Sea lamprey like the smell of little sea lamprey...but not enough to come home

Sea lamprey do not home to natal streams like salmon. In simpler terms, sea lamprey do not seek out the stream from which they were born. Instead they rely on chemical cues to help guide them to a location that will let them reproduce successfully. One of these cues is the smell of larval sea lamprey (ammocoetes) buried within the stream beds. New work suggests that this smell, although it is important in making sure adults examine the stream to determine if they want to enter it to spawn, is not enough to actual make them swim upstream (link).