I have tried every oven temperature to cook salmon, and slow roasting is by far the best in my opinion. The low and slow method yields super silky salmon that melts in your mouth like butter. It also cooks the salmon more evenly, without drying out the thinner sides. The low temperature also makes this recipe very forgiving - if you leave the salmon in the oven a few minutes longer by accident, you won't be stuck with dry, overcooked salmon like if you left it in a 400°F oven.