Recreational Fishery Stock Assessments :

1999/2000 Data Report with
Management Recommendations

 

PHOTO 1. Nelson Lake Aerial View, June 2001. Click image to view 92K JPG

PHOTO 2. Nelson Lake, May 2000. Click image to view 92K JPG

Introduction

This report presents the results of two stock assessment surveys conducted on Nelson Lake between 1999 and 2000. A gill net survey was performed on July 15, 1999 under a partnership arrangement between the Ministry of Environment, Lands and Parks and the Carrier Sekani Tribal Council (CSTC). A followup angling survey was subsequently conducted on June 25, 2000 to evaluate angling catch success rates and to obtain an additional sample of stocked rainbow trout for comparison with the 1999 data. This work was done in partnership with the Spruce City Wildlife Association. The following report presents the results of both assessments.

Nelson Lake is located 42 km south of Prince George, or 31.6 km south of Highway 16 on the Blackwater Forest Service road. The lake is accessed by a 100 metre trail from the road to the lake's shore.

The lake was first surveyed in October 1988, after it had been initially stocked with rainbow trout in May of the same year. No other species of fish were captured, and it is assumed that the lake was barren prior stocking. The lake was stocked to provide a low-use, high yield "family" fishery to recreational anglers. An alternate year stocking schedule was established in 1992, four years after its initial stocking, and the lake remained on this schedule until 1996.

In the spring of 1997 anecdotal reports were received that suggested a winterkill may have occurred during the winter of 1996/97, as no fish had been observed or angled that spring. A one day survey was completed by the Ministry in July 1997, (data on file) during which angling was conducted and a gill net was deployed. This effort yielded 9 rainbow trout, 8 of which were angled, confirming that a winterkill had not occurred, or at least had not significantly reduced the trout population.

Also in 1997 the SCWA elected to take an active role in the management of the Nelson Lake fishery by growing at their hatchery the yearlings that were originally earmarked for spring release into Nelson Lake. The trout were grown on site through the summer and were then released in the fall; the Association continued to hold, mark, and release yearlings in this manner until 1999.

By 1999 the lake was given a high priority for assessment in order to determine the status of the recreational fishery and the success of the SCWA summer rearing program. Funding for this work was obtained from Fisheries Renewal B.C., administered through the Upper Fraser-Nechako Fisheries Council. Margo French, Lawrence Ward, and James Prince of the CSTC conducted the fieldwork for the 1999 assessment.

Upon preliminary review of the 1999 field data, it was determined that the sample size of fish captured was too small to permit a thorough review of the status of the fishery. This was partially due to the vandalism of one of the net sets (see below) and the destruction of its catch. To increase the sample size while minimizing fish mortalities, a live sampling program was scheduled for 2000. This effort was funded internally by BC Environment and was performed by Ministry staff and SCWA volunteers.

Methods

1999 GILL NET SURVEY

A 91.4 m sinking monofilament gill net with experimental mesh sizes was set in Nelson Lake at 10:20 AM on July 14, 1999, according to the methods specified in the Resource Inventory Committee document Fish Collection Methods and Standards. The net was deployed in an E-W orientation from the east shore (Figure 1) and was retrieved on July 15 at 9:20 AM. The net was then re-deployed from the north shore in a N-S orientation and left overnight. On July 16, it was discovered that the net and the fish it had captured overnight had been pulled into shore and burned. Only the results of the first net set are reported here; the total soak time of this set was 23.0 hours.

FIGURE 1. Location of Nelson Lake gill net sets, July 15, 1999. Click image to view detailed 69K map.

All trout collected were sampled for fork length (mm), weight (to 50 g), sex, and maturity. Stomach contents were examined in the field. Scales were collected for age structure analysis, which was performed by Darlene Gillespie of TimeMark Consulting Ltd. (Nanaimo, B.C.).

2000 ANGLING SURVEY

A total of 9 anglers fished Nelson Lake on June 25, 2000 using a variety of hardware. Seven of the anglers fished from 10:20 AM until 2:20 PM; the remaining two anglers fished until 1:20 PM, for a total combined effort of 34 angler-hours. All but 10 captured fish were measured for fork length (mm) and weight (± 1 g). Sex, maturity, and stomach contents were not evaluated due to the live sampling techniques employed. Scale samples were collected, however these structures were not aged at the time of writing.

Results and Discussion

CATCH SUMMARY

1999 GILL NET SAMPLE

The net catch yielded 17 rainbow trout (RB) for a catch per unit effort (CPUE) of 0.74 RB per net-hour. No other species were captured. See Appendix 1 for specific fish attribute data. Two fish were classified as immature; the remaining 15 were mature. Fifteen fish were female, one was male, and the sex of one could not be identified.