Chapter 1. Introduction
Adaptive Management Work Group Costs
AMWG Member Travel Reimbursement
AMWG Reclamation Travel
AMWG Facilitation Contract
Public Outreach
AMWG Other
TWG Costs
TWG Member Travel Reimbursement
TWG Reclamation Travel
TWG Chair Reimbursement/Facilitation
TWG Other
Administrative Support for NPS Permitting
Contract Administration
Science Advisor Contract
Experimental Fund
Installation of Acoustic Flow Meters in Glen Canyon Dam Bypass Tubes
Native Fish Conservation Contingency Fund
Cultural Resources Work Plan
Integrated Tribal Resources Monitoring
Tribal Participation in the GCDAMP
Chapter 2. U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and Research Center Triennial Budget and Work Plan—Fiscal Years 2015–2017
Introduction
Purpose
Administrative Guidance that Informs the FY15–17 Triennial Work Plan
Overview of the FY 15–17 Triennial Work Plan
Allocation of the FY15–17 Budget
References
Project 1. Lake Powell and Glen Canyon Dam Release Water-Quality Monitoring
Project 2. Stream Flow, Water Quality, and Sediment Transport in the Colorado River Ecosystem
This project makes the basic measurements that link dam operations and reservoir releases
to the physical, biological, and sociocultural resources of the Colorado River ecosystem (CRe)
downstream from Glen Canyon Dam. This project conducts the monitoring of stage, discharge,
water quality (water temperature, specific conductance, turbidity, dissolved oxygen), suspended
sediment, and bed sediment. Measurements are made at gaging stations located in Glen Canyon
National Recreation Area, Grand Canyon National Park, the Navajo Reservation, and the
Hualapai Reservation and on lands administered by the Bureau of Land Management. The data
collected by this project provide the stream-flow, sediment-transport, sediment-mass-balance,
water-temperature, and water-quality data that are required to link dam operations with the status
of the CRe. In addition, the data collected by this project are used to implement and evaluate the
High Flow Experiment (HFE) Protocol and in evaluations of alternatives being assessed by the
Long-Term Experimental and Management Plan (LTEMP) EIS. The data collected by this
project are also used in other physical, ecological, and socio-cultural projects described
elsewhere in this Triennial Work Plan. Other project funds support interpretation of basic data.
Project 3. Sandbars and Sediment Storage Dynamics: Long-term Monitoring and Research at the Site, Reach, and Ecosystem Scales
This project consists of a set of integrated studies that (a) track the effects of individual High-
Flow Experiments (HFEs, or “controlled floods”) on sandbars and within-channel sediment
storage, (b) monitor the cumulative effect of successive HFEs and intervening operations, and (c)
advance general understanding of sediment transport and eddy sandbar dynamics. While the first
two efforts are focused on monitoring, the latter effort is focused on improving capacity to
predict the effects of dam operations, because management of the Colorado River downstream
from Glen Canyon Dam requires that managers balance the objective to achieve fine-sediment
conservation with other management objectives. Such balancing of objectives requires
comparing predicted outcomes of different dam operation scenarios, such as has been pursued in
the Long-Term Experimental and Management Plan (LTEMP) Environmental Impact Statement
(EIS) process.
The effort to achieve fine-sediment conservation in the Colorado River ecosystem in Marble
and Grand Canyons (CRe) is greatly constrained by the limited annual supply of fine sediments
to the Colorado River from ephemeral tributaries. The challenge of rehabilitating sandbars when
most of the fine-sediment once supplied to the CRe is now stored in Lake Powell reservoir has
been described in many scientific articles and management documents. More than a decade of
monitoring and research has demonstrated that eddy sandbars accumulate sand, as well as small
amounts of clay and silt (hereafter referred to as mud), during short periods of relatively high
flow, but these same sandbars typically erode during flows that occur in the months to years
between the high flows requisite for sandbar building. Adoption of the HFE Protocol in 2012
established a formal procedure whereby seasonal sand and mud (together referred to as fine
sediment) inflows are measured, and high flows are released from Glen Canyon Dam with the
purpose of redistributing that sand and mud from the channel bed to eddies. The long-term effect
of the HFE Protocol depends on the relative “gain” to eddy sandbars that occurs during the short
controlled floods and the intervening “loss” that occurs during other times. The Environmental
Assessment for Development and Implementation of a Protocol for High-Flow Experimental
Releases from Glen Canyon Dam (hereafter referred to as the HFE Protocol EA) asked, "Can
sandbar building during HFEs exceed sandbar erosion during periods between HFEs, such that
sandbar size can be increased and maintained over several years?" In other words, does the
volume of sand aggraded into eddies and onto sandbars during controlled floods exceed the
volume eroded from sandbars during intervening dam operations?
