If Wrex died in ME1 and you did not save Maelon's data in ME2, you can convince Mordin to sabotage the Shroud as the salarian dalatrass requested.
By doing so, you gain Mordin as a War Asset (he goes to work on the Crucible); you gain the support of the krogan clans (Wreav isn't smart enough to figure out sabotage happened, whereas Wrex does); and you gain the support of the salarian fleet. Yes, the krogan clans probably won't be as strong as they would have been if Wrex and Eve were both alive, but at least you can wring some points out of Mordin and the salarians. I don't know, however, if that's enough to off-set the decrease in krogan assets.