But they concede that schedules might have to change or other alterations be made to accommodate the spectacularly picky sturgeon, which will spawn only in certain areas.
"We are concerned about dredging and the impacts on the species," said NOAA's Kim Damon-Randall, supervisory fishery biologist. One of the agency's documents said the scope of the project, plus the ample unknowns about the fish's preferred spawning habitat, "indicate that the project could be very harmful" to the sturgeon.
In anticipation of the listing, the Army Corps has already been working with federal fisheries officials, said spokesman Ed Voigt.
"As we move forward, we're coordinating . . . to ensure that with each step of the project, we avoid impacts to the Atlantic sturgeon and other species."
But, he said, "there's no reason to expect some kind of change is going to transform the cost and scope of the project."
Maya van Rossum, the Delaware Riverkeeper, disagreed. She said the listing should "have significant ramifications" for the deepening project. If it does not, the Delaware Riverkeeper Network is "well positioned for a very strong legal case."
Scientists are still trying to figure out what portions of the river the fish prefers and why, and preliminary results indicate that a favored habitat is a tanker anchorage near Marcus Hook - which is slated for deepening.
"There are usually several big tankers anchored there, and right below them, baby sturgeon," said Delaware fisheries biologist Matt Fisher, who has caught young sturgeon and implanted acoustic equipment so they could be tracked.
'Critical habitat'