Thus, one of the most important objectives of this project is to monitor the changes in
sandbars over many years, including a period that contains several controlled floods, in order to
compile the information required to answer the fundamental question of the HFE Protocol EA.
The monitoring program described here continues the program implemented in the FY13–14
Biennial Work Plan and is based on annual measurements of sandbars, using conventional
topographic surveys supplemented with daily measurements of sandbar change using ‘remote
cameras’ that autonomously and repeatedly take photographs. Because these long-term
monitoring sites represent only a small proportion of the total number of sandbars in Marble and
Grand Canyons, this project also includes (1) the analysis of a much larger sample of sandbars,
using airborne remote-sensing data of the entire CRe collected every 4 years, and (2) periodic
measurements of nearly all sandbars within individual 50 to 130 km river segments.
Another critical piece of information that will be needed to evaluate the outcome of the HFE
Protocol and the LTEMP EIS will be the change in total sand storage in long river segments.
HFEs build sandbars by redistributing sand from the low-elevation portion of the channel to
sandbars in eddies and on the banks. The sand available for bar building is the sand that is in
storage within the channel, which is the sum of the sand contributed by the most recent tributary
inputs, all the sand that has accumulated during the decades since Glen Canyon Dam was
completed, and any sand that remains from the pre-dam era. The goal of the HFE protocol is to
accomplish sandbar building by mobilizing only as much sand as is most recently contributed by
the Paria River. Some of the mobilized sand is deposited in eddies where it maintains and builds
eddy sandbars. Some of the sand is eventually transported downstream to Lake Mead reservoir.
The most efficient floods for the purposes of sandbar building are those that maximize eddy
sandbar aggradation yet minimize the amount of sand transported far downstream, thus
minimizing losses to sand storage. Dam operations between HFEs also transport sand
downstream, causing decreases in sand storage. If sand storage is maintained or increased,
scientists expect the response to future HFEs to be similar to or better than that observed
following recent HFEs. In contrast, depleted conditions of fine sediment in the active channel are
potentially irreversible and threaten the long-term ability to rehabilitate eddy sandbars. Although
the total amount of sand in the active channel is not known and may never be known, changes in
the topography of the channel measured in this project reveal where fine sediment accumulates,
where it becomes depleted, and whether or not older fine sediment deposits are being
progressively eroded by HFEs and other parts of the flow regime.
This project also includes five research and development components: (1) improving
methods for making sandbar surveys rapidly and at low cost; (2) investigating bedload sand
transport; (3) developing a method to estimate the thickness of submerged sand deposits, (4)
developing a method to map submerged aquatic vegetation, and (5) developing of a new largescale
sandbar deposition/erosion model. These projects are, respectively, designed to improve
monitoring methods, improve estimates of sand transport, develop a new tool to estimate total
sand storage, develop a new tool to map submerged aquatic vegetation and improve acoustic bed
sediment classifications, and develop new tools for predicting how management actions
including HFEs and daily dam operations affect resources.
Project 4. Connectivity along the fluvial-aeolian-hillslope continuum: Quantifying the relative importance of river-related factors that influence upland geomorphology and archaeological site stability
The rate and magnitude of wind transport of sand from active channel sandbars to higher
elevation valley margins potentially affects the stability of archaeological sites and the
characteristics of other cultural and natural resources. The degree to which valley margin areas
are affected by upslope wind redistribution of sand is called “connectivity”. Connectivity is
affected by several factors including the sand source as well as physical and vegetative barriers
to sand transport. The primary hypothesis of this project is that high degrees of connectivity lead
to potentially greater archaeological site stability.
