fish movement at the springbank dam during open flow
conditions: pre-construction baseline monitoring
EXECUTIVE
SUMMARY
The
City of London and the Upper Thames River Conservation
Authority contracted Biotactic Incorporated to design
and conduct a study to collect baseline data related
to fish movement at the Springbank dam in the spring
before stoplogs are installed and the dam is
operated. These baseline data are to be used to
address provincial and federal directives pertaining
to the maintenance or enhancement of the status quo
of fish movement at the Springbank dam.
Radio-telemetry was used to track the movement of
sixty radiotagged white suckers, shorthead redhorse
and smallmouth bass at the Springbank dam from April
13 2006 to June 27 2006 (twenty fish of each species)
to establish a dataset related to fish movement at the
dam. All fish were collected from areas upstream from
the dam and released downstream after radio-tag
implantation. The vast majority of all fish passed
the dam with no apparent difficulty. The two
catostomid species (early migrating white suckers and
mid season migrating shorthead redhorse) that were
monitored, rapidly approached and passed the dam, and
some individuals returned downstream past the dam
several weeks after upstream migration. Late spring
upstream migrating smallmouth bass approached the dam
more slowly and sometimes used the structure as
habitat, although the majority of smallmouth bass
passed the dam with no apparent difficulty. Baseline
data related to fish movement at the Sprinbank dam in
2006 is summarized as follows:
1.
The
Springbank dam structure is not a barrier to fish
movement prior to dam closure each year and should
remain this way after new gates are constructed.
2.
Post-construction attraction efficiency of white
sucker, shorthead redhorse and smallmouth bass should
be statistically similar to pre-construction
conditions. These values (reported as efficiency with
95 % confidence interval in parentheses) are:
-
90% (70%
– 97%) for white sucker
-
80% (58%
- 92%) for shorthead redhorse
-
95% (76%
- 99%) for smallmouth bass
3.
Post-construction passage efficiencies of white
sucker, shorthead redhorse and smallmouth bass should
not be statistically different from values determined
under pre-construction conditions in 2006. These
values (reported as efficiency with 95 % confidence
interval in parentheses) are:
-
94% (74%
- 99%) for white sucker
-
94% (74%
- 99%) for shorthead redhorse
-
89% (69%
- 97%) for smallmouth bass
4.
Fish
movement should not be delayed to the point where
successful migration and reproduction are compromised.
Most fish rapidly approached and swam upstream through
the dam structure in 2006. The amount of time required
for dam passage should not be statistically different
between pre-construction and post-construction
conditions. The mean time (± standard deviation)
required for each species to pass the Springbank dam
was:
-
5.2 ± 7.4
minutes for white sucker
-
3.5 ± 2.6
minutes for shorthead redhorse
-
16.7 ±
22.1 minutes for smallmouth bass
5.
Post-construction
attraction efficiency and passage efficiency should be
monitored for a minimum of two years, and maximum 5
years after construction using radio telemetry
emulating 2006 baseline data collection methodology.
As with all
scientific research, the study would benefit from more
species, larger sample sizes and a multi-year
monitoring program. Additional opportunities to
monitor additional species or enhanced sample sizes
may become available through partnerships with other
agencies that may be interested in other fisheries
objectives such as development of a Fisheries
Management Plan that will greatly benefit the Thames
River.
