Prepare the Shell Stock:
In a large saucepan over low heat, add the canola oil and sweat the prawn shells with the diced onion, fresh thyme, bay leaves, black peppercorns, peeled lemon, and diced Roma tomato for 2 to 3 minutes. Add the white wine and water, then simmer for 45 minutes. Strain and reserve the liquid.
Cook the Vegetables:
In a large saucepan over low heat, add the canola oil and sweat the diced sweet onions, cooked bacon cubes, and diced celery for 5 to 6 minutes. Add the diced Yukon gold potatoes and sweat for another 5 minutes.
Simmer the Chowder:
Add the minced fresh thyme, prepared shell stock, and heavy cream to the saucepan. Bring to a simmer and cook for 15 to 20 minutes, or until the potatoes are tender.
Add the Salmon:
Add the cubed wild king salmon to the chowder. Season with salt and freshly ground black pepper to taste. Simmer until the salmon is cooked through.
Finish the Chowder:
Stir in the lemon juice, minced fresh tarragon, and minced fresh chives. Adjust seasoning as needed.
Serve:
Ladle the chowder into bowls and serve hot.