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News
District studies ancient fish
April 16, 2009
by Patrick Bloodgood
Norfolk District Public Affairs
NORFOLK, Va.—More than 400 years ago, Jamestown Settlement founder Captain John Smith penned that there were more sturgeon "Than could be devoured by dog or man."
Today, the Atlantic sturgeon, once dined on by American settlers, colonists and generations of Americans, is extinct in much of its original habitats and could end up on the nation's endangered species list.
The Atlantic sturgeon -- Acipenser oxyrhynchus oxyrhynchus -- is a member of the Acipenseridae family and is among one of the oldest fish species in the world. Its range extends from New Brunswick, Canada to the eastern coast of Florida. The fish can reach 60 years of age, 15 feet in length and weigh over 800 pounds. Rather than having true scales, the Atlantic sturgeon has five rows of bony plates known as scutes. Its coloration ranges from bluish-black and olive green on its back to white on its underside. It has a longer snout than other sturgeons and has four barbels at the side of its mouth.
Scientists suspect multiple reasons for the decline of the ancient fish, including overfishing, loss of suitable spawning habitat in the upper portions of river basins and incidental mortality from devices such as large fishing nets.
For decades, there have been concerns that dredging operations within river and estuary environments could negatively impact the sturgeon. These concerns stem from the impacts dredging has on the river bottom environment.
As part of dredging permit compliance, the Norfolk District, Army Corps of Engineers has joined with the U.S. Fish and Wildlife Service, the Virginia Institute of Marine Science, Virginia Commonwealth University and the James River Association, to study the Atlantic sturgeon to determine how they interact with ship traffic and dredging activities.
The goal of the study is to find out if sturgeon behavior is influenced by dredging operations.
As part of the supervised study, sturgeons were caught in nets and brought on board a research vessel. After being surgically implanted with a radio frequency tracking device, they were set free.
"We released them up river, near the dredge and then down river to see if the dredging operation would affect their behavior," said Sarah Cameron an environmental scientist in the district's Operations Branch.
This study phase lasted two weeks and employed both passive and active array sensing technology. Passive array sensors are stationary and set up in multiple locations along the river. It only records data when a fish comes near. Active array sensors constantly tracks and is used on a vessel to follow the sturgeons every move.
Even though the ancient fish date back at least 70 million years, not a lot is known about their behavior or reproductive cycle.
"Although there have been a wide array of studies conducted on the Atlantic sturgeon, small sample size and funding constraints have hindered research efforts," said Cameron.
Scientists here are forging ahead with their multi-year study, hoping to unlock some of the mysteries surrounding the ancient fish, including the impact dredging operations has on its habitat.
The Corps' takes serious its primary mission to maintain navigation in an environmentally friendly and sustainable way, stressed Cameron.