Biology Reference
In-Depth Information
In managing pathways for alien herpetofauna, the distinction between inten-
tional and unintentional introductions is of great importance. This is because
tactical methods and social requirements will vary for each of those two pathway
modes. Hence, it is important to know by which pathways species are most likely
to reach a jurisdiction. Most major taxonomic groups of organisms have the majority
of their introductions accounted for by only one or a few pathways, typically either
accidental or deliberate. For example, marine invertebrates largely travel uninten-
tionally via ballast water or by fouled ship hulls (Fofonoff et al., 2003), and most
plants have been moved deliberately for agricultural, silvicultural, or horticultural
purposes (Mack, 2003). Birds have largely been moved intentionally via the pet
trade and for game hunting, and mammals (except for rats and mice) largely inten-
tionally for game hunting and food or fur use (Kraus, 2003c). In contrast, we have
seen that both deliberate and non-deliberate pathways are important in dispersing
reptiles and amphibians (Figs. 2.15, 2.36). Given that mixed pattern, it is unsurprising
that the taxa moved deliberately are usually different than those moved unintention-
ally. What this means practically is that preventing further incursions of alien
reptiles and amphibians will require a greater diversity of prevention tools than are
needed for many other taxa - tools appropriate for both intentional and uninten-
tional pathways. Screening systems to evaluate proposed importations and
educational programs to elicit more responsible behavior from the pet-keeping
public will be key to effectively reducing deliberate introductions. Improved imple-
mentation of inspection programs for high-risk cargo and development of bulk
treatment methods for high-risk cargo must underlie any abatement of accidental
introductions. And bulk treatment methods are likely to prove useful in stopping a
variety of other pests too. Crucial to both will be educational efforts to make clear
to the public and government officials why the impacts of alien herpetofauna
warrant this attention.
Important too is recognition that pathway importance is not static. Instead, it
unambiguously varies taxonomically, temporally, and geographically. What this
means is that appropriate intervention tools must be correspondingly flexible.
Chronological trends indicate that, overall, pet-trade, cargo, and nursery-trade path-
ways are increasing in importance; therefore, stemming invasions via these routes
will clearly be high-priority goals in many regions for the foreseeable future. But
pathway importance also varies geographically, and different countries will need to
tailor their prevention activities to reflect the pathways of greatest import to their
own jurisdictions. For example, the nursery trade is clearly the single greatest con-
tributor to the movement of alien herpetofauna in the Caribbean and must be
addressed if further incursions are to be halted there. That same trade makes a neg-
ligible contribution to Europe's influx of alien herpetofauna, which is instead
closely tied to the pet trade and the deliberate actions of private herpetoculturists.
These fundamental facts of pathway heterogeneity must be understood and incor-
porated into management planning if meaningful prevention of further herpetological
incursions is to be achieved.
What then is logically required to incorporate these basic facts into manage-
ment programs? At a minimum, one needs detailed risk assessment - assessment
