Simon Towle of the World Wildlife Fund is the Manager of the Sepik Community Land Care Project in Wewak, PNG.
Photo: Chris Johnson
July 26, 2001
The Impact of Introduced Species
This is Genevieve Johnson speaking to you from Papua New Guinea.
The vast majority of the world's six billion people, no longer live inside what remains of their local ecosystems. Globalisation has given humans the freedom to traverse the planet in a matter of hours if we so desire. Unfortunately, we do not always travel alone. Domesticated as well as wild animals and plants often accompany us, sometimes intentionally but often without our knowledge.
The rapid transfer of alien species has reached catastrophic proportions in many of the world's seas, oceans, rivers, lakes and waterways. The acceleration in global trade is seeing species being moved across oceans as stowaways in ship ballast water. Some have escaped from marine aquaculture farms. Sometimes a species of plant or parasite will be inadvertently growing on the shells of cultured shellfish, while other species are intentionally released into waterways to grow and be harvested.
As a result, everyday around the globe, thousands of species are being introduced into new environments. Most introductions will die when the new conditions are too harsh to support them, others may survive as harmless constituents. The problem lies in those few species that thrive when the receiving environmental conditions are similar in temperature, salinity and dynamics to that from which they came. These opportunistic introduced species can wreck havoc, overwhelming and often forcing out the local flora and fauna that are often not equipped to cope with, or defend themselves against such invasions. It is believed that the introduction of exotic species is second only to habitat destruction as the leading cause of native species loss and endangering natural ecosystems.
Simon Towle of the World Wildlife Fund works as the Manager of the Sepik Community Land Care Project in Wewak. He discusses the consequences of recent fish introductions into the Sepik River:
"The Sepik River is one of the largest, untamed rivers in whole of the Asia Pacific. It is extremely important in terms of its wetland and forest values but it also has an enormous impact on the coastal marine environment.
The boar of the Sepik River goes more than 50 kilometers out to sea and it has an enormous impact on the whole north coast of Papua New Guinea. We have a number of issues we are dealing with in the river itself. One of them is that about 40 species of fish have been introduced into the Sepik into the last 10 years. They were introduced for reasons, which were perhaps founded on the belief that the communities needed more food and that fish would provide them. But unfortunately, relatively little science was done to look at the impact the introductions were going to have. Consequently, the extraordinary prawn (shrimp) fauna, which was endemic to the Sepik, has been compromised by an extraordinary degree by the introduction of these fish species. The other thing is that at least one of the species introduced appears to be dangerous to humans and there have been at least two recorded deaths associated with one of the introduced fish attacking swimmers and killing them.
Wetlands complex associated with the Sepik River is probably one of the most important wetland areas in the whole of Asia. Over the next couple of years we will be developing a very substantial marine program based here in Madang and also in Wewak aimed at getting a really good marine protection regime established on the north coast of Papua New Guinea."
Log by Genevieve Johnson