1R. C. MacWatters Intern in Aquatic Sciences, 2009. Fisheries & Wildlife Dept., SUNY Cobleskill. 2 2008, 2007 R.C. MacWatters Interns in Aquatic Sciences, Fisheries & Wildlife Dept., SUNY Cobleskill. 3 Prof. & Chair, Fisheries & Wildlife Dept., SUNY Cobleskill.

Walleye (Sander vitreus) seasonal activity and habitat utilization in Otsego Lake, New York

Justin Potter1, John M. Byrne2, Daniel S. Stich2 and John R. Foster3

Abstract: Ultrasonic telemetry was used to characterize seasonal distribution, activity, and habitat utilization of 7 Oneida Lake strain, adult walleye in Otsego Lake, New York. Comparisons of cumulative distance traveled from 24-hour surveys conducted from 2007 to 2009 were evaluated to determine the differences in activity from summer (n = 14) and fall (n = 11). Distance traveled in a diel cycle was significantly different between the summer (µ = 4684 m) and the fall (µ = 7390 m). Although tagged walleye were located predominately in the northern region of the lake in late July through November, hourly position data collected over entire 24-hour cycles determined seasonal differences in habitat utilization with increased activity in the fall.

INTRODUCTION Research on walleye activity and habitat utilization have been documented for riverine

systems (Paragamian 1989; Fago and Meegan 2000); reservoirs (Prophet et al. 1989; DePhilip et al. 2004); and lakes using mark-recapture techniques (Forney 1963) and sonic and radio telemetry (Foust and Haynes 2007; Holt et al. 1977; Palmer et al. 2005; Hanson 2006). In Otsego Lake, telemetry studies have indicated substantial differences with these earlier studies. Much greater variability in habitat utilization, distance travelled and activity occurred when observed throughout a 24-h period (Byrne et al. 2009; Stich et al. 2008).

Knowledge of seasonal distribution, habitat utilization and activity of game fish are critical components in fisheries research and management. Sonic and radio tagged walleye have exhibited seasonally specific activity ranges in complex systems that offered both lake and riverine habitats (Paragarmian 1989, Palmer et al. 2005; Hanson 2006). However, these previous studies have been conducted in relatively shallow lakes, reservoirs and rivers, using naturally reproducing walleye populations. Otsego Lake, a deep, elongated, steep sided, cold-water lake has a very different hydrography and ecology. Further, Otsego Lake’s walleye population is made up of stocked Oneida Lake strain fish.

Walleye telemetry studies in Otsego Lake by Golding et al. (2007) and Decker et al. (2008) indicate possible seasonal differences in habitat utilization, activity patterns and distribution than what have previously been reported elsewhere. However, the extent of available data prevented these earlier researchers from applying statistical analysis to seasonal comparisons of activity patterns and habitat utilization in Otsego Lake walleye. In this study, ultrasonic telemetry techniques were used to assess seasonal distribution, habitat utilization, and diel movements of Oneida Lake strain walleye stocked into Otsego Lake, New York. In order to maximize the number of observations, previous data collected by Golding et al. (2007), Stich et

al. (2008), Decker et al. (2008) and Byrne et al. (2009) on Otsego Lake walleye were combined with the data collected in this study.

MATERIALS AND METHODS Otsego Lake (42º40’N-70º00’W) is a long, narrow lake with a surface area of 1,711 ha, a

length of 13.28 km, and a mean width of 1.28 km. The lake is deep and steep sided with a maximum depth of 50.5 m and a mean depth of 24.9 m (MacWatters et al. 1980). Otsego Lake is dimictic with physical characteristics of an oligotrophic lake and a water chemistry of a mesotrophic lake (Harman et al. 1997).

In April 2009, three walleye from Shadow Brook and one walleye from Cripple Creek (Figure 1) were implanted with Sonotronics model CT-83-I temperature coded transmitters following Paragamian (1989) and Hart & Summerfelt (1975). This model of transmitter has a life expectancy of 36 months. Fish tagged by Stich et al. (2007) and Byrne et al. (2008) were also used in this study (Table 1). Transmitters were calibrated for an accuracy of ± 0.5 ºC. Pinger pattern, pulse interval, tag year, gender, and tag frequency of individual fish are provided in Table 1.

