BRIGANTINE, N.J. (AP)  --  Federal wildlife officials are drawing up plans to either coax or scare a group of wayward dolphins out of two shore area rivers where they have been living since June.

Two of the animals have died, and animal rescue volunteers are increasingly worried about the rest.

As many as 15 dolphins were spotted in the Shrewsbury and Navesink rivers. Between seven and 10 remain, according to officials with the National Oceanic and Atmospheric Administration.

Teri Frady, a spokeswoman for the agency, stressed that a decision has not yet been made on whether to intervene, but that the matter would be decided by the end of the month.

The agency is considering two options: using a U-shaped flotilla of boats to try to herd the dolphins out of the river and back out to sea or using recorded ``socialization sounds'' of other dolphins to try to lure them from the river into Sandy Hook Bay and ultimately the ocean.

Part of the proposal to herd the dolphins out of the rivers would involve playing loud or unpleasant noises underwater and creating a ``visual barrier'' such as a curtain of air bubbles in the water to try to guide the dolphins in a particular direction.

Of course, there is the very real possibility that neither the coaxing nor the scaring will work, said Brandon Southall, director of NOAA's Ocean Acoustics Program and a researcher at the University of California at Santa Cruz's Institute of Marine Sciences.

``The animals could ignore both of these,'' he said. ``We've tried this in the past where the animals didn't do what we wanted them to do.''

Since they surfaced in the Shrewsbury River around Father's Day, the dolphins have delighted large crowds that lined the banks of the river to watch them frolic and feed. The plight of the animals has drawn nationwide publicity, particularly in light of earlier disasters involving dolphins that took a wrong turn and wound up in the river.

Volunteer rescuers have been pushing since July for intervention to get the dolphins back out to sea. They worry that waiting too long could invite a replay of a scenario that resulted in the deaths of four dolphins who lingered too long in the Shrewsbury River in 1993. Ice eventually closed in on them and they drowned.

Teri Rowles, the lead veterinarian for NOAA's Fisheries Service and chief of its National Marine Mammal Health and Stranding Response Network, said the agency will study the water temperature in the Navesink River, where the remaining dolphins are, as well as the availability of bait fish that constitute their diet.

``We want not only to move them out of the river (but) give them the best opportunity to do an appropriate migration'' southward in the ocean, she said.

On Wednesday, a dead dolphin was found in the Navesink in Middletown, just across the river from where another dead dolphin was discovered two weeks earlier.