1

Summary of Comments from the

TWG Kanab Ambersnail Ad Hoc Committee

July 19, 2001

The Kanab ambersnail (Oxyloma haydeni kanabensis) KAS is a small endangered land snail. 

The subspecies was originally described from a population found in Southern Utah, and in 1991 

another population was discovered at Vaseys Paradise in Grand Canyon National Park. The 

snails at Vaseys Paradise live in vegetation that grows along the course of a perennial spring that 

emerges from the Redwall limestone and then flows some 200 meters to the Colorado River. 

After the closing of Glen Canyon Dam in 1963 the vegetation expanded down slope into areas 

closer to the river. Snails also moved into the new habitat and are now vulnerable to high 

releases from Glen Canyon Dam. The US Fish and Wildlife Service has issued a recovery plan 

and several biological opinions to help guide actions that could affect KAS or their habitat. 

In 1998 Grand Canyon National Park completed National Environmental Policy Act and 

Endangered Species Act compliance to attempt the establishment of one or more new 

populations of KAS in the Park. Translocations of KAS were made from Vaseys Paradise to 

three other sites along the course of the Colorado River. These attempts were made to increase 

the future flexibility of Glen Canyon Dam operations, by providing a potential means for 

meeting current and future requirements of Fish and Wildlife Service biological opinions on 

controlled floods carried out as part of the Glen Canyon Dam Adaptive Management Program 

(AMP). 

The AMP provides advice to the Secretary of the Interior about resources affected by Glen 

Canyon dam. In 1999 representatives of several participating organizations invited a panel of 

scientists to review information about the KAS and to prepare a report of their recommendations 

(Noss et al. 20001). This newly formed Kanab Ambersnail Ad Hoc Committee (KAS ad hoc) 

was charged by Technical Work Group (TWG) to evaluate the Panel’s report. The TWG is a 

subgroup of the Glen Canyon Dam Adaptive Management Work Group (AMWG) and both 

groups are in the AMP. The KAS ad hoc was also charged to prepare a draft response from the 

TWG to the AMWG and to send a report to the TWG by July 20, 2001. This is the KAS ad 

hoc’s report.

The members of the KAS ad hoc included Bob Winfree (Chair), Paul Barrett, Gary Burton, Bill 

Davis, Rick Johnson, Dennis Kubly, Bill Persons and Barb Ralston. Debra Bills and Della 

Snyder also joined the committee for discussions on specific issues. The independent Kanab 

Ambersnail Working Group (KAWG) has also reviewed the Panel’s report (Karas 20012). The 

KAS ad hoc review includes comments on the KAWG’s response to the Panel’s report and a 

summary of all three group’s recommendations on five specific resource management questions 

 

1

 Noss, R., M. Gordon, E. Hoagland, C. Lydeard, P. Mehlhop, and B. Roth. 2000. Report of Kanab Ambersnail 

Review Panel on Taxonomic, Ecological, and Translocation Issues Concerning the Conservation of Oxyloma

Snails in Arizona and Utah. 12 pp.

2

 Karas, C. D. March 13, 2001. Kanab Ambersnail Working Group response to the expert panel review. 3 pp.
2

identified through discussion. This report is divided into four parts: A. Summary of KAS ad hoc 

recommendations, B. Resource Management Questions, C. Issues, and D. Panel 

Recommendations. Several topics are discussed under more than one section, but the main 

points are summarized in part A.

A. Summary of TWG KAS Ad Hoc Recommendations Regarding 

Kanab Ambersnails at Vaseys Paradise (VP Oxyloma)

Research and Monitoring

• Implement low-impact monitoring of VP Oxyloma and translocated populations

• Model habitat and population responses to environmental change

• Seek funding outside the AMP for expanded taxonomic studies

• Continue using captive populations for research when needed

• Continue searching for other present and past KAS populations

Moving Snails

• Do not routinely move snails and habitat up slope during floods

• Do not establish new populations before the new Recovery Plan is completed

• Conduct a risk/benefit analysis before augmenting populations*

• Do not stock a translocation site from multiple founder populations 

• Avoid moving parasitized snails to new locations

• Do not release snails from captive populations

• Develop criteria for determining successful establishment*

Planning and Compliance

• Continue planning and compliance for flows above 45,000 cfs

• Develop a Recovery Implementation Plan as soon as possible

• Develop a new Recovery Plan when taxonomic questions are resolved

• Ensure broad peer review of the draft new Recovery Plan

• Develop acceptable means to meet incidental take requirements

• Consult on the proposed new program of experimental flows

• Adopt and incorporate these recommendations into the AMP strategic plan

B. Resource Management Questions

The KAS ad hoc identified five questions that need to be considered by the TWG and AMWG. 

