Slocan River Bull Trout Spawning Assessment 2018

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

Previous estimates of the risk category and total watershed escapement made assumptions about the relative contribution of the Slocan River tributaries. This pilot project allows the actual contributions of the Slocan Rivers tributaries (Little Slocan and Lemon) to be evaluated with the Slocan Lake tributaries contribution for the 2018 spawning season. The primary benefits of this project are to improve the understanding of the population size and trends for the entire Slocan Watershed Bull Trout population, to identify opportunities for restoration and enhancement and to provide the best available scientific information for establishing management tactics to meet conservation goals.

In total, 73.9 km of stream were surveyed, and 193 redds, 68 spawners (43 males and 25 females), and 2 unspawned females were observed for all streams combined.
In 2018, 137 redds, 34 male spawners and 15 female spawners, and 2 unspawned females were observed in Silverton Creek. Both Fennell and Maurier creeks have gradient barriers within the first 100 m from their creek mouths and neither contained unspawned females nor redds in 2018.
In 2018, 20 redds and 0 unspawned female were observed in Wilson Creek and 20 redds and 0 unspawned females were seen in Dennis Creek which together account for 20.5% of the total escapement. In addition, 7 female and 7 male spawners were observed in the surveyed systems.
In 2018, 14 redds and 0 unspawned females were observed in Lemon Creek. Two redds were observed in Holmson Creek and no redds nor females were observed in Crusader and Monument Creeks. One male spawner was observed in Lemon Creek and 1 female and 1 male spawner were observed in Holmson Creek.
In 2018, 0 redds, 0 spawners and 0 unspawned females were observed in Little Slocan Creek or its tributaries.
Bull Trout escapement (assuming 2.4 adults per redd and utilizing the low- and high-density expansion factors as described in the methods for creeks that were not surveyed in 2018) of all accessible Slocan Lake tributaries in 2018 was 442 adults, which was 92% of the watershed-wide escapement estimate. Escapement of Bull Trout from the Slocan River tributaries was estimated to be 39 fish, accounting for 8% of the escapement across the watershed. The average total escapement across the five years is 321 fish. Silverton Creek contributes the largest proportion (71%) of the total redds.Wilson and Little Slocan below the lakes and at the mouth were the warmest with temperatures in excess of 15°C, and the coolest creeks were Lemon and Hoder.

In total, 73.9 km of stream were surveyed, and 193 redds, 68 spawners (43 males and 25 females), and 2 unspawned females were observed for all streams combined.
In 2018, 137 redds, 34 male spawners and 15 female spawners, and 2 unspawned females were observed in Silverton Creek. Both Fennell and Maurier creeks have gradient barriers within the first 100 m from their creek mouths and neither contained unspawned females nor redds in 2018.
In 2018, 20 redds and 0 unspawned female were observed in Wilson Creek and 20 redds and 0 unspawned females were seen in Dennis Creek which together account for 20.5% of the total escapement. In addition, 7 female and 7 male spawners were observed in the surveyed systems.
In 2018, 14 redds and 0 unspawned females were observed in Lemon Creek. Two redds were observed in Holmson Creek and no redds nor females were observed in Crusader and Monument Creeks. One male spawner was observed in Lemon Creek and 1 female and 1 male spawner were observed in Holmson Creek.
In 2018, 0 redds, 0 spawners and 0 unspawned females were observed in Little Slocan Creek or its tributaries.
Bull Trout escapement (assuming 2.4 adults per redd and utilizing the low- and high-density expansion factors as described in the methods for creeks that were not surveyed in 2018) of all accessible Slocan Lake tributaries in 2018 was 442 adults, which was 92% of the watershed-wide escapement estimate. Escapement of Bull Trout from the Slocan River tributaries was estimated to be 39 fish, accounting for 8% of the escapement across the watershed. The average total escapement across the five years is 321 fish. Silverton Creek contributes the largest proportion (71%) of the total redds.Wilson and Little Slocan below the lakes and at the mouth were the warmest with temperatures in excess of 15°C, and the coolest creeks were Lemon and Hoder.