**DISCUSSION PAPER**

**SCREENING PROCESS FOR INTENTIONAL INTRODUCTIONS**

**(with hypothetical example of a screening process for intentional
introductions of living, non-native organisms intended for unrestricted
use and distribution within the continental United States)**

**(with comments on using a screening process for **

**unintentional introductions)**

Richard Orr

Invasive Species Council Staff

August 23, 2000

FOREWORD

The American people have a love/hate relationship with non-native
species. Few would disagree that much of the foundation for our current
high standard of living is due, in part, to the cultivation and use of
introduced plant and animal species. Americans enjoy a great variety of
non-indigenous species, ranging from domestic pets and aquarium fish to
their colorful flower beds and vegetable gardens. From the grass of our
lawns to the fruit/flower trees in the yard, most Americans knowingly or
unknowingly embrace non-native species. Few individuals would be willing
to give up the freedom to enjoy the current variety of non-native plant
and animal species available to them without a well justified reason.

And yet, like the wolf in sheep's clothing, a few non-native species
become unwelcome guests occasionally resulting in extensive ecological
and economic damage. Nature cares little for human values \-- introduced
species are intrinsically beyond good and evil. But when a non-native
species is introduced that causes man-valued damage, cries for action
abound. "Get that star thistle out my horse pasture." It means little to
the landowner that the horse and the forage grass planted in the pasture
last year are also non-native; it is the star thistle that gets labeled
as a big bad non-native species.

This also illustrates one of the difficulties in addressing (or
labeling) something as an invasive species. The land owner does not view
his horse or the forage grass in the pasture as a problem. But living
organisms react differently under different environmental stresses, and
their innate responses can be as varied as the values of the American
people. Under certain circumstances, wild horses can cause extensive
environmental damage, and those who have the responsibility in restoring
or maintaining native grasslands would quickly label the landowner's
introduced forage grass as a potential threat.

No one likes star thistle, so it is easy to label it as bad. But what
about horses and non-native forage grass? The truth is that under the
right (or wrong) environmental conditions, nearly all non-native (and
native) species have the potential to negatively trigger someone's
personal judgement as to what should be happening for a specific land or
water site.

Compounding this even further is that some areas, such as the Pacific
Islands and their associated coral reefs, are truly much more
susceptible to damage from invasive species than are other more
invasive-resistant, areas. A non-native species established in Idaho may
be harmless but when introduced to Florida would be devastating, and
vice versa.

When examined in detail, all non-native transplants have the potential
to change an existing ecosystem. This change may or may not impact human
values; if there is a noticeable impact, it may trigger either a
positive or negative reaction depending upon whom you ask. On the
opposite end of the spectrum, nearly all non-native introductions (not
necessarily establishments) may prove of some value. Even the entry
(with restrictions of course) of the Ebola virus into the United States
to be researched at the CDC, may be to the advantage of the American
people.

Two other very important human value judgements also come into play when
developing a screening process for non-native species. The first is the
increasing importance that the American public places on the remaining
native environment as more and more of it is degraded or lost to
development. This is reflected in the increased pressure on governments
to protect the remaining semi-pristine to pristine natural areas, clean
the water and air, and provide green areas for our cities. With the rise
of this environmental ethic and awareness comes the realization that the
unwelcome impact from introduced species on the environment has to be
addressed.

The second important human value judgement that comes into play is the
freedom of movement of people, their conveyances, and commodities
currently enjoyed in the United States. The vast majority of Americans
enjoy the freedom to travel, and to pick and choose what they wish to
bring with them, to own, or to plant in their flower beds. Restricting
this freedom has never been welcomed in our society and was, in part,
responsible for the demise of the public health quarantine requirements
at the ports-of-entry in the early 1900s. In addition, the current
philosophy in government is that you need a justification to regulate;
to do otherwise -- to regulate without justification \-- is never going
to be acceptable. There is a real price to pay each time we restrict
(regulate) the American people or, to put it slightly differently, there
is a real price to pay each time we restrict (regulate) the movement of
people and commodities. But obviously some additional restrictions on
the movement of people, conveyances, and commodities will be necessary
if we are to succeed in reducing the movement of invasive species into,
and around, the country.

Clearly mentally simplistic rhetoric like "*when in doubt keep it out*"
or "*not a clue let it through*" will never fairly address the problem.
Those who are xenophobic and demand total prohibition of non-native
species and the complete sterilization of imported material, along with
those who belong to the opposite camp that values personal capital gain
over all else and wishes for complete freedom to move whatever they
choose, will be disappointed in any logical screening process based on
demonstrable evidence.