In this section of the report we raise the questions, provide the Panel’s and KAWG’s 

perspectives on the issues, and provide our recommendations regarding future resource 

management decisions.

 

*

 Tasks that need to be completed before writing a biological opinion for new experimental flows
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1) Should TWG & AMWG support establishment of new populations of Kanab 

Ambersnail Oxyloma haydeni kanabensis through additional translocation of snails from 

Vaseys Paradise or other populations? 

The "panel believes that translocations into sites where no previous records exist is not advisable 

except under emergency circumstances", while KAWG was divided on "the need for redundant 

populations". KAWG noted that "The Recovery Plan is still in effect and at least five members 

wanted to preserve the opportunity to continue implementing the plan as a means of reaching 

recovery and de-listing".

The KAS ad hoc does not recommend establishment of new Oxyloma haydeni

populations within Grand Canyon National Park or Glen Canyon National Recreation

Area unless there is evidence that other populations of Oxyloma haydeni have been, or 

are likely to be, extirpated by human actions within these National Park Service areas. If 

the historic habitat cannot be saved or restored, then translocation to unoccupied or

constructed habitats should be considered with appropriate planning and environmental 

compliance. Any new populations should be founded from the population that is

genetically most closely related to the population of concern, if possible. Any

reintroduction sites should be above expected high water levels for regulated flows from

Glen Canyon Dam.

2) Should TWG & AMWG support augmentation of the existing translocated VP Oxyloma

populations at Keyhole Spring, Lower Deer Creek, or Upper Elves Chasm? 

The Panel recommended against "further augmentation of the populations already established 

within Grand Canyon National Park." The KAWG indicated that they reached "consensus [on 

other points] assuming some snails could be used to augment translocated populations".

The KAS ad hoc recommends against further augmentation of the existing translocated 

VP Oxyloma populations until the benefits and risks of such augmentation have been 

reevaluated, and until the reasons for apparent lack of success of the Keyhole and Deer 

Creek introductions are better understood. Evaluation of benefits and risks needs to be 

accomplished prior to any discretionary Federal action that would result in incidental take 

of VP Oxyloma.

3) Should TWG & AMWG support using captive refugia populations as reservoirs of 

animals for research, public education, or for possible future reintroductions? 

The Panel said, "We do not see a useful conservation-oriented purpose for the captive 

populations (refugia). These populations exist in an artificial selective regime and may harbor 

diseases that potentially could be disastrous if introduced to the wild.... On the other hand, they 

may be useful for controlled laboratory research”. While KAWG agreed with the utility of 

captive populations for research and educational purposes, we are unclear about KAWG's current 

position regarding potential use of captive snails for reintroductions. 
4

The KAS ad hoc recommends using experimental captive populations when needed for 

research. Maintaining captive populations of endangered species solely for educational 

or display purposes is not allowed under the Endangered Species Act, although public 

display of research populations may be permissible. Captive populations should not be 

used for reintroduction when other viable populations exist (see comments under 

Recommendation 3, below.)

4) Should the TWG & AMWG refrain from recommending test floods between 45,000 cfs 

and the pre-dam average annual maximum in order to protect the Vaseys Paradise snail 

population? 

The panel said, "a strong case can be made that releases should be increased to more closely 

match the pre-dam natural hydrologic regime, including inter-annual variability...There is no 

reason to believe that the population cannot survive floods of these magnitudes in the future". 

KAWG noted that "larger flows are not precluded but would require additional compliance" and 

"Factors such as recent climatic conditions and physical habitat would need to be considered."