This project is responsive to recommendations from stakeholders in the Glen Canyon Dam
Adaptive Management Program. The Bureau of Reclamation, the National Park Service, and the
tribes, collectively have identified the need for science that will improve understanding of how
cultural resources are linked to modern river processes. This project proposal is composed of two
integrated elements; the first (4.1) is a research element, and the second (4.2) is a monitoring
element. The research element (4.1) consists of three sub-elements that are landscape scale
analyses that will examine the connectivity between attributes of the active channel and
geomorphic processes and patterns at higher elevations (above the 45,000 ft3/s stage) at several
temporal and geographic scales. In the monitoring element (4.2), a year (2015) will be invested
to develop and draft a long-term monitoring plan to evaluate if and how much the interactions
between fluvial, aeolian, and hillslope processes affect the condition of cultural resource sites in
the Colorado River corridor. The monitoring plan will be drafted by USGS scientists with close
collaboration from tribes, National Park Service, and Bureau of Reclamation. The monitoring
plan will be implemented in years 2 and 3 (2016 and 2017, respectively) of the triennial workplan
effort.
Project 5. Foodbase Monitoring and Research
The productivity of the aquatic foodbase, particularly invertebrates, fuels production and
growth of fishes in the Colorado River. However, recent studies by Kennedy and collaborators
have shown that the productivity of this foodbase is low. Further, the foodbase in Grand Canyon
is dominated by only two groups of invertebrates: midges and blackflies, both of which are
small-bodied, relatively low-quality prey. Larger, more nutritious aquatic insects such as
mayflies, stoneflies, and caddisflies (hereafter, EPT), are virtually absent throughout Glen,
Marble, and Grand Canyons. These conditions of low invertebrate productivity and the absence
of high quality invertebrate prey have resulted in a fishery throughout Glen, Marble, and Grand
Canyons that is food-limited, negatively affecting the abundance of native fishes such as
humpback chub (Gila cypha), as well as the growth of recreationally-important non-native
rainbow trout (Oncorhynchus mykiss). If the factors and stressors affecting this low foodbase
productivity and diversity can be isolated, adaptive management experimentation intended to
ameliorate these stressors, and benefit the productivity and diversity of the aquatic foodbase,
could be considered.
In this proposal, we describe a multi-faceted approach to better understanding the conditions
effecting the low productivity and diversity of the foodbase in the Colorado River, as well as an
experiment to potentially improve these conditions. We focus principally on two methods:
sampling emergent aquatic insect adults on land, and sampling aquatic invertebrate larvae in the
drift. Sampling emergent insects allows for the observation of large-scale patterns in insect
dynamics through time and over large spatial scales, such as throughout the entire Colorado
River in Grand Canyon. In contrast, sampling invertebrate drift allows us to understand the finescale
factors affecting invertebrate populations, particularly during a phase (drifting in the water
column) in which these invertebrates are most available to fish. To a lesser extent, we also
describe the continuation of a monitoring effort to estimate algae production in the Colorado
River, which represents the base of the entire aquatic food web and the food resources available
to these invertebrate populations.
Many of the studies we propose here are logical continuations of projects initiated in FY13–
14, such as an expansion of the citizen science monitoring of emergent insects and the
development of a more mechanistic understanding of the factors controlling invertebrate drift. In
addition, we intend to synthesize published datasets to explore the factors affecting invertebrate
productivity, diversity, and EPT abundance throughout tailwaters in the Intermountain West. We
will couple this synthesis with natural history observations and lab studies of invertebrates in the
Colorado River and adjacent ecosystems. The goal of those studies is to better understand how
the specific insects present in the Colorado River and its tributaries in Glen, Marble, and Grand
Canyons respond to environmental conditions such as altered temperature regimes and daily
hydropeaking. We also propose to carry out insect emergence and drift studies in other Colorado
River Basin tailwaters and in Cataract Canyon to better characterize aquatic foodbase conditions
in reference ecosystems, and to determine whether the foodbase downstream of Glen Canyon is
unique, or broadly similar to other river segments in the region. Finally, based on logic described
below, we identify recruitment limitation of insects as a primary stressor limiting both
invertebrate production and the colonization of EPT in the Colorado River in Glen, Marble, and
Grand Canyons. Accordingly, we outline a flow experiment that could be implemented in FY15–
17 involving weekend summer steady flows that may mitigate this recruitment limitation. If
successful, this experiment would improve the short- and long-term productivity and diversity of
the aquatic foodbase and, ultimately, the condition of fish populations and the stability of food
webs in the Colorado River.
Project 6. Mainstem Colorado River Humpback Chub Aggregations and Fish Community Dynamics
Native and nonnative fish populations in Glen and Grand Canyons are key resources of
concern influencing decisions on both the operation of Glen Canyon Dam and non-flow actions.
