The fishmonger gave me a whole salmon rationed, and included the head and spine. I threw the head and spine away, but was wondering whether there is any culinary use for it.
Normally in a fish stock, I use white fish, not blue.
I agree that you can get some good meat from the head and could use it to flavour Bouillabaisse, i wouldn't however use it for stock as oily fish can lead to a cloudy fatty stock rather than the clearer and more flavoursome fish stock that can be derived from the off cuts and bones from white fish.
I use salmon bones in stock all of the time. It's delicious!
The heads contain a lot of natural collagen and meat, so they are perfect for making head cheese. Here is a good recipe for king salmon heads. Here is a picture of the result of that recipe.
If you actually like gnawing on bones (like my parents), you can sprinkle some seasoned salt and bake/smoke them... and then gnaw on them...
They also prepare the head in various ways like steaming in rice wine with a bunch of scallions and ginger or the aforementioned stocks. This also depends on whether you like picking meat off.