(Reuters) - Wal-Mart Stores Inc (>> Wal-Mart Stores, Inc.) Chief Executive Mike Duke earned $18.1 million last year, down from $18.7 million a year earlier, as the company's operating income and sales growth fell short of goals.

Wal-Mart also said Google Inc (>> Google Inc) executive Marissa Mayer would stand for election to the Wal-Mart board at the company's annual shareholders meeting on June 1. If elected, Mayer would become the sixteenth member of the board.

While the company's huge Walmart U.S. retail operation finally reversed its prolonged sales slump last year, overall performance and results at both Walmart U.S. and the retailer's international unit fell short of expectations.

Duke's cash incentive payment for fiscal 2012, ended January 31, fell to $2.88 million from $3.85 million a year earlier and $4.8 million in fiscal 2010, Wal-Mart said in a regulatory filing on Monday. Duke earned 71 percent of his target cash incentive payment for fiscal 2012, down from 97.4 percent in fiscal 2011 and 125 percent in fiscal 2010.

ONE OF FIVE STRATEGIES

The board's nomination of Mayer, 36, underscores Wal-Mart's desire to become a better online and mobile destination for shoppers.

"We are on the cusp of a massive transformation in the way people shop in our increasingly connected world," Wal-Mart Chairman Rob Walton said in a statement. "Marissa's insights and expertise in the technology and consumer areas are valuable assets to Walmart as we move forward."

In a letter to shareholders, Duke outlined five strategies for Wal-Mart's future, starting with development of the company's people. Winning in global e-commerce was third on the list.

Wal-Mart's board added a technology and e-commerce committee last year, Walton noted in another letter, emphasizing the focus Wal-Mart now has on e-commerce, social and mobile retailing.

Despite its dominance in traditional retail, Wal-Mart is only the sixth-largest Internet retailer, behind Amazon.com Inc (>> Amazon.com, Inc.), Staples Inc (>> Staples, Inc.), Apple Inc (>> Apple Inc.), Dell Inc (>> Dell Inc.) and Office Depot Inc (>> Office Depot, Inc.), according to industry publication Internet Retailer.

Mayer joined Google in 1999 as its first female engineer and has been its vice president of local and maps since 2010.

However, Mayer is not part of the "senior leadership" team listed on Google's website, a group that was revamped after Larry Page became CEO a year ago. She was appointed to Google's elite Operating Committee in October 2010, but she was not included when Page replaced that committee six months later with a different structure dubbed the L-Team.

U.S. SALES REBOUND, DUKE PAID LESS

Throughout fiscal 2012, Duke said his top priority was a return to sales growth at stores open at least a year -- a key gauge of retail health known as same-store sales -- at the Walmart U.S. chain.

Quarterly same-store sales at Walmart U.S. moved back into positive territory during the third quarter after nine consecutive quarterly declines.

Total sales rose 5.9 percent to $443.85 billion in fiscal 2012. Walmart U.S. sales rose 1.5 percent to $264.19 billion, with same-store sales up 0.3 percent.

Operating income rose 4 percent to $26.6 billion. Adjusted operating income grew 3 percent, less than needed for Duke to receive a larger cash incentive payout.

(Reporting by Jessica Wohl in Chicago, additional reporting by Alexei Oreskovic in San Francisco; Editing by Gerald E. McCormick, John Wallace and Steve Orlofsky)

By Jessica Wohl