In a large pot on low heat add olive oil and garlic, after 5 minutes add onion and butter, raise heat to medium. Cook for 5 minutes. Raise heat to high and add the rice. After 2 minutes add the crushed tomatoes. Constantly stirring, slowly add stock as liquid thickens. Salt and pepper to taste.
In a large pan on medium heat add olive oil and rosemary. Once pan is hot add shark, lemon juice, and capers, cook on each side for 2-3 minutes.
Plate shark with rosemary over risotto.