Wednesday, February 24, 2016

Dam Removal: Restoring Aquatic Life in the Penobscot River

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.
       On a global scale, many countries that are less developed have not yet built dams. With the knowledge that has been gained from these removal projects hopefully any furthur dam building can be prevented.    


No comments:

Post a Comment