Just put two eggs in the alien containment and let them breed more stalkers then when it is full take out all but two stalkers. That way you can continue breeding. Release the extras into the wild get a few metal salvage and stalker teeth galore.
No you cant, they are fairly common any so just set up a scanner room base in a kelp biome to find tons, as well as other useful stuff like metal salvage and sandstone/limestone outcrops
