What species of fish will benefit?
Upon successful completion of the Penobscot River Restoration Project,
all eleven species of native sea-run fish will benefit: American shad, Atlantic salmon, alewife, blueback herring, shortnose sturgeon, Atlantic sturgeon, sea lamprey, American eel, striped bass, rainbow smelt, and tomcod. Endangered
Atlantic salmon will be able to reach 52 percent of their historic
habitat, with only one dam to pass. According to a 2005 National
Academy of Sciences report, 80 percent of recent US Atlantic salmon runs
came into the Penobscot River, and the report recommended a program of
dam removal on the river. In 2012, the ten year average for salmon
caught at the Veazie fish trap was 1458, ranging from a low of 784 in
2002 to a high of 3,125 in 2011, indicating higher marine survival in
recent years for fish returning to the Penobscot River. Completion of
the project projects an increase of 10,000 to 12,000 salmon returning
each year to spawn.
Alewife runs are also expected to increase dramatically from the
thousands to several million, after dam removal. Alewives, along with
blueback herring are an important forage fish for coastal groundfish
stocks in the Gulf of Maine.
American shad could increase from near zero in the Penobscot River to
1.5 million a year, with project implementation. This species of sea
run fish is very sensitive to descaling and typically does not use fish
The Penobscot River watershed, which covers almost one-third of the
state of Maine, has the greatest potential of any river system in the
Gulf of Maine to restore self-sustaining populations of these species.
The recovery of populations of these species will bring widespread
ecological benefits to the Penobscot River watershed, and to the Gulf of
Maine. Read more on the sea-run fish of the Penobscot River
Why don't migratory fish just use the fishways on the dams?
Of the twenty operating hydropower dams in the watershed, five are located within the first 12 miles of river above head of tide. Eleven species of diadromous fish spend critical stages of their life cycles in East Coast rivers. For species where most of their historic habitat is located within this first 12 miles (striped bass, Atlantic and shortnose sturgeon, rainbow smelt, and tomcod), there is virtually no opportunity for restoration under current conditions, as there currently is no effective technology to pass these species. For species where most of their historic habitat is located above these first five dams (Atlantic salmon, American shad, alewife, blueback herring, and American eel), the cumulative losses from having to pass a large number of dams currently makes restoration of populations extremely difficult, if not impossible. Dam removal provides species benefits far beyond those achievable even through conventional fishway installation at all dams.
Removal of the two lowermost dams, Veazie and Great Works, will provide access to 100 percent of historic habitat to four species of sea-run fish that do not use dams. Threatened Atlantic sturgeon and federally endangered shortnose sturgeon will have access to virtually all potential spawning and juvenile growing habitat. Tomcod and rainbow smelt will also see increases in spawning habitat.
Overall, dam removal eliminates upstream and downstream fish migration obstructions, removes turbines that kill downstream migrating fish, restores natural seasonal flow variations, allows debris and nutrients to pass below the dams in order to create healthy habitat, and eliminates unnatural temperature variations below the dams.
How has the
project addressed concerns about invasive species like Northern pike spreading
in the watershed?
Northern pike are
one of several non-native fish that have been introduced into the Penobscot
watershed. Largemouth bass and black crappie are other species that were
relatively recently introduced within the Penobscot. Northern pike were first
reported in Pushaw Lake in 2003 and their presence was confirmed by Maine
Department of Inland Fisheries and Wildlife biologists in 2004 (pike have since
been confirmed in the Penobscot River below the Milford
Dam). Because of concern that pike might spread from Pushaw Lake up
the Penobscot River and through the proposed Howland Bypass into the
Piscataquis River, state and federal agencies requested that the Trust evaluate
the feasibility of a trap and sort facility in the Howland Bypass. The
Trust worked with the agencies to develop a scope for this evaluation, and
hired a team of fisheries biologists and passage experts to conduct it.
