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Published: 2010

When predator becomes prey

Robin Taylor

Shark attacks on swimmers or surfers have a tendency to make headlines. But, there has been less public interest in the insidious depletion of the world’s shark populations due to overfishing and other human activities. Robin Taylor reports.

Sharkfins drying on the deck of long-line pirate vessel, South Atlantic, 2000.
Credit: Greenpeace. Photo by Jeremy Sutton-Hibbert.

Conservation groups such as the Australian Marine Conservation Society (AMCS) and its patron, well-known writer Tim Winton, are campaigning to save Australia’s sharks. Already, they have successfully lobbied to reduce shark quotas in Queensland.

According to the Society, 100 million sharks are killed each year around the world, and shark numbers have declined by 90 per cent.

As a top predator, sharks are known as a keystone species. They maintain the balance of prey species, which sets up a cascading effect across the entire marine food web. For this reason, reducing the numbers of sharks has significant and unpredictable impacts on marine ecosystems.

Shark fins and bycatch

Compared with other fish species, the flesh of sharks is considered as low value and hardly worth the cost of freezing and transportation. However, the huge consumer demand for shark fins – largely driven by Hong Kong and an increasingly affluent Chinese market – has made sharks among the most valuable animals in the sea. In Asian markets, fins are sold for up to AU$500 per kg, and fins from the large whale and basking sharks can fetch more than $10 000.

In Australian waters, the brutal practice of shark finning – where fins are removed and the shark, often still alive, is thrown back into the sea – is banned. However, some fisheries still target sharks for their fins, while their carcasses are sold as cheap fish under names such as flake or tope.

Thousands of sharks are also killed each year as bycatch – for example, by open ocean long-line tuna fisheries.

The Great Barrier Reef

In Australia’s Great Barrier Reef Marine Park, the two most abundant reef shark species – the whitetip reef shark and gray reef shark – are under threat.

A 2006 survey of these populations by researchers at James Cook University1 found about 80 per cent fewer whitetip reef sharks and 97 per cent fewer gray reef sharks in open fishing zones than within the small area of ‘no-entry’ management zones. The researchers were surprised to find that numbers were similarly depleted in ‘no-take’ zones, and suggested the most likely reason was illegal fishing.

With commercial catches of sharks nearly quadrupling on the Great Barrier Reef between 1994 and 2003, and with recreational fishing also removing large numbers of sharks from the reef, the researchers concluded that the outlook for these shark species in the Great Barrier Reef Marine Park is not good.

Australian shark fisheries

AMCS marine campaigner, Mr Ben Birt, says because sharks are slow growing, late to mature and produce few young, they are more vulnerable to overfishing than most other fish. He argues that fishers shouldn’t be targeting sharks without scientific data about the population size – a proper stock assessment – which would enable them to set sustainable fishing levels.

Sharks are target species in a number of fisheries controlled by the Commonwealth, State and Northern Territory Governments, and are also taken as bycatch in more than 70 other commercial fisheries. Australia’s commercial shark fisheries take school shark, gummy shark, dusky shark, whiskery shark, sandbar shark and blacktip shark.

The Queensland East Coast Inshore Finfish Fishery, which includes commercial fishing in the Great Barrier Reef, has recently reduced the shark quota from 900 to 600 tonnes. This followed the recommendations of an independent review panel established by Federal Environment Minister, Peter Garrett, which included several other regulatory changes to make the fishery more sustainable. These include a maximum size limit of 1.5 metres for line-caught sharks, bag limits for particularly vulnerable species and new fixed net sizes.

Fishers have also been provided with new logbooks in which they can record 18 species of shark separately. Under the old logbook system, most sharks were simply recorded as ‘other’. Fishery Manager with Fisheries Queensland, Mr Mark Lightowler, says that as a result, since July 2009, fishers have collected useful species information that management will be able to use for stock assessment once they have enough data.

