Carnival reported lower first-quarter earnings but shares in the cruise operator rose after the group upped its full-year outlook thanks to improved booking trends.Net income in the three month ended 28 February dropped to $175m, or 22 cents a share, to $260m, or 33 cents a share. Revenues increased by $231m to $3.1bn, driven by a 9.6% increase in passenger capacity.However, the group said full-year earnings per share (diluted) are forecast to be in the range of $2.25 to $2.35, compared to $2.24 for 2009 and better than the December guidance range of $2.10 to $2.30.Second-quarter earnings per share (diluted) expected to be in the range of $0.26 to $0.30 compared to $0.33 in the same period last year, while net revenue yields for full-year are expected to increase 2 to 3% on a constant dollar basis (2 to 3% in current dollars), compared to flat to up 1% in the December guidance."Since the start of the calendar year, booking volumes for the remaining three quarters are running ahead of the prior year with prices significantly higher than last year's discounted levels," the group said.