Concern mounts as N.J. rivers that dolphins call home freeze

RUMSON, N.J. - Two New Jersey rivers that a pod of bottlenose dolphins have called home since the summer are freezing, increasing concerns that the mammals might not be able to survive much longer.

With air temperatures in the teens and water temperatures well below freezing, the Shrewsbury and Navesink Rivers have begun to freeze over.

The Navesink, near a bridge that the dolphins liked in the summer, was almost completely frozen over yesterday morning. The Shrewsbury River was swollen with chunks of ice, and several sections were frozen to the middle of the river.

No one had seen the five surviving dolphins yesterday morning.

"I keep hoping they would get out because of this ice," said Bob Schoelkopf, co-director of the Marine Mammal Stranding Center in Brigantine. He has been the loudest voice calling on federal wildlife authorities to let groups like his try to scare or coax the dolphins back out to sea.

However, the National Oceanic and Atmospheric Administration does not plan to try to move the dolphins from the rivers, even if it means letting them die. The agency says the dolphins are trying to expand their normal habitat and should be left alone.

The rivers freezing is what dolphin rescue groups have feared since 16 of the animals showed up in the two rivers in June. They cite the 1993 case of four dolphins who died when the Shrewsbury froze and an attempt to herd the dolphins out to open water drove them deeper under the ice, where they drowned.

Dolphins must surface to breathe air.

With a severe cold front moving through the region Thursday night, temperatures plunged overnight into single digits. That accelerated the buildup of ice in the rivers, which have frozen in four of the last five winters.

Ice-boating clubs have thrived on the Navesink for decades, and no dolphins have been spotted in the Navesink since late December.

State police, NOAA, the stranding center and volunteer dolphin spotters along the riverbank all said they had not seen the animals yesterday.

Three of the original 16 dolphins are known to have died. Authorities say eight may have left the area on their own, but caution there is no way to know that for sure.

NOAA said this month it expected more of the remaining five dolphins to either die or strand themselves this winter.