In a large ovenproof nonstick skillet, heat the canola oil until shimmering. Season the halibut with salt and white pepper and spread each fillet with 1/4 cup of the shrimp mousse. Add the halibut to the skillet, mousse side down, and cook over moderately high heat until golden brown, about 2 minutes. Using a spatula, turn the fish over and transfer the skillet to the oven. Bake for about 8 minutes, until the fish is just white throughout.