Esopus Creek Telemetry Study

Use of telemetry to assess potential effects of Schoharie Reservoir waters
on trout populations in the Upper Esopus Creek.
B.P. Baldigo, USGS, Troy, NY

Background
Turbid waters originating in the Schoharie Reservoir and watershed
allegedly impair habitat and resident trout populations in the Upper
Esopus Creek; however, to date no scientific studies have documented
adverse affects of the altered thermal, suspended sediment (turbidity),
and flow regimes on survival, growth, or behavior of individual trout or
the health of their populations (CCE, 2007a, b). The 192 mi2 Esopus Creek
watershed is a tributary to the Hudson River in the south-central Catskill
Mountains of New York State and is often considered to be two systems
separated by the Ashokan Reservoir. The Upper Esopus Creek is defined as
the reach between its source, Winisook Lake, and the reservoir near
Boiceville, NY (Smith and others, in press). Flows in the Upper Esopus
Creek are supplemented by inputs from Schoharie Reservoir via an aqueduct
connecting the reservoir (in the Mohawk River drainage) to Esopus Creek at
the portal near Shandakan, NY. When warm and (or) turbid, those discharges
purportedly cause adverse effects on fish and invertebrate assemblages at
sites downstream of the portal (CCE, 2007a).  However, the releases are
sometimes cooler than the Esopus and may some-times provide thermal-refuge
habitat (and benefits) for some resident species. Because any impacts that
the releases have on aquatic species or ecosystems in the basin are
speculative, stakeholders (who disagree on the management of local
resources) remain ill informed about the real problems and viable
solutions in the Upper Esopus Creek watershed. More information on
survival, growth, and behavior of individual trout and on health of local
fish populations can help make management decisions concerning portal
releases, drinking water supplies, and fish resources in the watershed
more ecologically sound.

Aside from the natural intrinsic value and ecological services that native
and naturalized fish populations provide in the upper basin, natural
resources of the Upper Esopus Creek are valuable because the system
supplies many economic and crucial water-supply benefits to the region.
The river provides thousands of people with recreational (fishing and
tubing) and income (business) opportunities and supplies approximately 40%
of New York City?s mean annual water supply (CCE, 2007a). The recently
updated New York State Waterbody Inventory List (NYSDEC, 2007) cites the
Upper Esopus Creek as either ?unassessed? (segments 1307-0005, -0029,
-0030, -0031, -0032, -0034, -0035, -0036),  ?impaired? (segments
1307-0004, -0007), or having ?no known impact? (segments 1307-0011, -0033,
-0008, 0037). The impaired segments consist of the Ashokan Reservoir with
pollutants listed as metals and silt/sedimentation, and the Upper Esopus
Creek and minor tributaries affected by silt/sedimentation.

Objectives
The US Geological Survey (USGS), the NY State Department of Environmental
Conservation (NYSDEC), and collaborating agencies propose to use fish
telemetry and temperature data to document differences in trout rates of
movement (and use of thermal refuges), apparent survival, and growth at
two reaches in the Upper Esopus Creek, an upstream control reach, and a
impact reach downstream of the portal. Differences in trout behavior
survival and growth will be used to evaluate potential beneficial and (or)
adverse effects of releases from the portal on individual trout (and their
populations ? by extrapolation), and the identification and enumeration of
thermal refuges (tributaries and seeps) will be used to evaluate the
potential effects of portal releases on downstream availability and use of
thermal refuges. This study will rely heavily on flow, turbidity, and
temperature data generated by active and temporary gages (currently
operating or newly funded through the companion study proposed by A.J.
Smith, Quantitative assessment of water quality in the upper Esopus Creek:
fish, macroinvertebrates, periphyton, turbidity and nutrients) to define
and assess trout and environmental relations. The study will help fulfill
one of the recommended actions listed in Cornell Cooperative Extension?s
Upper Esopus Creek Management Plan, Aquatic Ecosystem Research and
Assessment Strategy (CCE, 2007a) and Vol. I, Draft Summary of Findings and
Recommendations (CCE, 2007b).

Approach
The behavior response of wild or hatchery trout (rainbow or brown) to
Schoharie Reservoir waters from the portal will be evaluated by monitoring
the location, movement, and temperature of individual trout at the two
study reaches and assessing differences in rates of movement, apparent
survival, potential growth (measured and modeled), and utilization of
thermal refuges under the two different regimes. If fully funded, the
telemetry project will be initiated as a pilot study, possibly during the
first summer, and replicated during the second summer in an effort to
collect relevant data during at least one typical-flow year. Each summer,
radio-frequency (RF) transmitters will be surgically implanted in 40 1- or
2-year old rainbow or brown trout; about 15 will be released at each of
the study reaches (10 will be retained and monitored at a local hatchery
as controls) during June using methods similar to those used in the Indian
and Hudson River Study (Boisvert, 2008; Baldigo and others, in press). The
approximate location and temperature of each fish will be logged on a
frequent (daily or every-other-day) schedule for up to 60 days by either a
Cornell graduate student or a NYSDEC, NYCDEP, or USGS technician. Fish
temperatures at observation times will be compared to temperature,
turbidity, and flow data from the closest water-quality monitoring site
(generated by the study, Quantitative assessment of water quality in the
upper Esopus Creek: fish, macroinvertebrates, periphyton, turbidity and
nutrients) to determine local conditions, potential use of thermal refuges
(determined by any differences in fish and main-stem water temperatures),
and possible stresses that could adversely affect trout survival. Any
transmitter signals that indicate fish mortality will commence an active
search for the individual and an attempt to determine its cause of death.
Data from fish upstream and downstream of the portal will be assessed to
determine differences in (a) daily or weekly rates of movement, (b) the
frequency and duration of exposure to typical and altered water
temperatures, (c) actual availability and utilization of thermal refuges,
(d) apparent survival rates for tracked fish, and (e) actual and modeled
growth of study fish at affected or unaffected Upper Esopus Creek sites.
The various fish-telemetry indicators will also be related to other
physical and chemical conditions from nearby study sites to examine
inter-relations and to quantify impact gradients and possible thresholds
for selected stressors, such as turbidity or temperature, which may be
caused by inputs of Schoharie Reservoir waters. These data will then be
available to predict or model the effects that various portal-release
scenarios might have on trout populations (as influenced by altered
behavior, growth and survival) in the Upper Esopus Creek.

This Assessment, Planning and Research project will be a cooperative
investigation by the USGS (New York Water Science Center and New York
Cooperative Fish and Wildlife Research Unit), the NYSDEC (Biomonitoring
Unit & Bureau of Fisheries), Cornell University, Cornell Cooperative
Extension, and the New York City Department of Environmental Protection
(Fisheries). In addition to meeting the required 50% matching funds, the
USGS has committed a substantial amount of its federal
cooperative-research program resources that may also be treated as match.
Cooperating with the USGS on this project may be achieved by amending the
NYSDEC/USGS 2009-10 contract agreement.