By an 8-0 vote Monday, the San Diego City Council asked its staff to negotiate with the Navy to acquire Hickman Field, a 43-acre sports complex at Miramar Naval Air Station. The city manager's office had recommended that the council not pursue a land swap because the value of the land is high--estimated to be $10 million. But, led by Councilman Ed Struiksma, the council asked its staff to try to acquire the land as a park. Residents said that more than 5,000 children a year play on the baseball diamonds and soccer fields at Hickman. They said they had improved and maintained the field for years and would continue to do so if the city acquired it.