Table 1. Tag year, fish gender, frequency, ping pattern, pulse intervals, current status for walleye studied in Otsego Lake, 2009.

Year Sex Frequency Ping Pattern

I.D. Pulse Interval

(ms) Status

2007 Female 74D 3 3 4 4 960 Active

2007 Female 77D 5 7 8 7 1230 *EFF

2007 Male 75D 3 4 4 870 *EFF

2008 Male 69J 5 5 7 7 1210 Active

2008 Male 70J 5 5 7 8 1200 Active

2008 Female 71J 5 7 6 7 1230 Active

2009 Female 74P 3 4 7 4 1020 *EFF

2009 Male 75P 3 4 7 5 1030 Active

2009 Male 76P 3 5 5 7 1040 Active

2009 Female 77P 3 5 5 8 1050 Harvested 11/09 (*EFF- Stationary tag, indicating death or expulsion from fish, 2009 data was omitted.)

Data for each walleye included, position, time of day, water temperature at fish location,

water depth, and habitat characteristics. Walleye were located by boat using a Sonotronics DH-4 directional hydrophone and USR-96 receiver. Position data were recorded for each transmitter by

maneuvering the boat toward the direction of the greatest pinger volume detected by the hydrophone. Fish were located when the hydrophone could be rotated 360º without attenuating the signal strength. A Garmin GPS unit was used to collect coordinates on each fish’s horizontal location within ± 5 m. Water depth was measured with a Vexilar FL-18 flasher. ArcMap 9.3 GIS and Microsoft Excel were used to analyze data. Including previous seasonal diel observations, there were a total of 14 twenty-four hour summer tracks and 11 twenty-four hour fall tracks used in this study.

Figure 1. Bathymetric map of Otsego Lake, New York.

Cripple Creek

Sunken Is.

Hyde Bay

Shadow Brook

Pegg’s Pt.

Gravelly Pt.

Five Mile Pt.

Three Mile Pt.

Leatherstocking Creek

Point Judith Kingfisher Tower

Susquehanna R.

RESULTS

Seasonal Activity Levels Hourly position data collected over 24-hour periods from 2007 to 2009 were compiled to

compare total mean daily distances traveled per month (Figure 2). The average total distance during an hourly monitored diel cycle was greatest in June = 10,604 m followed by November = 8689 m. However, the number of samples was too small to test for significance; therefore summer months (June-August) were combined (N = 14), as were, fall (September-November) months (N = 11). Distance traveled in a diel cycle was significantly lower in the summer (mean = 4684 m) than the fall (mean = 7390 m; Wilcoxon two-sample test, P < 0.05).

0

2,000

4,000

6,000

8,000

10,000

12,000

June July August October November

(N = 2) (N = 5) (N = 9) (N = 9) (N = 2)

Dis

tanc

e tr

avel

ed (m

)

Month & Number Sampled

Figure 2. Total mean traveled distance over diel cycles (June- November, 2007-2009).

Seasonal changes in activity shown by individual fish followed a similar pattern (Figure 3). Individual walleye observed hourly over a diel cycle in 2009 were more active in the fall in comparison to the individual’s summer activity level. The activity of fish 74D was the exception. Its July 24-hour activity was not significantly different from that observed in the fall (t-test, P > 0.05). This walleye showed habitat fidelity between summer and fall (see Figure 15).

0

2000

4000

6000

8000

10000

JulyAug.Oct. JulyOct.Nov. JulyAug.Oct. JulyOct. JulyAug.Oct.Nov. Oct.

75P 70J 77P 74D 76P 71J

Dis

tanc

e (m

)

Fish ID

Figure 3. Total distance traveled during seasonal diel cycles for individual walleye, July-November 2009.

