Wash squash thoroughly. Place in a medium saucepan with boiling salted water to cover. Cook 25 minutes or until tender. Drain and cool slightly. Peel squash; remove seeds, and cube pulp. Set aside.
Combine shrimp and 1 tablespoon lemon juice. Let stand 10 minutes or until lemon juice is absorbed.
Sauté onion, celery, and green pepper in butter until tender. Stir in tomatoes, cubed squash, bay leaves, Worcestershire sauce, hot sauce, orégano, garlic powder, salt, and pepper. Cover and simmer 10 minutes. Remove bay leaves, and discard. Stir in shrimp and remaining lemon juice.
Spoon mixture into a lightly greased 2-quart casserole. Top with breadcrumbs. Bake at 350° for 20 minutes or until browned.