BP's mile-long tube is only collecting about one-fifth of the oil spewing into the Gulf of Mexico, its executives said Monday.
The energy giant's chief operating officer, Doug Suttles, said the tube has been siphoning more than 1,000 barrels a day, or 42,000 gallons, in an interview Monday with NBC's "Today Show." BP has estimated about 5,000 barrels a day, or 210,000 gallons a day, has been leaking out.
Suttles said they hope to be able to collect more oil as they ramp up the effort but they won't be able to get all of it.
In a major step toward containing the massive oil leak, BP PLC crews on Sunday hooked up the tube to funnel the crude into a tanker ship. However, millions of gallons of crude are already in the Gulf.
The contraption was hooked up successfully and sucking oil from a pipe at the blown well Sunday afternoon after being hindered by several setbacks. Engineers remotely guiding robot submersibles had worked since Friday to place the tube into a 21-inch (53-centimeter) pipe nearly a mile (1.6 kilometers) below the sea.
Kent Wells, BP's senior vice president for exploration and production, said during a news conference that the amount being drawn was gradually increasing, and it would take several days to measure it. Company spokesman Mark Proegler at the joint spill command center in Louisiana had initially said the tube was containing most of the oil coming from the pipe, which is contributing an estimated 85 percent of the crude in the spill.
In a statement Sunday, BP said that the tube was "successfully tested and inserted into the leaking riser, capturing some amounts of oil and gas."
"While not collecting all of the leaking oil, this tool is an important step in reducing the amount of oil being released into Gulf waters," BP said.
Previous attempts to use emergency valves and a 100-ton container had failed to stop the leak that has spilled millions of gallons of oil into the Gulf, threatening sea life, commercial fishing and the coastal tourism industry from Louisiana to Florida. BP PLC has also been burning small amounts of floating oil and spraying chemical dispersants above and below the surface.
The tube's success gave crews partial control of the leak for the first time in more than three weeks. Oil has been spewing since the rig Deepwater Horizon exploded April 20, killing 11 people and sinking two days later. The government shortly afterward estimated the spill at 210,000 gallons (795,000 liters) -- or 5,000 barrels -- a day, a figure that has since been questioned by some scientists who fear it could be far more. BP executives have stood by the estimate while acknowledging there's no way to know for sure.
Researchers warned Sunday that miles-long (kilometers-long) underwater plumes of oil from the spill could poison and suffocate sea life across the food chain, with damage that could endure for a decade or more.
Researchers have found more underwater plumes of oil than they can count from the blown-out well, said Samantha Joye, a professor of marine sciences at the University of Georgia. She said careful measurements taken of one plume showed it stretching for 10 miles (16 kilometers), with a 3-mile (5-kilometer) width.
The hazardous effects of the plume are twofold. Joye said the oil itself can prove toxic to fish swimming in the sea, while vast amount of oxygen are also being sucked from the water by microbes that eat oil. Dispersants used to fight the oil are also food for the microbes, speeding up the oxygen depletion.
"So, first you have oily water that may be toxic to certain organisms and also the oxygen issue, so there are two problems here," said Joye, who's working with a group of scientists who discovered the underwater plumes in a recent boat expedition to the Gulf. "This can interrupt the food chain at the lowest level, and will trickle up and certainly impact organisms higher. Whales, dolphins and tuna all depend on lower depths to survive."
She said it could take years or even decades for the ecosystem to recover.
BP has been casting about for ways to contain the leak since it was discovered several days after the blast. First robot submarines were unable to get valves to work on machinery at the well head called the blowout preventer. Then the company failed to capture the oil with a 100-ton box after icelike crystals formed in it.
A relief well, considered the permanent solution the leak, is still being drilled and is months away from completion.
The Associated Press contributed to this report.