Sharks having a whale of a time?

So here's my provisional hypothesis.

The recovery of the east Australian humpback population has injected a huge new source of imported energy into an existing seasonal coastal food highway. That has increased either the number of great white sharks the ecosystem can support, the amount of time they spend near the east Australian coast, or both.

It is only a hypothesis. There are plenty of competing explanations: protection of white sharks themselves, changes in fish stocks, water temperature, ocean currents and changes in shark behaviour or distribution.

But it is testable.

And there is a policy sting in the tail.

The great white remains federally listed as Vulnerable. The estimate usually quoted for the eastern Australasian population is about 5,460 animals, including only around 750 adults, based on work published in 2018.

Yet NSW has simultaneously been catching and detecting whites in numbers that seem difficult to reconcile intuitively with the picture many people have of an animal hovering on the edge of extinction.

Perhaps the science still supports that status.

But we ought to find out.

Because it would be a wonderful ecological irony if one consequence of rescuing the humpback whale from extinction was that we also helped rescue the great white shark.

And if we have, there comes a point at which conservation policy has to notice success.

If great whites are no longer genuinely threatened, and their increased abundance or changed behaviour is imposing a significant risk on people, then we should at least be prepared to ask the question conservationists won't like:

Have we reached the point where some targeted culling of great whites should be back on the table?