There is a lot of talk these days about unfair competition, "merger mania," corporate oligopolies and the squeezing out of small competitors - the kind of talk everyone is used to hearing about oil or steel or cornflakes - but now the focus is on publishing.

In recent years there have been more than 300 corporate mergers and acquisitions in the publishing industry. Most major hardcover houses have acquired paperback subsidiaries (or vice versa; some have grown, like Doubleday? Dell/Literary Guild, into publishing-centered conglomerates.

Others, like Simon & Schuster? Pocket Books, have been acquired by vast industrial concerns such as Gulf & Western (which lumps its book companies together with its movie company, Paramount, under the "leisure division" in its annual report) Random House/Knopf/Pantheon? Ballantine is owned by RCA. Other publishers belong to CBS, MCA and ITT.

In a recent interview with Publishers Weekly, the trade publication owned by Xerox, Simon and Schuster president Richard Snyder predicted that " What we are going to see now . . .is that like the seven sisters of the oil business we will have seven giant publishing companies."

Many publishing executives see this prospect as inevitable, even desirable, as books compete with other mass media for America's attention and money. But several publishers, and many writers , look on such a future with a kind of Orewellian horror.

"It is a sinister process," said author Herman Wouk. "In a conglomerate there is a narrowing down of margins - of what is safe and what is publishable." There is, he said, a concern to show the stockholders that no "bizzare" decisions have been made, and the problem, of course, is that some of the greatest literature ever published seemed quite "bizzare" when it first appeared.

Because of such fears, the Authors Guild of America, at a press conference yesterday, called for the Justice Department and the Federal Trade Commission to start proceedings that would eventually end the process of mergers and acquisitions in the book publishing industry.

They called for enforcement of section 7 of the Clayton Act, which provides for federal action when so much as a "trend to concentration" is perceived.

At the same time, Reps. Morris Udall (D-Wis.) reintroduced the "Competition Review Act" to the House.There are 25 co-sponsors for the bill, which proposed a study of the "state of competition" in several basic industries, including publishing; an examination of federal policies with regard to those industries; and specific prescriptions for stimulating competition.

The Authors Guild, represented at the press conference by lawyer Irwin Karp, as well as writers John Brooks, John Hersey, and Wouk, further proposed that a publisher should be allowed to acquire only a single category of rights to a book - say, hardcover publication in the United States - and that the rest be retained by the author to be sold separately. This is virtually impossible for the average writer to do today.