LAS VEGAS (AP) ¿ Troubled casino operator Riviera Holdings Corp. said Friday that its losses narrowed in the first quarter as the company booked a gain related to the fair value of derivatives, although its gaming operations continued to suffer. Riviera, which has defaulted on its credit agreements, is working to refinance or restructure its debt, but has said Chapter 11 bankruptcy protection may be necessary. On Friday, the Las Vegas-based company expressed confidence that it will maintain sufficient cash flow to meet its operating obligations and maintain its properties. Riviera owns and operates the Riviera Hotel and Casino on the Las Vegas Strip and the Riviera Black Hawk Casino in Black Hawk, Colo. Riviera lost $1 million, or 8 cents per share, in the period that ended on March 31. That's compared with a loss of $5.8 million, or 47 cents per share, a year earlier. Revenue tumbled 28 percent to $34.7 million from $48 million. As of March 31, Riviera had $16.3 million in cash and cash equivalents. Riviera chose to skip paying a $4 million interest payment in March to preserve liquidity. Chairman and Chief Executive William Westerman said Friday that "the continuing devastating competitive pressure on room rates, the rapidly declining visitation to Las Vegas, especially by convention attendees, verify we made the correct decision." Riviera shares surged 24 cents, or 13.3 percent, to $2.04 on Friday. The stock has traded between 79 cents and $18.12 during the past 52 weeks.