An international conference about the health of marine life is expected to bring some 250 researchers and industry leaders to Maine’s largest city. The second International Conference of Fish & Shellfish Immunology begins on Sunday and runs until June 30. The University of Maine Aquaculture Research Institute is hosting the event, which organizers say focuses on the health and welfare of wild and farmed aquatic animals. One of the keynote speakers at the event is Bassem Allam of the School of Marine and Atmospheric Sciences at Stony Brook University.