Too many of them exploding at high altitude and polluting the air.

New Scientist just had a recipe for fake gravlax using salt, sugar, and dill:

Start with a 1-kilogram piece of salmon and remove any pin bones with tweezers. Mix 50 grams of coarse salt and 50 grams of sugar, then add some spices if you like: a tablespoon of peppercorns, coriander seeds or caraway seeds, ground in a mortar, works well. Rub the mix into both sides of the salmon, then place it on a bunch of dill in a dish, skin side down. Top it with more dill and a plastic covering, then put a heavy item on top to press down on the salmon.

Keep it in the fridge for a day, then turn the salmon over, repack and refrigerate for another day or two. All you need to do then is scrape off the dill, cut some slices and serve with rye bread.