By John Dawes

According to many people in the ornamental aquatic sector, the topic of invasive alien species (IAS) is likely to be of greatest concern for the industry in coming years.

Trade representatives continue to debate whether various introduced species, such as the common goldfish (Carassius auratus), have been demonized.

The perception of invasive alien species that tends to pervade meetings, such as the CITES and CBD conferences, usually revolves around their negative impacts on native species and their habitats. Occasionally, someone raises a different perspective.

Most recently, Mark Davis, DeWitt Wallace professor and chair of Biology at Macalester College in Saint Paul, Minnesota, raised questions about the traditionally negative attitude toward IAS. He is quoted on Scientific American’s website as saying, “There have been thousands of non-native species introduced in the United States, and they have not caused one native species to go extinct.”

Professor Davis believes that alien species have been “demonized” and that resources have been wasted battling invasives that could have been better spent on other environmental issues, such as protecting habitats. Davis believes that the traditional distinction that is repeatedly made between native and alien [non-native] species doesn’t make biological sense any longer. It is more reasonable, he maintains, to consider “undesirable and harmful species.”

He also questions the long-held belief that invasive alien species are the second-most important source of species threat or endangerment after habitat destruction. In his book “Invasive Biology,” published earlier this year, he says this claim is based on the opinions of field researchers rather than on hard data, and he says most species that are facing threats from invasive aliens are located on islands, such as Hawaii.

At a conference held in South Africa, other scientists highlighted examples where accusations were not based on scientific data or where the long-term harmful effects have been “overblown.” They also referred to occurrences of native species adapting over time to the introduction of an alien species or even exploiting it.

It must be said, though, that such views are not widely held within the scientific community. There are those, however, who believe that the extent of harm we attribute to invasives might be overstated.

Our trade representatives undoubtedly face some difficult discussions at future IAS meetings. Since we believe we should help form the solution rather than bee seen as one of the problems, there is no doubt that they will familiarize themselves with various alternative views held by leading conservation and alien species specialists, Davis included. <HOME>