In the meantime, the commercial fishing industry claims the 600-tonne limit is too restrictive. Commercial fisherman, Mr Greg Radley, was part of the Queensland Government’s management advisory committee for the new management plan. He says that small vessel operators have been hamstrung by the new arrangements, and believes strong catch rates show that the shark fishery in Queensland is still healthy.

Can sharks be fished sustainably?

Sharks are also under pressure in southern Australia, where the school shark population is considered to be highly overfished. Between 1927 and at least 1999, the population of Australian school shark fell by about 90 per cent following historic overfishing. The species is now listed as conservation dependent.

Since 2001, the Australian Fisheries Management Authority has imposed substantial fishing restrictions, gear modifications and fishing ground closures to reduce the take of school shark.

While recognising that concern about overfishing is well founded, Mr Terry Walker, of Fisheries Victoria, asserts that sharks can be harvested sustainably – and, if carefully managed, can provide very stable fisheries.

‘In many ways, the dynamics of shark fishery stocks have more in common with whale and other marine mammal populations than they do with other fish or invertebrate fisheries,’ says Mr Walker.

‘Compared with other fish and invertebrate species, only small proportions of shark populations can be taken sustainably. Highly productive species such as squid and jellyfish, which live for less than two years, can have much higher proportions of their populations taken each year.’

Beyond our borders

Sharks move freely in the oceans and don’t observe national boundaries. Indonesia has the highest annual reported landings of sharks and rays worldwide – more than 100 000 tonnes – with the export of shark products worth over $13 million.

The shark fisheries in Indonesia are largely driven by the shark fin export market. However, managing these fisheries is difficult, because sharks and rays provide the main income source for millions of people.

In a collaboration funded by the Australian Centre for International Agricultural Research (ACIAR), CSIRO and Indonesian fisheries agencies compared the genetics of Indonesian sharks and rays with those found in Australian waters to assess the extent to which the stocks are shared.

The work highlighted the importance of managing sharks, not only from a fisheries perspective, but also for sustainability and biodiversity. More than 30 new species of sharks and rays were discovered. These species are documented in an ACIAR publication, Economically important sharks and rays, Indonesia, a major outcome of the project.2

An analysis of data from research vessel surveys in the Java Sea highlighted how dramatic the decline in shark numbers has been. Catch rates declined by at least one order of magnitude between 1976 and 1997; eg from 500 to 50 kilograms per square kilometre per hour.

The project also looked at possible management options for the fisheries. Project leader, CSIRO’s Dr Steven Blaber, says that closing areas to protect nursery grounds was not considered feasible for most shark species because of their wide-ranging movement patterns, which make all but very large marine protected areas ineffective. Capacity controls in terms of licensing and gear restrictions are possible options for some of the larger fisheries, but Dr Blaber says that trade restrictions may offer the best hope in relation to ending the market for shark fins.

Grey nurse shark on the Great Barrier Reef.
Credit: Commonwealth of Australia (GBRMPA). Photo by K. Hoppen.

CSIRO researchers about to secure a juvenile great white for tagging.
Credit: CSIRO

More information:

National Plan of Action for the Conservation and Management of Sharks (Shark-plan),

Gray reef shark among a school of sardines.
Credit: Commonwealth of Australia (GBRMPA).

The secret life of great whites

White sharks – also known as great whites or white pointers – are protected in Australian waters, but little is known about them. Scientists think their numbers have declined, but there is no baseline data. In fact, there are no accurate estimates for any populations around the world.

To help fill this knowledge gap, CSIRO scientists have tagged around 500 white sharks over the past 10 years and followed their movements, most recently off the NSW coast near Port Stephens, where juveniles tend to aggregate.

Using a combination of acoustic tags, satellite-transmitting tags and self-releasing satellite archival tags, the researchers are building up a picture of shark movements and behaviour that will be used as part of a national recovery plan.

CSIRO researcher, Mr Russell Bradford, hopes the Port Stephens tagging will lead to an improved understanding of shark habitat, and aid in devising strategies for monitoring the population. In particular, the research will help his team build up a picture of the long-term movements of juvenile white sharks, including whether individuals return annually to this area.

