This article is part of a series examining in depth the various threats to the Great Barrier Reef.

The Great Barrier Reef has deteriorated since its World Heritage listing in 1981 and, as a report from the Great Barrier Reef Marine Park Authority made clear, this downward trajectory is likely to continue without significant intervention. At the same time, the global demand for coal, gas and minerals has led to rapid port expansion along the Reef’s coast, most prominently at Abbot Point, Hay Point and Gladstone.

The impact of ports and dredging on the Reef’s values are a focal point of local and international attention. Dredging establishes shipping lanes, swing basins and berth pockets to service the navigation of large shipping vessels. But what about the ships themselves? The impacts of shipping have been reported as well managed in the past, but will this change as more ships move through the region?

Traffic report

More than 9,600 ship voyages were recorded in the Reef between 2012 and 2013, and 3,947 individual ships called in at Reef ports in 2012. At the current growth rate of 4.8% per annum, the projected increase in ship numbers calling into these ports will exceed 10,000 by 2032.

PGM Environment/port authorities

The average size of ships is also increasing: worldwide, average vessel size has grown by 85% over the past 15 years.

In addition to commodity vessels, the number of cruise ships, super yachts and navy vessels are also predicted to increase.

When the Chinese bulk coal carrier MV Shen Neng I ran aground on Douglas Shoal northeast of Gladstone in 2010, it left a 400,000-square-metre scar – the largest ever recorded in the Great Barrier Reef. More than 600 shipping incidents were recorded in the region between 1987 and 2009, not to mention the many near misses that have gone unreported.

AAP Image/GBRMPA

The potentially catastrophic impact of incidents such as collisions, groundings, or major oil or cargo spills has led the Australian Maritime Safety Authority to develop the North-East Shipping Management Plan, which features measures such as mandatory ship reporting. The Reef is also listed as a Particularly Sensitive Sea Area (PSSA) by the International Maritime Organisation (IMO), necessitating traffic monitoring of all vessels longer than 50 metres. Vessels are largely confined to dedicated shipping lanes in general use zones, and much of the region requires the compulsory pilotage of vessels over 70 m and all loaded oil tankers and chemical and natural gas carriers.

The result has been that, despite the reported increase in vessel traffic of about 1% per year over the past decade, the 2014 Outlook Report judged the likelihood of an acute shipping incident as “unlikely to impossible” – the same level as it was in 2009.

Accidents aside, what about the more gradual effects of growing traffic volumes across the Reef?

Chronic impacts - the sleeping giant?

The shipping industry has committed to continually improve the design and operation of ships to ensure they have no harmful impact on the environment. In practice, the biggest issues for the industry are cost and safety – the environmental conservation is not a priority, except in the case of acute events such as oil spills.

Yet the chronic impacts of shipping, despite generally causing only low-level damage, can accumulate significantly over time. Examples include physical damage from propellers and anchors, the introduction of invasive species, greenhouse gas and nitrogen oxide emissions, and contamination from the release of coal dust, rubbish, sewage, anti-fouling agents and non-synthetic compounds such as oil and heavy metals. The global trend toward deeper-draft ships is also increasing the likelihood of propeller scouring and the resuspension of sediment.

More ships moving through the Reef is increasing the likelihood of vessel strike on turtles, whales, dugong and other mammals, as well as exposing them to noise, light and pollution. Increased vessel traffic also presents a risk of collision with smaller boats, such as yachts and fishing vessels, which are vital to Queensland’s tourism and fishing industries.

The Commonwealth and Queensland government’s Reef 2050 Long-Term Sustainability Plan concentrates its actions, targets and objectives on acute shipping incidents. However, it does not address the monitoring or management of the cumulative impact of chronic shipping pressures that cover a much wider area then acute incidents.

Shift to environmentally sustainable shipping

The strategies to avoid shipping accidents on the Reef are arguably world-leading. But there is room for improvement. Materials and equipment for disaster responses are dispersed and difficult to mobilise in the Reef, particularly in the wet season, when many roads and airstrips can be unusable. Logistical difficulties and high transport costs limit the ability to respond quickly to accidents, especially in the remote north.

Good incident management needs sufficient funding, equipment, procedures and personnel, to provide for pilotage and assistance of stricken vessels, ship inspections, and immediate clean-up in the case of spills or groundings. Authorities should also consider closing the Reef’s waters to ships that don’t meet prescribed standards of crew competency and vessel condition, similar to the eco-certification of tourism vessels.

But if we are really to safeguard the Reef, we need to address chronic shipping pressures too. This could be done by shifting the current focus on ship safety to a broader approach that ensures shipping is doing its business in smarter, safer and greener ways. Here are some suggestions:

Move towards best environmental practice with introduction of Reef class vessels that are wider and shallower and result in less environmental impact than existing deep draught ships.

Develop an integrated monitoring program near major shipping routes, to measure the chronic impacts of shipping on species and habitats.

Implement the proposed National Vessel Strike Strategy and develop guidelines for noise levels to minimise harm to marine wildlife.

The shipping industry is an integral part of Australia’s maritime economy. But it needs to be managed in a way that will not increase pressure on the Great Barrier Reef’s unique values. Given the region’s World Heritage status and its vulnerable state, we should expect to see continued improvement in shipping management. If the government prioritises strategic planning, partnership and funding to shipping management like they have for Reef Rescue, we could see a transformation in the environmental sustainability of the shipping industry.

This article was co-written with Adam Smith, Director of Reef Ecologic and a former member of the Great Barrier Reef Marine Park Authority.