At least 8 000 great white sharks roam the waters off Australia, according to research released last Friday that is likely to renew debate about balancing conservation efforts with mitigating attacks. Great whites have been a protected species in Australia since 1999, when signs emerged of a long-term decline in their population in waters around the continent. But an increase in attacks on surfers and swimmers has prompted some Australian states to push for the culling of the apex predator despite their protected status. The landmark analysis involved extracting DNA from juvenile sharks to find genetic “marks” of both parents, the researchers wrote in the Scientific Reports journal. The scientists were then able to estimate using statistical methods how many adults had produced juveniles.