It is also worth mentioning that a regulatory screening process (no
matter how good) will only partly solve the problems with the movement
of invasive species. There will always be enough uncertainty that many
non-native organisms will fall in a semi-gray area of
"not-sure-if-the-benefits-will-out-weigh-the-damage". When this occurs,
it is most likely that the screening process will err on the side that
requires the least amount of federal regulation. Therefore, in addition
to a fair and reasonable screening process, it is important that the
public be educated as to the potential problems and benefits associated
with non-native species so that they will be able to make informed
decisions when confronted with using non-native species.

INTRODUCTION

A screening process for evaluating intentionally introduced species can
address an array of different protected areas and management practices.
These range from protecting specific high-risk protected areas (such as
a semi-pristine coral reef, a section of native prairie, or a Pacific
island) to the more general screening for the movement of non-native
plants and animals through the ports-of-entry for unrestricted
distribution. In order to do this, the SAME screening process design
would have to rely upon DIFFERENT criteria.

The purpose of this exercise was to develop the screening process and
not to develop the associated criteria or the weights to be assigned to
the criteria. However, in order to demonstrate the process, I had to
incorporate tentative criteria to show how it would work. It is
important to understand that I have included criteria and assigned them
weights (scores) for demonstration purposes only.

The example used to demonstrate the screening process is [the evaluation
of the movement of intentionally introduced, living non-native organisms
into the continental United States, intended for unrestricted use and
distribution ]{.underline}(i.e. most seed packages, pets, horticultural
and ornamental plants). This was the most difficult example I could
think of; since if the same organisms were being introduced into a
small, protected natural area, or were being imported for research,
biocontrol, medical, or food purposes, the criteria would be more
specific and thus easier to define. In addition, introductions to
zoological and botanical gardens would focus strongly on criteria
relating to containment facilities. My thinking was that a screening
process design is only as good as its toughest challenge, which will be
those organisms that will have the freedom to move throughout commerce
unrestricted. The hypothetical process used was kept general to
accommodate a wide taxonomic range. In reality is not likely that a
single general set of screening criteria would be found appropriate for
all types of organisms. Again the example screening process is provided
for demonstration only.

The end products of the screening process will either be 1) unrestricted
entry; the non-native is to be placed on an approved list (in which the
screening can be done reasonably quickly), 2) failure to qualify for the
approved list; the non-native is to be placed on an unapproved list
(which also can be done reasonably quickly), or 3) identify the need for
a more exacting risk/benefit analysis in which the evaluated organism
will not be allowed entry until the more detailed analysis is completed
(it is reasonable to assume that the detailed analysis would also have
to have a time limit).

When developing this screening process, I tried to be as open as
possible to all the issues surrounding non-native species introductions,
but I readily admit that my personal values played a role in the
selection and scoring of the criteria. Therefore, I am not claiming that
the example criteria should be supported or adopted, only that this was
the best I could come up with for this exercise. Again the purpose of
this exercise is to provide a workable process, not to bring consensus
on the criteria or their appropriate weights (scores).

**The screening process attempts to meet and balance the following
goals:**

1\) [Support the precautionary principle]{.underline} \-- By
precautionary principle I mean that the results of the screening process
would be known before the movement of the organism was allowed into the
protected area. In this case the protected area is the continental
United States. My use of the precautionary principle is synonymous with
pre-market accesses approval. However, with this statement comes a
weighty responsibility, that the screening process be fast and not
result in unnecessary delays. Ideally, the screening process should
quickly identify for the majority of the organisms evaluated whether or
not they will be allowed unrestricted entry and movement throughout the
continental United States.

If a modification of this screening process, or other screening process,
is ever accepted and becomes retroactive (expected to cover the
thousands of non-native organisms currently moving into the country)
some phase-in period will be necessary. In addition, great efforts will
have to be made to work with those industries who will be most impacted
by the screening process. This is important to keep in mind because most
non-natives which have a viable market (real or perceived) are already
moving into the United States.

2\) [Needs to be socially and politically feasible]{.underline} \--
Catering to the extremes on both sides of the invasive species spectrum
would quickly prove unworkable and ineffective.

3\) [Needs to be practical]{.underline} \-- The screening process must
be able to address the needs of the American public concerning
non-native species while using available resources. Restricting the
movement of all intentional introductions until definitive and complete
knowledge is gained (not really possible) will always be unworkable.

