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Methods
of Introduction & Spread
METHODS
OF INTRODUCTION & SPREAD
Although
wind and weather can transport and introduce NIS, people are most
often responsible for the introduction and spread. These activities
are as often unintentional as intentional, conscious as unconscious.
Unintentional
- Shipping
– Non-native species can be transported in cargo, attached
to modes of transport (ships, trains, and planes), or attached
to transport crew.
- Ballast
water – NIS can be taken aboard ocean-going ships
accidentally in ballast water, to be emptied in a foreign port
during vessel
stabilization procedures. The National
Ballast Water Information Clearinghouse collects and shares
data about the ships and volume of ballast water exchanged in
order to prevent the spread of aquatic invasive species. This
method, accepted throughout the world, is the primary method
to prevent the accidental spread invasive species from one region
of the world to another.
- Recreational
boating – Submersed and floating NIS from a lake
or stream can cling to recreational boats, boat trailers, and
outboard motors when they are moved from one water body to another.
- Angling
– Some NIS may be transported from one water body to another
in bait buckets, live wells, or on fishing tackle.
- Diving
– NIS can cling to diving suits and equipment.
- Pond
stocking – NIS larvae and plants can be transported
into private ponds along with the transport water carrying fingerlings
from hatcheries. Stocked fishes also may harbor parasites or
pathogens.
- Canals
and interbasin waterways – These provide convenient
pathways for non-native fishes, mussels, and plants to move
from infested into non-infested waters.
Intentional
- Agriculture,
horticulture, aquaculture, nursery trade – Deliberately
planting non-native species can have unintended consequences.
While they may produce income and attractive landscapes, they
may be capable of out-competing existing species or they may
harbor and possibly spread parasites or diseases.
- Food
markets – Deliberately introducing live fishes
or produce for specialty food markets can have unintended consequences.
While they may meet a market demand, their live release can
wreak havoc in weakened habitats. An example.
- Biological
control – Sometimes insects or other non-native
species are deliberately introduced to control an existing NIS.
Once these biological control agents have consumed or controlled
the existing NIS, they may begin to prey on or compete with
other native species in order to perpetuate their population.
- Aquarium,
watergarden and pet releases – When hobbyists
decide to give up an aquarium or a pet that no longer fits into
the family, they sometimes release the animal into the wild.
Such animals may establish a wild population or prey on existing
native species.
What
can people do to minimize the introduction and spread of NIS?
- Boaters,
fishers, divers, and hunters can control the spread of NIS with
a few simple steps. A national program, Protect
Your Waters, has more information and ideas.
- Remove
visible mud, plants, fish, or other live creatures from boat,
motor, clothes, tackle, bait buckets, live wells, decoys,
anchors, and other equipment at the boat ramp, dock, or parking
lot before leaving the area.
- Drain
all water from equipment before leaving the area.
- Never
put a plant or animal (including live bait) into a body
of water unless it came from it. If in doubt, place in trash
barrel.
- Hobbyists,
aquarium owners, plant and animal wholesalers and retailers
can control the spread of NIS. Nationally, wholesalers and retailers
have agreed to follow specific procedures to control
the spread of NIS.
- Never
release a plant or animal into a body of water unless it
came from it.
- Destroy
aquarium animals humanely or give them to another aquarium
owner. If possible, return them to the retailer.
- Insist
upon knowing the scientific name and details about the plant
or animal purchased for aquariums and water gardens. Try
to use native species.
- Don’t
empty aquariums into a water body or a storm drain.
- All persons
handling or promoting nonindigenous species in any way can follow
the codes of conduct provided by the National
Invasive Species Council.
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