Fisheries Surveys of Canadarago Lake, NY 1972-2014 Thomas E. Brooking James R. Jackson Lars G. Rudstam Anthony J. VanDeValk New York Federal Aid in Sport Fish Restoration Grants F-56-R, Job 1-2 and F-61-R, Study 2, Job 2-6 Cornell Warmwater Fisheries Program Cornell University Biological Field Station 900 Shackelton Point Rd. Bridgeport, NY 13030 http://cbfs.dnr.cornell.edu January 2016
Dedication Dr. David M. Green, PhD, retired from Cornell University in 1995 after many years of research in fisheries management. Much of Dave's career and life were spent doing the work at Canadarago Lake described in this report. Cornell University s involvement began in 1972 with the establishment of a field station at Canadarago Lake. Research projects addressed questions concerning nutrients, sewage treatment, and ways to improve water quality through fish stocking. Dave s work at Canadarago Lake was one of the first studies to demonstrate that top down food web effects could substantially improve water quality. A very popular Walleye fishery was a direct result of Dave s work establishing a naturally reproducing Walleye population from stocked fish. In 1981 personnel from the Canadarago Lake Field Station were moved to the Cornell Biological Field Station and the various programs were combined under one contract, creating the Warmwater Fisheries Program. Dave became the Warmwater Fisheries Program Leader in March 1991, after John Forney s retirement. Dave collected most of his own data along with field assistants, resulting in many memorable and entertaining late-night stories. Records from Canadarago Lake show that from 1972-1995 Dave and crew handled over 272,000 fish on at least 821 sampling dates, including at least 256 gillnets, hundreds of trawls and beach seines, over 1,333 trap net sets, along with limnology and zooplankton samples. Dave Green in his early years Electrofishing excited Dave the most, with over 1,149 electrofishing runs totaling at least 976 hours of on-time (118 hours of on-time in 1976 alone). At the time of his retirement, Dave had likely spent as much time in an electrofishing boat (all home-made) as anyone in NY. His research had statewide and national impacts including the development of a statewide Walleye fingerling stocking policy; evaluation of exploitation on Walleye, Yellow Perch, and panfish; the NY State Bass Study; research on angler diary programs and creel surveys; and development of the NYS Centrarchid Sampling Manual. This final report is dedicated to Dave in recognition of more than 25 years of outstanding research on Canadarago Lake. 2 Dr. David M. Green, Cornell University
Table of Contents Abstract 4 Introduction Historical perspective 5 The 1970s and 1980s 6 The 1990s and 2000s 7 Methods 9 Results Lower Trophic Levels Temperature and Oxygen 12 Nitrogen and Phosphorus 14 Chlorophyll a 16 Water Clarity 17 Zooplankton 18 Summary Discussion of Lower Trophic Levels 20 Fish Populations Alewife 21 Walleye 24 Yellow Perch 32 Smallmouth Bass 38 Largemouth Bass 41 Sunfish 43 Summary and Discussion 44 Future Fisheries Management Implications 48 Acknowledgements 48 References Cited 49 Appendix I. Maps of Canadarago Lake 53 Appendix II. Data Tables 65 Appendix III. Canadarago Lake Report List 88 3
Abstract The fisheries of Canadarago Lake have undergone centuries of change, from herring and American Shad in early Native American times to Walleye, Yellow Perch, and Alewife in recent times. Nutrient reduction and sewage treatment in the mid-1970s, combined with top-down control from a Walleye population established through stocking, resulted in balanced predator and prey populations and improvements in water quality. Stocked Walleye established an abundant naturally-reproducing population, resulting in improvements in Yellow Perch growth and size structure which persisted for several decades. Long-term monitoring data indicated cascading trophic impacts on fisheries and limnology from Walleye establishment, and then from introductions of non-native Alewife in 1999 and zebra mussels in 2001. Water clarity increased after the zebra mussel colonization. Alewife became abundant around 2006-2007 and have persisted for at least 16 years. Zooplankton declined, water clarity decreased, Walleye growth and condition increased, and Walleye natural recruitment was reduced to very low levels after Alewife became abundant. Walleye stocking was re-initiated from 2011-2015 to boost recruitment and maintain this important fishery. Yellow Perch growth and size structure were reduced almost to levels seen in the 1970s, as a result of high recruitment, a decline in predation, and declines in zooplankton. Long-term sampling has allowed fisheries managers to enact changes in regulations, implement or remove stocking strategies as needed, and better advise the angling public about changes in Canadarago Lake. A list of 138 reports and publications from Canadarago Lake was included as an Appendix to this report. Introduction Canadarago Lake is 767 ha (1,895 acres) with a mean depth of 7.5 m and a maximum depth of 13.4 m (see Maps in Appendix 1). It is located in east-central New York at an altitude of 389 m and forms one of the headwaters of the Susquehanna River. The lake in the 1970s was described by Harr et al. (1980) as eutrophic, with a Trophic State Index of 40-60 (Carlson 1977). Stratification occurred each summer with the thermocline forming at about 5-8 m, and the hypolimnion was generally anoxic for about 3 months. The lake supported a diverse fish community of at least 37 species (Greeley 1936). Predator populations were dominated by Walleye (see Table 1 for scientific names of fish), Largemouth Bass, Smallmouth Bass, and Chain Pickerel. Yellow Perch and sunfish were the dominant forage species in the past, along with introduced Alewife in recent years. 4
