Oil-splattered Norfolk beaches were closed yesterday and the Coast Guard temporarily shut the port's busy shipping channel after two cargo ships collided in the Chesapeake Bay, spilling 30,000 gallons of fuel oil into the estuary's prime blue crab hatchery.

The Sunday night accident, the largest on the bay since a 1988 barge spill of 212,000 gallons of oil, prompted Virginia officials to tell crabbers to catch at their own discretion, and an environmental group to renew its call for tougher shipping regulations.

The Coast Guard initially described the accident as a "major marine casualty because of the damage done and the oil spilled," but a government scientist said later that major damage to shellfish, birds or fish was unlikely. By late afternoon, there was one report of 50 mallard ducks coated with oil.

"We lucked out again," said Ann Hayward Walker of the National Oceanic and Atmospheric Administration, which advises the Coast Guard.

The collision took place in wind-whipped waters and fog about five miles northeast of Norfolk, between the outbound 635-foot Columbus America and the inbound 800-foot Neptune Jade. It ruptured the 140,000-gallon fuel tank of the Columbus America, which headed back to a local shipyard, spilling 30,000 gallons of No. 4 fuel, Coast Guard officials said.

No injuries were reported. The heavily damaged Neptune Jade, registered in Singapore, headed to port. Both ships were carrying containers of hazardous waste, which were damaged but did not leak, officials said.

The Coast Guard scheduled a hearing for today in an effort to determine why the Columbus America, which should have been in the southern part of the channel, was in the northern part, said Chief Petty Officer Todd Nelson, a Coast Guard spokesman. The channel was closed for four hours.

Routine drug and alcohol tests were given to personnel on both ships, but results were not available.

The National Transportation Safety Board dispatched an investigator to Norfolk.

The West German-registered Columbus America was surrounded by oil-containment booms after it docked, Nelson said, and the Navy sent skimmers to remove the oil yesterday morning.

By yesterday afternoon, most oil had dissipated from the bay and was sloshing around the Elizabeth River in downtown Norfolk and Portsmouth, where it coated boats and piers.

"We're covered in oil right now," Gordon Shelton of the Tidewater Yacht Services marina in Portsmouth told the Associated Press. "I want to know who the hell is supposed to clean it up."

Some oil also washed ashore on seven miles of beach in Norfolk's Ocean View, where one resident said it looked like foot-wide black raindrops had splattered the sand. The city barred swimming at the two miles of public beach in Ocean View, and a private firm, Industrial Marine Services, was hired to clean up the shoreline with rakes and shovels.

Despite the oil, swimmers and windsurfers were spotted in the water yesterday afternoon. The spill did not affect the popular Virginia Beach resort areas 20 miles south.

Nelson said cleaning up the oil in the Elizabeth River would be a "week-long war of attrition."

The Chesapeake Bay Foundation's Virginia executive director, Joseph Maroon, renewed his group's demand for an electronic vessel-tracking system for the bay, mandatory double hulls on ships and improved inspection and maintenance.

"We apparently haven't learned anything from the spills in Alaska and the Gulf {of Mexico}," said James Janata, president of the East Ocean View Civic League.

The area off Ocean View is a prime hatchery for the blue crab, which environmentalists said is particularly vulnerable because it is in its spawning season. But Walker said the oil was in the water so briefly that crabs and fish likely were not damaged.

Tougher penalties for spilling oil into the bay and its tributaries went into effect Sunday in both Maryland and Virginia. Late last week in the Virginia Beach area, another oil spill of undetermined origin dissipated before reaching shore.