4\) [Needs to be logically sound]{.underline} \-- Restricting entry must
be based on sound logical arguments and demonstrated by reasonable
scientific information. Uncertainty in the biological information should
be considered, but the focus should be on what is known or can be
justifiably extrapolated from similar species.

5\) [Needs to be transparent and well articulated ]{.underline} \-- The
screening process must be understandable to all and must be open to
evaluation.

6\) [Needs to provide a fair balance between the costs versus
benefits]{.underline} \-- Benefits from the importation of non-native
species need to be considered. A screening process that rejects a
non-native organism of great benefit to the public because of a minor
potential to do damage is not going to be acceptable.

7\) [Needs to be comprehensive in scope]{.underline} \-- The screening
process must be workable for a wide range of taxa that might be
intentionally introduced and encountered by the screening process.

**Components of Screening Process:**

This screening process proceeds using the following six logical steps:

Step 1 -- Determine if the species qualifies to be screened.

Step 2 -- Determine the likelihood of establishment and spread. Assign a
score.

Step 3 -- Determine the negative consequences if established. Determine
if it meets the

definition of an invasive species. Assign a score.

Step 4 -- Determine the benefits of the proposed introduction. Assign a
score.

Step 5 -- Combine scores of step 2 through step 4. Rank the organism.

Step 6 -- Assign the organism using its rank to an approved list,
unapproved list, or status-

undetermined list.

Each of these steps will be represented in a table format that will
provide the various criteria (options) available to the assessor. In
addition, for steps 1,2,3, and 4 in the screening process, the assessor
will have to fill in a "Rationale Section" explaining the rationale used
in assigning the organism to that table's rank, provide references (if
appropriate), and assign an uncertainty code. Steps 5 and 6 are strictly
mechanical and do not require justification from the assessor.

The Rationale Section is extremely important because it is here that the
assessor will justify his/her decision for assigning the organism to a
specific criteria. The strength of his/her argument, in the eyes of the
assessor, will be recorded by, as of yet, undeveloped uncertainty codes.
For the purpose of this demonstration the overly simplified uncertainty
codes used are:

  ---------------------- ---------------------------------
  **Uncertainty Code**   **Description**
  Very Certain           As certain as I am going to get
  Reasonably Certain     Reasonably certain
  Moderately Certain     More certain than not
  Reasonably Uncertain   Reasonably uncertain
                         
  Very Uncertain         A guess
                         
  ---------------------- ---------------------------------

In order to get a feel for how the screening process works, it is
recommended that after you have read through the process, go back and
run some hypothetical or real examples through and see how they come
out. Remember that for steps 1 through 4 you are required to provide
justification under the rationale section. If you can not make a
rational argument for your criteria selection, chances are that your own
biases are at play and that it is unlikely that you will be able to
justify your position to others.

STEP 1: Does the species qualify to be screened?

Determining that a species proposed for introduction qualifies for
screening is usually not a difficult task. Most deliberately introduced
species for commercial or personal use are usually easily identifiable
and reasonably well-known. However, the consideration of labeling a
species non-native based on subspecies level genetic differences only
(natural or man-made) needs to be tempered with common sense. Only those
strains, varieties, or subspecies that indicate a reasonable potential
to behave differently from the norm should be labeled as non-native. A
new variety of a well-known cultivated flower would not intrinsically
make the proposed introduction a non-native.

This also applies to a new Living Modified Organism (LMO) that has just
come onto the market or is requested to be introduced from a foreign
source. It terms of the screening process, the issue is not the
technology that is used to modify an existing organism but the possible
impact these modifications might have on the invasive status of the
organism. A well known species that has been modified by biotechnology
would not intrinsically make the proposed introduction a non-native.

The following table provides guidance on determining if a proposed
species qualifies to be screened.

  ---- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --------
       CRITERIA                                                                                                                                                                                      SCREEN
  1a   Species non-native, not established in continental United States                                                                                                                              yes
  1b   Species non-native, established in continental United States, and capable of further spread                                                                                                   yes
  1c   Species non-native, established in continental United States and reached probable limits of range, but genetically different enough (natural strains, subspecies, LMOs) to warrant concern.   yes
  1d   Species non-native, in country and reached probable limits of range and not exhibiting any of the other characteristics of 1c                                                                 no
                                                                                                                                                                                                     
  2a   Species native, but genetically different enough (strain, subspecies, LMOs) to warrant concern                                                                                                yes
                                                                                                                                                                                                     
  2b   Species native and not exhibiting any of the characteristics of 2a                                                                                                                            no
                                                                                                                                                                                                     
  ---- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --------

RATIONALE:

REFERENCES:

UNCERTAINTY CODE:

If the determination is that the species is not to be screened, then the
process can stop and the species can be allowed unrestricted entry. The
only additional concern would be if the imported organism is acting as a
pathway for the movement of other potentially harmful organisms. This is
a justified concern, but the evaluation of a pathway is beyond this
screening process (see comment on unintentional introductions at the end
of this paper). If the species is identified as a species that needs to
be screened, then move to Step 2.

