Borders, Boundaries, and Time Scales
Fronteras, Limites, y Escalas de Tiempo
Proceedings of the Sixth Conference on Research and
Resource Management in the Southwestern Deserts
ExtendedAbstracts: December 2006
Bill Halvorson, Editor
USGS Southwest Biological Science Center
Sonoran Desert Research Station
MAR - 1 2007
Native Fish Conservation and Climate Variability in
Doug Dunam' and Cregg Garfirl. 'U.S. Fisll 6- Wildlife
Xn';ct; ~CLJMj£,S- University 0/Arizona
The conservalion of nati,'c fish in southeastern Arizona
has always been reliant on finding waler that isn't "used," or
that is not constr.'lined by conflicts thai make sites
unavailable. Examples of conflicts that may render a site
unsuitable or unusable for native fish are: sport fisheries:
low-quality effluent; nonindigcnolls fish; and lando'ller.
lessee, or permittee resistance.
In addition 10 conflicts listed abo'e, the multiple
impacts flowing from other human activities in
southeastern Arizona also impacl ,,'aters. Another issue
impacting waters for native fish conservation is that other
rare aquatic species in southeastern Arizona also need
many of these valers. Some fish species arc not compatible
with other aquatic species in some sites. Climate variability,
including drought, and climate change both have the
potential to al!<'T sitrs for conservation of native fishes in
Here we consider southeastern Arizona that area east of
lhe Tohono O'odham Nation and the lower-most (north)
Santa Cruz River, and south of the Gila River. This area
includes parts of the Rio Concepcion, Santa Cruz River,
San Pedro River, Rio Yaqui, and Gila River Basins.
Depending on how they arc included, split, or lumped,
there are 21 species of native fish in southeastern Arizona.
Of those 21 species, 16 still occur in the area. four are
extirpated, and one is extinct. There are 13 species listed
under the Endangered Species Act; nine arc listed as
endangered, four as lhreatened, and an additional species
has been petitioned for listing.
There are a multitude of issues facing native fish in the
study area. Threats that have been factors in the listing of
fish and continue today include the standard litany:
nonindigenous species. species' habitat loss, and reduction
in habitat quality. Habitat destruction and the introduction
of nonindigenous species are responsible for the decline of
98 percem of North American fishes listed as endangered,
threatened, or of special concern (Williams et al. 1985).
Impacts to habitat and impacts from nonindigenous
spedes do not occur independently. Degradation ofaquatic
S)'Stems is a major faclor in the invasion, establishment.
and irruption of nonindigenous species (Aquatic Nuisance
SpecicsTask Force 1994).
Though the discussion here centers on native fish, it is
likely that negative impacts could also occur to olher native
aquatic vertebrates. There are three native ranid frogs
(Rana spp.) and a native salamander (Ambysroma tigr;l1l1m
srrbbet,sj) in southeastern Arizona. There are also several
garter snakes (11lamnoplJis spp.). All arc ofconservation
concern. The single greatest difference in how impacts to
aquatic systems will impact nati'e fish or herpetofauna, is
that the herpetofauna are far more mobile than fish and at
least ha'c the potential to move between aquatic s}'Stems.
That southeastern Arizona and much of the American
Southwest are in drought is well known. What is known
with far less certainty is how long this drought mightlasl.
Currently, only seasonal drought predictions are available
for three-month seasons (e.g.• February·Apri1), at a lead
time of two weeks in advance (e.g., issued January 15).
These predictions. based on a subjecti'e combination of
results of statistical and dynamical climale models and
insights from past climate history, are a'3ilable through the
NOAA Climate Prediction Center. State-of-the-art climate
science does not yet support multi-year or decade-scale
drought predictions. However, instrumental and
paleoclimate records from the South'est indicate that the
region has a history of multi-year and multi-dCClde
drought (Hereford el al. 2002; Jacobs et a!. 2005; Sheppard
et oIl. 2002). Multi-decade drought in the South'est is
controlled primarily by persistent Pacific Ocean-
atmosphere interactions. which have a strong effect on
winter precipitation (Brown and Comrie 2004; Schneider
and Cornudle 2005); persistent Atlantic Ocean circulation
is theorized to ha'e a role in multi-decadal drought in the
Southwest, particularly with respect to summer
precipitation (Gray et al. 20CB; McCabe et al. 2(04). Given
these multi-decade "regimes" of ocean circulation. and the
severity and persistence of the present multi-rear drought,
there is a fair likelihood that this droughl will persisl for
many more years. albeit with periods of high rear-to·year
precipitation variability characteristic of Southwest climate.
The information on how climate change might impact
southeastern Arizona is less certain than currenl drought
predictions. Howevcc, virtually all climate change scenarios
predict that the American Southwest will get '3rmer
during the 21st century (lPeC 2001). Precipitation
predictions show a greater range of possibilities, depending
on the model and emissions scenario (USGCRP 2001). To
maintain the present water balance with warmer
lemperatures and all other biotic and abiotic factors
constant, precipitation will need to increase to keep pace
with the increased evaporation and transpiration caused by
'3rmer temperatures. Key projections 10 keep in mind
• decreased snowpack - an increasing fraction of
winter precipitation could fall as rain instead of snow,
periods of sl10wpack accumulation could be shorter,
and snowpacks could be smaller; ironically, due to
changes in snow-precipitation characteristics. runoff
may decrease e"Cn if total precipitation increases
Borders, Boundaries, and TIme Scales 2006 41 CONSERVATION
• earlier snowmelt - increased minimum winter and
spring temperatures could melt snowpacks sooner,
causing peak water flows to occur that much sooner
than the historical spring and summer peak flows
(Stewart et aI., 2(04);
• enhanced hydrologic cycle - in a warmer ,rorld an
enhanced hydrologic cycle is expected; flood extremes
could be more common causing more large floods;
droughts may be more intense. frequent, and longer-
Continuing drought and climate change, when added
to the historical and continuing threats, will make native
fish conservation in southeastern Arizona even more
difficult. The impact to fish of site desiccation is obvious.
