Updated

Wildlife officials were hoping — but weren't particularly hopeful — that strong thunderstorms expected Thursday and Friday might scare a family of 15 dolphins out of their playground in the Shrewsbury River and back out to the ocean.

The bottlenose dolphins have been wowing spectators along both sides of the river and drawing growing crowds of boats, some of which are getting too close for comfort.

With thousands of boats expected in the area for the July 4th weekend, authorities want to try to get the dolphins out of the narrow waterway and back out into the ocean.

"I'm concerned that by July 3, with the fireworks and thousands of boats in the area, that we have animals surfacing with propeller cuts, or animals floating up cut in half," said Bob Schoelkopf, director of the Marine Mammal Stranding Center in Brigantine. The group is leading efforts to try to get the dolphins out of the river before then.

Thunderstorms forecast for Monmouth County Thursday night and Friday could scare the dolphins out of the river, he said.

"We're waiting for the storms to blow through there and see if that alters their swimming pattern," he said.

Assuming it doesn't, a team of about 40 animal rescue and environmental officials from as far away as North Carolina and Massachusetts will try to shoo the dolphins out of the river next week.

"The problem is, it's a deep river, and they might just dive and go right under the boats," he said.

The dolphins look healthy so far, but have not been observed feeding much, Schoelkopf said. That will soon lead them to start drawing on their fat reserves, which could weaken them if they stay in the river too long.

Schoelkopf said lone dolphins have been observed in the river before and gotten out on their own; larger groups have proved much more difficult to rescue.

In 1993, authorities tried to remove dolphins that had spent the summer and fall in the river. When the river froze, attempts to shoo the animals out to sea only chased them under the ice, where several drowned.

"We don't have very good happy endings with this river and dolphins," Schoelkopf said.