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Examining Brook Trout Habitat Use and Distribution in the Ausable River, NY

Final Report to the Edna Bailey Sussman Foundation, 2016

Carrianne E. Pershyn, M.S. CandidateDepartment of Environmental and Forest Biology

State University of New York College of Environmental Science and Forestry12/01/2016

Background

Brook trout are the state fish of New York, and have been identified as a species of greatest

conservation need. These fish occur in healthy watersheds in areas that will likely have some resistance to

climate change, and one of their last strongholds is in the northeastern US. This makes the fish

ecologically valuable, as well as the intact habitats in which they live. Brook trout are well loved by

eastern anglers, though they are not present in all prized fly angling waters, nor are they the largest

species in the rivers of the east.

Despite the large proportion of public and large tracts of privately held land in the northeast,

brook trout here are facing major human-induced threats, including habitat fragmentation, increasing

summer water temperatures, and competition from nonnative and introduced species. The Eastern Brook

Trout Joint Venture (EBTJV) and Interactive Catchment Explorer (http://ice.ecosheds.org/) have

identified the eastern and central Adirondack region of New York State as having a high proportion of

intact brook trout habitat and also a high probability of continued occupancy with increases in summer

temperatures between 2 and 6 degrees Celsius. Management priorities, as laid out by the EBTJV include

protection of intact populations, collecting finer scale catchment level data, improving water quality and

reducing fragmentation, and building partnerships for research and conservation. It is therefore important

to understand the historical and current status of brook trout in these intact watersheds in order to

understand and predict their future persistence in this region.

Introduction

The Ausable River in New York’s Adirondack Mountains is home to extraordinary trout

fisheries, and anglers from around the world travel to fish these waters. The Ausable watershed is 512

square miles and two branches of the river drain from the interior of the Eastern High Peaks Zone of the

Adirondacks, join in the town of Ausable Forks, and flow in a northerly direction where the river spills

into Lake Champlain. The headwaters of the east branch Ausable River are located within the Adirondack

Mountain Reserve (AMR), a 7,000-acre private reserve with extensive public access created in 1887 to

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protect scenic lands and mountains of the Adirondacks from lumbering and environmental degradation.

The streams and lakes that form these headwaters exhibit pristine habitat that has remained intact since

the AMR was created.

When the east branch leaves the AMR property, it flows for 28 miles before it meets the

confluence with the west branch, and is classified by NYSDEC as recreational. There are extensive public

fishing rights on this segment of the river, and DEC stocks the river with brook, brown, and rainbow

trout. There are a number of tributary streams that flow into the main stem, all with varying degrees of

land use, from protected wild forest to logging and private residential lands. Recent water quality and fish

surveys conducted on the waters of the AMR build on previous knowledge of the fisheries in these waters

and raised questions on current trends. The Upper Lake has a historic population of brook trout, lake

trout, and round whitefish, with the recreational fishery enhanced with stocked brook trout since the

1970s. In the past five years, anglers reported fewer captures of stocked trout, and are instead capturing

wild brook trout. The fishing committee and managers at the AMR were interested in understanding the

population status of wild fish, and I was subsequently invited to focus my research on these questions. In

summer 2015, my field season included a study of the streams on the property, and in 2016, I completed a

14-week internship at the AMR and along the upper east branch, under the supervision of William Curtis

and Newell Grant of the AMR and Dr. Neil Ringler at SUNY-ESF. This was a continuation of work

completed in 2015, and the data collection continued through the end of October 2016. The data I

collected from my 2015 and 2016 field season enables me to both characterize the Ausable Lakes system

with a focus on the streams to gain an understanding of population dynamics, habitat, and recruitment to

lake populations as well as examining changes in fish populations along the river continuum. Another

goal of the project was to estimate the population of the Upper Lake and determine whether fish are wild

or stocked.