The study determined that a trap and sort facility was not feasible because it
was unlikely to be totally effective in eliminating movement of invasive
species, and in addition, the sorting activities would result in delays,
inefficiencies, injury, and mortality to restoration species. All state and
federal fisheries agencies--ME DIFW, ME DMR, USFWS, and NOAA Fisheries- agreed
with the study findings and officially signed off on the plan to construct the
bypass with no trap and sort facility.
there are several potential ways by which pike may spread into the Piscataquis
River, the MDIFW led a technical team from ME DMR, ME DIFW, USFWS, and NOAA
Fisheries to conduct a risk assessment for upstream pike movements, and
to evaluate the potential for other barriers to prevent pike
movement. The risk assessment determined the risk for spread of Northern
pike through illegal introduction was higher than the risk that they would
spread into the Piscataquis watershed on their own. The assessment identified
the need to maintain specific upstream barriers above the Howland Dam to
prevent natural Northern pike movement into upstream cold-water resources
further inland. Project partners and state and federal agencies including
ME DIFW, ME DMR, USFWS, and NOAA Fisheries agree that the best way to minimize
the impact of non-native species in the Piscataquis watershed is to implement
the 2009 Penobscot River Invasive Species Barrier Agreement between the
Department of Inland Fisheries and Wildlife and the Maine Department of Marine
Resources, which calls for the maintenance of certain localized barriers within
the watershed as the best defense to limit the natural movement of Northern
pike and other invasive fishes.
What effects will the project have on the American eel?
The US Fish and Wildlife Service (USFWS) recently considered listing the American eel under the Endangered Species Act due to declining eel populations in US rivers. Listing did not occur, although the USFWS report notes that dams exact a heavy toll on migrating eels. Mortality was estimated at 40 to 60 percent in rivers with multiple dams. The Penobscot River Restoration Project will improve access to thousands of miles of potential eel habitat, helping eel populations recover. Read more
What are the ecological benefits of the restoration project?
Upon implementation of the Penobscot River Restoration Project, full access will be restored to historic habitat (below Milford) for striped bass, Atlantic and endangered shortnose sturgeon, rainbow smelt, and Atlantic tomcod. Significantly improved access will be achieved to nearly 1,000 miles of historic habitat located above the Milford dam for Atlantic salmon, American shad, alewife, blueback herring, and American eels. Finally, Atlantic salmon production habitat in the river between Milford and tidewater will be fully restored to its historic, free-flowing character.
The restoration of sea-run fish likely are expected to provide abundant new food sources for a wide variety of fish and wildlife inhabiting the Gulf of Maine including: important commercial species such as cod, haddock, pollock, halibut and tuna; important recreational species such as striped bass and bluefish; and species that are threatened or federally protected such as bald eagles, seals and whales.
What wildlife, other than fish will benefit?
Burgeoning fish populations will also provide new feeding opportunities for aquatic birds and mammals such as kingfishers, river otters, osprey and bald eagles. Waterfowl, such as the Barrows goldeneye, should find plenty of winter food in open waters resulting from restoring sections of now impounded river. Newly created habitat will support aquatic insects, mussels, amphibians and turtles. Overall benefits of the project will go far beyond restoring fish populations. The project promises to have cascading effects on biological communities; from insects to otters and from alewives to eagles. Link to Benefits to Birds page.
Will there be any detrimental effects on the lower estuary from sediment flushing during dam removal?
In the case of Veazie and Great Works dams, there was very little sediment behind the impoundments due to the fact that they were run of the river dams. Sediment was normally flushed out during the operation of the dams and river flow. Any negative impacts were prevented through proper removal techniques.
How soon will the Penobscot River recover after dam removal?
Rivers are very dynamic and resilient systems. In other dam removal cases, experience has shown that restoration occurs relatively quickly. Only months after the Grist Mill dam was removed on the Souadabscook River in Maine, state fisheries biologist Randy Spencer found evidence of spawning fish in the gravel upstream of the old dam site. After the removal of two dams and construction of a rock and pool fishway on the Segdeunkedunk Stream in Holden, sea lamprey and Atlantic salmon were observed spawning in the streambed the following summer, and salmon fry were discovered in the stream this past year. Adult alewife were documented returning to Sedgeunkedunk Stream this past spring, and juvenile alewife were observed leaving Fields Pond to go out to sea in the fall. After the Edwards Dam was removed on the Kennebec River in 1999, water quality improvements within one year led the state to upgrade the freed section of the river from Class C to Class B due to improved oxygen and aquatic insect communities. In addition, state biologists have documented large increases in eagles, osprey, great blue heron, waterfowl, mink and river otter. On the Sebasticook River, a tributary of the Kennebec, the alewife population expanded from zero before dam removal to what was considered the largest alewife run in the country in 2010 (with a harvest of over 450,000 alewife and an estimated total run of 1.5 million alewife).