To inform these decisions, it is imperative that accurate and timely information on the status of
fish populations, particularly the endangered humpback chub (Gila cypha), be available to
managers. A suite of adaptive experimental management actions are either underway or being
contemplated to better understand the mechanisms controlling the population dynamics of fish in
the Colorado River in Glen and Grand Canyons and to identify policies that are consistent with
the attainment of management goals. Much effort has been and continues to be focused on
humpback chub and rainbow trout (Oncorhynchus mykiss) both in the reach of the Colorado
River from Glen Canyon Dam to the Little Colorado River (LCR) confluence and in the LCR
itself (see Projects 7 and 9). While this work is important and meets critical information needs, it
is also important to have robust monitoring of mainstem fish populations downstream of the
LCR confluence. Status and trend information is needed to further understand mechanisms
controlling native and nonnative fish population dynamics, determine the effects of dam
operations and other management actions, and identify evolving threats presented by expansion
in range or numbers of nonnative predators. This type of information is also potentially useful in
assessing changes to the Federal Endangered Species Act listing status of humpback chub in
Grand Canyon.
Sampling mainstem humpback chub aggregations has been conducted periodically over the
last two decades. Fish were sampled by hoop and trammel nets at aggregations first described by
Valdez and Ryel (1995). Most captures of humpback chub in the mainstem Colorado River have
been downstream of the LCR (Persons and others, in preparation). Continuing to sample for
humpback chub in the mainstem river outside of the LCR and the LCR confluence area is
important for monitoring the status of the Grand Canyon population of this endangered species
and determining the effects of management actions like dam operations and translocations.
During the last few years the first 75 miles of the Colorado River downstream of Glen
Canyon Dam has been sampled extensively for fish by several projects including the following
projects in the USGS Grand Canyon Monitoring and Research Center’s (GCMRC) FY11–12 and
FY13–14 work plans:
- E.2 Juvenile Chub Monitoring Project near the LCR confluence Near Shore Ecology Project; BIO 2.R15.11 in FY11–12; and Project Element F.3 in FY13–14,
- H.2 Rainbow Trout Movement Project, a.k.a. the Rainbow Trout Natal Origins Project; Project Element BIO 2.E18 in FY11–12; and Project Element F.6 in FY13–14,
- D.4 System Wide Electrofishing Projectl; Project Element BIO 2.M4 in FY11–12; and Project Element F.1 in FY13–14
- H.1 Lees Ferry Trout Monitoring Project; Project Element BIO 4.M2 in FY11–12; and Project Element F.2 in FY13–14
- D.7 Rainbow Trout Early Life Stage Survey Project; RTELSS, Project Element BIO 4.M2 in FY11–12; and Project Element F.2.2 in FY13–14
The remaining portion of the Colorado River downstream of Glen Canyon Dam (between
approximately the LCR and Lake Mead) has been sampled using standardized methods since
2000 as described in Project 6.4, the System Wide Electrofishing Project and since 2010 as
described in Project 6.1, the Mainstem Humpback Chub Aggregation Monitoring Project. In
order to improve efficiencies and to reduce duplication of effort, GCMRC and cooperating
agencies conducting fisheries monitoring and research propose to coordinate and/or combine
several project elements in GCRMC’s FY15–17 work plan. These include the Juvenile Chub
Monitoring project and System Wide Electrofishing effort (see Project Elements 7.2 and 6.4) as
well as the Rainbow Trout Natal Origins study and Lees Ferry Trout Monitoring (see Project
Elements 9.1 and 9.2). In general, this will mean a reduction of electrofishing effort in the first
70 miles of the Colorado River downstream of Glen Canyon Dam and a focus on obtaining
abundance estimates rather than catch per unit effort (CPUE) indices through the updated Lees
Ferry Rainbow Trout Monitoring project (see Project Elements 9.1 and 9.2). Systematic
sampling of the mainstem Colorado River downstream of the Juvenile Chub Monitoring (see
Project Element 7.2) reference site (River Mile (RM) 63-64.5) will continue under Project
Elements 6.1, 6.2, and 6.4 (see Section 4) and will continue to collect and analyze species
composition and CPUE data.