STEP 2: What is the likelihood of the species establishing and
spreading?

If the non-native organism cannot become established within the
continental United States (the protected area of concern in this
screening process), then its ability to become an invasive species is
negligible (but not zero). Failure to establish can come from
environmental non-compatibility, environmental resistance (competition
from other organisms), or failure of the introduced organism to
reproduce (e.g. sterile or unable to find a mate).

For animals, non-compatibility can often be measured grossly by
comparing climate requirements with the needs of the introduced species
and the availability of a food source. For plants, which are primary
producers, climate ranks as most important.

It is realized that this is an extreme oversimplification of what really
takes place when a non-native organism is introduced into a new
environment. In reality, the ability of an introduced organism to
establish involves a mixture of the characteristics of the organism and
the environment. The level of complexity in the interactions between the
organism and the new environment is such that its failure or success
will be based on minute idiosyncrasies in that interaction. These, in
reality, cannot easily be predicted in advance. However, by comparing
the introduced species' overall needs as it relates to habitat, it can
generally be determined whether a potential establishment is grossly
possible.

One of the problems of trying to evaluate non-native species having free
movement throughout the continental United States is that North America
has such a wide range of climatic zones and ecosystem types. Almost any
non-native organism will appear to fit into one or more habitats found
in the United States. Therefore, in this screening example, most
non-native organisms will show a potential to become established.

Likewise, if a non-native organism can establish but is unable to
spread, then its ability to become invasive is diminished. However,
caution is warranted because many (if not most) invasive species at
first show little or no signs of spreading. To assume that they will
remain local is dangerous. On the other hand, many semi-domesticated
varieties of plants that survive well in flower beds or as crops under
cultivation have demonstrated that their ability to spread outside of
man's help is limited.

The following table scores the potential of a species to establish.
Assign the lower score if the species fits two or more of the criteria
equally.

  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------
  CRITERIA                                                                                                                                                                                                                                                                                                                SCORE
                                                                                                                                                                                                                                                                                                                          
  Non-native species will unlikely find adequate food and/or the general habitat conditions needed for survival.                                                                                                                                                                                                          0
  Non-native species not capable of, or highly unlikely to be capable of reproducing (e.g. inability of finding a mate, sterile, or otherwise lacks ability to complete its life cycle).                                                                                                                                  10
  Non-native species lacks a history of establishment in areas outside of its native range or, if it has a history of establishment in areas outside of its native range, then it shows no evidence of spreading.                                                                                                         50
                                                                                                                                                                                                                                                                                                                          
  Non-native species is imported with the purpose of establishment (e.g. aquaculture, ornamental/horticultural plants, etc.) and/or the non-native species demonstrates, based on history, of readily establishing in new environments. Convincing evidence of the non-native species being able to spread are present.   100
                                                                                                                                                                                                                                                                                                                          
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------

RATIONALE:

REFERENCES:

UNCERTAINTY CODE:

The assigned score will be used at the end of Step 3 to help determine
(in part) if the non-native species qualifies as an invasive species.

STEP 3: What are the negative consequences if it establishes

(demonstrated and perceived) & does it meet the definition

of an invasive species?

If a non-native species can establish, it does not automatically mean
that it is invasive. Indeed, many intentionally imported species such as
flower seeds and ornamental plants are expected to remain healthy in the
protected area. In order for a non-native species to qualify as an
invasive species, a negative impact must be convincingly argued.

It is also important that the potential negative impacts be measurable.
For economic impact, this can obviously be done in dollars. However, for
some aspects of negative impacts on the environment or society (e.g. in
protecting the culture of ethnic groups), dollars may not be the best
measuring device. It is important to stress that measurable components
are necessary for use in the screening process but need not be
restricted to dollars.

The following table captures and scores the negative primary impacts.
Although it is recognized that secondary impacts can, and do, add up,
generally these will require a more in-depth evaluation than is feasible
in a general screening process. Choose the category that correctly
assigns the highest negative impact.