The KAS ad hoc recognizes that the Colorado River watershed evolved with frequent 

flooding above 45,000 cfs, and believes that the potential for ecological benefits warrants 

continued planning for high flows and other experimental flows. However, such 

planning should include consideration of Endangered Species Act compliance 

requirements and potential impacts to VP Oxyloma and their habitat. Continued 

monitoring and a reasonably predictive model of habitat and population responses to 

environmental change are needed to make informed decisions about potential impacts 

and appropriate mitigation measures for future high flows.

5) Should TWG & AMWG recommend consultation on Biological Opinion issues and/or 

development of a new Recovery Plan? (Note: These are not AMWG responsibilities, but 

they would affect the Adaptive Management Program.) 

The panel concluded "that the recovery plan and biological opinions regarding the Vasey's 

Paradise and other Oxyloma populations should be revised as soon as the major taxonomic and 

distributional issues are resolved by further morphological, anatomical, and molecular genetic 

studies and new field surveys". The KAWG agreed that the Kanab Ambersnail Recovery Plan 

"should be re-written as soon as the major taxonomic issues are resolved" and KAWG concurred 

with the need for "reconsideration of current management direction for these snails and their 

ecosystems". KAWG also recommended that "an interim strategy for obtaining the 

recommended data and moving toward recovery should be developed." 

The KAS ad hoc recommends consultation and development of a new Recovery Plan. 

Consultation should proceed as soon as a new program of experimental flows has been 

designed. A new Recovery Plan should be developed as soon as taxonomic, genetic, and 

distribution questions have been resolved. A Recovery Implementation Plan should be 

developed to bridge this gap. 
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C. Discussion of Individual Issues Addressed 

By the Kanab Ambersnail Review Panel

This section follows the numbering system used in the Panel’s original report. Comments that 

relate to specific subtopics in the Panel’s report (1A, 1B, 1C, etc.) are included in the general 

response to the issue. The Kanab Ambersnail Working Group response (Karas 2001) did not 

specifically refer to the issues listed below. 

Issue 1. This issue involves the molecular genetics, shell morphology, internal anatomy, and 

taxonomy of Oxyloma snails in the Colorado River drainage.

The KAS ad hoc concurs with the Panel’s recommendations for more genetic and 

taxonomic research. Despite new information that has been produced since the panel met 

(Miller et al. 20003, Stevens et al. 20004), additional taxonomic and genetic work are still 

needed to better understand the VP Oxyloma. We recommend that the Grand Canyon 

Monitoring and Research Center (GCMRC) work with subject matter experts and with 

the TWG to identify information needs priorities, and appropriate technologies for 

resolving these questions. Supplemental funding should be sought from sources outside 

the AMP for work with Oxyloma and with related succineid species in the event that 

AMP funds are insufficient.

Issue 2. This issue concerns the observed wide seasonal and annual fluctuations of the Vaseys 

Paradise population in relation to the 1994 Biological Opinion.

The KAS ad hoc does not fully concur with the Panel on the question of whether “There 

is no reason to believe that the population cannot survive floods of these magnitudes 

[around 125,000 cfs] in the future”. While we can assume that the VP Oxyloma have 

weathered numerous high flow events at Vaseys Paradise, we have little information 

about other changes that may have occurred since the population was established. Where 

were the founding population(s) and do they still exist? No one knows when the VP

Oxyloma first reached Vaseys Paradise and we have no way of knowing whether other

populations were destroyed by construction of Glen Canyon or Hoover dams. Nor do we 

know how often, if ever, the Vaseys population was augmented through rafting or other 

natural processes. Has the elimination of high, warm, debris laden pre-dam flows 

reduced any opportunities for accidental introductions from upriver populations, and to 

down river habitats? Is the population as resilient as ever, or have new diseases, 

parasites, or other factors limited its ability to recover from major environmental

changes? The question is how to proceed given the uncertainty of questions that may 

never be answered. As the Panel noted, several methods for risk analysis and 

population modeling are available to help guide decision-making (e.g., James et al. 

