Preheat oven to 275 degrees Fahrenheit. Coat the salmon with oil and season with salt and pepper.

Spread half of the blood orange, orange and lemon slices into a shallow baking dish and place salmon on top. Arrange the rest of the citrus over the salmon.

Roast salmon until it’s just cooked through (the tip of a knife will slide through easily and flesh will be slightly opaque), 30–40 minutes for medium-rare.

Combine orange juice, lemon juice, water, sugar and salt in a small saucepan. Bring to a boil over medium-high heat and mix well. Cook until reduced by half. Let cool until the glaze is thick and sticky.

Transfer salmon to a platter and drizzle with citrus glaze. Serve at room temperature.