Many people are aware of the nutrient loading which has plagued the Chesapeake Bay and the effect of shellfish restoration to remedy the effects:
Chesapeake Bay Foundation:
OYSTER RESTORATION –
Video: Time-lapse of Oysters Filtering Water
Windows Media
CBF’s oyster restoration program provides citizens with the tools and information needed to help restore native oysters to the Bay. Until the 1980s, oysters supported the most valuable fishery in the Bay. Today, as a result of decades of pollution, over-harvesting, and disease, the Bay’s native oyster population is merely about 2% of historic levels. Yet they remain an important part of the Bay’s ecology.
Oysters form large reefs that provide habitat for a wide range of marine plants and animals. In addition, they feed by filtering microscopic plants from the water, and in the process improve water quality and clarity.
Rebuilding reefs and stocking them with oysters is a high priority for the Bay. It is a long-term process that will require the participation and commitment of federal and state agencies and citizens alike for many years. But it is important to restore native oysters to the Chesapeake.
but not many people know the impact of constructing eel ladders on dams can potentially bring back the american eel to it’s original habitat…
Blockages to upstream habitats. Eels are hindered, or blocked altogether, from 84 percent of their historic habitats in Atlantic Coast tributaries.
and the restoration of the american eel may have the potential to bring back shellfish to the tributaries:
The developing story, if correct, suggests that when power companies built a series of large hydroelectric dams in the lower Susquehanna during the 1900s, they disrupted a delicate ecological linkage no one imagined at the time.
Biologists at the USGS lab, who research rare and endangered mussels, began examining the issue after they completed a large-scale, two-year survey of freshwater mussels in a 125-mile stretch of the upper Delaware River.
The survey showed that 98 percent of the mussels in the river consisted a single species: Elliptio complanata—not a huge surprise as it’s the most common mussel in the Northeast.
and
He pointed out that eels are important food sources for other fish and birds of prey, plus they play a role in mussel reproduction because mussel larvae attach to eels. In rivers that no longer have eels, the mussels are gone, too.
and shellfish in the tributaries can provide the necessary nutrient filtration needed to restore the Chesapeake Bay.
So why not build a eel ladder on the Conowingo Dam?
The Maryland Department of Natural Resources’ Biological Stream Survey found that the average density of American eels in the Susquehanna River basin below the 100-foot-high Conowingo Dam was about 500 per square mile. Above the dam, the survey found only one eel at 11 sites surveyed in Maryland.
Cost of Building an eel ladder?:
New York Power Authority Project: $2 Million
Will an eel ladder at Conowingo cost much more?
The amount of money expected to be spent on nutrient removal upstream (point and non-point sources) to meet new nutrient limits will easily be 10 to 100 times that.
External Links:
Demise of eels may have doomed Susquehanna mussels, hurt Bay
Without a Passage, Eels future May Be Dammed
Eel passage under consideration for dam on Susquehanna
Eels get free pass through dams
What an eel ladder looks like:
(Hydro Quebec)
[tags]eel, Chesapeake, nutrient removal, oysters, mussels, conowingo[/tags]