  -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------
  CRITERIA                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 SCORE
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
  The non-native species has consistently produced serious or moderate economic damage in other parts of the world and/or the non-native species has consistently produced serious or moderate environmental damage in other parts of the world to one or more of the following: 1) keystone species, 2) a major biotic component of a human-valued ecosystem or other significant changes to valued habitats, 3) native biodiversity, or 4) endangered species. This potential damage would be directed towards similar components present in the continental United States.                                                                                                                              100
  The non-native species has been reported to cause, on occasion, moderate or severe economic damage and/or the non-native species has caused, on occasion, moderate to severe environmental damage to one or more of the following: 1) keystone species, 2) a major biotic component of a human-valued ecosystem or other significant changes to valued habitats, 3) biodiversity, or 4) endangered species. This damage would be directed towards similar components present in the continental United States.                                                                                                                                                                                           95
  The non-native species has been reported only rarely as having an economic impact, or characteristics of the non-native species convincingly show that the potential for moderate or severe impact in the protected area is possible and/or the non-native species has been reported only rarely as having an environmental impact, or characteristics of the non-native species convincingly show that the potential for moderate or severe impact in the protected area is possible to one or more of the following: 1) keystone species, 2) a major biotic component of a human-valued ecosystem or other significant changes to valued habitats, 3) native biodiversity, or 4) endangered species.   90
  The non-native species has no record of ever causing an economic impact, but characteristics of the non-native species convincingly show that the potential for a negative impact in the protected area is possible, and/or the non-native species has no record of ever causing an environmental impact, but characteristics of the non-native species convincingly show that the potential for a negative impact in the protected area is possible to one or more of the following: 1) keystone species, 2) a major biotic component of a human-valued ecosystem or other significant changes to valued habitats, 3) biodiversity, or 4) endangered species                                            80
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
  The non-native species has no record of ever causing an economic impact, and characteristics of the non-native species do not show a convincing potential for becoming an economic pest, and the non-native species has no record of ever causing an environmental impact, and characteristics of the non-native species do not show a convincing potential for becoming an environmental pest.                                                                                                                                                                                                                                                                                                          0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
  -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------

RATIONALE:

REFERENCES:

UNCERTAINTY CODE:

If the sums of the two scores from Step 2 and Step 3 are equal to 130 or
more, the non-native species qualifies as a potential invasive species
as defined in the Executive Order.

STEP 4: What are the benefits of introduction (demonstrated and
perceived)?

Life is a balance between risk and benefits. To include risk (defined in
this context as a potential invasive species) without considering the
benefits is a useless concept and is without real context. The greater
the chance of benefits, the greater the risk one (or a society) will be
willing to take. Potential invasive species are not above this.

The purpose of the ranking in step 4 is to capture the positive benefit
component of the introduction of a non-native species regardless of
whether it establishes or not, and independent of whether it carries
perceived or real negative impacts.

One of the most important issues in measuring benefits is determining to
whom the benefit would accrue. Every request to import a non-native
species is seen as a benefit to the importer \-- why else would he/she
wish for the importation? There is also a benefit, to the American
people, of not regulating (restricting personal freedom) unless it is
demonstrably or convincingly justified; for this reason even an import
of a non-native species with limited social benefit should not be
regulated without reason.

When considering benefits, it will be best to consider the overall
benefit to the American people in general and not to focus on just the
benefits to a few or to a single industry. General benefits (those that
influence the most people) should normally carry the most weight.
However, there are going to be exceptions. Benefits that provide
advantage to small ethnic groups or to protected industries or markets
that influence national security or meet international obligations might
have to be taken into consideration, but if so, this would have to
explained in full under the Rationale Section.

The following table captures the positive primary economic, social, or
environmental gains if an non-native species is moved into a protected
area. Although it is recognized that secondary gains can, and do, add
up, generally these will require a more in-depth evaluation than is
feasible in a general screening process.