Historical perspective One of only two large lakes in Otsego County, Canadarago Lake has been an important ecological resource to the local community both before and after European settlement (Ritchie 1952). Hiteman (1966) reports the first archeological signs of habitation in this region date to around 7,000 B.C., with the use of this lake by hunting, fishing, and gathering people as early as 3,500-1,300 B.C. It is ironic that as we report gillnetting results even now, over 100 fishing net sinkers (along with many other artifacts) have been uncovered in archeological excavations around Canadarago Lake and Deowongo Island, from a period >3,000 years ago. Herring and American Shad reportedly ascended the Susquehanna River prior to dam construction on Oak s Creek in 1825 and on the Susquehanna River in 1835, and were present in Canadarago Lake in vast schools (Bailey 1874; Ward 1898). Walleye were introduced to the Susquehanna River system through the Chemung River in Elmira around 1812, and reportedly spread rapidly reaching high abundance throughout the river system (Pennsylvania Fish Commission 1896). Bailey and Ward also reported historical catches of salmon in the tributaries to Canadarago Lake, however serious doubt is cast on these reports as the Pennsylvania Fish Commission reports that walleye were often referred to as Susquehanna salmon or just salmon. Trout were abundant in the tributaries, and appear occasionally in current fish surveys in the lake. Mineral and sulfur springs were present at the northern end of the lake and the Village of Richfield Springs (New York State Museum 1895). In 1903, the New York Times reported that the United States Fish Commission at Washington had made a fisheries investigation of Canadarago Lake, but no further information could be found (New York Times, 1903). Ice fishing using tip-ups was temporarily prohibited in Canadarago Lake in 1925, through an emergency order by the State Conservation Commission (now the NY State Department of Environmental Conservation, NYSDEC) to protect pickerel from overfishing (Oneonta Daily Star, 1925). Modern environmental investigations included the NYS Conservation Department Biological Survey in July 1935, which surveyed fish populations (Greeley 1936), aquatic vegetation (Muenscher 1936), invertebrates (Nevin 1936), limnological parameters (Tressler and Bere 1936), and watershed hydraulics (Odell and Senning 1936). Moore (1936) outlined early stocking programs at Canadarago Lake, including the stocking of Smallmouth Bass, Yellow Perch, Walleye, and bullhead from 1925-1935. Shepherd (1959) reported that as a result of the 1935 surveys at Canadarago Lake, the stocking of Yellow Perch and bullhead were discontinued, with Largemouth Bass and Smallmouth Bass stocked 5
when available from fish salvage operations from 1936-1953. The stocking of Walleye fry was also continued from 1936-1960 at the rate of about 750,000 fry per year. Muskellunge fingerlings and adult Northern Pike were also stocked periodically from 1925-1972 (Green and Sanford 1995). As a result of reports of poor fishing by the Richfield Springs Sportsman s Club and the Mohawk Fish and Game Club, NYS Conservation Department conducted a fisheries and limnology survey in 1958 (Shepherd 1959). Shepherd s survey included trap nets, gillnets, seining, electrofishing, and limnology including depth soundings of Canadarago Lake (Appendix I). At least 31 studies from 1954 through 1974 focused on water quality in Canadarago Lake as well as nutrient inputs from its surrounding watershed. A chronological list of 138 reports on Canadarago Lake is provided in Appendix III. The Canadarago Lake Improvement Association, a voluntary organization of property owners around the lake, was instrumental in getting a water control structure built in 1964 to stabilize water levels during the summer months (Malcolm Pirnie, Inc. 2011). This concrete dam replaced a dilapidated dam built in 1825 (Ward 1898) on Oaks Creek approximately one mile downstream from the lake s outlet. From that time forward water levels remained more stable, which likely stabilized shoreline habitat and marshes around the lake. The 1970s and 1980s Water quality studies initiated in 1968 by the NYS Health Department, NYS Conservation Department, United States Geological Survey, and the New England Interstate Water Pollution Control Commission