EPA's Vessel General Permit and Small Vessel General

� Minimize the transport of any visible living aquatic organisms from one waterbody to
another by regularly cleaning and maintaining the hull.
� Vessel hulls must be periodically inspected, and if necessary, cleaned to prevent the
spread or dispersal of potentially invasive species.
� Prior to transporting the vessel from one waterbody to another overland, you must inspect
the visible areas of the vessel for any attached or visible stowaway living organisms. If
organisms are found, they must be removed and appropriately discarded onshore.
Removed organisms may not be discharged into waters subject to this permit.
It is not clear, from reading the BE or the permits, the extent to which these requirements will
minimize the risk of ANS invasions. For example, EPA requires vessel owners to minimize the
transport of ANS, but EPA does not require anti-fouling coatings in either the VGP or the sVGP.
If vessel owners/operators use AFCs, EPA requires that they “give consideration” to selecting
the most effective product for their vessel type, but EPA does not provide guidance on which
AFCs are the best available technology for each vessel type. The sVGP requires hull cleaning
but does not require that debris containment systems be used to collect ANS. The VGP requires
the use of such technology when feasible; however, the BE states that vacuum systems “are not
widely commercially available; hence EPA has not required that they must be used in this
permit,” (BE). For these reasons, we conclude that the VGPs are not likely to substantially
reduce the exposure of listed resources to ANS via hull fouling or hull husbandry.
The permit requirements to “minimize” ANS are not likely to result in major changes to vessel
operations. Therefore, we will use the above estimates of hull area and hull fouling coverage to
provide a rough estimate of fouling organisms. It is important to note that not all hull fouling
organisms are non-native; not all are likely to become invasive; and not all are likely to affect
listed species and critical habitat. We do not have data to tease out these variables; therefore, our
estimate is the worst-case scenario of biofouling.
According to the U.S. Maritime Administration, there are ~60,000 vessel calls at U.S. ports
annually (http://www.marad.dot.gov). As described above, Sylvester et al. (2011) estimated hull
fouling propagule pressure at 600,000 invertebrates per vessel. This provides a rough estimate of
36 billion hull fouling organisms entering waters of the U.S. annually. (Note: this estimate does
not differentiate between native and non-native species or the myriad of plant, vertebrate, or
microbial organisms that foul hulls.)
While we are unable to quantitatively estimate how many of these organisms are likely to
become established in waters of the U.S. (NAS 2011), we used the NEMESIS database to
quantify the annual number of newly documented hull-fouling ANS. It should be noted that this
database does not include all ANS that were introduced by hull fouling; rather, it represents the
number of hull-fouling 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. Also, this number of documented ANS likely underestimates the total number of
invasions because there are no monitoring programs throughout most of the waters of the U.S.
Still, these data provide a qualitative measure of exposure of listed resources to documented hullfouling
ANS.
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