BWM regulation

Protecting the environment against the invasive species...

Ships transport over 80% of the world’s commodities, and transfer 3 to 5 billion tons of ballast water annually between oceans, all the while ballasting and discharging water during operation. Ballast water contains many marine organisms, larvae, eggs, plankton… that, when introduced into a new environment, may survive and invade the local marine ecological system. It has been estimated that more than 7000 species are transported each day through ballast tanks, and that some 40 recent invasions occurred because of ballast water discharge.

The impact of these invasive species can be divided into three main categories:

  • Ecological threat to the native biodiversity and/or ecological processes,
  • Risk to human health as toxic organisms and pathogens may be introduced, potentially causing illnesses to fauna, flora and humans,
  • Economic impact for fisheries, coastal industry, and other commercial activities and resources than can be disrupted.

IMO Ballast Water Management Convention
The direct economic impact as well as the potential long term damages to the environment and people has led to the development of international, national, and regional regulations in order to control the transport and discharge of aquatic organisms. In 2004, the IMO adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (a.k.a. BWM Convention), which will enter into force 12 months after ratification by 30 states representing 35% of the world merchant shipping tonnage.

Finland recently ratified the ballast water convention, the 8th September 2016. Thus it will come into force on the 8th September 2017.

USCG Ballast Water Management Regulation in the USA
The USA adopted their own regulation regarding the Management of Ship's Ballast Water and Sediments.

There is no unique definition, but a common and unofficial one could be:

"Non-indigenous or non-native species which, when introduced in a new environment, either accidentaly or intentionally, can adversely affect the habitats and ecosystems they invade, with potential harm to the local economy, environment, health and/or ecology."

These “alien species” can be plants, animals, or microbes. They are often introduced in new areas without their native predators, and may outcompete native species for resources (food, nutrients, light, physical space, water), until reaching competitive superiority.

Invasive species can also survive at low population densities, and then proliferate by using resources or filling ecological niches previously unavailable to native species, or by taking advantage of a change occurred in the ecosystem.


The International Maritime Organization (IMO) lists the ten most unwanted species as: the Cladoceran Water Flea, the Mitten Crab, Toxic algae (red/brown/green tides), Cholera, the Round Goby, the North American Comb Jelly, the North Pacific Seastar, the Zebra Mussel, the Asian Kelp, and the European Green Crab.


choleraCholera (Vibrio Cholerae)
In 1991, a ship from Asia brought a new, virulent strain of vibrio cholera to the port of Lima, in Peru, probably through contaminated bilge water. The bacteria soon infected shellfish and spread to humans, rapidly reaching epidemic proportions, with a million cases of cholera and up to 10,000 deaths.


zebra-musselThe Zebra Mussel (Dreissena polymorpha)
Native to the Caspian and Black Seas, it is one of the most infamous examples of a biological invasion. Causing large damages to infrastructure, suffocating natural ecosystems, the mussel’s financial impact in the US is estimated at between USD 750 million and USD 1 billion between 1989 and 2000.


comb-jellyfishThe Comb Jellyfish (Mnemiopsis leidyi)
This carnivorous predator eats all forms of zooplankton, including fish eggs and larvae.
Accidentally introduced to the Black and Caspian Seas in the early 80s, the comb jelly caused at least
USD 240 million annual losses in catches of marketable fish by disrupting the food chain.


seastarThe Japanese Seastar (Asterias amurensis)
The large yellow and purple starfish is another of those attractive creatures that appear harmless but can have disastrous consequences when they invade new habitats. Native to Japan and northern Pacific area, its density in Tasmania reached 1100 per m2 in 1995, becoming the dominant invertebrate and voracious predator, eating all that it can find.

Ecological Impact and Biodiversity

Invasive species can alter the food chain, replace or hybridize with the native species, reduce plant and animal diversity, disturb the functions of ecosystems, damage soil and/or water quality, change hydrology or fire regimen.

Economic Impact

Economic costs from invasive species can be separated into direct costs through production loss (agriculture, forestry, fishing, tourism and recreation) and indirect costs through management (control and damage remediation).


Introduced animals (birds, rodents, insects...) can become vectors of human diseases (malaria, yellow fever, typhus...). Microbes such as Vibrio cholerae, and toxic algae are often transported via ballast water. Besides, control efforts (such as pesticides) can have long term impact on public health, water and soil pollution.


Non-indigenous species can also present benefits. Asian Oysters, for example, are more resistant and filter water pollutants better than native oysters. They could be introduced in new environments to help restore oyster stocks and remove pollution. Some other invasions might offer potential commercial benefits (for example, there is high demand for the valuable Chinese Mitten Crab). Nevertheless, intentional introduction has to be always well evaluated, prepared and controlled.