Environmental Best Practice Port Development: An Analysis of International Approaches

10.5.2Shipping operations and dredging impacts on fauna

Shipping is an international business. In order for regulation to be effective controls need to be consistent and coordinated across international boundaries. The IMO is responsible for the safety and security of shipping and the prevention of marine pollution by ships. The IMO is largely a technical organisation which undertakes work in the following areas:

Dangerous goods, solid cargoes and containers

Fire protection

Flag state implementation

Safety of navigation

Radio communications and search and rescue

Ship design and equipment

Stability and load lines and on fishing vessels safety

Standards of training and watchkeeping.

The IMO has developed International Conventions on these issues which are adopted individually by member states which then bring these conventions into their own legal frameworks. Through its history the IMO has developed over 50 conventions and protocols. Individual ports are bound by their government’s adoption of IMO conventions and protocols into their local regulations.

Large marine fauna including whales, dolphins and porpoises, large sharks, dugong and large fish such as sunfish can be injured or killed through collisions with vessels. This can have impacts on marine ecosystems. The incidence of collision with cetaceans is difficult to determine but it is believed that up to one third of whales found dead have signs of vessel strike (Laist et al., 2001). In the case of endangered, endemic or geographically-isolated cetacean populations (such as the North Atlantic Right Whale) ship strikes may pose a significant conservation threat. Increasing speed of vessels is thought to be a contributing factor to the increase in collisions (Laist et al, 2001). There are limited means of avoidance as ships cannot change course or stop within any reasonable distance. The most effective avoidance mechanisms identified in the international literature are vessel speed and operational locations. Vessel speeds are generally regulated with respect to safety, local conditions and navigational rules. A certain minimum speed may be required to enable the vessel to be safely steered so slowing to very slow speeds may not be possible.

In 2008 the IMO provided guidance for minimising the risk of ship strikes with cetaceans. IMO Circular MEPC.1/Circ.674 advocates actions for gathering and disseminating information, education, and consideration of new technology. The IMO circular also recommended operational measures such as routing and reporting to assist in the avoidance of cetacean strike. These were non-binding measures and the effects of their application remain unclear.

There are a number of situations internationally where governments have taken action. Alterations to shipping routes and speed restrictions have been introduced in response to the incidence of ship collisions with whales. Offshore from the North East Atlantic Seaboard of the US the Atlantic Right Whale is an endangered species at risk from collision with large vessels operating in the area. Between 1999 and 2003 there was an average of 2.6 deaths per year attributed to ships strikes. There are a series of locations along the coast where vessels in excess of 19.8 metres are restricted to 10 knots or less between 1^st of April to July 31^st each year. The effectiveness of these mandatory restrictions is expected to be evaluated in late 2013.

Research is being undertaken to determine whether restrictions of shipping routes may also help reduce collisions between ships and Atlantic Right Whales. A preliminary assessment in 2012 (Silber and Bettridge, 2012) reported that the timeframe for analysis had been insufficient to obtain statistically rigorous results but there was a suggestion that the speed limits for shipping were potentially effective in reducing the potential risk to the whales.

In 2007 ship strikes are thought to have caused the deaths of four Blue Whales in and around the Santa Barbara Channel offshore from the southern California coast. In response the IMO announced in late 2012 that it had adopted proposals to reduce ship strikes with ships on the approach to San Francisco Bay, the Santa Barbara Channel and the ports of Los Angeles and Long Beach including the changing of shipping routes.

All cetaceans in Australian waters are protected under the EPBC Act and all vessels operating in Australian waters are obliged to avoid harming these animals. An example of this being applied in practice is the EMP Port of Melbourne Channel Deepening Project, which contained specific requirements for monitoring for cetaceans and required actions for vessels in the event of a cetacean sighting. The EMP, including the cetacean monitoring requirements, was subject to internal as well as external independent audit.

Dredging and direct impacts on fauna

One of the identified potential interactions between dredges and marine fauna is the potential for fauna (turtles in particular) to be entrained into the dredge with fatal results. Worldwide turtles have been reported as being injured and killed by dredging operations and most species of turtles appear to be affected.

A number of mitigation measures have been proposed including:

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  Appropriate siting of dredge operations - this is often difficult for existing ports but is an essential consideration for any new ports in contemporary ports planning. Siting of new ports should consider all environmental values and if risks to these values can be mitigated through choice of location of the port then this should be considered if at all possible.
  
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  Timing of dredging operations. Periods of turtle nesting are potentially times when incidents with dredges are more likely and therefore if possible dredging should be schedule to avoid these times.
  
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  Dredge type; section dredges are more likely to cause impacts on marine megafauna than mechanical dredgers.
  
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  Modifications to dredges. There are modifications such as turtle deflectors and chains that can be used to limit the potential for intake into the dredge.
  
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  Operational methods such as not operating the suction pumps when the drag head of the dredge is not on the bottom.
  

Figure Number of turtle takes per dredging projects in the US for the period 1990-2010. Protection methods were introduced in 1992 (from Dickerson, 2010)

Discussion of many of the potential sources of direct ecosystem impacts has been included in other sections of this report. For example many of the shipping issues are covered in the section on impacts on water quality. The issues of direct and indirect impacts through land clearing and reclamation are primarily port planning issues, however construction environmental management plans can be used to minimise impacts on species during clearing.

The actions that are adopted by ports in response to the issue of direct impacts on fauna through shipping and dredging operations are generally implemented through environmental management plans for these operations. In general, the responses are common techniques used by ports such as speed limits and shipping route restrictions to avoid ship-strikes and technical measures for dredging operations.