Slocan Lake Bull Trout Redd Monitoring 2016

Author: J.T.A. Baxter, R.L. Irvine

The objective of this study is to complete three years of redd count surveys of all potential Bull Trout spawning tributaries draining into Slocan Lake from 2014-2016 following on the pilot study in 2013. The project goal is the estimation of spawner distribution and abundance in the Slocan Lake population of Bull Trout and identification of restoration opportunities in the watershed.

In total, 34.24 km of stream were surveyed, and 105 redds and 5 unspawned females were observed for all streams combined. Redd counts varied from 1 redd in Wee Sandy Creek to 75 redds in Silverton Creek.
Bull Trout escapement (assuming 2.4 adults per redd) of all accessible Slocan Lake tributaries in 2016 was 264 adults with Silverton Creek making up the largest proportion of the total spawning fish with 71% of the redds. The escapement estimate was mainly based on redd numbers with only 5 unspawned females observed during the surveys indicating accurate timing for the surveys in 2016. The escapement numbers through the four years of the study have ranged from just under 200 fish to almost 400 fish with no years greater than 500 fish. The average total escapement across the four years is 290.3 fish.
Data loggers were downloaded in Fall 2016 and several loggers are now deployed year-round to allow winter temperatures and ATUs to be calculated annually. Most of the creeks in which temperature was monitored stayed below 15°C with the warmest creeks being Glade, Bonanza and Carpenter. Sharp Creek was the coolest creek overall while Carpenter and Fennell Creeks showed the widest diel variation in water temperature throughout the spring and early summer period. Silverton creek shows a relatively similar temperature curve by year for the 3 years of record, with the low water year of 2015 showing higher peak temperatures on average and wider diel variation in the summer months.

In total, 34.24 km of stream were surveyed, and 105 redds and 5 unspawned females were observed for all streams combined. Redd counts varied from 1 redd in Wee Sandy Creek to 75 redds in Silverton Creek.
Bull Trout escapement (assuming 2.4 adults per redd) of all accessible Slocan Lake tributaries in 2016 was 264 adults with Silverton Creek making up the largest proportion of the total spawning fish with 71% of the redds. The escapement estimate was mainly based on redd numbers with only 5 unspawned females observed during the surveys indicating accurate timing for the surveys in 2016. The escapement numbers through the four years of the study have ranged from just under 200 fish to almost 400 fish with no years greater than 500 fish. The average total escapement across the four years is 290.3 fish.
Data loggers were downloaded in Fall 2016 and several loggers are now deployed year-round to allow winter temperatures and ATUs to be calculated annually. Most of the creeks in which temperature was monitored stayed below 15°C with the warmest creeks being Glade, Bonanza and Carpenter. Sharp Creek was the coolest creek overall while Carpenter and Fennell Creeks showed the widest diel variation in water temperature throughout the spring and early summer period. Silverton creek shows a relatively similar temperature curve by year for the 3 years of record, with the low water year of 2015 showing higher peak temperatures on average and wider diel variation in the summer months.