The great white shark is shrinking. The burgeoning market for shark fin soup and overfishing of the species it preys on have led to the predator getting smaller, researchers say.
The scientists behind the study used measurements of sharks caught in nets used to protect Australian beaches from attacks since 1950.
The report says: "The annual mean lengths of great white sharks has declined from 8.2ft to 5.7ft between 1950 and 2007."
The findings also show that the number of sharks has declined. One beach recorded 167 great white shark captures in 1950, compared with 20 in 2008.
American scientists have found similar trends in other species. Neil Hammerschlag, an assistant research professor at the University of Miami said: "Shrinking sharks are a real problem. We call it ‘fishing down the food chain' where the first thing people remove is the biggest sharks.
"It means the population is younger, and therefore smaller, but it also acts as a form of natural selection.
"We are selectively killing the biggest animals and so reducing genetic diversity.
"It means we are putting pressure on them to breed earlier and stay smaller. This in turn means it could be a permanent change." A study by WildAid, a charity, says the global production and trade of shark products has doubled since 1991 and is now worth about £200m a year with 79m sharks killed annually.