BRIGANTINE, N.J. - Federal lawmakers are increasing pressure on wildlife officials who have refused to try to rescue a dwindling group of bottlenose dolphins from two New Jersey rivers.

The dolphins' continued presence in the rivers has led to worries they may die soon.

On Wednesday, the National Oceanic and Atmospheric Administration, which has jurisdiction over the dolphins, said it was able to count only five of the original group of 16 dolphins that have taken up residence in the Shrewsbury and Navesink Rivers since June.

The agency also said it expected more of the animals to die or strand themselves this winter but said it would not authorize any attempt to remove or coax the dolphins back out to sea.

Yesterday, U.S. Rep. Frank Pallone Jr. (D., N.J.) said the agency appeared to have changed its original stance that it would intervene if the dolphins appeared to be in imminent danger.

Three have died. Of the 12 animals spotted in early December, eight appeared to be losing weight. The latest dolphin to die, a pregnant female found on Christmas, had nothing in its stomach.

"It seems like they are changing their mind, and I want to know why," Pallone said. "They always said that if the dolphins were in distress, they'd move to a secondary plan. How much more distressed do they have to get?"

Teri Frady, a spokeswoman for the agency, said the five animals observed in the Shrewsbury River on Monday and Tuesday "were feeding, behaving normally, and not showing any signs of distress. While we can't assume the eight animals that are no longer in the river are currently alive, neither can we assume that they're dead."

Also yesterday, U.S. Sen. Robert Menendez (D., N.J.) wrote to NOAA's acting administrator, William J. Brennan, urging him to get the dolphins out of the river or let volunteer groups try.

"With the advent of a very cold winter, the dolphins are facing extreme exposure and inability to find adequate food supplies," he wrote.

The dolphins are at the center of a tug-of-war between federal wildlife officials - who plan to leave them alone unless they appear to be in imminent danger - and animal rescuers who want them removed or coaxed out of the river and out to sea.