resulted in the installation of a sewage treatment facility for the Village of Richfield Springs in January 1973 to reduce nutrient inputs to the lake (Fuhs 1972). The detailed nutrient studies of Canadarago Lake before and after sewage treatment were used as a demonstration project to develop methods for sewage treatment facilities throughout New York and much of New England (Green and Smith 1976). Further reductions in nutrients were achieved through statewide bans on phosphorus in detergents. Green and Smith (1976) also produced a map of bottom substrate types for Canadarago Lake (Appendix I Map 5). Markham (1978) surveyed aquatic vegetation in Canadarago Lake with aerial photography (Appendix I Maps 7 and 8). A detailed description of the watershed, land use, chemical and physical limnology, flora, and fauna of Canadarago Lake was produced by Harr et al. (1980). 6
Cornell University studies began in 1972 (Forney 1972; Green 1972) through a partnership between the Cornell Warmwater Fisheries Program and the NYSDEC. Sampling included both fisheries and limnology surveys through the 1970s and 1980s, when major changes were occurring in the fish community and limnological characteristics of Canadarago Lake (Green and Smith, 1976; Green 1986; Green and Sanford 1995; Olson et al. 2001; and others). Increases in water clarity were observed and attributed to nutrient control and changes in the fish community. A large population of small, slow growing Yellow Perch dominated Canadarago Lake throughout the 1970s and early 1980s. These small perch primarily ate zooplankton, sometimes leading to declines in zooplankton, increases in algae, and decreased water clarity. American Eel were caught through the 1970s (Harr et al. 1980), and adult Walleye were mostly absent during this time (before 1978). The Walleye fingerling stocking program from 1977-1982 utilizing fall fingerlings rather than fry, resulted in establishment of an adult Walleye population. Predation by Walleye reduced Yellow Perch numbers and increased perch size. The successes at Canadarago Lake led to the development of a fingerling Walleye stocking policy for New York State (Green 1982). Stocking of tiger muskellunge also established a moderate trophy fishery (Field and Stream 1986; Green and Sanford 1995), and NYSDEC installed artificial spawning reefs to enhance Smallmouth Bass populations (Keller 1984). The more diversified predator-prey system during this time period resulted in improved zooplankton populations and water clarity, along with increased angling opportunities. Fingerling Walleye stocking established a naturally-reproducing population in the 1980s. Spawning occurred on shoals and in at least 3 tributaries of the lake, and strong natural year-classes of Walleye were produced from 1984-86 (Green 1986; Green and Sanford 1995). By 1987, natural reproduction was high enough to cause concerns that Walleye had become over-abundant, and growth rates had declined such that few age-4 fish reached 18 inches (Rudstam et al. 1996). As a result, the angling regulations were liberalized prior to the 1988 open water season from 3 to 5 fish per day, and the minimum length limit decreased from 18 to 15 inches. Anglers responded, harvesting an estimated 81-95% of the Walleye population >15 inches in 1988 that had built up just under the previous 18 inch size limit. An intensive creel survey in 1989-90 indicated that just a year later, the number of Walleye harvested had returned to more normal levels of about 5-11% of the legal sized fish (Green and Sanford 1995; Wilms and Green 2007). 7
The 1990s and 2000s Fisheries and limnology surveys were continued through the 1990s (summarized in Brooking et al. 2001) and the 2000s (reports produced most years from 2001-2012 by Brooking et al.; also in Rudstam et al. 2011; Olson et al. 2001). Surveys during the earlier part of this time period indicated high numbers and good growth for both Walleye and Yellow Perch (Rudstam et al. 1996). Populations of bass, sunfish, Chain Pickerel and others were monitored as well. Tiger muskellunge were stocked by NYSDEC to provide a trophy fishery, but stocking was terminated in 2011 due to lack of success. Unauthorized introductions of Alewife in 1999 and zebra mussels (Dreissena polymorpha) around 2001 (Horvath and Lord 2003) set the stage for changes in Canadarago Lake. Alewife can dramatically alter a lake through predation on zooplankton (Wells 1970; Foster 1993; Warner 1999; Harman et al. 2003), and on fish larvae (Brooking et al. 1998, Brandt et al. 1987). Zebra mussels can increase water clarity by filtering phytoplankton, which can impact zooplankton and fish populations (Mayer et al. 2000; Idrisi et al. 2001). An angler diary program and post-card survey of anglers in 2004 indicated that the overall catch rates of Walleye had declined since the 1989-90 creel survey, but catch rates of legal sized Walleye had increased (McBride 2006). Bass fishing effort had increased, and Largemouth Bass had replaced Smallmouth Bass as the more abundant species in angler catches. Regulations allowing winter and spring catch