Project 6 is comprised of eight Project Elements and includes monitoring and research
projects in the mainstem Colorado River, with particular emphasis on humpback chub
aggregations. Over the last several years humpback chub in the LCR aggregation have increased
in abundance (Coggins and Walters, 2009; Van Haverbeke and others, 2013; Yackulic and
others, 2014). Humpback chub at many other aggregations have also increased in abundance, and
some aggregations appear to have increased their distribution (Persons and others, in
preparation). Recruitment to aggregations may come from local reproduction (e.g. 30 Mile
aggregation; Andersen and others, 2010; Middle Granite Gorge Aggregation; Douglas and
Douglas, 2007), the LCR aggregation, and translocations to Shinumo and Havasu Creeks.
Annual monitoring of the status and trends of the mainstem humpback chub aggregations has
been identified as a conservation measure in a recent Biological Opinion (U.S. Fish and Wildlife
Service, 2011) and will continue to be monitored in Project Element 6.1, although effort will be
reduced to a single trip per year down from two trips annually in the FY13–14 work plan. We
will also continue to sample in conjunction with the National Park Service (NPS) near Shinumo
Creek and Havasu Creek to assess contribution of translocated humpback chub to mainstem
aggregations.
Understanding recruitment at aggregations continues to be an area of uncertainty. Humpback
chub otolith microchemistry (Hayden and others, 2012; Limburg and others, 2013) was proposed
as a method to determine sources of humpback chub recruitment in the FY13–14 Work Plan.
However, due to Tribal concerns about directed take of humpback chub we were unable to
collect the otoliths necessary for these analyses. During FY15–16 we plan to further evaluate the
use of otolith microchemistry to identify surrogate fish hatched in Shinumo Creek, Havasu
Creek, 30-Mile springs or other locations in Project Element 6.2. We will work with NPS staff to
collect water samples and otoliths from brown trout (Salmo trutta), rainbow trout, and other
fishes sacrificed as part of their trout removal activities. We will also make use of any humpback
chub incidentally killed during other sampling efforts. Further, we will place additional emphasis
on catching and marking juvenile humpback chub to assist in determining sources of recruitment
to aggregations. During FY15–16 we propose to evaluate slow shocking and seining as methods
to capture and mark more juvenile humpback chub with passive integrated transponder (PIT)
tags in order to assess juvenile humpback chub survival and recruitment to aggregations. This
will also provide a possible method to assess dispersal of juvenile humpback chub marked in the
LCR with visible implant elastomer (VIE) and PIT tags (see Project Element 7.3).
Project Element 6.3 will continue efforts that began in the FY13–14 work plan to locate
additional aggregations by standardized sampling and by the use of remotely deployed PIT-tag
antennas. GCMRC has had success in deploying relatively portable PIT-tag antennas in the LCR
and proposes to work with NPS and U.S. Fish and Wildlife Service (USFWS) personnel to
develop antenna systems that can be deployed at mainstem aggregations and other locations to
detect PIT-tagged fish. If successful, these systems will provide an opportunity for collaborative
citizen science with commercial and scientific river trips whereby river guides could deploy
antennas overnight at camp sites in an attempt to detect PIT-tagged fish in areas not sampled
during mainstem fish monitoring trips.
The System Wide Electrofishing Project (Project Element 6.4) will continue to collect longterm
monitoring data following the methods described in Makinster and others, (2010) and will
evaluate the efficacy of a mark-recapture approach downstream of the LCR confluence. To
eliminate duplicative efforts, we propose that sampling be conducted in areas not sampled by the
Rainbow Trout Natal Origins and the Juvenile Chub Monitoring projects (Project Elements 7.2
and 9.2). We will also increase sampling effort downstream of Diamond Creek to monitor for
native and non-native fishes. Continued concerns over upstream movement of non-native
warmwater predatory species such as striped bass (Morone saxatilis), largemouth bass
(Micropterus salmoides), channel catfish (Ictalurus punctatus) and walleye (Sander vitreus)
from Lake Mead highlight the need to continue to monitor the river for non-native fishes.
Electrofishing is effective at capturing bass species, sunfishes (Centrarchidae), and walleye, so
this sampling should detect upstream movements of these species. Channel catfish on the other
hand, are not effectively captured by electrofishing, so monitoring of catfish distribution by
standardized angling (Persons and others, 2013) will continue during electrofishing trips.
