Heat the olive oil in a large pot over medium-high until shimmering, slice the fennel thinly, and add it to the pot along with the chopped onion, remaining salt and garlic powder, Italian seasoning, crushed red pepper, and bay leaves.
Saute the vegetables and seasonings until tender and fragrant (approx. 3 to 5 minutes).
Clear a space in the center of the pot and add the tomato paste.
Continue to cook, stirring, until a brown film forms on the bottom of the pot.
Deglaze the pot with the white wine, scraping with a wooden spoon to lift the brown coating up off the bottom of the pot and into the mixture.
Stir in the diced tomatoes and their juice, along with the chicken stock, and turn the heat down to a bare simmer.
About 8 to 10 minutes before serving, slip the salmon and lobster into the pot and allow them to poach in the broth.
About 5 minutes before serving, add the shrimp and scallops to the pot.
About 2 to 3 minutes before serving, add the mussels and clams to the pot.
When the mussels and clams have opened, ladle the stew into bowls and garnish with crabmeat and the reserved gremolata.