GMSMON-17 WILLISTON RESERVOIR TRIBUTARY - BC Hydro

May 22, 2012
Report No. 1114920016-R-Rev0-2000 7
GMSMON-17 WILLISTON RESERVOIR TRIBUTARY HABITAT
REVIEW
and increased water flows by the time the crews reached the northern tributaries, Ole and Factor Ross creeks
were not angled or snorkelled.
2.1.2 Juvenile and Small-Bodied Fish Surveys
Backpack electrofishing was used to sample juvenile and small-bodied fishes in the study creeks during the
summer site visit (9 to 18 August, 2011). A multiple-pass removal-depletion survey with stratified sampling by
habitat type was used to estimate the abundance of target and other species. A fish collection permit was
obtained from the Ministry of Natural Resource Operations (Permit # PG11-70349) and a copy is found in
Appendix C. Fish species identifications were determined by experienced field staff and confirmed by reference
to photographs and to McPhail (2007).
2.1.2.1 Sampling Sites
Electrofishing sites were 100 m long and 2 to 3 sites were sampled in each creek. Sites were randomly selected
from the first 1.1 km of stream from the mouth because this zone is most likely to be influenced by enhancement
and site access to upper reaches of the streams was difficult. Random selection of sampling sites was
conducted using Generalized Random Tessellation Stratified (GRTS) survey design protocol as suggested by
Stevens and Olsen (2004). This method provides a compromise between purely stratified design and complete
randomness, and results in randomly selected sites that are spread out across the zone of interest. It also allows
the additional of random sites if originally selected sites cannot be sampled for some reason (e.g., not feasible to
access site). The R program language module and details in the methodology can be found at:
http://www.epa.gov/nheerl/arm/designing/design_intro.htm., and is provided in Appendix I.
Habitat units (strata) within each sampling site were classified as one of the following categories: glide, pool,
riffle, or rapid. The length of the site along the thalweg and the mean width was measured using a measuring
tape or hip-chain. Approximate stream flow conditions in relation to the channel width and bankfull depth were
classified as low, medium or high. A Reconnaissance Fish and Fish Habitat Inventory Site Card were also
completed for each electrofishing site.
2.1.2.2 Multiple-removal depletion electrofishing surveys
Once a suitable sample site was selected (at the downstream end), the upstream block net location was
measured with a hip chain. It was placed 100 m upstream, or at the closest suitable location. The site length was
then recorded on the form. A site card was completed at each site to provide detailed habitat information. The
sampled area was then calculated by multiplying the average channel width by the distance between the block
nets.
Sample sites were isolated using block nets installed across the channel at the upstream and downstream end
of the site, preventing fish from entering or leaving the site during sampling. Block nets were installed using rebar
pounded into the substrate and rope attached to shore; small rocks and boulders were used to secure the net to
the creek bottom. Backpack electrofishing was conducted using a Smith-Root LR-24 backpack electrofisher with
a programmable output wave form that enables fish to be caught efficiently with minimal risk of injury. The
sampling crew consisted of two to three members, with one person operating the electrofishing unit and one or