Standardized electrofishing sampling is also effective at capturing native sucker species
including flannelmouth sucker (Catostomus latipinnis), bluehead sucker (Catostomus
discobolus), and razorback sucker (Xyrauchen texanus). Recent captures of razorback sucker
downstream of Diamond Creek by this project have been widely publicized and ongoing
monitoring will help document if this once extirpated species continues its apparent recolonization
of Grand Canyon.
Nonnative brown trout are effective fish predators known to preferentially prey on native
Colorado River fishes including humpback chub (Yard and others, 2011). Determining the
source or sources of this species in Grand Canyon will help scientists and managers better target
efforts aimed at controlling this threat to native fish populations (see Project Element 8.1).
Project Element 6.5 will conduct research on the use of brown trout pigment patterns to identify
natal origins of brown trout; data and images will be collected during the System Wide
Electrofishing Project and other projects that encounter brown trout.
One risk to the Grand Canyon humpback chub population is that it includes only one selfsustaining
spawning population, the LCR aggregation. The USFWS has identified the
establishment of a second self-sustaining spawning population of humpback chub as an
important step towards recovery of this endangered species (U.S. Fish and Wildlife Service
1995). Project Element 6.6 will develop plans and conduct necessary compliance activities to
experimentally translocate humpback chub from the LCR to a mainstem aggregation in 2016 or
later.
The Rainbow Trout Early Life Stage Survey (Project Element 6.7 - RTELLS) seasonally
monitors rainbow trout egg deposition and population early life history dynamics, particularly
age-0 survival in Glen Canyon. This project in particular, provides managers with an initial
indication of the annual cohort strength of rainbow trout recruiting into the population. Findings
from this also have relevance to the Natal Origin research project (see Project Element 9.2).
The Lees Ferry Creel Survey (Project Element 6.8) monitors the health of the rainbow trout
fishery and provides information on the influence of Glen Canyon Dam operations, other
management actions, and natural disturbances on recreational fishing. Information on the levels
of direct harvest as well as angler use and satisfaction of the important recreational fishery is also
provided.
Project 7. Population Ecology of Humpback Chub in and around the Little Colorado River
During 2013–14 we developed models that integrate data collected in the Little Colorado
River (LCR) with data collected by the juvenile chub monitoring (JCM) project to provide a
holistic picture of humpback chub (Gila cypha) population dynamics (Yackulic and others,
2014). This manuscript suggests that chub movement between the LCR and Colorado River prior
to adulthood is relatively rare, with the exception of young-of-the-year outmigration and that
growth and survival rates are very different in these two environments. This journal article also
identified the need for studies of trap avoidance among older humpback chub in the LCR, a need
that can potentially be addressed by increased use of remote technologies for detecting
humpback chub. We then used a modified version of these models to explain interannual
variability in mainstem growth and survival in terms of monthly temperature and estimated
rainbow trout (Oncorhynchus mykiss) abundances in order to support the development of the
Glen Canyon Dam Long-Term Experimental and Management Plan (LTEMP) Environmental
Impact Statement and address the key uncertainty surrounding the relative importance of
rainbow trout and temperature in humpback chub population dynamics (Yackulic and others, in
prep.). While parameter estimates in these models are based on field data collected in the LCR
and JCM, this modelling was aided conceptually by lab experiments exploring impacts of trout
and temperature on chub growth and survival (Ward and others, in prep).
Simulating future dynamics under alternative management strategies as part of the LTEMP
process highlighted the importance of uncertainty associated with several key population
processes, especially the production and outmigration of young-of-the-year humpback chub from
the LCR. Available information suggests that the number of Age-0 chub present in July in the
LCR has varied from roughly 5,000 to 50,000 in recent years and that the overall outmigration
rate can vary from 25% to 75%. To address this uncertainty, already identified in the Grand
Canyon Monitoring and Research Center’s workplan for Fiscal Years (FY) 2013–14, we initiated
juvenile humpback chub marking with visible implant elastomer (VIE) tags in the LCR during
early July, a period when humpback chub are just becoming large enough to have a reasonable
chance of surviving in the mainstem. Although LTEMP obligations have delayed a formal
analysis of these data, preliminary work suggests that this effort will allow us to estimate
juvenile humpback chub abundance and outmigration with acceptable precision. We also
analyzed data collected by the U.S. Fish and Wildlife Service (USFWS) from 2001–2013 to
characterize spatio-temporal variation in survival, growth and movement of sub-adult humpback
chub in the LCR (Dzul and others, in review). This work suggests both that winter growth is
strongly and negatively correlated with the extent of winter/spring flooding and that habitat
quality for sub-adult humpback chub is better in upper reaches of the LCR. This follows work by
Vanhaverbeke and others (2013) indicating that when winter/spring flooding was minimal,
juvenile production was poor. Other activities during FY13–14 included pilot work to determine
the best ways to characterize spatio-temporal variation in the food base in FY13, with plans to
rigorously sample the LCR food base in calendar year 2014.