The team is using ongoing aerial surveys of the habitat at Port Stephens to gather accurate counts of juveniles, which will provide information about recruitment.

‘While the sharks are in the shallow water they are clearly visible and easy to count,’ explains Mr Bradford.

Robbins W, Hisano M, Connolly S and Choat J. (2006) Ongoing collapse of coral-reef shark populations. Current Biology 16(23): 2314– 2319.
ACIAR Publications,

Published: 2010

Empowering vision

Cynthia Karena

Educational filmmaker and sustainability advocate, John Liu, has a knack for effectively communicating the complex in ways that make people sit up and take notice. A key to his success is leveraging the power of the image to inspire hope and a commitment to action.

John Liu in Rwanda – <i>Hope in a Changing Climate</i> documents local communities and government working together to rejuvenate the land.
John Liu in Rwanda – Hope in a Changing Climate documents local communities and government working together to rejuvenate the land.
Credit: John Liu

John D Liu’s mission is to make it easy for people to understand climate change.

‘The issue is knowledge. For either the public or for policy makers, ignorance is a good excuse,’ says Mr Liu, founder of the Environmental Education Media Project (EEMP), which produces audiovisual environmental education materials for broadcast and educational audiences.

For more than ten years, the project has been documenting best-practice methods for large-scale restoration of damaged or destroyed ecosystems.

‘If (people) don’t know what to do, they are unlikely to be able to do much,’ says Mr Liu. ‘But if we know that it is possible to rehabilitate large-scale degraded ecosystems and we don’t do it, then we have crossed a line, because our knowledge is responsibility.’

An American with a Chinese father and an American mother, Mr Liu has lived in China for more than 30 years. He trained as a journalist in the United States, and moved to China to help open the CBS News Bureau in Beijing in 1979.

After a decade of living in China, Mr Liu became concerned about the levels of pollution and the rapid pace of development.

With his ‘knowledge brings responsibility’ philosophy, he founded the Environmental Education Media Project for China (the precursor to EEMP) and has been engaged in researching, documenting and educating people about ecology ever since. As an environmental filmmaker and ecological field researcher, he has produced and directed documentaries for CBS, National Geographic and the BBC.

John Liu on location in the 1990s, soon after establishing his environmental education media project.
John Liu on location in the 1990s, soon after establishing his environmental education media project.
Credit: John Liu

In 2006, Mr Liu was named the Rothamsted International Fellow for the Communication of Science. Rothamsted – a non-profit organisation working towards sustainable agriculture in developing and emerging countries – supports his PhD work with the Soil Sciences Department at the University of Reading in the United Kingdom.

Mr Liu is also a member of the Steering Committee of the Global Forum on Media for Development, and an Associate Professor at George Mason University’s Center for Climate and Society in the US.

Stories of hope

Mr Liu says most policy makers and the public assume that the human impact on climate is limited to the copious emissions of carbon dioxide and other greenhouse gases generated by fossil fuel combustion over the past century or so.

‘The problem with this is that it is only partially true,’ he says. ‘Human impact on the climate began long before egregious emissions of CO2 and other greenhouse gases, when human beings began to reduce biodiversity, biomass and accumulated organic matter. These impacts are exacerbated by egregious emissions.’

Re-balancing the world’s carbon equilibrium, according to Mr Liu, is not just a matter of reducing carbon dioxide emissions.

‘If we restore all degraded land on the entire planet as well as reduce emissions, you can extrapolate massive carbon uptake, [as well as] re-regulated hydrological flows, increased fertility and productivity, and the ability to ensure that the highest level of genetic diversity possible survives into future generations,’ he says. ‘That seems like a much more comprehensive result.’

EEMP’s most recent documentary is Hope in a Changing Climate, filmed on location in China, Ethiopia and Rwanda.1 The film aims to demonstrate that damaged ecosystems and degraded land can be restored to health, and that such an outcome economically improves the lives of local people.

