December 25, 2015
Steve Spangle, Field Supervisor
Arizona Ecological Services Office
2321 West Royal Palm Road
Phoenix, Arizona 85021
602/242-0210, x-244
Comment on Gila Chub Draft Recovery Plan, FR Doc No: 2015-27259
sent by email to Steve_Spangle@fws.gov
ISSUE: Isolation management and recovery to delisting
The recovery plan makes many statements about management actions and isolation management.
Isolation management is contrary to the goals of natural connectivity, natural functioning and genetic
exchange among metapopulations etc. The recovery plan also makes statements that the Gila chub is
more vulnerable to extinction because desiccation has created isolated populations. But the challenges in
the habitat are so severe that isolation is presented as the only viable solution. At page 51 we find the
statements that isolation will prevent the genetic exchange needed for long term survival, but it is
the needed solution.
Fragmentation/genetic isolation
An essential element for long-term survival of a species is connectedness among populations that
allows for exchange of genetic material that can enhance a species’ ability to adapt to changing
environments (Pringle 2001, Hermoso et al. 2011). Evidence from genetic studies (Schwemm
2006, Dowling et al. 2008, Dowling 2013) indicates Gila chub likely exhibited a metapopulation
distribution with movement of individuals among populations in the same subdrainages during
pluvial times and isolation during drier periods. Most Gila chub populations are now mostly
isolated from each other due to interference by nonnative fishes, desiccation of connecting
habitats, and other factors.
Given the degree of human impacts to streams of the Gila River basin, natural connectivity
among populations of Gila chub is unlikely now and in the foreseeable future. In fact, the
near-ubiquity of nonnative fishes across the Gila River basin that are known to suppress
or eliminate populations of Gila chub (e.g., Dudley and Matter 2000) requires that the
native and nonnative taxa be segregated (see Fausch et al. 2009 for a discussion of the
tradeoffs between connectedness and isolation relative to threats of nonnative fishes). Such
isolation management (Novinger and Rahel 2003) is typically practiced via placement of artificial
barriers that prevent upstream movements of fishes, management upstream of natural barriers,
or directed control of nonnative fishes where barriers do not exist. Provision for genetic
connection among such segregated tributary populations will likely occur only from
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human-assisted transfers, guided by genetic information to inform managers of levels of
past connectivity. In the absence of nonnative fishes, retention of connectivity among
populations is the preferred management condition. However, where nonnative fishes
threaten persistence of Gila chub, isolation management is the inelegant but compelling
approach to conservation.
The recovery plan does not reconcile the statements about isolation management with statements in
Table III.1 Major recovery objectives needed to recover the Gila chub. (p. 60).
Objective 1 is not possible because some habitats can’t be effectively isolated. The plan offers no
management actions to control nonnative parasites. Not all streams can be controlled with fish barriers.
Objective 2 could be met only by establishing “island” of genetically isolated populations. Objective 3 is
non-attainable according to the discussion on page 51.
Nevertheless, Table III.2 includes the recovery action under Listing Factor E, to “Maintain refuge
population until the species is delisted”. The recovery plan holds many statements like page 51
indicating that recovery in the ESA sense (self-sustaining wild populations) is high unlikely.
The plan is
tacitly proposing that the species be kept from extinction only by artificial means. It would require intense
human intervention, captive populations, manipulated breeding for genetics…and this would go on (as
page 51 says) “for the foreseeable future”. This means the species could never be delisted or at best
there is really no schedule and estimate of costs for delisting.
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Despite the somber assessment of the unpleasant reality, the recovery plan also makes oddly optimistic
statements that recovery actions could lead to delisting. For example, page 67 says that refuge
populations would be maintained as a necessary step on the way to delisting the Gila chub. Refuges are
described as suitable short term solutions. But according to page 51, refuges would have to go on
forever, to artificially support isolated populations and manipulate the genetics.
4. Establish and maintain refuge populations in protected ponds or hatcheries as appropriate
Establishment of refuge populations is a necessary step for downlisting until all available remnant
populations are replicated sufficiently in the wild to meet delisting criteria. Refuge populations in
theory should be simpler to establish than wild populations, but they require greater human
involvement to maintain over a long period of time. Refuges can provide suitable short-term
population redundancy until wild sites are established.
REMEDY: We have used these examples to show there are two very opposite views being presented in
the recovery plan. The Service needs to resolve this and decide where it stands and what actions it
supports. There is a big difference between admitting delisting is virtually impossible because the primary
threats are so intractable, and asserting that the Gila chub can be delisted if we just try long enough and
hard enough. The plan cannot present a coherent integrated proposal when it doesn’t know where it’s
headed. A plan for perpetual human intervention to support isolated populations is not the same as
recovery to achieve delisting, as described in the ESA. We also consider the estimates of costs of
recovery. We don’t know if these costs are based on the pessimistic assumption or the optimistic
assumption. If the pessimistic assumption holds, the time frame of recovery in 50 years is not supported.
The Service needs to answer these questions, for itself, for the public and for the other federal agencies
that look to the recovery plan as guidance for its decisions.
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