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


Moats full of fish: the history of aquaculture in Europe

It is common to begin articles about aquaculture with a mention of its long history. Evidence of its long history is often supported by citing mentions of aquaculture in writing in China from the 400 BC and depictions of aquaculture on Egyptian hieroglyphics. The focus is usually on the well documented history of aquaculture in Asia. I have not see as much written about the history of fish culture in Europe. A recent essay by Whit Richardson addresses this gap. It is filled with literary and popular references to Eurpoean aquaculture from ~100 AD through the mid 1800’s.

The article is well researched and includes hyperlinks to the references that are available online. The information provided reenforces the fact that aquaculture is not new.  It has been present in Europe in one form or another over the entire span of written history. References include the Canterbury Tales the harnessing of castle moats for fish production.

It is a very Eurocentric treatment of the subject, as a result, some of the generalizations need to be read with caution. For example, in his treatment of carp, Richardson suggests that carp were once popular but have fallen out of favor. It is true that in Europe, carp production is mostly limited to goldfish and koi. However, carp is still widely cultivated as a food fish in Asia. In fact, carp is still the dominant fish cultured in China. Since China dominates worldwide fish production, today, carp remains the single most widley cultured fish in the world.

When I read articles like this, I often find myself searching the web to locate the references mentioned. The hyperlinks included in this article made that easy.  I am looking forward to reading over the many great, historical references Richardson shares.


Photo source: http://www.geograph.org.uk/photo/771243