Small oil companies had a paltry showing at a U.S. Central Gulf of Mexico oil and gas lease sale on Wednesday, a sign that they want to conserve cash during a period of low oil prices and tight credit.

Large producers, including Royal Dutch Shell (RDSA) and BP PLC (BP), dominated the list of winners in a sale that attracted $703 million from 70 companies in high bids and was conducted by the U.S. Department of Interior's Minerals Management Service, or MMS. Shell won 39 bids for offshore leases, offering a total of $153.6 million. It was followed by BP, which won 27 bids totaling $77.5 million, the MMS said.

In last year's record-breaking sale, Hess Corp. (HES) and Cobalt International Energy LP were the top two bidders with $437.5 million and $389.1 million, respectively. Both companies presented offers this year but weren't among the top 10 bidders.

Leasing blocks in the Gulf of Mexico is an exploratory activity that represents high level of uncertainty for oil companies, a risk that only financially-strong oil companies are able to take in the current environment, said Phil Weiss, an analyst with Argus Research in New York.

"Smaller companies, especially the ones trying to live within their cash flow, are going to try to shy away from exploration activity," Weiss said. "Major oil companies do have more money and a better position to work through this."

Marathon Oil Corp. (MRO) and Noble Energy Inc. (NBL) were also among the top bidders, with $62.4 million and Noble Energy Inc. (NBL) with $55.4 million, respectively.

But although large producers had a strong presence this year, the MMS will collect less money than last year, when it raised a record $3.7 billion from 78 companies lured by booming prices for oil and gas.

MMS officials said the sale attracted fewer companies and less money because some of the prospects weren't as alluring to oil companies and are mainly in shallow waters.

Officials said that one surprise from the sale was to see major oil companies coming back to bid for blocks in Gulf of Mexico Shelf, a sign of their interest in producing natural gas, a hard-hit commodity in the U.S. market.

Ecopetrol America S.A. was the dark horse among the small-cap oil companies attending the sale. The U.S. unit of Colombian oil firm Ecopetrol S.A. (ECOPETROL.BO) won 26 bids, spending $20.6 million and becoming the 10th top bidder. Ecopetrol's interest in the U.S. Gulf is part of a move to increase exploration both off- and on-shore in Colombia and abroad. The company, Colombia's largest, already operates in the Gulf of Mexico with different partners, including Shell.

The company is seeking to boost its daily production to 1 million barrels of oil equivalent per day from an average 447,000 barrels of oil equivalent a day in 2008.

-By Isabel Ordonez, Dow Jones Newswires; 713-314-6090; isabel.ordonez@dowjones.com

(Angel Gonzalez in Houston and Brian Baskin in New York contributed to this report.)