FORT WORTH, Texas — Airlines are taking in less money from bag fees than they did two years ago, but they are making up for it by adding charges for a slew of extras, including getting a decent seat.

The government reported Monday that U.S. airlines raised $3.35 billion from bag fees in 2013, down 4 percent from 2012. That is the biggest decline since fees to check a bag or two took off in 2008.

Some passengers avoid bag fees — usually $25 to $35 for domestic flights on the biggest airlines — by using airline credit cards or earning elite-level frequent-flier status. Others carry their bag on board and fight for space in the overhead bins.

The bag-fee figure was part of information released by the U.S. Department of Transportation, which said that airlines earned $7.3 billion in the fourth quarter of last year, reversing a loss of $188 million in the same period of 2012.

The airlines also raised $2.81 billion last year from fees for changing a reservation or ticket, a 10 percent increase over 2012. Fees on checked bags, reservation changes and other services have become a larger share of airline revenue and a big reason why carriers are making money.