How Do They Get Here?

World travel, the Internet, and international mail are among the many pathways that have made it possible for exotic species from all over the globe to find their way to our state. Sometimes exotics are brought here intentionally, and sometimes they hitchhike along with unknowing travelers.

Nonnative species are transported to Florida through a variety of pathways. Marine exotic species can arrive in the ballast water in ships. Ships take on water from foreign ports along with thousands of aquatic species, and release that water when they reach their destination. After the introduction of the zebra mussel, ballast water has become highly regulated in freshwater, but it remains less regulated in U.S. coastal waters. Many ships are voluntarily releasing marine ballast water in the open ocean before entering U.S. waters, which helps to prevent exotic introductions. However, ballast water exchange is still a potential route for exotic marine species to enter Florida, as illustrated by the green mussel, which was introduced to Tampa Bay in 1999.

Other aquatic species such as barnacles and aquatic plants that can encrust surfaces or become tangled around blades can make their way to Florida on the hulls or propellers of recreational boats. Boats can also pick up an exotic species in one lake and transport it to another that has not been infested, helping to spread the exotic species from lake to lake. Aquaculture farmers raise aquatic species for food or the pet trade, and often these animals are kept in outdoor ponds. During times of high rainfall, non-native species can escape from these flooded aquaculture ponds into nearby lakes and streams. However, laws pertaining to the aquaculture industry have resulted in greatly reducing this particular pathway of introduction.

The freight industry uses all manner of wooden crates and spools to ship materials from other countries. This foreign packing material is often infested with exotic wood boring species. Other types of packing material that may harbor non-native species include seaweed and sea water used to pack seafood and plant matter used to pack fruits and vegetables. Non-native species can also arrive in Florida is through international food markets. These markets carry many live animals intended to be used for food, but there is always the chance of escape. In 2001, several live snakehead fish, which are prohibited in Florida, were confiscated from an Asian market in Broward County. These are just some of the many pathways that exotic species use.

However, the greatest pathway by which non-native fish and wildlife species find their way into Florida's habitats is through escape or release by pet owners. Currently we are dealing with Burmese pythons in the Everglades. These large snakes can prey on native wildlife as well as pets like dogs and cats, and are large enough to injure people. Nile monitor lizards in Cape Coral pose a threat to the Florida burrowing owl, which is a protected species. Gambian pouched rats are reproducing on Grassy Key. If these large rats find a way to the mainland they may cause damage to agricultural crops. Monk parakeets build large colonial nests that can damage electrical power poles and cause power outages. Cuban treefrogs outcompete native treefrogs for food, and eat smaller species of native frogs. These are just a few of the many examples of non-native species that have escaped or been released from their owners.