As I studied the streams and lakes on the AMR property, I began to wonder if the streams along

the remainder of the east branch had healthy brook trout populations, and how the fish assemblages

change overall along the longitudinal gradient of the river. Initially, I hypothesized that 1) the lake

population is self-sustaining, consisting mostly of wild fish that use high-quality habitat in the adjoining

streams for spawning and juvenile development, 2) that water temperature and pool availability affect the

density of juvenile trout in streams, and finally 3) Fish species richness and relative abundance will

increase from the headwaters downstream towards the confluence of the east and west branch, with

primarily brook trout/sculpin dominated communities in the headwaters, and more diverse communities

with less brook trout in downstream habitats.

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Sampling Sites and Methods

Stream Sampling: There are approximately 50 streams that flow into the east branch from the headwaters

at Marcy Swamp to the confluence with the west branch at Ausable Forks. I focused my efforts at the

AMR on four streams, and I conducted fish community and habitat surveys on 17 other tributaries that

drain into the east branch Ausable River downstream from the AMR property (table 1 and fig. 1). Fish

were sampled from the confluence with Upper Ausable Lake or the east branch, upstream to the first

natural barrier or culvert with Smith-Root backpack electroshocker units, using multiple-pass depletion

electrofishing with block nets on 50 to 100 meter stream reaches. All fish captured were identified to

species, measured, and salmonids were weighed. In addition, from July to November 2015 and May to

October 2016, Onset HOBO Water Temperature Pro v2 Data Loggers were installed in pools of the four

streams at AMR (Sawtooth, Otis, Cedar, and Crystal Brooks), and water temperature readings were

recorded at 30-minute intervals. Habitat surveys of stream width, depth, velocity, substrate, % canopy

cover, and forest type were recorded at 5-10 meter intervals along all study streams. In addition, water

quality data were measured at each stream, including water temperature, dissolved oxygen, pH, and

conductance.

Lake sampling: Previous gill net surveys on Upper Ausable Lake from 2010 to 2015 targeted lake trout,

but also caught brook trout and lake whitefish. These surveys showed very low abundances of stocked

brook trout (based on fin clips), and subsequently led to a halt in stocking of brook trout in spring 2015.

In order to survey the full species assemblage and estimate population density of brook trout in Upper

Ausable Lake, a mark-recapture study was conducted using Oneida-style trap nets were set for 48-hour

sets at five sites from May 11-19, 2016 and repeated at the same sites on October 10-16, 2016. Nets were

set near the mouths of Otis, Crystal, and Cedar Brooks, as well as near two potential spawning sites. All

fish were identified to species, counted, and all salmonids were measured and weighed, with scale

samples collected for aging purposes, and then were given a

temporary caudal fin clip before being released. All marked

fish that were recaptured were noted.

Table 1. Streams, brook trout presence, and diversity on 21 Ausable tributariesStream Number

Stream Name* Brook trout present?

Species richness

S-W Index of Diversity**

1 Cedar Brook* Yes 1 0.002 Crystal 1* Yes 6 1.193 Otis (Lost Brook)* Yes 3 1.004 Sawtooth* Yes 3 0.955 Deer Creek Yes 4 1.096 Crystal Brook 2 Yes 4 1.177 Mossy Cascade Yes 8 1.68

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8 Flume Brook Yes 6 1.449 John's Brook NO 5 1.3410 Phelps Brook (Beede) Yes 6 1.3811 Porter Brook NO 6 1.2412 Walton Brook Yes 3 1.0413 Dart Brook NO 7 1.6314 Gulf Brook NO 5 1.3715 Cascade Brook Yes 7 1.3716 Clifford Brook NO 8 1.8317 Styles Brook NO 6 1.3818 Phelps Brook 2 Yes 5 1.0219 Lewis Brook Yes 8 1.6820 Otis Brook 2 NO 4 1.2921 Rocky Branch Yes 11 1.95

*denotes 2015 sample event**Shannon-Weiner index of diversity, where values near 0 are representative of low

diversity, and values of 1 and above represent sites with high diversity. This index takes species abundance and evenness into account in the sample.

