NEW ORLEANS: Cleanup work resumed in some areas of the Gulf of Mexico oil spill Saturday, but heavy swells kept many boats docked, halting efforts to fight the ecological disaster.

A Taiwanese mega-skimmer dubbed the "A Whale" was in position near the site of the leak and set to undergo 48 hours of "proof of concept" testing, Coast Guard spokeswoman Ayla Kelley told AFP.

The 300-yard (275-meter) long tanker can vacuum up 21 million gallons of oily water a day, separating oil from water and spitting the seawater back out.

Small skimming boats that have been patrolling the Gulf for the past 10 weeks have only collected 28.2 million gallons of oily water to date, and rough weather made seas off Louisiana too choppy for them to even go out Saturday.

Coast Guard Petty Officer Kelly Parker at a Houma, Louisiana information center said crews were resetting protective booms along fragile coastal areas, but skimming and controlled burns of spilled crude had been halted.

However, around the Chandeleur Islands, a chain of uninhabited barrier islands and wildlife refuge at Louisiana`s easternmost point, boom and skimming operations resumed Friday, said a representative of Admiral Thad Allen, the top official overseeing the spill response.

"These are the most environmentally sensitive areas. The good news is that we saw only light oil and there were hundreds of boats working in the area resetting boom and skimming," rear admiral Paul Zunkunft told reporters after he flew over the islands.

"The areas are critical to defend because they are home to turtles, shrimp and other wildlife," Zukunft said.

Despite containment efforts, he warned: "We are not out of the woods yet."

An estimated 35,000 to 60,000 barrels of oil per day has gushed from the ruptured well since the BP-leased Deepwater Horizon drilling rig sank on April 22, some 50 miles (80 kilometers) off the coast of Louisiana.

A containment system has captured about 557,000 barrels of oil, but rough seas delayed the deployment of a third vessel that could boost capacity from 25,000 barrels to 53,000 barrels a day.

That means an estimated 1.9 to 3.6 million barrels -- or 79.5 to 153 million gallons -- of oil has now gushed into the Gulf.

Using the high end of that estimate, the spill has now surpassed the 1979 Ixtoc blowout, which took nine months to cap and dumped an estimated 3.3 million barrels (140,000 million gallons) into the Gulf of Mexico.

It is topped only by the deliberate release of six to eight million barrels of crude by Iraqi troops who destroyed tankers and oil terminals and set wells ablaze in Kuwait during the 1991 Gulf War.

And it will likely be mid-August at the earliest before the Gulf well is permanently capped by injecting mud and cement with the aid of relief wells.

Skimmers had been collecting about 12,000 barrels of oil a day before they were sent back to port after Hurricane Alex whipped up waves earlier this week, while about 8,000 barrels of oil was being burned off the surface.

But the spill has so far oiled at least 450 miles (725 kilometers) of US shorelines, 74 days into the worst environmental disaster in US history.

Admiral Allen said he hoped to have the third containment vessel, the Helix Producer, in place by Wednesday.

Once the Producer is working, officials will also have a better sense of just how much crude is leaking, "just by the visual evidence of how much oil is actually coming out around that cap," Allen said.

They will then have to decide if the existing system should stay in place, or if it would be best to undergo a risky procedure to replace the cap with another system capable of capturing up to 80,000 barrels of oil a day.

"The decision window associated with that would be sometime in the next, I would say, seven to 10 days," Allen said in a conference call Friday.

In addition to boosting capacity, the new system would also greatly reduce the amount of time oil could gush freely into the sea if crews had to evacuate due to a bad storm.

Meanwhile, Environmental Protection Agency chief Lisa Jackson was headed to Pensacola, Florida to oversee coastal clean-up operations in the state, where tourist draws Miami and the Florida Keys face the likelihood of fouled beaches.

BDST: 8:44 HRS, July 4, 2010