FAO helps fish farmers evaluate responsible use of exotic species

The Fish Site
by The Fish Site
27 February 2007, at 12:00am

There are aliens among us, hiding in plain site. In our towns. Our homes. Even... in our refrigerators.

Alien visitor... or dinner?

Some have been here for years; others are more recent arrivals.

Consider the potato: an alien transplant to Europe from the new world, today it is a staple for millions of people. Positively mundane. An alien, nonetheless.

Maize, coffee, tomatoes, sugar cane, turkeys, cows, sheep -- all were transported from one place to be raised in another. Nowadays, these edible aliens are commonplace. We don't even think of them as foreign. But they are.

The next wave

Today, the colonization of our supermarkets and dinner tables by aliens continues apace.

The latest wave -- finned, shiny, with bulbous eyes -- seem more akin to the extraterrestrials of science fiction than the drab potato: fish.

There are good reasons why farmers choose to raise alien species of fish, molluscs and crustaceans: they frequently offer significant benefits -- they grow faster and bigger; they are hardier and easier to raise; they sell for more at market.

Fifteen years ago African tilapia was an oddity outside of its native range; today it is a highly popular fish grown around the world and found in supermarkets from Kansas City to Stockholm.

In parts of Asia, where it is now widely raised, tilapia is providing major numerous economic and food security benefits to the rural poor. "It's not only a fish that everybody likes to eat, it's a fish that anybody can easily raise, with few demonstrated negative environmental impacts," says Devin Bartley of FAO's Fisheries Department. "Asians are eating them locally and selling them for export."

In Chile in the mid-1980s aquaculturalists introduced Pacific and Atlantic Salmon -- today they support a thriving industry and Chile is the world's top producer of farmed salmon, to the tune of US$680 million a year.

Not all aliens are friendly

But exotic fish species do not always perform the same way in their new habitat as they did in their old home, sometimes with serious consequences. Despite economic returns from some introductions, others have caused massive economic losses or widespread environmental damage.

The voracious Nile Perch, introduced to Lake Victoria in the 1950s, has been blamed with causing the extinction of several hundred native species. (At the same time, it is a major source of income for lakeshore communities, with exports to Europe valued at around €170 million a year.)

The golden apple snail, brought to the Philippines and other countries in Asia in the early 1980s, is another example. Easy to rear and fast breeding, the snail's high protein content seemingly made it an ideal supplement to the diets of the rural poor as well as a product for export. Unfortunately, the snails did not take off with consumers. But they did escape into irrigated rice fields, where they have evolved into a major pest, devouring thousands of hectares of young rice.

New fish species can also bring with them new diseases, to which native stocks have no resistance. The shrimp farming industry in Taiwan Province of China was nearly wiped out in the early 1990s when that happened.

There are other examples of aliens changing habitats, competing with or feeding on local species, or breeding with their relatives and causing a form of genetic pollution.

FAO database a tool for responsible introductions

In the 1980s, with long-distance introductions of fish species into new habitats for fish farming becoming increasingly common, FAO began tracking these movements.

For a long while, FAO monitored only inland fish species -- around 1,300 in all. But as world appetite for fish continued to grow, both in terms of net demand as well as demand for greater diversity in fish products, more species became farmed, and FAO started collecting information on marine species and species other than fish.

The organization recently launched an expanded version of its database which includes introductions of all taxa being produced via aquaculture; it now contains over 5,000 records of introductions of several hundred species. The expansion was largely funded with funds from FAO's regular working budget and the FishCode Project, but vital support also came from the Netherlands via the FAO-Netherlands Partnership Programme (FNPP).

The database is being made available on a CD-ROM which also includes a virtual library of reports and studies by FAO as well as the text of major international instruments relating to the transport and introduction of aquatic species.

For each species introduction listed, the database provides information on where and when the first introduction occurred, who introduced it and why they did so, and whether or not positive or negative impacts resulted. That information is supplemented by links to references for additional information.

"The idea is to make people aware of the benefits and risks of introducing a given species into a specific area, as well as international regulations governing those introductions, so that they can avoid mistakes and make good, and legal decisions," explains Bartley. "Introductions shouldn't happen without a precautionary risk/benefit analysis being conducted ahead of time. Our goal with this CD-ROM package is to provide a tool for doing that."

TheFishSite News Desk