Special to the TimesThe New England Aquarium is looking forward to welcoming guests during the upcoming April school vacation week with extended hours, exciting animal encounters along the exhibit path, and special educational programming on Massachusetts Right Whale Day, plus the return of Boston Duck Tours to Central Wharf plaza.The Aquarium will be open from 9 a.m. to 6 p.m. daily the week of April 20 when public schools in Massachusetts, Maine, and Vermont are on spring break. Hours of opera