The Penobscot River is
home to many aquatic species, such as salmon, shad, strgeon, alewives, and eels
(Bidggod,
2013). These species all play a critical role in their ecosystem; they
provide food for many other species, and they created industry such as
fisheries. Many of these crucial species that were once abundant, have been
pushed to endangerment in recent decades.
The decline in fish
started when dams were built in the Penobscot. Thirty foot dams such as the Veazie
Dam (picture below) and several others make it increasingly hard for fish to
make it up river to their spawning grounds (Miller,
2015).
If the fish do not make it to their spawning grounds it is likely that they
will die before they can replace themselves.
Dam
removal projects such as the one in the Penobscot work to restore the natural
state of the waterway. The project in Maine began in 1999, and it was led by
the Penobscot River Restoration Trust (Bidgood, 2013). The
project required emhense cooperation between the state and federal government, a
power company, and the Penobscot Indian Nation (Tercek,
2012);
overall it cost upwards of $60 million (Carpenter, 2012)
Dam
removal has provided over 1,000 miles of open river habitat. This has
drastically increased
fish population size in just a few years.
Since the removal alewives, American shad and other aquatic species are rising
in numbers. Fish sampling has estimated a 45-fold increase since 2013 (Miller, 2015).
The shortnose sturgeon is
a unique species of fish present in the Penobscot. It is characterized by its
bony body and is capability to live over 50 years. Problems such as overharvesting,
loss of habitat, and pollution led to the fish being placed on the endangered
species list in 1967. The take down of the Veazie Dam and the Great Works Dam
has given the shortnose sturgeon access to 100% of its historic habitat. Since
the dam removals, the species has been found up stream in habitat it hasn’t had
access to in over 100 years (University
of Main, 2015).
Furthermore,
the Penobscot is one of the few rivers left that is home to the Atlantic
Salmon. Since dam removal population size has fluctuated greatly. The year
after removal was and all time low for the specie, but the following year in
2013 the species was approximated to be 726 salmon (Miller, 2015). This
is not a ideal population size, but it does show growth. The lack of
flourishing could be due to the salmon’s complicated life cycle. As the diagram
below shows, salmon have many stages of life and can take several years to come
in shore to reproduce. Even if the population size has not shown much growth
yet it could very likely be caused by a lag in its life cycle.
This
is one of the largest dam removal projects to take place so far. In just a few
short years fish populations have improved exceptionally. Many hope that the
positive results of this project will lead to other dam removals nationally.
References:
University of Maine, After
more than a century, endangered shortnose sturgeon find historic habitat post
dam removal (17 Nov 15)
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