GMSMON-17 WILLISTON RESERVOIR TRIBUTARY - BC Hydro

May 22, 2012
Report No. 1114920016-R-Rev0-2000 22
GMSMON-17 WILLISTON RESERVOIR TRIBUTARY HABITAT
REVIEW
current at several sites) and many potential sites were not feasible to sample because of practical or safety
constraints. Access to sample sites with electrofishing and block net equipment (by boat and hiking) was also
labour and time intensive, which limited the number of sites that could be sampled. For these reasons, we
recommend that alternative methods be considered for the juvenile and small-bodied fish population survey
component of this monitoring program.
One suggested alternative is a mark-resight program to estimate juvenile fish abundance. Minnow traps would
be used to capture juvenile and small fish, which would be marked with hook and yarn markers and released at
the capture site. A night-time snorkel survey would be conducted to enumerate the number of marked and unmarked
fish at the sample sites. Fluorescent lights can be used during snorkel surveys to help observe
fluorescent dye VIE tags. A population estimate would be generated based on the number of marked and unmarked
fish observed. Similar mark-resight programs have been used in other locations to estimate the
abundance of small and juvenile fish in small streams (Bonneau, Thurow, and Scarnechhia, 1995) and for other
BC Hydro studies (Decker, Mcnair and Lewis, 2010). Surveys would be conducted at index sites that would be
re-sampled each study year. These methods offer several advantages over closed-cell electrofishing depletion
surveys, including potentially more accurate population estimates (Decker, Mcnair and Lewis, 2010) and less
time and effort for transporting and installing block nets.
4.2 Amphibians
Very few amphibians were observed or heard during the three sampling surveys. In addition, little off-channel
habitat was present at any of the four streams. Most of the habitat that was observed turned out to be ephemeral
in nature and may not have supported appropriate conditions for amphibian breeding or rearing. Suitable habitat
is present within the zone of inundation (wet mud flats) at all the stream mouths, evidence of breeding observed
in this area included long-toed salamander eggs at Six Mile Creek and numerous juvenile western toad at the
mouth of Factor Ross.
4.3 Birds
As the abundance and diversity of migratory birds is invariably linked to numerous factors throughout their range,
it is anticipated that linking changes in the diversity or abundance of birds in riparian areas to proposed
enhancement works will be difficult and likely not possible. As such, it is recommended that songbird monitoring
be suspended and that efforts be reallocated to fish monitoring where the designed enhancement is most likely
to yield a change.
4.4 Vegetation
The key management question relating to the riparian vegetation section of the Tributary Habitat Review
monitoring program is: does riparian vegetation along tributaries increase in abundance and diversity as a result
of enhancement? The primary sampling objective of the riparian vegetation task is to address the management
question posed above by collecting data necessary to draw inferences and to test the following null hypothesis: