Acipenser brevirostrum Photo: Nancy Haley, NOAA http://digitalmedia.fws.gov/ Atlantic sturgeon photo courtesy of Robert Michelson http://www.nmfs.noaa.gov/stories/2012/01/31_atlantic_sturgeon.html Threatened and Endangered Species Issues on the Kennebec River, Maine Obstacles to Dredging due to the Presence of Shortnose Sturgeon, Atlantic Salmon and Atlantic Sturgeon Kenneth M. Levitt Valerie A. Cappola Ph.D. USACE New England District Troy R. Bennett / The Times Record Bangor Daily News, September 1, 2011
Kennebec River Federal Navigation Channel Phippsburg to Bath (approximately 13 miles) Maintained by the U.S. Army Corps of Engineers Bath Iron Works depends on channel to move Navy vessels Extremely dynamic and subject to unpredictable shoaling
Two reaches where shoaling has historically occurred: Doubling Point, approximately 12 miles upstream from mouth of river Popham Beach, where river joins Atlantic Ocean
Kennebec River Provides Habitat for Three Federally Listed Fish Species 1. Shortnose Sturgeon (Acipenser brevirostrum) http://www.stewart.army.mil/dpw/fish/sturgeon_facts.htm
2. Gulf of Maine DPS of Atlantic Salmon (Salmo salar) (Salmo salar) Photo: William Hartley, USFWS http://digitalmedia.fws.gov
3. Gulf of Maine DPS of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) Atlantic sturgeon photo courtesy of Robert Michelson http://www.nmfs.noaa.gov/stories/2012/01/31_atlantic_sturgeon.html Photo: USFWS
All three species will move throughout the Kennebec River to access various habitats during their life cycles, passing through the areas that are periodically dredged Consultation with the National Marine Fisheries Service (NMFS) under Section 7 of the Endangered Species Act (required) Biological Opinion (BO) established dredge windows, reasonable and prudent measures and incidental take statements (for SNS) November 1 to April 30 of any year Dredging outside the windows - In 2003 dredged in October to move the Navy destroyer the U.S.S. Chafee Resulted in 5 Incidental takes of SNS
Biological Opinion Determined that 5 incidental takes of shortnose sturgeon did not jeopardize their continued existence in the Kennebec River
Shoaling in late 2010 and early 2011 Dredging would need to occur to move the U.S.S. Spruance Scheduled for departure on September 1, 2011 Would need to be dredged in August (outside of window)
Shortnose and Atlantic sturgeon acoustic telemetry data
A total 27 takes of shortnose sturgeon could occur without jeopardy (NMFS BO) Assumption that sturgeon would be in the area of active dredging and likely be entrained in the dragarms. Also very low probability of contacting Atlantic salmon Provided reasonable and prudent measures and equipment specifications to avoid/minimize contact with endangered species that included: 1. Turtle deflectors on the dragarm 2. Methods to maintain the dragarm in contact with the substrate during dredging 3. Removing the grates and screens from the dragarms and outflow pipe(s) 4. Endangered Species Observers
Turtle Deflectors Developed by the U.S. Army Corps of Engineers Prevents turtles from becoming entrained. Can also be used for sturgeon Were installed on the dredge, Atchafalaya in 2011 http://www.theartofdredging.com/turtle.htm
Grates and screens initially removed from dragarms and inflows of dredge Atchafalaya Later replaced
Public opposition lead to legal action against the USACE, the State of Maine Department of Environmental Protection, and NMFS Injunction against the USACE denied in federal court. Also revised BO was issued by NMFS (due to legal challenge) Dredging began on August 1, 2011 No evidence of shortnose or Atlantic sturgeon takes observed after 12 days with minimal entrainment of any other fish (i.e. several flounder were observed) Grates were re-installed. No indication of sturgeon entrainment after approximately 2 more days of dredging
Assumed that the implementation of the reasonable and prudent measures may have helped to avoid contact with the endangered shortnose and threatened Atlantic sturgeon They were reasonably expected to be in the dredging areas Dredging completed successfully (with no takes) The U.S.S. Spruance departed on schedule on September 1, 2011 Troy R. Bennett / The Times Record Bangor Daily News, September 1, 2011