Eastern Airlines yesterday announced in Miami that it earned $6.31 million in 1985, its first annual profit since 1979 and a $44.2 million improvement over the previous year.

During the fourth quarter of 1985, Eastern posted a $67.4 million loss, $78.2 million below 1984's fourth quarter. But the airline's record $122.3 million profit during the first half of 1985 offset second-half losses, pushing Eastern above the break-even point for the year.

Eastern lost $1.22 a share during the fourth quarter compared with a profit of 9 cents a share in the fourth quarter of 1984. Operating revenue for the fourth quarter of 1985 was $1.127 billion compared with $1.118 billion in the same quarter of 1984.

There was a per-share loss of 36 cents for all of 1985 compared with $1.53 in 1984. Eastern's total revenue for 1985 was $4.8 billion compared with $4.4 billion for 1984.

The company lost $379.8 million between 1979 and 1984, and remains locked in a struggle with its unions concerning the future management and course of the carrier.

Eastern officials said they still plan to seek additional wage concessions from employes despite the annual profit. Eastern's long-term debt is about $2.5 billion, and the company's lenders are pressing Eastern to sharply reduce its labor costs by Feb. 1.

*Meanwhile in Cupertino, Calif., Apple Computer Inc., which is emerging from a major reorganization, yesterday reported record net earnings of $56.9 million (91 cents a share) in the first quarter of its fiscal year that ended Dec. 27.

The latest earnings compare with $46.1 million (75 cents) for the first quarter of fiscal 1985.

Net sales fell to $533.9 million from $698.3 million for the same period a year ago.

Apple reorganized in 1985 to concentrate on machines that appeal to business. Abandoning a go-it-alone attitude, it said it would make its computers able to communicate with those of industry leader International Business Machines Corp.