This is a great way to prepare a smaller size land-locked salmon or brown trout. If you smoke it whole, it is much easier to get all off the cooked meat off the bones, rather than filleting it first.
Ingredients for brine:
1/2 cup pickling or sea salt
2 quarts cold water
2-4 tablespoons brown sugar
2 tablespoons pickling spices (you can experiment with other flavors, such as dill and lemon peel, garlic, asian flavorings of soy, ginger and lemongrass, etc)
Make the brine by mixing all ingredients, making sure the salt dissolves. Make sure the brine is cold when the fish is placed in it. Use a glass, ceramic or other non-reactive container. Cover the fish in the brine for 6 hours up to a whole day, turning every now and then.
After you have brined your fish, place it on a metal rack (can use the smoker rack) and let it dry for about one hour to form a slight glossy shine, called a pellicle. This locks in the juices and flavors. A fan can be used to speed up the process.
Preheat the smoker and then smoke your fillets according to the directions of your smoker. Usually the fish will be smoked at 200-225 degrees until it reaches an internal temperature of 145 degrees (about 2 hours).