The Port of New Orleans will implement increases in port fees July 1, instead of over the next 18 months, port officials announced last week, much to the dismay of the local maritime community.

The increases, the first in three years, include a 15 percent hike in dockage and harbor fees, a 10 percent rise in wharfage fees and a 30-cent-a- ton cargo handling fee for stevedores not leasing Dock Board wharves.Additionally, wharfage fees would go up another 5 percent July 1, 1991.

The increases are said to bring shipping costs in New Orleans to $2.06 a ton, higher than Houston at $1.90 or Mobile, Ala., at $1.50.

J. Ron Brinson, port president, told port commissioners at their monthly meeting Thursday that the increases were needed immediately to enable the port to carry out its "financial mission" and restore by mid-year $3.5 million in revenue lost from fee cuts between 1985 and 1986.

The New Orleans Steamship Association, the New Orleans Board of Trade and the New Orleans Freight Forwarders Association all scheduled emergency meetings to address the surprise announcement.

The main concern of the maritime industry is that shippers and other operators have contracts that go beyond the July 1 increase date. Because those contracts don't include the fee increases, the shippers would have to make up the difference.

"These fee increases will cause us to have to take a long,hard look at continuing to do business in New Orleans," said a local shipper, who asked not to be identified. "Our profit margins are so slim that these kinds of increases make a difference."

David Burns, president of the New Orleans Steamship Association, added: ''We're concerned what it will do to New Orleans as a competitor in the Gulf of Mexico."

Several shipping agencies, which asked not to be named, told The Journal of Commerce that principals they represent have indicated they might take their business elsewhere.

''The main issue is, the port has repeatedly said we're going to be lower than other ports, but by the time you add the fees all together - the terminal operators have said they can't do the stevedoring fees, so the shippers will have to absorb it - that's not true," said George Duffy, president of Navios Shipping Agencies.

''They don't seem to realize that shippers look at the bottom line, and by that bottom line with these increases, the port is not competitive," he said.

The Steamship Association had proposed that 10 cents of the stevedoring fee become effective Dec. 1, with an additional 10 cents tacked on next year, if necessary. The group also had asked that wharfage fees be raised only 8 percent instead of 10 percent.

Mr. Duffy, who presented the proposal to Mr. Brinson for the Steamship Association, said he and his board were under the impression that Mr. Brinson was considering their proposal and would get back to them.

''We thought we had had some encouragement from him," Mr. Duffy said. ''We were under the impression it was a negotiable issue."

''We still have some questions about the amounts," Mr. Burns of the Steamship Association said. "Anytime you raise costs, the shippers take a close look at those increases.

''And the vessels pretty much control where the cargo goes," Mr. Burns said. "There's no doubt it absolutely will cause shippers to have second thoughts" about shipping cargo through New Orleans.