Good luck to find salmon caviar, you can't replace it by anything else.
If you need it anyway, I give you one more recipe.
Sour cream 14%, red salmon caviar, fresh cucumber, crab meat (can be replaced by made from fish) , small shrimps, dill.
Chop cucumber and crab meat on small peaces, chop dill, mix everything with cream. Proportion according to taste but general idea is everything should be equal.
Used for stuffing baked potatoes.