Preliminary Results

In my 2016 field season, I collected 16,608 fish from Upper Ausable Lake, and 1,037 fish from

17 different tributary streams along the east branch. Of these, brook trout were abundant in the lake,

(n=88), abundant in the four AMR tributaries, and present in 10 of 17 study streams outside of AMR

property. Table 1 summarizes the stream names and reports brook trout presence-absence, overall species

richness or the number of species caught per stream, and the Shannon-Weiner index of diversity, which

takes into account the total number of species and their abundances.

Within the tributaries, as few as one, and as many as eleven species were caught per stream.

Three species of juvenile salmonids were caught across the watershed. At the AMR, only juvenile brook

trout were caught, along with slimy sculpin, dace, creek chub, and tessellated darter (Appendix, Fig 2).

Species richness increased from upstream to downstream reaches and five additional species were caught

in downstream tributaries (common shiner, tessellated darter, white sucker, brown trout, and rainbow

trout), and adult trout were caught in these streams.

In the trap net surveys of Upper Ausable Lake, a total of 13 species were caught, all native to

New York State except for a single rainbow trout. Total catch by season is summarized in Table 2,

appendix. In May, 67 brook trout were caught with three recaptures, and 21 brook trout were caught in

October (one recapture). The recapture rate of marked brook trout for both sampling events was 4.3%,

and my initial estimate of the total population of brook trout in the lake, using the Schnabel estimator for

May catch data is 850-900 fish. Based on the low recapture rate, however, I will research alternative

methods of reaching a confident population estimate, and comparing them statistically. Of all the brook

trout captured in trap net surveys, only two fish had one of the special fin clips given to stocked fish,

suggesting the remainder were wild fish.

Future Work

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Preliminary results show tributaries with healthy populations of juvenile brook trout, and the lake

with large adults spawning near stream mouths and in sufficient lake spawning habitat. This supports my

first hypothesis that the lake population is self-sustaining, consisting mostly of wild fish that use streams

for juvenile development. I will focus next on aging some of my fish using scale samples, in order to

create an age structure analysis for stream and lake fish. I will also continue to work with the extensive

habitat dataset that I collected to compare brook trout presence and abundance to physical habitat

variables such as temperature and pool availability, in order to further explore hypothesis 2. Additionally,

I will extend this analysis outside of the AMR, using the physical habitat variables and water quality

information collected this fall along the river gradient that I sampled outside of AMR. I will explore the

possibility of creating a habitat suitability index for brook trout, and also using multivariate statistical

methods to compare sites by habitat variables and local land use (private preserve, logging preserve,

actively/recently logged). Finally, I preserved the fin clips from all marked fish, and will consider

partnering with someone to do a genetic analysis of these fish to compare relatedness between stream and

lake populations and to determine if there are unique strains of native Brook Trout at AMR.

The fish communities in tributaries change markedly along the river continuum, and the data

presented here support hypothesis 3 that fish species richness and diversity increases from the headwaters

downstream. I plan to expand this dataset and analysis to include data from preliminary surveys

completed in 2014 on 11 other streams on the AMR property, as well as incorporating historical data

from as far back as 1929 (Greeley, 1930) to note how stream communities have changed over time. This

far reaching preliminary assessment of the east branch Ausable River allows for future comparisons of

fish community and habitat change.

This study will provide baseline data that can guide management and future research in the

Ausable River watershed. It may allow for the prediction of future conditions under different climate

change scenarios, and could also help answer questions about whether the east branch can support wild

trout populations. The Edna Bailey Sussman Foundation will continue to be acknowledged in all products

of this work, including presentations at conferences, in posters, on the ESF website, in my thesis and

published works resulting from this study.

