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.
pouched rats are reproducing on Grassy Key. If these large rats
find a way to the mainland they may cause damage to agricultural
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.