Longshoremen shut down the Port of New York and New Jersey and Packer Avenue Marine Terminal in South Philadelphia Tuesday to protest Del Monte Fresh Produce Co.'s move from Camden to a cheaper-labor terminal in Gloucester City. Pickets by members of the International Longshoremen's Association forced work stoppages at four ocean terminals in Port Elizabeth, Newark, and Bayonne, N.J. and Staten Island, N.Y., idling 12 ships and costing each carrier about $50,000 a day, said the New York Shipping Association.