and release fishing for bass were implemented in 2006 for many NY waters including Canadarago Lake. Surveys of young bass in Canadarago Lake were incorporated into an analysis of these regulations and no evidence of negative impacts on production of young bass was found (Jackson et al. 2015). In 2010, an acoustic survey of aquatic macrophyte abundance was conducted (Brooking et al. 2014). In 2011, a report entitled The State of Canadarago Lake, 2011 was completed by the SUNY Oneonta Biological Field Station and the Otsego County Soil and Water Conservation District (Albright and Waterfield, 2012). That study compared limnological conditions and lower trophic levels in the lake and watershed with those documented by Harr et al. (1980), and included GIS maps of land use, bedrock geology, and tributaries within the Canadarago Lake watershed. They also identified starry stonewort (Nitellopsis obtusa), an invasive macroalgae that forms dense beds, for the first time. Also in 2011, Malcolm Pirnie Inc. (2011) completed a hydrologic study of Canadarago Lake and its tributaries, entitled Canadarago Lake Beneficial Use Study. This study modelled impacts of differing 8
water levels on the lake, in respect to potential repairs or modifications of the dam on the outlet. A Watershed Protection Plan (Bailey 2014) was completed in 2014 by the Canadarago Lake Improvement Association and SUNY Oneonta. A boat inspection program at Canadarago Lake identified two instances of water chestnut (Trapa natans) found on boat trailers in 2013, however it is believed none made it to the lake (Coe 2013). The recent studies we report on here have focused on monitoring changes in the Walleye and Yellow Perch populations in Canadarago Lake resulting from establishment of Alewife and zebra mussels, with concurrent monitoring of zooplankton, limnology, and aquatic vegetation. Walleye population estimates were conducted in 2004 and 2008 to monitor changes in the adult population. Surveys for larval fish were instituted in 2005 to measure larval recruitment. In response to evidence of reduced Walleye recruitment in the presence of Alewife, NYSDEC initiated Walleye fingerling stocking in 2011. In addition to summer limnology collections, winter temperature recorders were deployed to assess potential for overwinter survival of Alewife. Alternate year gillnetting for adult fish, annual electrofishing surveys for adult and juvenile fish, and annual small-mesh gillnetting along with an acoustic survey for Alewife were continued. This report summarizes these more recent studies in the context of the long-term studies conducted at Canadarago Lake. Methods Table 2 provides a timeline of sampling events in Canadarago Lake. Gillnetting was conducted annually from 1973-1980, and in alternate years after 1981 (26 years total) by Cornell University and staff from NYSDEC Region 4. Standard gillnets and procedures were used since 1983 as outlined in the NYSDEC Percid Sampling Manual (Forney et al. 1994; see also Brooking et al. 2001). Two nets per month were set in June, July, August, and September. Nets were 45.7 m (150 ft) long, 1.8 m (6 ft) deep with six different panels of monofilament mesh from 38-102 mm (1.5-4 in), in 13 mm (1/2 in) increments. Nets were set overnight for approximately 18 h. All fish were measured and a subsample weighed. Scales were taken from Walleye and Yellow Perch to estimate age. Walleye were examined for fin clips as part of a population estimate in some years, and for evaluation of stocking in other years. Growth rate was estimated from length-at-age using scales for Walleye and Yellow Perch. Electrofishing surveys were conducted starting in 1973 (42 years total). Standard fall night-time electrofishing was carried out by Cornell University and NYSDEC Region 4, along a 3.1 km site on the 9
western shore of the lake (Brooking et al. 2001). Walleye, bass, and Chain Pickerel were generally collected the entire time, and all fish were collected for 0.25 h on two or more runs in most years. All fish were identified, counted and measured. Catch rates were reported separately for age-0 and adult fish. Scales were taken from a sample of Walleye and Yellow Perch for age determination. An additional electrofishing survey was conducted in spring 2010 by NYSDEC Region 4 according to standardized Centrarchid Sampling Manual methods (Green 1989). Mark-recapture estimates of adult Walleye were conducted in 2004 and 2008. Trap nets were set inside the mouths of Hyder Creek and Ocquionis Creek, with additional nets set off points along the west shore and the shoal off the south tip of the island. Up to 7 trap nets were set immediately after iceout and checked every 1 to 2 days. Walleye were removed from the nets, counted by sex, marked with a fin clip, and released. A sample from each site was measured and scales taken for aging. Nets were fished until the catch decreased substantially, usually 10-14 days. Walleye caught later in the year by electrofishing and gillnets were examined for fin clips, and the total population of adult Walleye was estimated based on the ratio of fin-clipped