The differences in summer and fall activity levels of individual walleye are illustrated in their 24-hour tracks (Figure 4-6). In the summer, the activity of walleyes tracked hourly over a diel cycle increased primarily at night. Movements were either carried out in short bursts or over extended periods. The activity of fish 76P was minimal and concentrated within the rocky shelf along Sunken Island (Figure 4), whereas fish 75P (Figure 5) remained highly active between 2000hrs and 0440hrs—utilizing a range of habitats including the deepest portions of the lake. 28-29 July 2009 6-7 November 2009

Sunken Is.

Sunken Island

Figure 4. Movement of Fish 76P in July (Total Distance Traveled = 1,881 m) and November 2009 (Total Distance Traveled = 6,372 m).

24- 25August 2009 11-12 October 2009

Figure 5. Movement of Fish 75P in August (Total Distance Traveled = 7,349 m) and October 2009 (Total Distance Traveled = 9,688 m).

28-29 July 2009 11-12 October 2009

Sunken Island

Figure 6. Movement of Fish 70J in July (Total Distance Traveled = 3,518 m) and October 2009 (Total Distance Traveled = 8,392 m).

Fall activity of fish 76P and 70J in a 24-hour period significantly increased. Walleyes remained active and in pelagic waters throughout the day and night. In October, fish 70J had vacated Gravelly Point and moved north. During the afternoon and evening of 11 October fish 75P and 70J utilized similar habitats between Clarke Point and Sunken Island (Figure 4 & 6).

Seasonal Temperature Utilization

Monthly temperature profiles collected by Biological Field Station staff in the deepest area of the lake were used to provide a framework of temperature utilization by walleye. In the summer walleye often utilized either shallow inshore waters or in surface waters. For example, in July all walleye but 74P and in August all walleye, but 77P, occurred at mean temperatures exceeding those in off-shore surface waters. These fish were utilizing shallow inshore waters which were warmer than offshore surface waters (Table 2).

The average temperature utilized by walleye during the summer of 2009 was 22.0ºC with a maximum temperature of 26.0 ºC and a minimum temperature of 12.0ºC. Walleyes observed hourly throughout diel cycle occurred temperatures that rarely deviated beyond ± 4º (Table 2). The mean temperature selected by walleye was 15.2ºC in early to mid-October, 11.7ºC in late October, and 9.6ºC in November. Surface water temperatures decreased in the fall from 19.5°C in September to 9.6°C in November.

Table 2. Mean and range of temperature utilized in a 24-hour cycle, summer and fall 2009.

Tag

July August October November Mean Temp. °C

Temp.Range

Mean Temp. °C

Temp.Range

Mean Temp. °C

Temp.Range

Mean Temp. °C

Temp.Range

70J 22.4 2.0 14.7 1.5 9.9 1.0

71J 15.9 1.0

74D 21.5 1.0 15.4 2.0

75P 23.8 3.5 24.0 6.5 15.0 0.5

76P 22.9 0.5 24.9 0.5 16.2 4.0 10.1 0.5

77P 23.0 1.5 22.4 12.5 14.5 3.5

Temp./Depth Surface -

Thermocline

22.4-12.8°C 12 m

22.5-20.9°C 8 m

16.1-14.9°C 12 m

10.3-9.0°C 18 m

Seasonal Depth Utilization

Seasonal depth utilization collected from 2007-2009 indicated monthly differences (Figure 7). Except for the month of November, walleye consistently occurred over deeper water at night than they did during daylight hours (t-test, P < 0.05). Walleye were found in relatively shallow water in May and July through September, but were found over deeper water in June, October, and November.

0

5

10

15

20

25

30

May

Day

Nig

ht

June

Day

Nig

ht

July

Day

Nig

ht

Aug.

Day

Nig

ht

Sept

.

Day

Nig

ht

Oct

.

Day

Nig

ht

Nov

.

Day

Nig

ht

Wat

er D

epth

(m)

Figure 7. Comparison of average monthly water depth (May-November, 2007-2009) where walleye were observed during the day and night.

