BP's oil spill clean-up efforts in the U.S. Gulf of Mexico were returning to normal on Saturday, amid a report that some major investors expected the British energy giant to replace its top executives.

BP said its oil-capture systems at its leaking well collected or burned off 25,290 barrels of oil during operations on Friday, as it ramped up spill containment efforts that had been disrupted by Hurricane Alex.

The storm passed through the spill area off the coast of Louisiana without doing major damage.

But the corporate fall-out from the worst offshore oil spill in U.S. history -- BP's market capitalization has shrunk by about $100 billion and its shares have lost more than half their value since the spill began -- appeared far from over.

The Financial Times reported that BP investors expected to see a change in the company's leadership, possibly once the leak is capped, with both Chief Executive Tony Hayward and Chairman Carl-Henric Svanberg in jeopardy.

When this is over there will be a full investigation, and we would expect some action to replace the top team, the British newspaper quoted a top 10 UK shareholder as saying in its Saturday edition.

Without steps to steady the ship, BP could become a takeover target of companies like ExxonMobil, Royal Dutch Shell or PetroChina, the FT said, citing a source working on BP's strategy. A BP spokesman declined to comment.

BP's top executives have been under intense pressure since an April 20 rig explosion killed 11 workers and unleashed the torrent of oil now threatening wildlife and tourist and fishing industries in the U.S. Gulf region.

The Obama administration also has criticized the company's response to the crisis, now in its 75th day.

The U.S. Interior Department, one of the departments spearheading Washington's response to the spill, could issue a revised offshore oil drilling moratorium for U.S. waters in the coming week.

A federal court last week lifted a six-month drilling ban imposed by the Obama administration as a result of the spill. The new moratorium is expected to be more flexible and could be adjusted to allow drilling in certain subsea fields.


Apart from economic damage, the spill is seen as an environmental catastrophe for the Gulf coast. Whale sharks, the biggest fish in the sea, may be the latest victims.

Officials at the National Oceanic and Atmospheric Administration reported this week that four of the polka-dotted creatures, stretching about 40 feet long, had been spotted swimming in oily water in search of food.

Since whale sharks are filter feeders -- scooping up plankton and small fish as they swim just beneath the surface -- scientists are concerned they could be harmed or killed from swallowing large amounts of oil.

The problem is that these are surface feeding animals and if they digest the oil they will sink and we will not know how many are dying, said Dr. Eric Hoffmayer of the University of Southern Mississippi.

I don't think there is any question we're going to lose whale sharks to this oil spill. That's why we need to tag these sharks so that we can determine how they are impacted by the oil, Hoffmayer told Reuters on Friday.

(Additional reporting by Leigh Coleman Ocean Springs, Mississippi; writing by Ed Stoddard, editing by Paul Simao)