EPA's Vessel General Permit and Small Vessel General

While there are many examples of fresh water species extinctions as a result of ANS, marine
equivalents are less prevalent in the literature; however this may be a result of underreporting
and low detection power (Roberts and Hawkins 1999). As terrestrial animals, humans are less
likely to notice declines and extinctions in the marine environment; furthermore, many marine
species have yet to be described, and their extinction would go unnoticed. Though we were
unable to find any examples of marine extinctions caused exclusively by ANS, there are several
examples where ANS invasions led to the decline of native species. For example, egg predation
by an introduced starfish (Asterias amurensis) led to the decline of the critically endangered
spotted handfish (Brachionichthys hirsutus) in Australia. In California, the introduced Japanese
mud snail (Batillaria attramentaria) outcompetes the native snail (Cerithidea californica) and is
predicted to eventually replace the native species (Byers 2000). Molecular analyses of museum
specimens suggest that alien mussels (Mytilus galloprovincialis) displaced the native mussel (M.
trossulus) in southern California, some time in the last century (Geller 2001).
We present statistics on ANS-related extinctions and endangerments to illustrate that ANS
invasions have reduced the viability of numerous populations and species and are likely to do so
in the future. As described above, ANS invasions affect species by predation, competition for
habitat or prey, reduction of the prey base, habitat alteration, disease transmission, and
ecosystem restructuring. These types of impacts rarely affect one or a few individuals; they are
more likely to affect many individuals or an entire population. For example, we described
several diseases that ANS are likely to transmit to listed fish, abalone, corals, and seagrass.
These infectious diseases would first affect exposed individuals, but they would quickly spread
through these small immunologically naïve populations, which often exhibit low genetic
diversity a reduced ability to mount an effective immune response. Ultimately, such ANStransmitted
diseases would reduce the viability of the population, and the loss of populations
would reduce the viability of species. Similarly, we described above how ANS are likely to
reduce the survival of salmonids and Pacific eulachon through competition, predation, disease
transmission, habitat loss, and ecosystem restructuring. Again, these mechanisms are likely to
affect many individuals, reducing the viability of populations, and thus the species (or listed
DPS). A significant loss in the abundance of salmonids and Pacific eulachon is likely to reduce
the fitness of many Cook Inlet beluga whales and southern resident killer whales that depend on
these species as their primary prey. These DPSs have already experienced severe population
declines, in part as a result of reduction in their prey base. Additional reductions would reduce
the viability of these species. In conclusion, ANS invasions, which are likely to occur as a result
of the discharges authorized by EPA, are likely to result in reduced population and species
viability of listed fish, marine mammal, invertebrate, and plant species.
Critical Habitat
Invasive species are likely to adversely affect water quality in marine, estuarine, and riverine
freshwater environments by altering processes such as sedimentation rates and nutrient cycling.
Introduced non-native algal species from ballast water (as well as other sources) combined with
nutrient overloading may increase the intensity and frequency of algal blooms. An
overabundance of algae can degrade water quality upon bacterial decomposition, which depletes
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