  --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --------
  CRITERIA                                                                                                                                                                                                                                                                                                  SCORE
                                                                                                                                                                                                                                                                                                            
  The non-native species demonstrates a large potential for direct gains for the economic and/or the social well-being of the American public or the environment.                                                                                                                                           \- 100
  The non-native species demonstrates a potential for moderate gains for the economic and/or the social well-being of the American public or the environment, or shows future potential positive gains for a segment of society or industries that are generally deemed important by the American people.   \- 90
  The non-native species demonstrates little potential for future gains for the American people as a whole, but demonstrates a significant potential gain to the importer and the associated industry/market, or benefits limited to a small segment of the country or industry.                            \- 80
                                                                                                                                                                                                                                                                                                            
  The non-native species demonstrates little potential for future gains except to a limited number of importers.                                                                                                                                                                                            \- 60
                                                                                                                                                                                                                                                                                                            
  --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --------

RATIONALE:

REFERENCES:

UNCERTAINTY CODE:

A negative scoring is used to offset the positive score from Step 3
(negative impact).

STEP 5: Combine scores of Steps 2 through 4

If the economic and environmental consequences of a non-native species
are considered positive by the general public, the non-native species is
viewed as beneficial; if negative then invasive. Those established
non-native species that do not readily impact upon the public as a whole
are generally ignored. Disputes are strongest when non-native species
have both the potential for benefits and to cause damage.

When the pluses and negatives of introducing a non-native species are
relatively equal then resolution rarely can be reached without
compromise. A good example is the domestic house cat. Clearly cats
provide benefits to their owners and to the market that serves them.
Unfortunately, feral cats can and do cause extensive damage to
indigenous small animal populations. Thus, cats qualify as an invasive
species. However, the final solution will not rest with either
prohibiting the movement of cats in the continental United States or by
ignoring the negative environmental impact of cats. Solutions can only
result if individuals act reasonably and recognize both sides of the
issue and are willing to work toward a compromise. The purpose of a
screening process cannot be to resolve these types of issues, but only
to identify them.

The following three tables are divided up by the establishment scores
assigned from Step 2. If a proposed introduced species received a score
of zero in step 1, it was automatically kicked out of the screening
process because it was considered native. In reality, these three tables
are really one large table. These tables match all possible combinations
of scores, and rank them with each other. The higher the rank, the
greater the concern. The ranking numbers themselves should not be taken
as a quantitative entity, since they can only be defined when compared
to other ranked numbers. For example, an organism that has a rank of 20
is of greater concern than one ranked 10, but the two numbers do not
represent real quantitative values (e.g. the rank of 20 is not twice as
"bad" as a rank of 10).

**Ranking of organisms with a probability of establishing score of
100:**

+---------------+----------+---------+-------+------+
| Step 2        | Step 3   | Step 4  | Total | Rank |
|               |          |         |       |      |
| Establishment | Negative | Benefit | Score |      |
|               |          |         |       |      |
| Potential     | Impact   | Impact  |       |      |
|               |          |         |       |      |
| Score         | Score    | Score   |       |      |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 100           | 100      | -60     | 140   | 33   |
+---------------+----------+---------+-------+------+
| 100           | 95       | -60     | 135   | 32   |
+---------------+----------+---------+-------+------+
| 100           | 90       | -60     | 130   | 31   |
+---------------+----------+---------+-------+------+
| 100           | 100      | -80     | 120   | 30   |
+---------------+----------+---------+-------+------+
| 100           | 80       | -60     | 120   | 30   |
+---------------+----------+---------+-------+------+
| 100           | 95       | -80     | 115   | 29   |
+---------------+----------+---------+-------+------+
| 100           | 90       | -80     | 110   | 28   |
+---------------+----------+---------+-------+------+
| 100           | 100      | -90     | 110   | 28   |
+---------------+----------+---------+-------+------+
| 100           | 95       | -90     | 105   | 27   |
+---------------+----------+---------+-------+------+
| 100           | 100      | -100    | 100   | 26   |
+---------------+----------+---------+-------+------+
| 100           | 90       | -90     | 100   | 26   |
+---------------+----------+---------+-------+------+
| 100           | 80       | -80     | 100   | 26   |
+---------------+----------+---------+-------+------+
| 100           | 95       | -100    | 95    | 25   |
+---------------+----------+---------+-------+------+
| 100           | 90       | -100    | 90    | 24   |
+---------------+----------+---------+-------+------+
| 100           | 80       | -90     | 90    | 24   |
+---------------+----------+---------+-------+------+
| 100           | 80       | -100    | 80    | 22   |
+---------------+----------+---------+-------+------+
| 100           | 0        | -60     | 40    | 15   |
+---------------+----------+---------+-------+------+
| 100           | 0        | -80     | 20    | 12   |
+---------------+----------+---------+-------+------+
| 100           | 0        | -90     | 10    | 10   |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 100           | 0        | -100    | 0     | 8    |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+

