Saving just two female northern right whales a year could halt the decline of the species. Female right whales are by far the most vulnerable among the species, shows an analysis of over 10,000 right-whale sightings since 1980 by Masami Fujiwara and Hal Caswell at the Woods Hole Oceanographic Institution in Massachusetts, USA. "Once they become mothers their mortality increases,' says Fujiwara. But mothers are crucial to boosting the population's dwindling numbers (www.newscientist.com [2], November 30, 2001).