“A much larger-scale operation is needed,” she said. “It hasn’t been monitored. It’s a mystery.”

In Beijing, officials have been eager to demonstrate that the government was doing everything possible first to respond to the disaster and then to protect the health of its economically and politically sensitive fishing industry, which employs 14 million people.

They have issued regular statements and held briefings, showing video of efforts to clean up the condensate and to monitor the sunken wreck, which was located at a depth of 115 meters, or about 377 feet. It is believed to still be leaking condensate and other fuels.

Han Xu, deputy director of the fisheries administration bureau of the Ministry of Agriculture, told reporters at a news conference in Beijing late last month that the accident had “a certain impact on the density of fishery resources” in the area, but that the government did not yet know the extent of the threat.

“At present, the investigation and monitoring are still ongoing and we are awaiting results of investigations into pollution and successive fishery resource investigations,” he said.

In the meantime, the authorities have ordered a ban on fishing in the areas affected.

In the East River Fish Market in Putuo, one seller brusquely dismissed questions about the spill as she stood beside a stall full of fish, including a tuna selling for roughly $100. “Our fish are not from out there,” she said, though some of them very likely were.