**Ranking of organisms with a probability of establishing score of 50:**

+---------------+----------+---------+-------+------+
| Step 2        | Step 3   | Step 4  | Total | Rank |
|               |          |         |       |      |
| Establishment | Negative | Benefit | Score |      |
|               |          |         |       |      |
| Potential     | Impact   | Impact  |       |      |
|               |          |         |       |      |
| Score         | Score    | Score   |       |      |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 50            | 100      | -60     | 90    | 24   |
+---------------+----------+---------+-------+------+
| 50            | 95       | -60     | 85    | 23   |
+---------------+----------+---------+-------+------+
| 50            | 90       | -60     | 80    | 22   |
+---------------+----------+---------+-------+------+
| 50            | 100      | -80     | 70    | 21   |
+---------------+----------+---------+-------+------+
| 50            | 80       | -60     | 70    | 21   |
+---------------+----------+---------+-------+------+
| 50            | 95       | -80     | 65    | 20   |
+---------------+----------+---------+-------+------+
| 50            | 90       | -80     | 60    | 19   |
+---------------+----------+---------+-------+------+
| 50            | 100      | -90     | 60    | 19   |
+---------------+----------+---------+-------+------+
| 50            | 95       | -90     | 55    | 18   |
+---------------+----------+---------+-------+------+
| 50            | 100      | -100    | 50    | 17   |
+---------------+----------+---------+-------+------+
| 50            | 90       | -90     | 50    | 17   |
+---------------+----------+---------+-------+------+
| 50            | 80       | -80     | 50    | 17   |
+---------------+----------+---------+-------+------+
| 50            | 95       | -100    | 45    | 16   |
+---------------+----------+---------+-------+------+
| 50            | 90       | -100    | 40    | 15   |
+---------------+----------+---------+-------+------+
| 50            | 80       | -90     | 40    | 15   |
+---------------+----------+---------+-------+------+
| 50            | 80       | -100    | 30    | 14   |
+---------------+----------+---------+-------+------+
| 50            | 0        | -60     | -10   | 7    |
+---------------+----------+---------+-------+------+
| 50            | 0        | -80     | -30   | 6    |
+---------------+----------+---------+-------+------+
| 50            | 0        | -90     | -40   | 5    |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 50            | 0        | -100    | -50   | 4    |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+

**Ranking of organisms with a probability of establishing score of 10:**

+---------------+----------+---------+-------+------+
| Step 2        | Step 3   | Step 4  | Total | Rank |
|               |          |         |       |      |
| Establishment | Negative | Benefit | Score |      |
|               |          |         |       |      |
| Potential     | Impact   | Impact  |       |      |
|               |          |         |       |      |
| Score         | Score    | Score   |       |      |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 10            | 100      | -60     | 50    | 17   |
+---------------+----------+---------+-------+------+
| 10            | 95       | -60     | 45    | 16   |
+---------------+----------+---------+-------+------+
| 10            | 90       | -60     | 40    | 15   |
+---------------+----------+---------+-------+------+
| 10            | 100      | -80     | 30    | 14   |
+---------------+----------+---------+-------+------+
| 10            | 80       | -60     | 30    | 14   |
+---------------+----------+---------+-------+------+
| 10            | 95       | -80     | 25    | 13   |
+---------------+----------+---------+-------+------+
| 10            | 90       | -80     | 20    | 12   |
+---------------+----------+---------+-------+------+
| 10            | 100      | -90     | 20    | 12   |
+---------------+----------+---------+-------+------+
| 10            | 95       | -90     | 15    | 11   |
+---------------+----------+---------+-------+------+
| 10            | 100      | -100    | 10    | 10   |
+---------------+----------+---------+-------+------+
| 10            | 90       | -90     | 10    | 10   |
+---------------+----------+---------+-------+------+
| 10            | 80       | -80     | 10    | 10   |
+---------------+----------+---------+-------+------+
| 10            | 95       | -100    | 5     | 9    |
+---------------+----------+---------+-------+------+
| 10            | 90       | -100    | 0     | 8    |
+---------------+----------+---------+-------+------+
| 10            | 80       | -90     | 0     | 8    |
+---------------+----------+---------+-------+------+
| 10            | 80       | -100    | -10   | 7    |
+---------------+----------+---------+-------+------+
| 10            | 0        | -60     | -50   | 4    |
+---------------+----------+---------+-------+------+
| 10            | 0        | -80     | -70   | 3    |
+---------------+----------+---------+-------+------+
| 10            | 0        | -90     | -80   | 2    |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+
| 10            | 0        | -100    | -90   | 1    |
+---------------+----------+---------+-------+------+
|               |          |         |       |      |
+---------------+----------+---------+-------+------+

STEP 6: Assigning the organism using its rank to an approved,
unapproved, or status-undetermined list.

