Heat the oil and melt the butter in a large pot. Add the carrots, onion, and celery and cook until the onion is translucent and the veggies are soft.
Add the flour and cook for 1 min. Slowly add the chicken stock stirring well. Let the mixture come up to a boil and thicken. Season with salt and pepper.
Add the corn and the potatoes and boil for 15 min. until just tender.
Add the shrimp and salmon and cook for 4 to 5 min. until just cooked through.
Add the cream, clams, and dill and heat through but do not boil. Adjust seasoning if necessary.