 

3 Miller, M. P., L.E. Stevens, J.D. Busch J. A. Sorenson and P. Keim. 2000. Amplified fragment length 

polymorphism and mitochondrial sequence data detect genetic differentiation and relationships in endangered 

southwestern U.S.A. ambersnails (Oxyloma spp). Can. J. Zool. 78:1845-1854.

4

Stevens, L.E., P. Keim, M.P. Miller and S. Wu. 2000. Morphological and genetic relatedness among succineid 

landsnails in the United States and Canada, with emphasis on the endangered Kanab ambersnail (Oxyloma haydeni 

kanabensis). Draft Final report for GCMRC, Flagstaff, AZ.
6

19975). Low-impact monitoring can provide data needed for modeling, and can provide 

advance notice of changes to population or habitat.

Issue 3. This issue is focused on the Vaseys Paradise site and raises questions about the 

vegetative habitat of the snail population there.

The KAS ad hoc differs with the panel, believing that the Panel misunderstood the Kanab 

Ambersnail Interagency Workgroup’s use of the words “primary” and “secondary” 

habitat. These terms originally referred to areas of high or low snail density and were 

associated with specific vegetation types and other factors unrelated to stage. The 

Panel’s response suggests that secondary VP Oxyloma habitat is restricted to repeatedly 

inundated and scoured areas below 45,000 cfs that were historically of less importance to 

the population’s long-term survival than were habitats located further above the river. 

This interpretation was incorrect, and there is other information that must be taken into 

account when evaluating the effects of flows on VP Oxyloma and its habitat. The 

monitoring record above 60,000 cfs at Vaseys Paradise is incomplete, and the 

relationship between snail density and habitat type is less well documented. Other 

factors, such as vegetation type, soil moisture, slope, etc., also affect habitat suitability. 

Historic stage data also indicate that there were periods when maximum flows remained 

near 25,000 cfs for several years at a time, even in the pre-dam era. Vegetation may have 

expanded rapidly if floods laden with sediment and floating debris were followed by 

several seasons of low flows. While we agree that habitats above the historic high water 

line have probably always been critical to the species, the importance of lower elevation 

habitats to the VP Oxyloma during low water or drought years, and for accidental 

transport of snails to down river habitats during the pre-dam era remains unknown.

Issue 4. This issue deals with the proportion of the Vaseys Paradise snail population that could 

be lost in a given year without adverse long-term consequences.

The KAS ad hoc differs with the Panel. While the historic high water line certainly 

provides information about historic flooding at Vaseys Paradise, more information is 

needed to answer questions of how much loss the VP Oxyloma population can tolerate, 

how frequently, and under what other conditions. We are not confident that we have 

sufficient historical information about Vaseys Paradise or other Oxyloma haydeni 

kanabensis populations (past or present) to conclude, “initial take of 40% would almost 

certainly not threaten the persistence of the snail population.” The USFWS Biological 

Opinions on incidental take of habitat (10%) have been revised (up to 17%) (Harlow, 

20006) since the panel met to reflect new information. We recommend that current 

information about the status of all populations within the CRE (habitat condition, snail 

numbers, snail distribution, etc.) be included in consultation when planning future flows 

above 45,000 cfs.

 

5

 James, F. C., C. A. Hess, and D. Kufrin. 1997. Species-centered environmental analysis: indirect effects of fire 

history on red-cockaded woodpeckers. Ecological Applications 7:118-129.

6

 Harlow, D. L. Biological opinion amendment for Kanab ambersnail in Arizona. (2000). Memorandum to the 

Regional Director, Bureau of Reclamation, Salt Lake City, Utah. Dated June 23, 2000. 3 pp.
7

Issue 5. This issue again deals with managed flood regimes; approaches for predicting population 

responses to environmental change, and appropriate mitigation activities.

The KAS ad hoc differs with the panel, because this issue cannot be addressed only from 

a biological perspective. There are also legal and philosophical issues to consider. We 

agree that natural flooding has probably scoured soils and vegetation and reduced snail 

numbers frequently during the VP population’s history. However, the Kanab Ambersnail 

is a designated endangered species, the VP population is currently regarded as a 

population of endangered Kanab ambersnail, and present day dam releases are under 

human control. The Endangered Species Act requires that Federal agencies minimize 

the impact of their actions on endangered species, as do agency policies and our own 

philosophical considerations. The KAS ad hoc recognizes that several alternatives for 

reducing incidental take have been considered and tested in the past. We recommend 

that a wide range of alternatives also be considered during future planning, and that the 

selection of appropriate Reasonable and Prudent Measures be determined through 

consultation among subject matter experts, resource managers, and responsible agencies. 