It is unlikely that a mitigation measure would be found that would
reduce the risk of establishment for an intentionally introduced
non-native species that would be allowed full access and unrestricted
use throughout the continental United States. Therefore, the assigning
to an approved, unapproved, or status-undetermined list based upon the
rank of a non-native organism is reasonably straight forward.

C Total score = 40 or less (ranks 15 to 1) **no restrictions on entry**
(**approved list**).

C Total score = 70 or more (ranks 21 to 33) **prohibited from having
full access and unrestricted entry** (**unapproved list**)

C Total score = 45 to 65 (ranks 16 to 20) **requires a more intensive
risk assessment and benefit analysis** before approval for full access
and unrestricted entry can be granted (**status-undetermined list**).

The cut-off scores for the approved list, unapproved list, and
status-undetermined list reflect my value judgements and again are here
to demonstrate how the process would work. There is no argument that the
criteria, assigned ranking scores, and appropriate levels of separation
between the approved, unapproved, and status-undetermined lists will
have to be reached by wide public discussion and agreement.

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

COMMENTS ON UNINTENTIONAL INTRODUCTIONS:

I generally do not recommend this type of screening process for
unintentionally introduced species. Although some exceptions exist,
usually protection will be much better served by identifying the highest
risk pathways (or vectors) for non-native introductions and then
determining the most equitable/feasible/effective mitigation strategies
to reduce the ability of that pathway to carry unintentional organisms
in commerce.

The current practice for regulating many types of unintentional
non-native invasive species in the movement of international commodities
throughout the world is focused on a species-by-species,
commodity-by-commodity, country-by-country approach. For the short term,
the U.S. is locked into this process by necessity since there are few
international standards covering pathways. However, ultimately I do not
believe that unintentional invasive species should be handled in this
way. The current process is self-defeating because extensive resources
are often needed to identify target organisms moving in a specific
commodity or conveyance. Even with extensive resources at hand, the
uncertainty surrounding the associated foreign biota makes identifying
the target invasive species difficult or at times impossible for certain
types of commodities (e.g. raw timber or wild-harvested, unprocessed
plant material or water moving with fish stocking) or conveyances (e.g.
ballast water or aircraft cargo holds).

This also leads to inequitable protection between countries because only
a small handful of countries have the resources to conduct in-depth
species-by-species, country-by-country, commodity-by-commodity risk
assessments required to protect themselves from invasive species. This
allows only the richer countries to effectively protect themselves under
the current umbrella of international protection. This has had the
unfortunate, unintentional effect of placing poorer countries at a
disadvantage when compared to richer countries in the movement of many
types of economically important commodities.

Instead, a much more equitable and effective goal to control
unintentionally introduced species is to aim for international treaties,
conventions, and agreements that require exporting countries to minimize
the risk of invasive species moving in those pathways that have been
identified as high risk. In other words, a global safety net needs to be
developed in which specific mitigation standards for high-risk pathways
are required for international movement.

For example, requiring propagative material, at some future time, to
meet a strict level of pest mitigation by a not-yet-developed "*Global
Standard for the Movement of Propagative Material*" would ultimately
provide better protection from accidental introductions of invasive
plant pests throughout the world than requiring each importing country
to identify all the invasive species, for each species of propagative
plant, coming from each and every country wishing importation. If future
international requirements are effective and enforced (both nationally
and internationally), there will be little need for each individual
country to have import requirements to protect against unintentional
invasive species introductions. Not only would the protection be global
in scope, it would greatly reduce the current country-by-county
squabbling over invasive species and the mitigation measures surrounding
the exchange of commodities and their conveyances.

The good news is, that in most cases, international agreements are
already in place that can accomplish this. The bad news is that far too
little resources and energy are currently directed toward the
development of international standards intended to clean up high risk
invasive species pathways.

The same approach will work for domestic movement of unintentional
invasive species which are moved on commodities and/or conveyances. In
the long run, national standards on the movement of these high risk
pathways will be more effective than having each individual State enact
its own requirements on commodities and conveyances for protection from
unintentional invasive species.

The ultimate goal would be to have effective international standards and
national standards be one and the same.