 North Pacific right whales, on the other hand, with populations reduced to the low hundreds in the west and about 30 in the east, are showing little, if any, recovery at all and illegal Soviet whaling may be the eventual demise of the eastern population, as it has little genetic diversity due to its minuscule size (though greater than the closely related North Atlantic right whale).The effect of Soviet whaling on fin, sei, Bryde’s, and minke whales is less known, but there is no doubt that it contributed to the decline of all of these species and only minkes survived in large numbers due to their abundance.Sperm whales were heavily depressed in both the Southern Hemisphere and North Pacific due to Soviet whaling, being the mainstay of the industry everywhere, and populations are recovering very slowly; the effect of the killing of unusually large numbers of females in the North Pacific has yet to be fully understood.