We agree that modeling of habitat and population responses to environmental change can 

and should guide planning and consultation.

Issue 6. This issue involves management actions to avoid jeopardy, including moving snails to 

higher ground, establishing redundant wild populations, and establishing captive populations.

The KAS ad hoc shares the Panels concerns, but differ in several significant details. We 

recommend against translocation of Kanab ambersnails to any new location within the 

Colorado River Watershed before the Kanab Ambersnail Recovery Plan has been revised. 

We recognize that there are risks associated with any translocation. Translocated 

organisms may not survive or prosper, translocation may introduce disease, parasites, or 

weeds to the new habitat, or the translocated species may interfere with organisms 

already present at the new site. These risks were considered before the VP Oxyloma was 

moved in 1996. Although there are differences of opinion about the potential risks and 

benefits, neither the Panel, KAWG, nor this group is recommending for their removal at 

this time. The existence of a redundant population at Elves may reduce the risk of losing 

the VP Oxyloma population from unforeseen circumstances at Vaseys Paradise, and its 

existence will also be considered in future consultation. The translocated populations 

also have full protection under the Endangered Species Act and cannot be removed 

without additional consultation between the National Park Service and the US Fish and 

Wildlife Service, neither of which has proposed taking such action. 

We do not recommend routinely adding more snails to translocated populations at 

Keyhole Spring, Lower Deer Creek, and Upper Elves Chasm without well documented 

evaluation of the risks and benefits. Among these three sites, only the population at 

Elves appears to be expanding at this time. Two potential benefits were identified for 

augmentation of the Elves population. 1) Augmentation could reduce the potential for 

inbreeding due to the small founder population size (about 150 snails). 2) Augmentation 

may be an appropriate mitigation action for losses that would otherwise occur with future 
8

high flow experiments. However, some risks associated with the original translocation 

would be repeated with each additional stocking (i.e., disease introductions). Other 

appropriate mitigation actions that do not involve translocation may also be identified. 

We recommend against moving additional snails to the Elves, Keyhole or Deer sites until 

the benefits and risks are evaluated, and status of the original introductions and the 

species habitat needs are better understood.

We are encouraged by the discoveries of additional populations of Oxyloma in Utah and 

recommend for additional research to find and characterize other sites where Oxyloma 

haydeni previously existed (fossil evidence) and where they may still exist in tributaries 

and side canyons in the Colorado River watershed. 

Issue 7. This issue deals with the significance of the Leucochloridium parasite found in VP 

Oxyloma.

The KAS ad hoc does not fully agree with the Panel on this issue. The translocation procedures 

chosen in 1996 to safely move snails without moving their parasites (by moving snails less than 

5 mm in length) appear to have accomplished their purposes. Recent scientific evidence 

suggests that the parasite has co-evolved with VP Oxyloma and does not significantly reduce the 

survival or reproduction of these or other known species. However, some of us remain reluctant 

to knowingly transport a disease organism into a location where it does not currently exist. This 

difference of opinion is based on principles, policies (DOI 20007), past experience, and 

uncertainty about long-term effects. We recommend that the risks and benefits of moving snails 

larger than 5 mm be reevaluated in light of the best available information before any additional 

translocations or augmentation are undertaken in the future.

Issue 8. This issue deals with the questions of how to differentiate between distinct populations 

and how to measure the success of a reintroduction effort.