to unclipped fish using Bailey s modification of the Petersen index (Kohler and Hubert 1999). Only age-3 and older Walleye were included in the estimate. Biomass of Walleye was estimated based on abundance of each age group and length-weight relationships. Walleye stocking was resumed in 2011 due to observed declines in Walleye recruitment. Intensively reared fall fingerlings were stocked from 2011-2013 with the following fin clips: 2011- RV, 2012- LV, 2013- RV. In 2014-2015 stocking was changed to intensively reared, 50-day old Walleye fingerlings due to hatchery production changes. In all years, stocking density was 50/ha (20/ac). Alewife gillnets (Brooking and Rudstam 2009) were set at 4-5 sites each fall beginning in 1999 (16 years), when Alewife were first found in the lake. Nets were 21 m long by 6 m deep, with seven 3 m wide panels of different mesh sizes (square mesh sizes of 6.25, 8, 10, 12.5, 15, 18.75, and 25 mm). Nets were set inshore in approximately 6 m of water from the surface to the bottom. Mid-lake sets were also conducted using two nets; one floating net from 0-6 m deep, and one sinking net from 6-12 m deep. Nets were set at night and fished for 4-14 hrs. Alewife were counted, measured and weighed. Otoliths were removed from a sample of Alewife for aging. Whole Alewife were dried in a drying oven, and the dry to wet weight ratio was used as an index of energy density and condition (Rand et al. 1994; Hartman and Brandt 1995). 10
Hydroacoustic sampling using a 70kHz split beam unit (2003-2004) or a 123 khz split beam unit (2005-2014) was conducted on the same night as Alewife gillnetting to estimate the number of Alewife in the lake, beginning in 2003 (12 years). Surveys included 7-9 acoustic transects each year. Data were later processed to estimate the density of fish. Coefficient of variation (CV) was estimated using the sum of the variance from the acoustics analysis and the variance from the gillnet catch. Data collection and processing details are provided in Rudstam et al. (2011). Larval fish were sampled with Miller high-speed samplers beginning in 2005, and compared with samples from 1976-1988 (14 years total) to estimate the abundance of Walleye and Yellow Perch fry in the spring. Samplers consisted of a clear Plexiglas tube with 540 micron mesh nets (Miller 1961). Four samplers were towed simultaneously at a speed of approximately 3.5 m/sec (7.8 mph) for 7.5 minutes. Each sampler strained about 12 m 3 of water/sample. Approximately 48 hauls were done each year from 2005-2014 covering most areas of the lake. Sample depths were stratified to cover the entire water column down to 10 m. Collected fry were identified, counted and measured. Water quality data were collected in most years since 1968 (39-47 years, varies by parameter). Since the mid-1980s, water quality samples were collected once a month from May to October at one standard, center-lake station. This station is located in 12.2 m (40 feet) of water, approximately halfway between Sunken Island Shoal and the east shore (Brooking et al. 2001). Temperature and dissolved oxygen (DO) concentration were recorded at 1 m depth intervals, and water clarity was measured using a Secchi disk. A water sample was also collected just under the surface for total phosphorus, nitrate, and chlorophyll a concentrations. Samples were analyzed using standard techniques described in Idrisi et al. (2001). Phytoplankton sampling from 1968-1976 was reviewed by Harr et al. (1980). In most years since 1972, a vertical zooplankton tow was taken from the bottom to the surface in about 12.2 m (40 feet) of water using a 0.5 m, 153 um mesh net at the same time as the water quality sample (38 years total). Number and species of zooplankton were counted and measured to obtain density (number/l), average size (mm), and biomass (dry weight, ug/l). Sampling results are summarized below, with most data presented in table format. Simple linear regression (coefficient of determination [r 2 ]; degrees of freedom [df]; probability [P]) was used to describe trends in variables that changed over time. In addition, two time periods were chosen to represent major biological periods in the lake s recent history: 1993-2001 referred to as the 11
Walleye/Yellow Perch years, and 2006-2014 referred to as the Alewife/zebra mussel years. This allowed comparison of the two time periods while excluding the years 2002-2005 when the lake was undergoing varying stages of change. A two-sample t-test assuming unequal variance was used to compare the means (t-statistic [t]; degrees of freedom [df]; probability [P]) of major variables during the two time periods. In most instances, a one-way test with α = 0.05 was used to test for changes in one direction (increase, or decrease), with no adjustments made for multiple tests. For multidirectional comparisons a two-tailed test with α = 0.05 for acceptance was used. Limnology and Lower Trophic Levels Results Temperature and Oxygen Monthly temperature and DO profiles indicate Canadarago Lake continues to exhibit patterns typical of a dimictic lake with stratification during