In a large saucepan or high-sided skillet, combine 5 cups water, vinegar, 3 sprigs rosemary and 1/2 teaspoon salt and bring to a boil. Reduce heat to medium and simmer 10 minutes. Season both sides of salmon with 1/4 teaspoon salt. Place salmon skin-side down in the pan of simmering liquid and cook, adjusting heat to maintain a light simmer. Cook 10 to 12 minutes or until salmon is just opaque in center. Carefully transfer salmon to a serving dish. (Discard the poaching liquid.)
Meanwhile, in a medium saucepan, whisk together heavy cream, cinnamon, nutmeg, cloves, remaining rosemary sprig and remaining 1/8 teaspoon salt. Bring to a simmer over medium-high heat. Simmer until thickened, about 15 minutes, stirring frequently. Remove rosemary sprig and discard. Serve sauce over poached salmon and garnish with fresh rosemary.