Acknowledgements

I am extremely grateful to the Edna Bailey Sussman Foundation for the generous support of my

summer internship with the Adirondack Mountain Reserve. I am also appreciative of John Schuler, Roger

Roumpf, and Kevin Strait, as well as William Curtis and Newell Grant of the Fishing Committee at

AMR, for the resources granted to me to for the access of AMR property and the tremendous opportunity

to study their unique and well protected resource. The study was expanded down the length of the east

branch with the support of NYSDEC Region 5 staff, the Ausable River Association, and the permission

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of various private landowners. In addition, the support, guidance, and field assistance of Dr. Margaret

Murphy was critical to the completion of my project, and I wouldn’t be involved in this project without

her direction and field assistance. Dr. Neil Ringler has been especially supportive of my work and I am

extremely grateful at his willingness to allow me to work on my thesis part-time while working as a

young professional in the environmental field. Finally, I am grateful to my various field assistants,

Margaret, Barbara, Janelle, Nicole, Cassie, and Ben, for their gift of long days in the field and heavy

lifting to help me pursue my passion.

References and Appended Figures

"Department of Environmental Conservation." Wild, Scenic and Recreational Rivers - NYS Dept. of Environmental Conservation. N.p., n.d. Web. 22 Nov. 2016."Department of Environmental Conservation." Spring 2016 Trout Stocking for Essex County - NYS Dept. of Environmental Conservation. N.p., n.d. Web. 09 Oct. 2016. Carlson, Douglas M., Robert A. Daniels, and Jeremy J. Wright. Atlas of Inland Fishes of New York. Albany: New

York State Museum, 2016. Print. Record 7.Fausch, Kurt D., et al. "Landscapes to riverscapes: bridging the gap between research and conservation of stream

fishes a continuous view of the river is needed to understand how processes interacting among scales set the context for stream fishes and their habitat." BioScience 52.6 (2002): 483-498.

Greeley, J.R. 1930. Fishes of the Lake Champlain watershed. Pp 48-87. In: E. Moore(ed.). A Biological Survey of the Champlain watershed. Supplemental to the Twenty-third Annual Report New York State Conservation Department (1929). Albany, NY.

Sheldon, A. L. (1968). Species diversity and longitudinal succession in stream fishes. Ecology, 193-198.Vannote, R. L., Minshall, G. W., Cummins, K. W., Sedell, J. R., & Cushing, C. E. (1980). The river continuum

concept. Canadian Journal of Fisheries and Aquatic Sciences, 37(1), 130–137.

Table 2. Total trap net catch by species, Upper Ausable Lake, 2016Common name May October Total

brook trout 67 (recaptured=3) 21 (recaptured=1) 88round whitefish 1 1 2common shiner 5,674 1,602 7,276

white sucker 2,724 439 3,163lake chub 1,934 2 1,936

brown bullhead 720 1,543 2,263longnose dace 553 0 553Pumpkinseed 101 1,081 1,182

creek chub 22 70 92slimy sculpin 17 0 17

black nose dace 12 6 18n. redbelly dace 7 0 7rainbow trout 0 1 1Grand Total 11,832 4,766 16,598

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AMR-Cedar

AMR-Crystal1

AMR-Otis1

AMR-SawtoothDeer

Crystal 2

Mossy Casca

deFlume

Johns

Phelps beede

Porter

Walton

DartGulf

Cascade

Clifford

Styles

Phelps DEC

LewisOtis

Rocky0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Fish community composition in Ausable River tributaries

Brook trout Brown trout Rainbow trout White sucker Slimy sculpinBlack-nose dace Long-nose dace Northern redbelly dace Tesselated darter Fantail darterCreek chub Common shiner

Rela

tive

Abun

danc

e (%

)

Figure 2. Species composition by % abundance from upstream to downstream tributaries (left to right) along the east branch Ausable River.

Figure 3. Selected photos from field research clockwise from top left: Carrianne electrofishing in summer, view of Upper Ausable Lake, Crystal Brook at AMR, and adult brook trout captured in trap net, October, 2016.

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