Fisheries Monitoring Report For Rush, Lee Vining, Parker and Walker creeks, 1999

By Chris Hunter, Brad Shepard, Darren Mierau, Ken Knudson, Ross Taylor

Executive Summary

This report presents the results of the first year of fish population monitoring for Rush, Lee Vining, Parker and Walker creeks pursuant to State Water Resources Control Board (SWRCB) WR 98-07. We evaluated four different techniques to estimate trout populations: mark-recapture electrofishing; mark-recapture utilizing electrofishing for the marking run and snorkeling (day and night) for the recapture run; snorkeling and electrofishing depletion. We concluded that mark-recapture electrofishing provided the most reliable estimates for the larger waters (Rush and Lee Vining creeks). Electrofishing depletion estimates provided reliable estimates for Parker and Walker creeks.

We recommend that the methods described in the White Book (LADWP, 1997) be changed to reflect the results of the 1999 efforts. Electrofishing mark-recapture should be used to estimate fish populations in the Rush and Lee Vining creek main channels. Electrofishing depletion estimates should be conducted on Parker and Walker creeks and the Lee Vining side channels.

We compared the estimated fish population data for Rush and Lee Vining creeks to the termination criteria adopted by the SWRCB. The termination criteria are:
1. Lee Vining Creek sustained catchable brown trout averaging 8-10 inches in length.
2. Rush Creek fairly consistently produced brown trout weighing ž to 2 pounds. Trout averaging 13-14 inches were also regularly observed.

Lee Vining Creek does contain a small number of brown trout 8 inches and greater in length. However the numbers are so low, less than 6 per 100 meters in the lower sampling section and less than 7 per 100 meters in the upper sampling section, that we don't believe the population can be sustained in the face of harvest.

We collected two fish in Rush Creek that would meet the termination criteria of weighing between ž and 2 pounds or attaining a length of 13 to 14 inches. We collected one fish that would meet these criteria in each of the Upper and Lower sections of Rush Creek. We did not sample any fish in the County Road section that would meet these criteria.

The SWRCB requires us to recommend additional quantitative termination criteria for Rush and Lee Vining creeks as well as quantitative termination criteria for Parker and Walker creeks. The lack of historic fish population data makes it very difficult to make recommendations for quantitative termination criteria with any confidence that they are reasonable. We recommend that data collection be continued for a few more years before we attempt to define additional quantitative termination criteria.

We recommend that the two existing termination criteria be changed to specifically state they must be met by self-sustaining trout populations. We also recommend that the following two termination criteria be adopted:
1. Fish population monitoring shall be terminated for any stream if it is opened to any level of harvest or if fish stocking is initiated.
2. Fish population monitoring of Lee Vining Creek shall be terminated because the stream has been opened to harvest. If the monitoring is continued, then a creel census study should be conducted to evaluate the effect of harvest on the trout population. If harvest is shown to have a negative effect on the self-sustaining trout population, then the harvest should be stopped or the fish population monitoring terminated.

End of Executive Summary