Operational Plan for the Restoration of Diadromous Fishes to the ...

to preclude the upstream passage of pike in the drainage. Renowned fisheries
scientist and expert on Northern pike, Dr. John Casselman, agreed that a 30-inch
jump is adequate to prevent the upstream passage of pike through the fishways
(pers. comm.).
After the confirmation of the presence of northern pike, a lake management plan was
developed with the main goal of preventing further spread of the invasive and
controlling the population in Pushaw Lake (Gallagher et al. 2006). The Pushaw Lake
management plan also examined methods for potentially eliminating or suppressing
the pike population in Pushaw Lake. The plan noted that the large lake with
considerable wetlands and residential development would be unsuitable for chemical
reclamation. Several barrier methods were considered for the outlet but none were
deemed feasible for a variety of reasons. The plan concludes that eradication of pike
from Pushaw is unlikely, but that suppression or control methods should be explored
and have been underway since 2006.
Spring removal efforts have been conducted for three years (2006-08) with some
success. So far, there has not been a dramatic increase in the pike population at
Pushaw Lake as evident by the low capture rate of pike by anglers. To date records
indicate 60 female pike have been removed in 3+ years through angling and spring
trap netting. The total pounds of females removed is ~ 300 which translates into
about three million eggs (~ 10,000 eggs per pound of body weight).
Following confirmation of northern pike in Pushaw Lake, and the
recognized potential for upstream migration, the parties to the MPA agreed to
undertake an evaluation for feasibility of creating a fish passage barrier and trap and
sort capability within any bypass channel to be constructed at Howland. Extensive
hydraulic engineering and modeling was underway (by the Trust) to determine if a
bypass channel capable of unrestricted upstream passage for restoration species
could in fact be designed.
Accordingly, USFWS fishway design engineers and passage experts at the Conte
Lab provided detailed evaluation. From that evaluation it was determined that
any benefits of a bypass channel to provide free-swim migration for restoration
species would be completely negated by measures necessary to provide assurance
of near-100% exclusion of pike. Extensive additional excavation of the channel and
an elaborate upstream barrier dam and trap and sort facilities would be required. In
addition, notwithstanding the high cost of construction and ongoing operation, even
the most effective trap and sort operation possible at this site was considered
to cause unacceptable delay in migration of the various restoration species. Under
the MPA, if a free-swim bypass channel could not be constructed the
alternative was breach or removal of the Howland Dam.
The agencies and restoration interests agreed the best alternative (rather than
breaching or removing the Howland dam) would be to undertake a risk assessment
for upstream pike movements and to evaluate existing or potential upstream
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