Seasonal differences in water depth throughout a 24-hour period were evident in fish 76P

(Figure 8), 75P (Figure 9), and 70J (Figure 10). Note that these are the total water depths at which the walleye were located, not the depth at which the fish were suspended. In a diel cycle, walleye were located in shallower water depths in the summer compared to fall. However, in August, fish 75P utilized pelagic waters in the deepest portion of the lake during the night.

0.0

20.0

40.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Wat

er D

epth

(m)

Hour of Day

76-P (28-29 July) 76-P (24-25 Aug.) 76-P (3-4 Oct.) 76-P (6-7 Nov.)

Figure 8. Water depths at which Fish 76P was observed over a diel cycle during the summer and fall, 2009.

0.010.020.030.040.050.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24W

ater

Dep

th (m

)Hour of Day

75-P (28-29 July) 75-P (24-25 Aug.) 75-P (11-12 Oct.)

Figure 9. Water depths at which Fish 75P was observed over a diel cycle during the summer and fall, 2009.

0.010.020.030.040.050.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Wat

er D

epth

(m)

Hour of Day

70-J (28-29 July) 70-J (11-12 Oct.) 70-J (6-7 Nov.)

Figure 10. Water depths at which Fish 70P was observed over a diel cycle during the summer and fall, 2009. Seasonal Habitat Utilization

Seasonal habitat utilization varied among individual walleye. Several walleye exhibited habitat fidelity in the summer (Figure 11 & 12). However, 76P was more active in the fall, traveling south and returning to previously occupied habitat in the north (Figure 11), while 74D remained along the shoals north of Five Mile Point (Figure 12). Fish 70J moved south from Hyde Bay in mid-June then utilized shoals and steep drop offs throughout the summer in a portion of the lake that differed from its fall positions (Figure 13). Walleyes 77P (Figure 14), 75P (Figure 15), and 71J (Figure 16) were the only tagged fish known to move south of Three Mile Point in the summer. In the fall, the majority of tagged walleye selected pelagic waters and were seldom located in littoral zones.

Figure 11. Habitat utilization of walleye 76P Figure 12. Habitat utilization of walleye 74D in the summer (N = 102) and fall (N = 64), the summer (N = 67) and fall (N = 37), 2009. 2009.

Figure 13. Habitat utilization of walleye 70J Figure 14. Habitat utilization of walleye 77P in the summer (N = 81) and fall (N = 79), the summer (N = 95) and fall (N = 39), 2009. 2009.

Figure 15. Habitat utilization of walleye 75P Figure 16. Habitat utilization of walleye 71J in the summer (N = 91) and fall (N = 50), the summer (N = 31) and fall (N = 23), 2009. 2009.

DISCUSSION

Biotelemetry studies of walleye in Otsego Lake have been conducted to evaluate spawning migrations (Decker et al. 2008), movement and distribution (Golding et al. 2007), and diel habitat utilization and activity (Stich et al. 2008; Byrne et al. 2009). This study is the first examination of walleye seasonal activity and habitat utilization in Otsego Lake.

Sonic and radio tagged walleye have exhibited seasonally specific activity ranges in

complex systems that offered both lake and riverine habitats (Paragarmian 1989, Palmer et al. 2005; Hanson 2006). In Otsego Lake walleye activity also varied with season. Position data collected hourly over diel cycles from 2007 to 2009 indicated that average movement over a 24 hour period was greatest in June (10,604 m), followed by November (8,689 m). Walleye were least active in July (3,132 m). Distance traveled in a 24-hour period was significantly greater in the fall compared to the summer. Decreased activity of walleye during summer months also occurred in riverine systems (Paragarmian 1989) and shallow lakes (Holt et al. 1977). Hanson (2006) evaluated the seasonal activity levels of walleye in three stages; where post-spawning migrations (April-June) were significantly greater than summer movements (July-August), and that walleye movements increased during the fall (September-February) due to increased foraging and decreases in the daily photoperiod.

