Project Number: 09042
Initiated: 1997
Status: Ongoing
Location: Connecticut River (field study)
Upstream and downstream fish passage facilities have been in place
on the lower Connecticut River mainstem (Vernon Dam, Turners Falls Dam,
Holyoke Dam) since 1981. The Turners Falls Dam fishway complex has been
historically inefficient in passing American shad (Alosa sapidissima).
This study evaluates passage performance of the Turners Falls fishways
by marking and releasing large numbers of American shad with passive
integrated transponder (PIT) tags and detecting tagged fish at strategic
sites within the fishways (e.g., entrances, exits, turnpools and straight
runs of pools) by automated PIT tag detectors. Data are integrated to
determine passage success or failure, rates of ascent, delays, and passage
"bottlenecks". The experimental design also allows for experimental
modifications of the fishways (e.g., lighting, flow alteration, or limited
physical modifications) to be implemented and evaluated during testing.
Overall, passage efficiency through the larger fishways was low, averaging
about 17%. Mean passage efficiency within the power canal was 37% .
Median transit times through the larger fishways averaged 10 hours,
but was highly variable between fish. Median transit time through the
canal was 25 days. Modifications to the fishways (opening surface weirs
in-line, replacing sharp-crested weirs with chutes) improved efficiency
and reduced transit times on a per-weir basis, but modification of the
entire fishway was predicted to have produced a marginal improvement
to the entire fishways, based on the large number of weirs in each fishway.
Addition of a secondary exit channel out of the canal is expected to
improve canal passage efficiency.