The KAS ad hoc concurs with the Panel’s responses to the questions posed in 8A-8D. We 

also agree that species conservation areas should not be constrained by state/political 

boundaries. However, we do not agree with the panel’s assumptions regarding the origin 

of the VP Oxyloma. Without information about pre-dam populations, we feel it is 

important to evaluate proposed management actions in light of the hypothesis favored by 

the Panel and also for the alternative hypotheses. The panel inferred that the VP 

Oxyloma evolved at its present site, or nearby, and has always been approximately as rare 

as it is now. One alternative hypothesis is that the VP Oxyloma evolved elsewhere and 

reached Vaseys Paradise more recently than the first hypothesis suggests. Another 

alternative view is that the VP Oxyloma may have been, or may still be, more widespread 

than we now know (i.e., Pleistocene relict theory). Accepting all three hypotheses as 

equally likely is a more conservative approach to resource management, as it involves 

consideration of a broader range of alternatives. We feel a conservative approach is 

appropriate when dealing with a designated endangered species. We recommend that the 

 

7

 DOI. Department of the Interior and Department of Commerce. 2000. Policy regarding controlled propagation of 

species listed under the Endangered Species Act. Federal Register. Vol. 65, No. 183. pp. 56916-56922.
9

National Park Service coordinate with Arizona Game and Fish Commission, GCMRC, 

the Bureau of Reclamation, the US Fish and Wildlife Service, and other appropriate 

entities to develop criteria for determining when the attempts to reintroduce VP Oxyloma

at the Keyhole, Deer, and Elves sites should be abandoned or declared a success (USFWS 

19988). The Panel’s report, this document, and the draft KAWG criteria for defining 

“establishment” include draft criteria for consideration.

Conclusion

The Panel’s conclusion restates several of their assumptions, comments on current 

management approaches, and proposes alternative uses of limited funds. While we 

concur with many of the Panel’s specific recommendations (listed above), we do not 

agree with all of their conclusions. We are not confident that natural flow processes and 

patterns (e.g., timing, duration, stage, sediment content, temperature, floating debris, 

existence of upriver and down river habitats) can be restored in the near future, given 

current legal and operational constraints for Colorado River dams. Consequently, we feel 

that other management actions on behalf of the VP Oxyloma are warranted for a variety 

of biological, legal, and philosophical reasons already discussed. Development of an 

interim Recovery Implementation Plan, a new Recovery Plan, and new biological 

assessments and biological opinions associated with future actions, are appropriate means 

of selecting those actions. The Panel’s report has contributed much useful information to 

this effort, and will undoubtedly be referenced frequently in future planning documents.

D. Discussion of Individual Recommendations Made 

by the Kanab Ambersnail Review Panel and also

Addressed by the Kanab Ambersnail Work Group

The following paragraphs follow the numbering system used by Karas (2001) to address 

recommendations listed on pages 1-2 of the Panel’s report.

Recommendation 1. Additional analyses of shell morphology, anatomy, and molecular genetics 

(e.g., mitochondrial DNA), using state-of-the-art methods, are urgently needed to resolve 

taxonomic, phylogenetic, and, in part, distributional questions.

The KAS ad hoc concurs with the Panel and KAWG. (Also see comments under Issue 1, 

above.)

Recommendation 2. Also urgently needed are additional field surveys of potential succineid 

habitats both upstream of Glen Canyon dam and downstream within the Colorado River 

drainage, as well as in regions outside the Colorado River basin that provide potential habitat.

The KAS ad hoc concurs with the Panel and KAWG.

 

8

 USFWS. U.S. Fish and Wildlife Service. 1998. Section 7 consultation for the establishment of the endangered 

Kanab ambersnail into Grand Canyon National Park.
10

Recommendation 3. In contrast, additional efforts at translocation and establishment of captive 

populations are not warranted.

The KAS ad hoc does not fully agree with the Panel’s recommendation or with KAWG’s 

recommendations.

 

We recommend against establishment of new populations in the Colorado River 

watershed before a new Recovery plan has been approved. 

We have not categorically ruled out augmentation to sustain and maintain existing 

populations at the translocation sites and meet the original objectives of the current 

Recovery Plan and Biological Opinion. However, we recommend against stocking a 

translocation site from more than one founder population (issue 1 E) if sufficient numbers 

from one founder population can be obtained to prevent inbreeding. 

We recommend for a thorough reevaluation of risks and benefits of augmenting the three 

translocated populations before moving more snails to any of those sites. This evaluation 

needs to be completed before writing a biological opinion associated with future 

experimental flows. 