In FY15–17, we will: (a) continue to monitor humpback chub in the LCR and Colorado
River reference site (river mile (RM) 63.0-64.5) and to mark young-of-year humpback chub
throughout the lower 13.6 km of the LCR in July, (b) develop field and analytical techniques to
better use remote technologies for detecting passive integrated transponder (PIT) tags to address
questions of trap avoidance and to potentially minimize future handling of chub, (c) develop new
non-lethal tools for measuring the health and condition of humpback chub in the field, (d)
undertake targeted, cost-effective research to understand mechanisms underlying observed
population processes, including the roles of high CO2 at base flow, gravel limitation, parasites,
and the aquatic food base, and (e) continue to develop models that integrate findings from the
above projects. The proximate goals of these activities is to better understand the relative roles of
LCR hydrology, water quality, intraspecific and interspecific interactions, and mainstem
conditions in humpback chub juvenile life history and adult recruitment, as well as to better
estimate the current adult abundance. The ultimate goal of these activities is to continue to
develop tools that allow us to better predict the impacts of dam operations and other management
activities on humpback chub populations as well as appropriately account for uncertainty in these
predictions. Specific questions of interest include:
- To what extent does young-of-the-year humpback chub production and outmigration from the LCR vary between years and how is this variation driven by LCR hydrology and intraspecific interactions (i.e., cannibalism and competition)?
- What are the drivers of interannual and spatial variation in survival and growth of juvenile and sub-adult humpback chub? In particular, what are the roles of LCR and mainstem conditions in the overall trajectory of the population?
- Are there factors, such as heterogeneity in skip-spawning rates, heterogeneity in adult humpback chub capture probabilities in the JCM, or trap avoidance in the LCR that bias estimates of the adult population size and population processes?
Juvenile humpback chub are the most sensitive life stage to mainstem conditions and an
understanding of their life history is the key to predicting the influence of dam operations on this
species. Prior to the Near Shore Ecology (NSE) project (2009–2011) and the more recent JCM
project (2012–current), our understanding of humpback chub early life history was limited to
back-calculations of cohort strength (number of fish surviving to adulthood from a given hatch
year) derived from abundance estimates of humpback chub greater than 200 mm and believed to
be four years old (Coggins and others, 2006; Coggins and Walters, 2009). However, given the
disparity in growth rates between humpback chub living in the LCR and Colorado River
(Yackulic and others, 2014) this approach was almost certainly misleading as humpback chub
could be anywhere from 4–10 years old when they reach 200 mm depending on where they had
spent most of their time (LCR or mainstem Colorado River) and what environmental conditions
had been like in those locations.
Since 2009, we have developed the field techniques (including a fixed reference site in the
Colorado River) and analytical methods that allow us to understand humpback chub early life
history in the detail required to begin to tease apart the effects of variation in population
processes caused by mainstem temperature, trout abundance, and conditions in the LCR. For
example, in support of the LTEMP process we were able to fit relationships between monthly
temperature and estimated rainbow trout abundance and juvenile humpback chub survival and
growth using only data from 2009–2013 that accurately predicted trends in adult humpback chub
numbers from 1989–2009 (Figure 1). While there is still room for improvement in these models,
this represents a dramatic step in our ability to predict the consequences of management options.
While conditions in the LCR are not directly affected by dam operations, they nonetheless play a
vital role in determining the degree to which temperature and rainbow trout numbers in the
Colorado River must be managed (Figure 2). For example, if juvenile humpback chub
production and export are high, this may suggest less need for rainbow trout management and/or
lower flows to increase water temperatures in the mainstem. Alternatively, a better understanding
of the factors leading to increased humpback chub production could provide decision makers
opportunities to strategically implement management actions in years when they would have the
largest effect. For example, the 2000 Low Steady Summer Flow experiment may have been
ineffective simply because it followed two years of potentially minimal production of juvenile
chub. Improved information about the drivers of humpback chub population dynamics could
have helped managers and scientists plan this experiment such that it occurred when conditions
were more likely to result in a detectable response. Likewise, management actions such as
mechanical removal of nonnative fishes will be much more effective if they occur in years of
high humpback chub production. If variation in production is primarily driven by exogenous
factors (e.g., extent of flooding) as opposed to endogeneous factors (e.g., competition between
cohorts) this also has implications for long-term population dynamics.
