The lunacy of Australia's shark culls

Let's call a spade a spade: As environmental initiatives go, they don't get much dumber than the ongoing culls of big sharks off the coast of Western Australia.

There are scarier things out there than sharks  (from

There are scarier things out there than sharks (from

That's the main conclusion of a resolution by over 300 marine and environmental scientists, who are asking that the culls be halted -- arguing that they are based on the flimsiest science imaginable.

After an initial 13-week trial, the Western Australian government is now proposing to run a three-year shark-killing spree -- and public comments on the program are invited.  This would involve deploying up to 72 lethal drum lines that are expected to kill around a thousand tiger sharks and great-white sharks in total.

As the alpha predators in the sea, big sharks are important in maintaining an ecological balance -- for instance in regulating the numbers and activity of medium-sized fish, sea turtles, and dugongs that in turn affect smaller marine species and seagrass beds.  

Notably, Australia has been taking a leading role in criticizing Japan for its so-called 'scientific whaling' in the southern oceans.  Whales, of course, are not the only big animals that have a large influence on marine ecosystems -- sharks matter too.

The leading environmental website ConservationBytes is taking an especially lively poke at the Western Australian shark cull.  One can usually count on ConsBytes not to pull any punches.

Notably, in Europe and North America, conservationists and scientists are now working hard to reintroduce large predators such as wolves and bears into ecosystems from which they were formerly extirpated.  Known as 'rewilding', these efforts are increasingly gaining public support.

Of course, an even better idea is not to wipe out big predators in the first place.  Let's hope the Western Australian government figures that out before it's too late.

The mystery of Australia's small mammal declines

Across the top end of Australia, from Cape York to the Kimberly Mountains, populations of smaller marsupials and native rodents are collapsing.  What's going on?

Tapping into traditional knowledge to help solve a mystery (photo by Ian Morris)

Tapping into traditional knowledge to help solve a mystery (photo by Ian Morris)

Several studies in recent years have documented the declines.  A few have shown major changes in a single location, such as Kakadu National Park.  Others have compiled scattered information over a much broader area; one innovative study used interviews with Aboriginal communities to piece together evidence (find study here).

The bottom line: many species that used to be common have become vanishingly rare, or have geographic ranges that are collapsing. 

What is causing all this?  No one is sure.  Some suspect it could be severe overgrazing by livestock, especially during droughts.  During such times the vegetation can become badly damaged--as we're seeing at present in many areas

Others think altered fire regimes are the cause.  And yet others suspect predation by feral cats, with a possible role for lethal cane toads for certain predatory mammals.

Whatever the cause, this might be a new biodiversity crisis for the Land Down Under, which has already lost more native mammal species than any other continent.