Add the fennel to the pot and cook, stirring, about 5 minutes, until golden. Add the onion, garlic, fennel seeds, and a teaspoon of salt. Cook until fennel is lightly browned, about 3 more minutes. Add the tomatoes and their juices, the wine, and the chiles. Return the sausages to the pot, lower the heat to low, cover and cook for 15 minutes. Uncover and simmer until the sausages are cooked through and the sauce has thickened, about 45 more minutes. Garnish with fennel fronds and serve hot.