With respect to adult humpback chub, key uncertainties revolve around our understanding of
capture probability and movement. In particular, heterogeneity in capture probability in the LCR
caused by some adult humpback chub (especially potential residents) avoiding hoop nets could
lead to underestimates of abundance. At the same time, the potential for temporary emigration in
the JCM reach is a cause for concern and could lead to overestimates of abundance. Lastly, a
better understanding of skip-spawning in adult humpback chub is essential because many adults
are only vulnerable to capture during spring sampling in the LCR and thus inferences about their
survival and abundance depends on assumptions about the skip-spawning process. Answering
the above uncertainties is dependent both on new data streams from remote tag readers and
intellectual investment into developing the appropriate models to incorporate this information
and test hypotheses.
Project 8. Experimental Actions to Increase Abundance and Distribution of Native Fishes in Grand Canyon
This project encompasses two ongoing management actions and two new projects, all
designed to increase survival of juvenile native fishes in Grand Canyon. In addition, we propose
to convene a protocol evaluation panel comprised of external experts to conduct a review of the
fisheries research, monitoring, and management actions conducted in support of the Glen
Canyon Dam Adaptive Management Program (GCDAMP). In FY15–17 we will continue
ongoing mechanical removal of rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo
trutta) using electrofishing near the confluence of Bright Angel creek, in support of Grand
Canyon National Park’s goals to reduce nonnative fish abundance in and around Bright Angel
Creek for the benefit of juvenile native fish. We will also continue to translocate juvenile
humpback chub (Gila cypha) annually from the Little Colorado River (LCR) into areas within
the LCR and continue to support translocation efforts into Havasu Creek and Shinumo Creek, to
increase survival and distribution of humpback chub. In FY16 or FY17 we will participate in a
review by external experts of these activities and other fisheries projects (see Projects 6, 7, and
9). The review of Project 8 activities will emphasize evaluation of the effectiveness of these
experimental actions in meeting GCDAMP or National Park Service (NPS) goals and objectives
as appropriate, and the panelists will be asked to make recommendations as to how projects can
be adapted to meet project goals and objectives and whether the continuation of these efforts are
warranted in future years. NPS will also consider the review panel’s recommendations, but any
changes in implementation are under the discretion of the NPS consistent with the
Comprehensive Fish Management Plan for Grand Canyon National Park (NPS, 2013). This
project also includes two new project elements that will inform future potential management
actions: 1). An assessment of invasive aquatic species within the LCR drainage, to evaluate
potential risks to humpback chub populations and 2.) Genetic monitoring of humpback chub to
confirm that ongoing management activities do not have detrimental effects on the genetics of
the Grand Canyon population of this endangered species.
Project 9. Understanding the Factors Determining Recruitment, Population Size, Growth, and Movement of Rainbow Trout in Glen and Marble Canyons
Project 10. Where does the Glen Canyon Dam rainbow trout tailwater fishery end? - Integrating Fish and Channel Mapping Data below Glen Canyon Dam
Project 11. Riparian Vegetation Monitoring and Analysis of Riparian Vegetation, Landform Change and Aquatic-Terrestrial linkages to Faunal Communities
Project 12. Changes in the Distribution and Abundance of Culturally-Important Plants in the Colorado River Ecosystem: A Pilot Study to Explore Relationships between Vegetation Change and Traditional Cultural Values
Project 13. Socioeconomic Monitoring and Research
Project 14. Geographic Information Systems (GIS) Services and Support
Project 15. Administration
Appendices
Appendix 2-A. Fiscal Year 2015 Funding Recommendation
Appendix 2-B. Fiscal Year 2015 Budget
Appendix 2-C. Fiscal Year 2016 Budget
Appendix 2-D. Fiscal Year 2017 Budget
Appendix 3. Logistics and Schedules of River Trips and Field Work
Appendix 4. TWG Triennial Budget Input FY15–17 Consensus by full TWG on April 9, 2014
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