Aquaculture and invasive species

Right after the reports of Asian Tiger Prawns invading the Gulf of Mexico, comes a report from National Geographic of the spread of Cajun Crayfish in East Africa.
Crayfish were imported from the U.S. into Kenya in the 1970’s to be raised in aquaculture facilities.  Some escaped into the wild and  have been spreading into local freshwater environments.  As they spread, they consume and compete with native species.
As evidenced by these two news stories, the risk of  aquaculture contributing to the spread of invasive species is real. Species that are attractive for aquaculture share a number of traits:
  • reproduce readily in captivity.
  • Have dietary requirements that are easy to meet.
  • Grow fast.
  • Thrive under sub-optimal culture conditions.
These same traits are ones that make it easier for them to survive if and when they escape into the wild.
While aquaculture has contributed to the spread of invasive aquatic species, it is not the only human activity responsible.  In the U.S, non-aquaculture related activities have results in the spread of the zebra mussel, green crab and spiny water flea to name just a few.

Photo by Tim Ebbs via Flickr