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: Inadequate information on nonnative parasites and pathogens
The recovery plan has many statements about reducing nonnatives to manageable or controlled levels,
but never explains what “manageable” or “controlled” means, or provides measurable targets. We ask
the Service to define what manageable and controlled mean for the threats of nonnative parasites and
pathogens as well as for nonnative fish. We question the idea of reducing nonnatives to “manageable
levels”. It takes only two fish to start a nonnative population, and one infected fish to introduce parasites
and pathogens. We find nothing in the recovery plan about management actions for the parasites and
pathogens (Asian tapeworm, “Ich”, anchorworm) that are identified in the Final Rule. The management
actions in the plan (fish barriers, isolation) address nonnative fish but do not address nonnative parasites
and pathogens. The Service is directed by the ESA to address the threats identified in the Final Rule.
Page vi of the plan lists the recovery objectives. Objectives 1, 2 and 3 are:
1. Maintain and protect all remnant populations in the wild.
2. Ensure representation, resiliency, and redundancy by expanding the size and number of
populations within Gila chub historical range via replication of remnant populations within each
RU.
3. Manage or eliminate threats of predation and competition with nonnative fishes and associated
habitat-related modifications or loss.
For objective 1, to protect the remnant populations in the wild, the Service will have to address the
parasites and pathogens. The plan has no discussion of this. Objective 2 will require fish to be
established in currently unoccupied locations, some of which are likely infected with parasites and
pathogens. There is no discussion of how these would be removed to make the locations safe for the Gila
chub. Objective 3 discusses only nonnative fish. One might read between the lines to guess that
“associated habitat-related modifications” could include habitat inflected with parasites and pathogens.
But we shouldn’t have to make guesses. We ask the Service to clarify what this means. We ask that
management of parasites and pathogens be explicitly included under Objective 3.
Treatment for parasites and pathogens typically requires keeping the fish contained in water that is being
dosed with the treatment. Fish that are disease free in a refuge will become infected if returned to infected
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habitats. The recovery plan does not discuss how or if infected habitat would be treated to cleanse them
of nonnative parasites and pathogens. The Service must describe the consequences if the habitats are
not treated, and what that means for recovery of the Gila chub. This would also apply to the plan’s
proposals to prepare currently unoccupied areas to receive salvaged or refugia chub. Since there are no
management actions for parasites and pathogens, we ask if cost estimates for these are included in the
costs of recovering the species.
The issue of nonnative parasites and pathogens must be identified as a threat separate from nonnative
fish, because the challenges and management actions are different. The threat of the nonnative
parasites and pathogens must be ranked, separately and in relationship to nonnative fish. The ranking of
the parasites has to consider their relationship to other threats, as indicated at page 20: (bold added).
While currently known nonnative diseases appear affect Gila chub survival, they do affect other species
and are modifying the ecosystem.
Nonnative parasites such as Asian tapeworm, Ich, and anchor worm are found within the Gila
basin (USFWS 2005b). The effects of nonnative parasite infections can be exacerbated
when combined with other environmental stressors such as temperature variations and
food reduction, which lead to increased mortality of infected fish (USGS 2004, 2005). See
section I.6 Life History and Population Ecology (above) for a more detailed description of the
impacts of parasites on Gila chub and native fishes in general. No diseases have been identified
that appear to affect Gila chub survival.
The actions proposed for nonnative fish (i.e. fish barriers and isolation) are not effective for habitats
already containing nonnative parasites and pathogens. A discussion of the management actions for
nonnative parasites and pathogens must necessarily address what to do with desirable native species
(fish, plants, invertebrates) that may be carrying the nonnative parasites and pathogens.
Page 64 informs us that the proposed management actions of piscides and mechanical removal will not
control the threat. It is obvious that partial removals or treatments only leave individual nonnatives to
repopulated the habitat. The statement about novel methods being used as they are developed is
hopeful, but hope does not qualify as a management action under the ESA. (bold added)
Piscicides are ineffective against species such as nonnative crayfish, however, and it may
not be possible to completely rid a stream of all unwanted nonnatives. Mechanical control of
nonnatives may be practical in certain limited circumstances. Novel control methods should be
considered for implementation as they are developed.
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REMEDY: Provide describe the management actions for the addressing nonnative parasites and
pathogens in occupied and unoccupied habitat. Clearly identify if there are no management actions
available for certain threats. Explain what “manageable” and “controlled” mean for nonnative fish,
parasites and pathogens. Provide cost estimates for treating nonnative parasites and pathogens as part
of the required cost estimates in the recovery plan. The costs should include treatment of habitats and
consideration of infected native species.
Thank you for the opportunity to comment,
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