We recommend for establishment and maintenance of experimental populations in 

captivity when they are needed for research that is in the species best interests. 

We recommend against using captive populations for reintroduction unless appropriate 

protocols have been rigorously applied to prevent disease introductions or unintended 

genetic selection to artificial environments (e.g., DOI 2000)9, and then only when 

sufficient numbers of animals cannot be obtained from closely related wild populations. 

Recommendation 4. Population viability analysis of the Vasey’s Paradise population, and 

probably other Oxyloma populations, is not likely to be informative or helpful for conservation 

of these populations; preferable alternatives to population viability analysis exist.

The KAS ad hoc concurs with the Panel and KAWG that there are potentially useful 

alternatives to PVA (e.g., James et al. 1997.) and we think that GCMRC should evaluate 

the full range of assessments in addressing this issue. 

Recommendation 5. Flooding from dam releases within the historic (pre-dam) seasons and 

levels is justified ecologically and is unlikely to pose a significant threat to the Vasey’s Paradise 

snail populations, which appears to have evolved under an intense flooding regime.

The KAWG did not reach consensus about this recommendation. The KAS ad hoc does 

not feel that there is sufficient information available to concur with the Panel (also see 

comments under Issue 2, above). However, we feel that the risks of higher flows can be 

evaluated and managed under the following circumstances: 

 

9

 Department of the Interior and Department of Commerce. 2000. Policy regarding controlled propagation of 

species listed under the Endangered Species Act. Federal Register. Vol. 65, No. 183. pp. 56916-56922.
11

Resource monitoring should continue at an appropriate level (details to be determined by 

the GCMRC in consultation with TWG). 

A reasonably predictive model of habitat and population responses to environmental 

change needs to be developed. 

Acceptable means must be determined to meet incidental take requirements.

Recommendation 6. No scientific basis exists for heroic efforts to maintain or create artificially 

large or multiple populations of the Vasey’s Paradise snail; instead, available information on 

historical ecology supports a minimally invasive approach to management of Vasey’s Paradise 

and other populations of Oxyloma.

The KAWG did not reach consensus on the first part of this recommendation, and they 

did not agree with the Panel on the second part. The KAS ad hoc agrees that a minimally 

invasive approach to management of the VP Oxyloma population is appropriate. Like the 

KAWG, we do not agree among ourselves about the benefits and risks of establishing 

redundant populations of endemic species. However, we are in agreement that that no 

new populations of Oxyloma haydeni kanabensis should be established in the Colorado 

River watershed before the Recovery Plan has been revised. We are not recommending, 

as a routine flood mitigation measure, that snails or vegetation be moved to higher 

elevations.

Recommendation 7. The Recovery Plan for the Oxyloma populations in this region should be rewritten as soon as the major taxonomic issues are resolved. The Vasey’s Paradise population 

may warrant listing and conservation as a distinct, imperiled taxon, perhaps as a single-site 

endemic.

The KAS ad hoc agrees with the Panel and the KAWG that the Kanab Ambersnail 

Recovery Plan should be rewritten as soon as major taxonomic issues are resolved. We 

agree with KAWG that the Panel’s second statement about listing the Vaseys Paradise 

population as a “distinct, imperiled taxon” was somewhat speculative, pending additional 

research on genetics, morphology, taxonomy and population dynamics, and that an 

interim strategy is needed for obtaining the recommended data.

Recommendation 8. The administrative and management implications of new taxonomic 

findings should be discussed and disseminated widely and promptly to all parties. Any 

subsequent management or recovery plan should be subjected to a review process similar to that 

of this panel prior to implementation.

The KAS ad hoc concurs with the Panel and with KAWG. The Recovery Team, Federal 

Register Notice, and external peer reviews can accomplish this.

Recommendation 9. Our conclusions suggest a reconsideration of current management 

direction for these snails and their ecosystems.
12

The KAS ad hoc concurs with the Panel and with KAWG. We think that the series of 

reviews on management practices for the VP Oxyloma, including ours, have been very 

beneficial in setting management direction and objectives for this taxon and other 

inhabitants of spring habitats in the Colorado River ecosystem.