Assessment of Elizabeth Lake as a Potential Candidate for Stocking Region 1, Nanaimo West Coast Planning Unit Ministry of Water, Land and Air Protection Prepared by: Laura Cassin Scott Silvestri 2002
1.0 Introduction 1.1 Objective Elizabeth Lake, in the West Coast 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 Elizabeth Lake evaluation will focus on: 1.2 Background determining the presence/absence of both native and non-native fish species confirming Elizabeth Lake is barren of fish and assessing it as a potential candidate for future stocking providing background information to further aid in the management of the lake Elizabeth Lake has never been formally surveyed or assessed. It is located approximately 31 km west of Port Alberni. The lake lies in the Coastal Western Hemlock Biogeoclimatic Zone within the South Island Forest District. The lake drains into an unnamed stream which then drains into Great Central Lake. Elizabeth lake is situated at an elevation of 870 m in management unit 1-07. The surface area is 16.8 ha and the perimeter is 2.8 km. The lake attains a maximum depth of 20.0 m. The lake has never been stocked and is a potential candidate for future stocking. 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. Elizabeth Lake had never been previously investigated and thus reconnaissance information was recorded, along with the standard temperature/oxygen profiles and fish sampling procedures. The lake was assessed by boat and depth measurements were performed using a Lowrance X65 sounder. 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 were only intended to give a general overview of the lake (Figure 1). The temperature/oxygen profile and secchi disk reading were performed in the deepest part of the lake. The temperature/oxygen profile was obtained using a model 51B YSI meter.
Figure 1. An unofficial bathymetric map of Elizabeth 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.
3.0 Results 3.1 Temperature-Oxygen Profile The layer of water above 10 meters is relatively well mixed, excluding the surface oxygen reading, and has an almost uniform temperature/oxygen profile (Figure 2 and Appendix A). The temperature values decrease from 11.0 o C to10.2 o C and the dissolved oxygen values fluctuate between 10.0 mg/l and 9.7 mg/l. There is, however, a sharp change in both values at the thermocline. The temperature value at 10.0 meters changes to 8.0 o C, with a corresponding change in oxygen to 9.2 mg/l. The temperature values continue to decline until 14 meters, where they then hold constant at around 5.0 o C to a depth of 18 meters. The oxygen levels continue to decrease from 7.6 mg/l at 11.0 meters to 1.6 mg/l at 18 meters. Depth (m) 0 2 4 6 8 10 12 14 16 18 20 Oxygen (mg/l) Temperature (C) 0 2 4 6 8 10 12 Figure 2. Temperature-oxygen profile of Elizabeth Lake. October 24, 2002. 3.2 Netting Data No fish were captured in either of the two gill nets set during the overnight period on October 24, 2002. Specific information regarding the net sets is listed in Appendix B. The netting result confirms the notion that the lake is barren of fish. 3.3 Presence/Absence of Non-Native Species The absence of fish in both gill net sets suggests that Elizabeth Lake is barren of fish. Minnow trapping was not performed during the reconnaissance survey of Elizabeth Lake, therefore species (ie. Stickleback) not easily captured in gill nets may still inhabit the lake.
4.0 Discussion 4.1 Temperature-Oxygen Profile The temperature-oxygen profile for Elizabeth 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, except for perhaps the deepest sections of the lake. Considering only a small portion of the lake is greater than 15 meters deep, the low temperature and oxygen levels are likely inconsequential to fish survival. 4.2 Netting Data The data from the net sets show the absence of fish species in Elizabeth Lake. 5.0 Conclusion The overall assessment of Elizabeth Lake as a candidate for future stocking is good. The lake appears to have conditions ideally suited for the growth and propagation of trout. The inlet stream has the flow and gravel required for spawning, so successful natural recruitment is likely. Photos of Elizabeth Lake are located in Appendix C and reconnaissance information is described in Appendix D. 6.0 Recommendations Recommendations by the Regional Lakes Biologist are for an initial stocking of Elizabeth Lake with 4000 Steelhead fingerlings in the fall of 2003 followed by a stocking assessment in 2006. The future stocking assessment would determine the health and abundance of the stocked fish and would indicate the level of natural recruitment.
