What was going on when I was born?

A Federal judge yesterday approved a proposal by 18 Wall Street brokerage houses to pay $140 million to investors who purchased annuities through the brokerages from the bankrupt Baldwin-United Corporation. But the proposal, approved by Judge Charles L. Brieant of the Southern District of New York, does not mean that policyholders will be receiving checks soon. Instead, the brokerages hope to place their $140 million into a bigger pool of money that may soon be assembled to pay policyholders.

Twice a day, at the end of the flood tides, 100 commercial fishermen from Edgewater to Germantown, N.Y., harvest a bounty of shad. Although commercial fishing for many species has been banned for years on the Hudson River because of high levels of PCB's, or polychlorinated biphenyls, the commercial shad fishery remains open. Shad have low levels of PCB's, which cause cancer in animals, because they spend most of their life outside the river. If the tide is right, motorists stalled in traffic on the West Side Highway get a glimpse of this springtime ritual that dates to when Indians were the only inhabitants of the region.

''I, Ronald Reagan, President of the United States of America, find that the policies and actions of the Government of Nicaragua constitute an unusual and extraordinary threat to the national security and foreign policy of the United States and hereby declare a national emergency to deal with that threat.'' - Presidential Executive Order. [A8:1.]

Nicaragua's Vice President condemned the economic embargo ordered by President Reagan today, and said it would bring the Sandinista Government closer to the Soviet Union. Vice President Sergio Ramirez Mercado, calling the measures ''absolutely illegal and arbitrary,'' said his Government intended to protest to the International Court of Justice at the Hague. ''Nicaragua is going to add this to the case we have initiated before the World Court against the U.S. Government,'' Mr. Ramirez said. The World Court heard Nicaragua's complaint about the United States' mining of its ports in 1983. The United States has refused to accept the court's jurisdiction in the matter, which is still pending.

A CLASS of fifth graders in a public school here is having an innovative art lesson. The subject is collage, but colored paper and paste pots are nowhere in sight. All eyes focus on a screen that projects a print of a famous collage, part of a series the artist called ''Jazz.'' To judge by the number of hands in the air, almost everyone knows the artist's name. ''It's that dude, Henry Matisse,'' says a boy in the back row. A French-speaking boy looks horrified. '' Henri !'' he calls, '' Henri Matisse!''

The Defense Department's highly publicized assertions about cracking down on overcharging and abuse by military contractors are exaggerated, according to Congressional critics and the Pentagon's own Inspector General. Over the last two years there has been a stream of Pentagon announcements and statements by top officials, such as Defense Secretary Caspar W. Weinberger, purporting to show that the Defense Department is saving or recovering large sums from contractors. These assertions have been part of an effort to answer critics in Congress of the Administration's military budget who contend that there is widespread waste and abuse in military procurement. Less Than Projected However, outside critics assert and Pentagon documents note that recoveries often have been less than the sums initially projected by Defense Department auditors, and that claimed savings have been overstated or theoretical.

If neither snow, nor rain, nor heat, nor gloom of night can stop mail carriers, then it would probably take nuclear war to keep Manhattan's real-estate brokers from completing their appointed rounds. There are certainly plenty of them. Manhattan now has 16,852 licensed real-estate brokers, salesmen and saleswomen, up from 13,138 in 1981, according to the New York Department of State, and they account for 42 percent of all the licensed real-estate brokers and sales personnel in New York City. In the world of residential brokers, the elite is made up of people who, after all the hours of showing residences to prospective buyers or renters, push their incomes well into six figures by selling one or two expensive cooperative or condominium apartments every month or renting a couple of apartments every week. ''You really have to be hungry and you really have to be aggressive,'' said Lewis B. Kaye, chairman of L. B. Kaye Associates Ltd., which specializes in co-ops and condominiums. ''But you have to have a certain amount of elegance as well.''

New York City police officials said yesterday that an unmarked police car had struck an 11-year-old girl riding her bicycle in Queens on Saturday and that the driver had fled without offering assistance. The girl, whose identity was withheld, was not seriously injured and was treated for bruises at a nearby hospital, the police said. But the department's chief of inspectional services, John Guido, said investigators were trying to find out why the driver, whose name was not made public, had left the scene and why Police Headquarters was not informed of the accident after witnesses and family members reported it to the 105th Precinct in Queens Village. Chief Guido said investigators had located what they believed to be the car, a gray Plymouth Fury with scratches and traces of blue paint on its hood. It was parked at Highway Unit 3 of the department's Traffic Division at 198-15 Grand Central Parkway.

THURSDAY, MAY 2, 1985 International U.S.-Nicaragua trade will be halted, President Reagan ordered. Mr. Reagan told Congress in a letter that the policies and actions of the Sandinista Government constituted a threat to American security. Mr. Reagan also ordered Nicaraguan aircraft and ships banned from the United States. [Page A1, Columns 4-6.] Nicaragua condemned the embargo ordered by President Reagan, saying a halt in all Nicaraguan trade with the United States would bring the Sandinista Government closer to the Soviet Union. [A1:4-5.]

The decision to impose a trade embargo on Nicaragua was made more for symbolic reasons than out of any expectation that it would cause more than temporary economic hardship to the Sandinista Government, Reagan Administration officials said today. Traditionally, economic sanctions against a country are taken either with military action - such as those the Truman Administration imposed on China during the Korean War - or as a substitute for military moves, as during the first days of the Iranian hostage crisis. But in recent years, sanctions by themselves have not brought political changes in the countries being punished. From all indications, the Administration's move was a substitute for military action rather than a precursor to it and was ordered because of the unwillingness of Congress to support military aid to the Nicaraguan rebels, a naval quarantine of Nicaragua or an American military invasion.

President Reagan ordered an embargo on trade with Nicaragua today, telling Congress that the policies and actions of the Sandinistas constituted a threat to United States security. Mr. Reagan also banned Nicaraguan aircraft and ships from the United States. The announcement came in the form of an executive order and an accompanying letter to Congress. Both were made public only hours after Mr. Reagan arrived in West Germany for the 11th annual economic conference of seven major industrial nations. The three-day meeting opens Thursday in Bonn.

Rupert Murdoch, the publisher who recently expanded his empire into the movie business, now is setting his sights on the television industry. A source close to Mr. Murdoch said yesterday that the Australian publisher was engaged in ''serious'' negotiations to acquire some of the television stations owned by Metromedia Inc., a major broadcasting company. Mr. Murdoch already owns several American newspapers and magazines, including The New York Post, The Chicago Sun-Times and The Village Voice. He fulfilled another ambition in March when he purchased 50 percent of the 20th Century-Fox Film Corporation for $162 million, giving him a toehold in movie production and television programming in the United States.