the summer months. Water temperatures at 2 m depth often reach 24-26 C in summer (Table 3; Figure 1), which is generally 10-14 C warmer than bottom temperatures at that time. Stratification often starts in late May-June and persists until August- September, with the lake typically homothermal again by October. This results in oxygen depletion in bottom waters from June through September (Figure 2), which can affect fish distribution and cause soluble nutrient releases from bottom sediments through anaerobic respiration. No increasing trend in May-October annual mean temperature was detectable at Canadarago Lake from 1990-2014 (linear regression: r 2 = 0.01; df = 24; P = 0.70), or in June-August annual mean temperature (linear regression: r 2 = 0.02; df = 24; P = 0.52), and no differences in mean temperature were found between the Walleye/Yellow Perch time period and Alewife/zebra mussel time period (Table 4). Sampling intensity of once a month was likely not sufficient to detect small changes in water temperature. 12
Dissolved oxygen (mg/l) Temperature (C) 30 25 Monthly temperature Annual mean temperature 20 15 10 5 0 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year Figure 1. Monthly water temperature and annual mean water temperature in Canadarago Lake at 2 m depth from 1990-2014. 12 10 8 6 4 2 0 5 6 7 8 9 10 11 Month Figure 2. Mean Canadarago Lake dissolved oxygen concentration at different depths by month, 1990-2014. 4 m 5 m 6 m 7 m 8 m 9 m 10 m 11 m 12 m 13
Mean number of days 160 140 120 Oneida Lake 2002-2009 7 year mean Canadarago Lake 2002-2009 6 year mean Cayuta Lake 2002-2007 5 year mean 100 80 60 40 20 0 At or below 1 C At or below 2 C At or below 3 C At or below 4 C Winter water temperatures Figure 3. Winter water temperatures at Canadarago Lake and two other lakes, 2002-2009. Graph shows mean number of days at or below the specified temperature. During the winter, water temperatures in the deep area of the lake 1 m above bottom often remained below 2 C for an extended time at Canadarago Lake (mean = 90 d from 2001-2009) but never went below 1 C (Figure 3). In comparison, winter temperatures at Oneida Lake, NY nearly always went below 1 C, while temperatures at Cayuta Lake, NY seldom were below 2 C. Temperature often determines overwinter survival of cold-sensitive species like Alewife (Colby 1971; Lepak and Kraft 2008; Fetzer 2009). Winter die-offs of Alewife were not unusual at Canadarago Lake in the past 5 years (Preddice 2009), but Alewife have persisted there for 16 years. Nitrogen and Phosphorus Annual mean nitrate (NO 3 ) levels have ranged between 150-400 ug/l since 1968, and averaged 114 ug/l over the last decade (Table 3; Figure 4). Annual mean nitrate decreased significantly between 1985 and 2014 (linear regression: r 2 = 0.64; df = 24; P < 0.01). Annual mean total phosphorus levels generally ranged from 6-50 ug/l (Figure 5). Phosphorus annual mean has decreased significantly over the whole time series (linear regression: r 2 = 0.31; df = 38; P < 0.01), however no significant trends were found from 1990-2014 (linear regression: r 2 = 0.03; df = 20; P = 0.45). Nutrients in Canadarago 14
NO3 (ug/l) Lake have been discussed by many authors since as early as 1936 (Shepherd 1959; Fuhs 1973; Harr et al. 1980; Albright and Waterfield 2012; Bailey 2014; and others, see Appendix III). Nitrate levels in Canadarago Lake were about the same as those found in Oneida Lake over the past two decades, however the total phosphorus concentrations were about half that of Oneida Lake (Jackson et al. 2014). Nitrate concentrations were significantly lower during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period, however total phosphorus was not different (Table 4). 1200 1000 Monthly nitrate concentration Mean annual nitrate concentration 800 600 400 200 0 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 Year Figure 4. Monthly nitrate (NO 3 ) concentration and annual mean nitrate concentrations in ug/l in Canadarago Lake, 1968-2014. 15
Total Phosphorus (ug/l) 160 140 Monthly total phosphorus concentration Annual mean total phosphorus concentration 120 100 80 60 40 20 0 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 Year Figure 5. Monthly total phosphorus concentrations and annual mean total phosphorus concentrations in Canadarago Lake, 1968-2014. Chlorophyll a Levels of chlorophyll a have ranged from 1.5-27.0 ug/l (Table 3; Figure 6). The highest levels were observed before the sewage treatment plant was established in 1973. Though variable, a significant decline was observed through the entire period (linear regression: r 2 = 0.44; df = 37; P < 0.01), with the lowest values found in recent years. No significant difference in chlorophyll a was detected between the Walleye/Yellow Perch and Alewife/zebra mussel time periods (Table 4). Over the last decade, chlorophyll a values at Canadarago Lake were not significantly different than those in Oneida Lake (2-tailed t-test, unequal variance; t = 1.64; df = 16; P = 0.12; Jackson et al. 2014). 16