Appendix Appendix A Temperature-Oxygen Profile Locality: Elizabeth Lake Date: October 24, 2002 Bottom Depth: 20.0 m Secchi Depth: 8.6 m Weather: Sunny, warm and slightly windy Depth (m) O 2 (mg/l) Temperature ( o C) Surface 10.8 11.0 1.0 9.7 11.0 2.0 9.9 11.0 3.0 9.8 11.0 4.0 9.9 10.9 5.0 9.9 10.9 6.0 10.0 10.8 7.0 9.9 10.7 8.0 10.0 10.6 9.0 10.0 10.2 10.0 9.2 8.0 11.0 7.6 6.5 12.0 6.4 6.0 13.0 4.9 5.4 14.0 4.1 5.0 15.0 3.4 5.0 16.0 2.6 5.0 17.0 2.2 5.0 18.0 1.6 4.9
Appendix B Net Set Information and Catch Record Floating Gill Net Parameter Floating Gill Net Date Set : 24-Oct-02 Time Set : 16:03 Date Lifted : 25-Oct-02 Time Lifted : 10:04 Shallow End Depth (m) : 1.0 Shallow End Substrate : Angular gravel Deep End Depth (m) : 3.5 Deep End Substrate : Unknown Max. Depth Along Net (m) : 7.0 Netting record key RB - rainbow trout CT - cutthroat trout DV - Dolly Varden EBT - eastern brook trout GBT - german brown trout CO - coho salmon KO - kokanee PM - pumpkinseed sunfish BNH - brown bullhead SMB - small mouth bass IMM - immature MG - maturing MT - mature R - ripe SP - spent? - unknown LM - left maxillary RM - right maxillary AD - adipose NO - not marked Fish Characteristics Sample Stomach Contents Number Species Fork Length (cm) Weight (g) Sex Maturity Mark Age Type Bottom Organisms Plankton Terrestrial Fish Volume Comments No fish captured Sinking Gill Net Date Set : Time Set : Parameter Sinking Gill Net 24-Oct-02 15:49 Date Lifted : 25-Oct-02 Time Lifted : 10:16 Shallow End Depth (m) : 1.0 Shallow End Substrate : Angular gravel Deep End Depth (m) : 9.0 Deep End Substrate : Unknown Max. Depth Along Net (m) : 11.0 Netting record key RB - rainbow trout CT - cutthroat trout DV - Dolly Varden EBT - eastern brook trout GBT - german brown trout CO - coho salmon KO - kokanee PM - pumpkinseed sunfish BNH - brown bullhead SMB - small mouth bass IMM - immature MG - maturing MT - mature R - ripe SP - spent? - unknown LM - left maxillary RM - right maxillary AD - adipose NO - not marked Fish Characteristics Sample Stomach Contents Number Species Fork Length (cm) Weight (g) Sex Maturity Mark Age Type Bottom Organisms Plankton Terrestrial Fish Volume Comments No fish captured
Appendix C Photos Picture 1. Elizabeth Lake, looking north from trail access. October 24, 2002. Picture 2. Elizabeth Lake, looking north northeast from trail access. October 24, 2002.
Picture 3. Elizabeth Lake, looking northeast from trail access. October 24, 2002. Picture 4. Elizabeth Lake, looking east northeast from trail access. October 24, 2002.
Picture 5. Elizabeth Lake, looking east from trail access. October 24, 2002. Picture 6. Elizabeth Lake, looking southwest from lake inlet. October 24, 2002.
Picture 7. Elizabeth Lake, looking upstream where the inlet stream enters the lake. October 24, 2002.
Picture 8. Elizabeth Lake inlet stream, further upstream than Picture 7. October 24, 2002.
Picture 9. Elizabeth Lake inlet stream, further upstream than Picture 8. October 24, 2002.
Picture 10. Elizabeth Lake inlet stream, further upstream than Picture 9. October 24, 2002.
Picture 11. Elizabeth Lake, looking downstream where the outlet stream leaves the lake. October 24, 2002.
Picture 12. Elizabeth Lake outlet stream, further downstream than Picture 11. October 24, 2002.
Appendix D RECONNAISSANCE INFORMATION Location Location: approximately 31 km west of Port Alberni Elevation: 870 m UTM: 10U 335475N 5465914E Management Unit: 01-07 NTS Map: 092F06 1:20K Map: 092F.034 Watershed Code: 930-137400-99500-65100 Waterbody Identifier: 00899ALBN Drainage: Elizabeth Lake unnamed stream (Great Central Lake) Stamp River Somass River Physical Data Surface Area: 16.8 ha Perimeter: 2.8 km Max Depth: 20.0 m Secchi Disc Depth: 8.6 m Terrain Features Immediate Shoreline: The shoreline vegetation consists of alder, willow and blue huckleberry backed by a forest of yellow cedar and mountain hemlock. The shoreline substrate consists of angular gravel. The shoreline along the south side of the lake drops off rapidly to 8-10 m. The shoreline along the north side also drops off rapidly but only to a depth of approximately 2-4 m. Surrounding Country: The lake is positioned in a small depression surrounded by small rolling hills. The hills are all forested except those along the south side. The hills along the south side are clearcut with a 15 m forest leave strip along the lake shore. Access Directions: Turn right off the Pacific Rim Highway (Highway 4) 30.7 km past the Somass River bridge. At 0.8 km from the Highway keep to the right. At 8.0 km turn right. At 8.2 km keep to the right. At 8.8 km keep to the left. At 9.0 km keep to the left. At 9.6 km keep to the right. At 10.2 km take the middle fork in the road and the boat launch is at 10.3 km. The boat launch is on the shore of the small lake that is approximately 100 m from Elizabeth Lake. The boat launch does not provide direct boat access to Elizabeth Lake. Any boat must be portaged between the small lake and Elizabeth Lake.
Road Type and Conditions: The gravel logging roads were in good condition. There were cross-ditches on the upper roads but 4WD was not required. Restrictions: There is a gate at the beginning of the logging road. It was not locked at the time of the survey. Lake Access: The logging road reaches the edge of the small lake that is approximately 100 m from Elizabeth Lake. The boat was motored across the small lake and then carried approximately 100 m down the trail to Elizabeth Lake. Resorts and Campsites: None Other Developments: None. Observations Aquatic Plants: Sparse beds of potomageton spp. Wildlife Observations: A flock of six ducks (Buffleheads?) and bear scat were noted during the survey. Miscellaneous Comments: There is a hiking trail around the lake that was well-maintained at the time of the survey. Lake Drainage Description: The inlet stream enters the lake from the east side and the outlet stream leaves the lake from the north side and flows west. Inlet Stream: The inlet stream has a 1-2% gradient with pool-riffle sequences. The streambed consists of angular gravel, boulders and some volcanic bedrock outcrops. The inlet stream was flowing at the time of the survey. The inlet stream has the flow and gravel required for spawning. Outlet Stream: The outlet stream has a low gradient and only marginal suitability for spawning. The substrate consists of angular boulders with some angular gravel. History of Previous Surveys No formal survey or assessment of Elizabeth Lake has previously been completed.