the shoreline. Surrounding Country: The lake is positioned in a small valley surrounded by partially logged hillsides. The surrounding vegetation is sub-alpine in nature with scrubby old-growth western hemlock and sparse cedar. Access Directions: From Nanaimo River Road, follow the road past the TimberWest Camp. Continue to the Green River Junction and turn left onto the K Branch. Drive 6.4 km and then turn right onto the K26 Branch. After driving 5.6 km, head uphill on the unmarked road to the right. On the unmarked road there is a locked gate. The key for this gate can be obtained from the TimberWest Camp office. Proceed through the gate and drive 4.4 km. At the fork in the road, continue down the lower road for 0.4 km to reach the lake.

Road Type and Conditions: The gravel logging roads were in good condition. The last sections of the road become steep and 4WD is recommended. Restrictions: There is a locked gate 4.8 km down the road from the lake. The key for the gate may be borrowed from the TimberWest Camp office on Nanaimo River Road. Lake Access: The logging road goes to the edge of one of the lake’s small bays. There is a shallow narrowing between the bay and the main lake which, during low water conditions, a boat must be carried across (~10m). Resorts and Campsites: Primitive site with space available for 1 camping unit only and is located at the boat launch. Other Developments: None Observations Aquatic Plants: Some lily pads and grasses around the shoal areas. Wildlife Observations: A couple common mergansers and Steller’s Jays were seen. Miscellaneous Comments: None Lake Drainage Description: The inlet stream enters the lake from the west side and the outlet stream leaves the lake from a marshy area on the northeast side. Inlet Stream: There was some gravel substrate in the inlet, however, it is unknown if there would be sufficient flow to create significant spawning potential. It may also be too cold to allow proper egg development. Outlet Stream: It is likely that the outlet stream provides spawning habitat for Gillespie Lake. However, it appears that only the first 50 meters is likely usable. The substrate consists of gravel and angular cobble/boulders. Water Level at time of viewing appeared uncommonly low. History of Previous Surveys No formal survey or assessment of Gillespie Lake has been completed. In 1976, a letter by Ted Burns was sent to the Fish and Wildlife Branch which included some rough field notes describing Gillespie Lake. Part of the letter stated that back in the early sixties, two Nanaimo men (one being Al Brown) packed some fish into the lake. To their discovery after stocking it, they saw larger fish swimming near the shoreline, possibly the progeny of fish stocked earlier by the man for whom the lake is named for. In 1998, a gill net was set in the lake overnight and caught 11 rainbow trout ranging from 10.5 cm to 34.0 cm.