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Experts clash over shark  numbers
Making a comeback: Great white sharks off the WA coast. Picture: Supplied

Great white shark numbers have been recovering off WA's coast since commercial whaling ended in the 1970s, according to a respected former Fisheries Department boss.

Peter Rogers, who served as head of the department between 1991 and 2006, has rebuffed claims by researchers it was biologically impossible for mature white shark numbers to be increasing.

University of WA scientist Shaun Collin argued last week that the population of WA white pointers had only been recovering since the species was protected in 1997, meaning adult numbers would not rise until at least 2017.

But Dr Rogers, who until Easter was the chairman of the WA Marine Science Institution, disputed the comments by saying the species had been on the rebound for at least 10 years before they were protected.

According to Dr Rogers, the closure of WA's last remaining whaling station in Albany in 1978 heralded the turning point because up until then game fishermen could easily target great whites drawn to the area.

Since then, he noted, the predators had become significantly more elusive and along with a rebound in the populations of seals and whales - their natural prey - it was likely their numbers would have risen accordingly.

"All the things were positive for it at a much earlier time than simply bringing in the protection and therefore the recovery of white pointers is much earlier than people think," Dr Rogers said.

"The fad in terms of catching great white sharks did drop off before the protection came in."

At a conference last week, Professor Collin suggested white pointer numbers had been suppressed until hunting them was banned in 1997 and it was ecologically impossible for adult stocks to have recovered.

"They have been protected since 1997 and knowing a lot about the reproductive cycles of great whites, they in fact take 20 to 30 years to get to maturity," Professor Collin said.

"The fact is there is really no evidence to suggest (adult) numbers are increasing and even during this period they are still prone to being taken as bycatch."