Although significant increases in the total distance traveled during a 24-hour observation

were detected from July through November in Otsego Lake, tagged walleye utilized a smaller portion of the lake (north of Five Mile Point) and these fish were less spatially separated from each other from September to November. Similarly, Golding et al. (2007) noted that walleye were most often located at the north end of Otsego Lake, when tracked randomly between May and November. The convergence onto a selected region of the lake during the fall with increased movement and activity in pelagic waters, was also described by Johnson et al. (1988). Mark and recapture studies in Oneida Lake, a relatively shallow, mesotrophic, cool-water lake, also indicated that post-spawning walleye were widely distributed during late summer and then converged into a limited region in the fall (Forney 1963).

Palmer et al. (2005) described the vertical distribution of walleye in Claytor Lake,

Virginia as being strongly fixed just above the thermocline. Stich et al. (2008) noted that the summer temperature/depth preference were the primary factors determining walleye position in the water column of Otsego Lake. Analysis of seasonal temperature utilization of walleye in Otsego Lake from 2007-2009 illustrated a mean water temperature preference of 22.0ºC during the summer and a mean fall temperature selection of 13.7ºC. These findings suggest that walleye occur much closer to the surface and seldom go below 7-10 m in the summer or fall. This analysis agrees with Byrne et al. (2009) who suggested that the temperature and depth utilized by alewives (Brooking and Cornwell 2005, 2008) was correlated to the depth and temperatures selected by walleye.

The mean depth over which walleye were located showed a decrease from June (18.5 m)

to July (9.6 m) and consecutive increases from August (9.5 m) through November (27.2 m). Further comparisons of depth illustrated that walleye remained over deeper portions of the lake throughout the entire fall diel cycles; 18 m during the day and 24.7 m at night, respectively. In the summer, walleye were found over a mean depth of 8.9 m during the day and over a mean depth of 15.6 m at night.

Tagged walleye in Otsego Lake were distributed throughout the lake during the summer

of 2009. Nomadic behavior was observed in several walleye over the course of this study and previous Otsego Lake studies (Stich et al. 2008; Byrne et al. 2009). However whether individuals roam in search of suitable habitat or to follow prey items could not be determined. Palmer et al. (2005) affirmed that walleye tracked from winter through post-spawning seasons migrated back to their winter locations and that walleye developed home ranges. Some walleye studied in Otsego Lake also appeared to have ranges of central activity. For example, in August 75P showed strong evidence of homing, moving across the lake and returning to the spot where it started 24 hours earlier period. The distribution data also indicated that at least some fish confined their activity to a limited area and these home ranges may have seasonal differences. However, the fish that appeared to have home ranges in Otsego Lake generally occurred over a much larger area than those observed in Honoeye Lake, a nearby shallow, eutrophic warm-water lake (Foust and Haynes 2006). These same Oneida strain walleye only moved 31 m a day in the summer.

Seasonal differences in habitat utilization, distribution and movement patterns of Oneida Lake strain walleye in Otsego Lake appear to be strongly influenced by lake hydrography, thermocline depth, diversity in habitat types, and prey availability. While this is the most comprehensive study of walleye seasonal habitat utilization and movements in Otsego Lake, much more research is needed. To date, very little data has been collected from December to May. Collecting that information should be the focus of future studies.

ACKNOWLEDGMENTS

SUNY Cobleskill’s Fisheries and Wildlife Technician Kevin Poole provided considerable effort in the field and guidance throughout this project; furnishing the map of Otsego Lake used to analyze movement and position data. Henry Whitbeck also provided support in developing the GIS models. Interns at the Biological Field Station and SUNY Cobleskill Fisheries and Wildlife students assisted during surveys. Special thanks to SUNY Cobleskill Fisheries and Wildlife students Ian Sutherland, Corey Tizzio, Kristen Wokanick, and John Byrne; and SUNY ESF’s Carter Bailey for their help during individual 24-hour surveys. Dr. Willard Harman, Matt Albright and Holly Waterfield of the SUNY Oneonta Biological Field Station provided valuable insight and technical support throughout the duration of the field work.

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