The segment on China’s Loess Plateau proves the point, with location footage showing how a barren, brown landscape covering an area the size of Belgium was transformed into a functioning, green ecosystem where rainfall infiltrates, water is retained and crops are readied for export. Importantly, this has enabled local communities to prosper.

Hope ... also interviews world leaders, bankers, students, presidents, journalists, scientists and local people. According to the film’s website, the Government of Rwanda has adopted a new national land-use policy based on EEMP’s presentations and analysis.

The film aired on BBC World last year, and screenings were held for world leaders at the Copenhagen climate change summit.

Reversing the damage

Degraded farmland in developing countries may be one of the best opportunities we have to reverse the trend toward reduced ecological function, says Mr Liu.

‘What human beings have done historically to damage the environment can be understood rather simply. We have interrupted evolutionary trends. This has resulted in reducing biodiversity, which has caused a reduction in biomass, which has in turn caused a reduction in the accumulation of organic matter. These changes have caused disruptions to fundamental systems that all life relies on.

John Liu’s documentation of the transformation of China’s Loess Plateau from barren landscape (top) to fertile oasis (bottom) has inspired communities in other ecologically damaged areas.
John Liu’s documentation of the transformation of China’s Loess Plateau from barren landscape (top) to fertile oasis (bottom) has inspired communities in other ecologically damaged areas.
Credit: John Liu

‘Through our ignorance, we have reduced gas exchange through photosynthesis, lowered nutrient recycling through the decay and transformation of each generation of life, and massively disrupted the infiltration and retention of rainfall in the biomass and in the soils.

‘If we return vegetation to degraded landscapes we can sequester large amounts of carbon from the atmosphere. This is done through photosynthesis. If we return vegetation, we also can lower temperatures because of shade, and we can increase soil moisture and relative humidity by restoring microclimates below vegetated canopies.

‘The Global Partnership for Forest Landscape Restoration has roughly estimated that one billion hectares of the Earth have been degraded and could be restored. This represents a huge potential, through understanding and positive work, to improve what is now a quite bad situation.’

Urban responsibility

The principles of conserving biodiversity and utilising biomass and accumulated organic matter are not just applicable to rural areas, says Mr Liu.

He sees the Earth as made up of five different landscape types; urban landscapes, pristine or functional landscapes, agricultural landscapes, industrial landscapes and large degraded landscapes.

‘In urban and industrial areas we have in many cases created “dead zones” without any biology. This is not true of all cities. In great cities [such as] London, Beijing, Tokyo, Paris and New York, there are lovely parks, but the buildings, the streets, the parking lots, the factories and businesses are mostly not designed to include these principles.’

Mr Liu says that if you lower biodiversity, biomass and organic matter, you get elevated temperatures. Another impact of losing biomass and organic matter to impervious ground cover such as pavement is the loss of capacity to retain and infiltrate rainfall. This results in flooding during rainy seasons. Further, water that would have been captured by living plants and roots during rains is not available to an ecosystem during the dry season.

‘If we understand these principles, and design our cities, our transportation systems and our buildings around them, then we will have a very different, a very liveable and a sustainable future,’ he says.

‘If we continue to fail to learn this, then I think we are in for very serious problems very soon.’

Not ‘them’ – just ‘us’

Australia’s pollution has little impact on the world compared with China or India, which may lead some Australians to feel complacent about the environment. However, this type of thinking suggests an ‘us’ and ‘them’ approach, says John Liu.

‘From my perspective there is just “us”. Humanity is a species. We need to have a species response now to our problems, not suggest that this is “their problem”. It is our problem because we are affecting global systems,’ he says.

Mr Liu gives the example of persistent organic pollutants. These human-made substances travel all over the world and accumulate up the food chain, but the highest concentrations can be found in Inuit peoples who are thousands of miles from any source.

‘Pollution somewhere is pollution everywhere,’ he says. ‘There is no them. Just us.’

More information

Environmental Education Media Project,


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