Extinction with minimum chips - episode 2

3 Feb 2011 0 1,321 VIEWS



Of all the living things on our planet, sharks occupy a unique role, embodying the darkness in our hearts, evoking everything that spooks us about the deep.

But the relationship is more complex than eating and being eaten. Sharks inspire all manner of ritual and symbolism, strains of belief and superstition that persist throughout human history. Their sleek lines are a metaphor for anything fast and predatory: moneylenders and lawyers especially. They are the men in grey suits. They are Jaws the hideous, and Bruce the loveable. We’ve professed to loath them, but we’re addicted to the idea of them. They are as much a part of our history as we are. And they’re disappearing.

Jock Serong explores the problems facing sharks, possible solutions, and why we should care…


Protecting our beaches
Shark nets and drumlines have been a part of Australian beach culture since the mid-sixties. Queensland's Department of Primary Industry confirms that nets "minimise the threat of shark attack on humans in particular locations, (but are) not designed to provide a distinct barrier between sharks and humans."

Amity Point, the site of the first shark attack on a netted beach, in 2006.

Amity Point, the site of the first shark attack on a netted beach, in 2006.

In fact, about 40% of shark entanglements occur on the beach side of the nets, because sharks are able to swim over and around them.

Until a fatality occurred at Amity Point on the Moreton Bay side of Stradbroke Island in the summer of 2006, there had never been a death by shark attack at a netted beach.

Does it work?
Shark meshing does not enjoy universal scientific approval. It's been listed as a Key Threatening Process by the New South Wales Fisheries Scientific Committee. Australian Marine Conservation Society director Darren Kindleysides told the Courier Mail last year that the nets were working, but at huge cost to whales, dolphins and turtles.

A shark caught in a fishing net is hauled aboard.

A shark caught in a fishing net is hauled aboard.

Even Hervey Bay shark hunter Vic Hislop, a man not renowned for advocating tolerance for large sharks, agrees the nets cause too much damage to the marine environment, and that the answer lies in scaring sharks off rather than capturing and killing them.

"Every two weeks government repair boats pull the nets in with holes in them that you could drive a train through," he claims. "Those holes are made by Great Whites that have learned to feed off dolphins and sting-rays trapped in the nets."

Bycatch
The so-called "non-target" bycatch in the nets includes marine animals such as Dugongs and Loggerhead turtles (both of which are listed as Endangered Species), and Green turtles, Leatherback turtles, Humpback Whales and Australian fur-seals. Non-target shark species are also killed in the nets, including protected and endangered species.

A turtle caught in a shark net.

A turtle caught in a shark net.

Many nets are now equipped with acoustic 'pingers' to deter marine mammals which rely on sonar, such as dolphins and whales. Plastic hook guards have also been introduced on drumlines to minimise turtle hooking.

Tighter monitoring of water temperature has also led to a better understanding of the factors that cause marine mammal entanglements.

A shark caught in a beach-protection net.

A shark caught in a beach-protection net.

The Queensland government is even watching research in South Africa which adapts the well-known technology behind electromagnetic shark repellents to an open ocean setting: a 'shark pod' for an entire beach.


Doing the maths
Paradoxically, shark meshing is a valuable source of data. Meshing on Sydney beaches goes back as far as 1937, so we know for example that in the first year of meshing, approximately 1000 sharks were taken off Sydney beaches. In the 52 years from 1950 to 2002, more than 11,500 sharks were caught and killed in the nets, with annual shark deaths during this period ranging up to 648 sharks.

Only four species of sharks are considered responsible for human fatalities along this stretch of coast: the great white, the tiger, the bull shark, and the oceanic whitetip whaler. Captures of these four villains in the Sydney shark meshing program total 3670 over the last 52 years, with the bull shark scoring lowest on the tally. 526 great whites were captured, or roughly 10 per year.

In the same period, at least 8000 sharks of other species met their demise in the nets, although death rates have dramatically decreased in the last 30 years, and the last kill of 69 is the lowest ever recorded.

Nursing populations back to health
Dave Pollard is credited with getting protection for the grey nurse. He believes that "because the nets are very consistent in terms of their placement and the regularity of their checking, they've given us a very good data set back to the 1950s. That's how we knew the grey nurses were in danger. Back in the 50s, the nets were trapping about 60-80 grey nurses a year. By the 1980s, it was 0-1 grey nurse per year."

Desptie their toothy appearance, Grey Nurses have never been implicated in an attack on humans.

Desptie their toothy appearance, Grey Nurses have never been implicated in an attack on humans.

There are now believed to be only 300-500 grey nurses left on the entire NSW coast, down from a peak of about 10,000. This means that in conservation-speak, they're critically endangered. But even now, there's a net placed close to a designated grey nurse habitat at Magic Point, on the southern headland of Maroubra beach.

A strange side-note to all this is that grey nurses aren't necessarily killed by entrapment in nets, because unlike, say, great whites, they don't need to be moving to obtain oxygen.

Where are the nets?
Originally, Sydney beaches from Palm Beach to Cronulla were meshed. In 1949 beaches in Wollongong and Newcastle were added, with Central Coast beaches added in 1987. Today a total of 49 beaches covering approximately 200 km of coastline are meshed for eight months of the year from September to April.

Some of Queensland's most heavily surfed beaches are netted – Burleigh, North Straddie, Noosa, and Greenmount to name only a handful. The equipment is serviced every second day, weather permitting, by independent contractors. The Queensland Shark Control Program (SCP) large mesh nets are 186m long, and are specifically designed to catch sharks over two metres in length. Despite this, many sharks drown every year after becoming entangled in nets intended for other species.

What can you do?



The writer would like to thank Ingrid Neilson at the Australian Marine Conservation Society and Kent "Black" Stannard at WhiteTag for their generous help in researching this article. You can check out their very informative websites at www.amcs.org.au and www.whitetag.com.au



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