EPA's Vessel General Permit and Small Vessel General

quantify the annual number of newly documented ballast water ANS. It should be noted that this
database does not include all ANS that were introduced by ballast water; rather, it represents the
number of ballast-water-mediated ANS documented nationwide. Therefore, in using this
database, we expect considerable ascertainment bias, i.e., greater effort is likely to increase the
number of ANS detected. The number of documented ANS grossly underestimates the total
number of invasions because there are no monitoring programs throughout most waters of the
U.S. Still, these data provide a qualitative measure of exposure of listed resources to
documented ballast-water-mediated ANS.
In querying the database (http://invasions.si.edu/nemesis/browseDB/searchQuery.jsp), we
limited our search criteria to only include ballast water ANS documented in a single calendar
year. We performed this search for each year between 2008 and 2011 (years covered under the
previously issued VGP). The annual number of newly documented ballast-water-mediated ANS
in waters of the U.S. ranged from 2 to 8 species, with a mean of 5.75 (95% CI: 4.5 – 7.0).
The numeric standards in the VGP are likely to reduce ballast-water-mediated ANS invasion
rates; therefore, we expect that the number of documented ANS invasions is likely to be reduced
over the life of the permit. Under the sVGP, however, equivalent standards are not required, and
the only sVGP requirement that would substantially reduce exposure of listed species to ballastwater
ANS is “minimize or avoid ballast water discharge and update in critical habitat.” Thus,
there remains a small likelihood that listed resources would be exposed to ANS invasions as a
result of ballast water discharges authorized by the VGPs.
Other Vectors
Several other discharges incidental to the normal operation of a vessel serve as potential vectors
for ANS. These include effluent from chain lockers, seawater cooling systems, and use and
disposal of live bait. Less is known about these discharges and their potential to serve as ANS
vectors; however, they are generally considered to be significantly less important than hull
fouling and ballast water.
Chain locker effluent is water that collects in the below-deck storage area during anchor
retrieval. A sump collects the liquids and materials that enter the chain locker and discharges it
overboard or into the bilge. Chain locker effluent may contain marine organisms including ANS.
The sVGP does not require any actions to minimize ANS transfer in chain locker effluent. To
minimize the number of ANS in chain locker effluent, EPA has included the following
requirements in the VGP:
� The anchor chain must be carefully and thoroughly washed down (i.e., more than a
cursory rinse) as it is being hauled out of the water to remove sediment and marine
organisms.
� Chain lockers must be thoroughly cleaned during dry-docking
The surfaces of seawater cooling systems, especially sea chest intakes and seawater piping, can
support the growth of fouling organisms including ANS. In vessel sea chests, Coutts et al.
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