There are many less obvious effects that could occur with
drought and a wanner climate. A site with reduced
str~mf1ow, or a pond or pool with low water levels could
become fishless due to reduced dissoh-ed oxygen. We haw
set"n this occur at three important natural Gila topminnow
(P. ocddenrafjs) sites (i.e. Sharp Spring, Redrock Canyon,
Drought and climate change will also impact
watersheds and subsequently the water bodies in those
watersheds. Drought, and especially long-term climale
change will impact how ecosystems and watersheds
function. These changes will cause a cascade ofecosystem
changes, which may be hard to predict and are likely to
As an example. drought and climate change will cause
changes in fire regimes in all southeastem Arizona
vegetation communities. The timing, frequency. extent, and
destructiveness of wildfires is likely to increase and may
also facilitate the invasion and increase of nonindigenous
plants. These changed fire regimes will change vegetation
communities, the hydrological cycle, and nutrient cycling
in affected watersheds (Brown ct OIL 2004). Some regional
analyses conservatively predict that acreage burned
annually will double with climate change (MacKenzie el a1.
2004). Such watershed impacts could cause enhanced
scouring and sediment deposition, more extreme flooding
(quicker and higher peak flows), and changes to water
quality. ) Severe watershed impacts such as these, 'hen
added to reductions in e~1ant aquatic habitats. will severely
restrict sites ll'ailable for the consenration of nati"e fish
and other aquatic vertebrates and make management of
extant sites more difficult.
Many of the predictions about the impacts of climate
change arc based on modcling. but man}' predictions have
already occurred. The tree die-offs and fires that have
occurred in the Southwest early in this century shO' the
impacts of the curren! drought.
The potenlial impacts from climate change and drought
need to be addressed, while considering the potential
duration of and uncertainly of their effects. The
precautionary principle should be adhered to when
planning for native fish conservation. While there may not
necessarily be solutions to the problems presented by
drought and climate change, there are things that can be
done to minimi7-c the impacts to native fishes and increase
the resilience of fish habitat in southeastern Arizona.
After the fires of 2005, the Ari7.0na Game and Fish
Department and U.S. Fish and Wildlife Service began
drafting a salvage protocol for native fish. This protocol
should be expanded to include any impacts to nati>e fish,
such as drought and climate change, invasion of
nonindigenous species, and release of em'ironmental
We recommend the following actions:
• Natural resource managers should be informed about
• Constructive dialog regarding native fish consen-ation
needs and drought and climate change should occur
• Consen'ation planning should address climate change
through adaptive management provisions;
• Important fish populations should be replicated across
the landscape when possible:
• Important fish populations should be replicated in
• Genetic information will be crucial to determine
• Natural resource and land management agencies
should begin work on identifying and creating
potential refuge sites.
Regular and systematic monitoring of important
aquatic sites and fish populations, and expanded
monitoring programs are essential to enhancing drought
prerarcdness for fish conservation. Also, research focused
on specific impacts of climate change in southeastern
Arizona would be incredibly useful 10 managers. Lastly, th"
uncertainty surrounding the timing and impacts of climate
change requires flexibility and the need for adaptive
management Agencies do not have a good track record of
effectively implementing adaptive management, but the
conservation of native fish and other aquatic wrtebrates
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La conservaci6n de peces nativos en el surestI.' de
Arizona ha sido sicmpre un asunto rclacionado con
encontrar agua que no estc slendo "us.1da~ 0 tenga
confliclos que haccn cl sitio indisponible. Ejemplos que
causan a un sitio inapropiado 0 inusable para peces nativos
son: pesca deportiva, aguas corrientes de baja calidad, peces
no nativos y uso por ganado. La variabilidad c1imatica, es
dccir.los cambios c1imaticos y la sequia tiencn eI potencial
de aherar negativ3 )' dr.i5ticamente las actividadcs de
conserv3ci6n para peces nath'Os. Adcffias de los impactos
enlistados arriba, los impaetos multiples que fluyen de
actividades humanas en eI sureste de Arizona tambien
impactan las aguas. EI ultimo asunto que impacta las aguas
para consen'3ci6n de peces nativos 10 conforman otras
especies acuaticas raras en el sureste de Arizona (ranas
r3nidas y una salamandra) tambien necesitan muchas de
estas aguas. A!gunas especies de peces pueden no ser
compatibles con otras especies acu31icas raras en algunos
sitios. Los impactos potenciales del cambio c1imatico y la
sequla nccesitan ser alcndidos par cl factor tiempo y la
incertidumbre de los cfcclOS. Debe anadirse el principio
preventivo a los planes de conservaci6n para peces nativos.
Aunque puede no haber necesariamente soluciones a los
problemas prcsentados por la sequla y los cambios
c1imaticos. existen cosas que pucdcn hacerse para
minimizar los impactos en peces nati'os del $Urestc de
Borders, Boundaries, and Time Scales 2006 43 CONSERVATION