How do you think the mass effect fields Mordin mentions in ME2 help with sex?

I think the implication is that salarians reproduce more like salamanders, which doesn't involve sexual intercourse.  Their "reproductive contract" allows the male to fertilize the eggs of the female.  Salamanders can do this in two ways:  1) the sperm is spread over the already laid eggs or 2) the sperm is spread and then collected by the female and used to fertilize the eggs internally.  I think Salarians reproduce in large numbers... probably comparable to krogan (before genophage), but the thing preventing them from being viewed as the same sort of problem as the krogan are their short lifespans.