Chlorophyll a (ug/l) 50 45 40 Monthly chlorophyl a concentration Mean annual chlorophyl a concentration 35 30 25 20 15 10 5 0 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 Year Figure 6. Monthly chlorophyll a concentration and mean annual chlorophyll a concentration in Canadarago Lake, 1968-2014. Water clarity Water clarity as measured by Secchi disk varied seasonally, with highest transparency typically observed in spring and lower transparency in summer as a result of algae blooms. Water clarity in Canadarago Lake increased from 1968-2005 (linear regression: r 2 = 0.56; df = 37; P < 0.01; Table 3; Figure 7). Increased water clarity was likely due to nutrient reduction by the sewage treatment plant, Walleye being established and reducing the large numbers of Yellow Perch, and the establishment of zebra mussels. Water clarity declined from 2005-2014 (linear regression: r 2 = 0.64; df = 9; P = 0.01), likely as a result of increased Alewife predation on zooplankton. In 2014 mean water clarity was 2.3 m, similar to the range seen in the 1970s period. No significant difference in water clarity was detectable between the Walleye/Yellow Perch and Alewife/zebra mussel time periods (Table 4). Water clarity at Oneida Lake has averaged 3.0-4.5 m after the arrival of zebra mussels, and also benefited from reduced nutrient levels in past decades (Jackson et al. 2014). 17
Water clarity (m) 9 8 Monthly water clarity Annual mean water clarity 7 6 5 4 3 2 1 0 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 Year Figure 7. Monthly water clarity and mean annual water clarity as measured by Secchi disk depth (m) in Canadarago Lake, 1968-2014. Zooplankton Zooplankton mean size (Table 3; Figure 8) has varied seasonally, with larger mean size (>0.9-1.2 mm) typically found in spring and smaller mean size (0.3-0.5 mm) in summer, presumably due to fish predation. Annual mean size of zooplankton in 1972-1976 before establishment of Walleye was small (0.58 mm), but was significantly larger for the period 1981-2008 (mean = 0.80; t-test, unequal variance; t = -9.3; df = 27; P < 0.01). From 2009-2014 annual mean zooplankton size has varied, presumably in relation to Alewife density (discussed later). Average size of 0.45 mm in 2010 was the smallest we have seen at Canadarago Lake in the 36 year sampling period. Mean zooplankton size was significantly smaller during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). Mean zooplankton density increased from 1989-2014 (Figure 9; linear regression: r 2 = 0.44; df = 25; P = 0.01), while zooplankton biomass has varied but not shown a significant trend (Figure 10; linear regression: r 2 = 0.02; df = 25; P = 0.51). Biomass reached a record low of 126 ug/l in 2014. Biomass of Daphnia spp. (a large, preferred zooplankton) declined to low levels after 2009 and switched mostly to Daphnia retrocurva, a smaller bodied Daphnid often found when planktivory is intense. Mean zooplankton density was significantly higher during the 18
Zooplankton density (#/l) Avg. size (mm) Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period; mean biomass was not significantly different, but biomass of Daphnia spp. was significantly lower (Table 4). 1.30 Monthly zooplankton average size Mean annual zooplankton average size 1.10 0.90 0.70 0.50 0.30 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 8. Monthly zooplankton average size and mean annual zooplankton average size in Canadarago Lake, 1972-2014. 200 180 160 140 Monthly zooplankton density Mean annual zooplankton density 120 100 80 60 40 20 0 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 9. Monthly zooplankton density and mean annual zooplankton density in Canadarago Lake, 1972-2014. 19
Zooplankton biomass (ug/l) 900 800 Monthly zooplankton biomass Mean annual zooplankton biomass 700 600 500 400 300 200 100 0 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 10. Monthly zooplankton biomass and mean annual zooplankton biomass in Canadarago Lake, 1972-2014. Summary Discussion of Lower Trophic Levels Lower trophic level changes in Canadarago Lake over the past 42 years have been observed in zooplankton, nutrients, and water clarity. Depending on the parameter, monthly samples were taken from 101-194 times over the 42 year period, and combinations of annual averages can be compared in 25-37 years depending on the parameter. Nitrate, zooplankton mean size, zooplankton density, and Daphnia spp. biomass all showed significant differences between the Walleye/Yellow Perch time period and the Alewife/zebra mussel time period (Table 4). Significant relationships were also found between several variables such as water clarity, zooplankton size, density, and biomass, and several measures of nutrients (Table 5). As expected, water clarity was positively correlated with zooplankton size, and negatively correlated with chlorophyll a concentration. Chlorophyll a was positively correlated with total phosphorus. These findings mostly confirm relationships that are well-established in the literature, and are what might be expected given the changes in nutrients, zebra mussels, Yellow Perch, Walleye, and Alewife. Correlations with fish abundance are discussed later in this report. 20
