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Opinion: Dredging up our fishing future?

THE issue of dredging on the Great Barrier Reef coast has been receiving a lot of media attention lately, however, there seems to have been limited discussion of what it means for fishers.

The potential impacts on the reef and the $6 billion tourism industry it supports have been making headlines, while the potential impacts on recreational and commercial fishing have seemingly been “flying under the radar”.

Looking back we remember the shocking images of dead fish in Gladstone after dredging operations. As Fishing World readers will be aware the project has been a source of ongoing problems within the Gladstone fishing community. The problems escalated from April 2011 until a three-week fishing ban was imposed in September of 2011 due to an outbreak of diseased fish in the harbour.

Fishermen believed the outbreak was caused by contaminants released into the water by dredging activities. Over 40 fishermen developed health symptoms, including painful boils on their arms and legs after contact with the water[i]. Presently, a group of over 50 commercial fishermen are seeking $20 million in compensation for losses from which the fishing industry may never recover.

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Satellite view of Gladstone Harbour following dredging activity in 2011 and (top) images of diseased barra, turtles and dugong from that period.

Ports corporations have publically stated that dredging and dumping have little impact on our marine environment; however, scientists such as Prof Terry Hughes have described these claims as “untenable”. Prof Hughes warns that any improvement in preventing runoff from land reaching inshore reefs would be completely swamped by the dumping of dredge spoil at sea.

Port expansions and related dredging and dumping are key concerns of the World Heritage Committee who will be considering the listing of the Great Barrier Reef as “World Heritage in Danger” in 2015.

What is proposed?

There are massive plans afoot for dredging along the reef. Plans exist for over 100 million tonnes of dredge spoil to be removed and dumped in coming years. In the Port of Cairns alone it is proposed to remove 4.4 million cubic metres (at least 4,500,000 tonnes) of fine mud and potential acid sulphate soils, with dumping in the marine park one of the main options being considered.

To put this in context, James Cook University scientist Jon Brodie has written that the government’s multi-million dollar Reef Rescue program reduced land based sediment loads draining to the reef’s waters by just 360,000 tonnes from 2009 to 2011.

What are the potential impacts on fishing?

Our commercial fishing industry, recreational pastime and fishing tourism industry are all at risk from poor water quality.

Leading Australian scientists in a “declaration by concerned scientists on industrial development of the Great Barrier Reef coast” statement endorsed by hundreds of expert scientists, have made it clear that increased sediment and nutrient loads are a key cause of decreased water quality leading to a “very serious decline in the quality of the Great Barrier Reef’s inshore habitats and the abundance of key species.”

Poor water quality leads to increased crown of thorn starfish numbers and poor reef recovery from storms, cyclones and bleaching. Sediments suspended by dredging can block the light required by seagrass and corals, choke and smother marine life interrupting ecosystem balance and lead to fish disease and even human health problems.

Scientists “are concerned about the additional pressures that will be exerted by expansion of coastal ports and industrial development, accompanied by a projected near-doubling in shipping, major coastal reclamation works, large-scale seabed dredging and dredge spoil disposal – all either immediately adjacent to, or within the Great Barrier Reef World Heritage Area.”[ii]

Key threats to fishing include:

  • Potential major fish kills such as seen in Gladstone harbour.
  • Re-suspension and mobilisation of contaminants (metals and metalloids including persistent antifouling chemicals) from sediments.
  • Increased parasitism due to stress, immunosuppression and external irritation from poor water quality and toxicoses.
  • Increased underwater noise impacting on fish behaviour, including feeding and breeding.
  • Generation of toxic algal blooms due to disturbance of sediments and release of nitrogen, iron and other nutrients. [iii]Damage to fish and prawn nursery habitat including seagrass and mangroves reducing overall fish numbers. The unseen and difficult to record impact on planktonic larvae of crustacea and fish. Potential exposure of acid sulphate soils (causing acidification of water).

Time to increase our engagement with the issues
As fishers we are all stewards of our marine environment and fishing future. Together our voice is powerful and it is important that we engage in this crucial issue. By raising these issues in our fishing clubs, public forums, letters to the editor and by engaging in government dredging approval processes, we can help ensure that a better balance between the demands of big business and the needs of our fishing and tourism industries is achieved.

About the Author:
Josh Coates is a marine biologist with a lifetime of experience as an avid recreational fisher. Josh is based in Cairns where he currently works as the Marine Programs Coordinator for the Cairns and Far North Environment Centre. Contact marine@cafnec.org.au (07) 4032 1586
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Further reading:

Dredging set to swamp decades of Great Barrier Reef protection

Mounting evidence shows dredge spoil threat to the Great Barrier Reef

Must watch:
4 Corners – Battle for the reef

[i] Fishing World. (2013, 11 18). Gladstone cover-up exposed. (Yaffa Publishing Group) Retrieved 12 17, 2013, from Fishing World: http://www.fishingworld.com.au/news/gladstone-cover-up-exposed

[ii] Declaration by concerned scientists on industrial development of the Great Barrier Reef coast http://media2.apnonline.com.au/img/media/pdf/Science_statement_020613.pdf

[ii] Adapted from: Investigation of the Causes of Aquatic Animal Health Problems in the Gladstone Harbour and Nearshore Waters – Dr Matt Landos BVSc(HonsI) MANZCVSc , 1 October, 2012, Report commissioned by the Gladstone Fishing Research Fund.

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