Alewife CPUE (#/net-h) Fish Populations Alewife Alewife were first documented in NYSDEC gillnetting on August 5, 1999 when two fish were caught. In the standard Percid gillnets, Alewife catch increased slowly through 2014 (linear regression: r 2 = 0.46; df =8; P = 0.02). The catch in small-mesh gillnets set specifically for Alewife remained low (0-11/net-hour) with a slow increase from 1999-2006, and peak catch in 2014 at 123/net-hour (Table 6; Figure 11; linear regression, 1999-2014: r 2 = 0.48; df =15; P < 0.01). By 2014 Alewife were the most abundant fish captured in the standard Percid gillnets, surpassing Yellow Perch. Catch in the standard Percid nets was significantly correlated to the catch in the small-mesh Alewife nets (Pearson correlation: r 2 = 0.45; df = 8; P = 0.02). As expected, Alewife catch rates were significantly higher during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). 140 120 100 Small-mesh alewife nets Standard Percid nets 80 60 40 20 0 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year Figure 11. Small mesh gillnet and standard Percid gillnet catches of Alewife in Canadarago Lake, 1999-2014. 21
Alewife abundance (#/ha) Alew density top to bottom (#/ha) Acoustic survey estimates also indicated the Alewife population remained low (<30 fish/ha) from 2003 through 2005 (Table 6; Figure 12). From 2005 to 2010, the population increased from about 9 Alewife/ha to nearly 3,500 Alewife/ha (though the 2010 peak was not seen in small-mesh gillnet catches; Figure 11; linear regression: 2003-2010; r 2 = 0.61; df =7; P = 0.02). At 3,500 Alewife/ha, Canadarago Lake was comparable to densities found in other Alewife lakes (Figure 13). Alewife abundance was greatly reduced in 2011 to only 110 fish/ha, then returned to higher levels of 700-1,500 fish/ha by 2013-2014. Alewife acoustic estimates were correlated to catches in the standard Percid gillnets (linear regression: r 2 = 0.63; df =7; P = 0.02; Table 7). 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 0 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 12. Acoustic estimates of Alewife abundance (#/ha +/- 2SE) in Canadarago Lake, 2003-2014. 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0 Canadarago Lake, 2003-2014 Cayuta Lake, 1995-2009 Figure 13. Comparison of pelagic fish abundance (mean and range) from acoustic surveys in Canadarago Lake and several other lakes with alewife. 22 Onondaga Lake, 2005-2013 Silver Lake, PA, 2008-2013
Length (mm) Alewife growth rates were initially high (Figure 14), and age-0 length-at-age was negatively correlated with Alewife abundance in Canadarago Lake (Table 7). Alewife condition as measured by dry:wet weight ratio was also initially high and showed similar trends, but the relationships with abundance were not significant (Figure 15; regression statistics in Table 7). Rudstam et al. (2011) presented a full analysis of the compensatory responses of Alewife in Canadarago Lake. Impacts of Alewife on the Walleye, Yellow Perch, and zooplankton communities will be discussed below. 300 250 Age-2 and older Age-1 Age-0 200 150 100 50 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 14. Observed mean length-at-age of Alewife in Canadarago Lake, 2003-2014. 23
Ratio of dry:wet weight 0.5 0.45 Age-2 and older Age-1 Age-0 0.4 0.35 0.3 0.25 0.2 2003 2005 2007 2009 2011 2012 2014 Year Figure 15. Condition of Alewife in Canadarago Lake, 2003-2014 expressed as dry:wet weight ratio. Walleye Abundance From 1973 to 1977, no Walleye were caught in 232 gillnet sets (Table 8; Figure 16). The first Walleye were caught in 1978, and by 1983 the catch averaged 9.4 adult Walleye/net, presumably as a result of stocking. By 1985, the catch had peaked at 23 adults/net with strong natural recruitment in the early 1980s. A significant increase in catch rate was found for the period 1973-1985 (linear regression: r 2 = 0.65; df =10; P < 0.01). The catch decreased from 1985-1989, though not significantly (linear regression: r 2 = 0.70; df =3; P = 0.16), but then increased significantly from 1989-2003 to about 21.6 Walleye/net (linear regression: r 2 = 0.94; df =7; P < 0.01). A significant decline to about 9.1 Walleye/net was observed from 2004-2012 (linear regression: r 2 = 0.65; df =5; P = 0.05), likely due to lack of natural recruitment discussed below. Catch rate in 2014 was 12.6 Walleye/net which included recruitment of stocked fish to the adult stock. The gillnet catch rate of adult Walleye was significantly lower during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). The gillnet catch rate of adult Walleye over the last two decades (mean = 15.4 fish/150 foot net) was still about four times higher than the catch rate in Oneida Lake (mean = 4.3 fish/150 foot net; 2-tailed t-test, unequal variance; t = -9.46; df = 12; P < 0.01) and is considered high for New York State waters (Forney et al. 1994; Jackson et al. 2003). 24
CPUE (#/150 foot net-night) 25 20 15 10 5 0 1973 1975 1977 1979 1981 1985 1989 1993 1997 2001 2004 2008 2012 Year Figure 16. Catch per unit effort (CPUE) of Walleye in standard gillnets in Canadarago Lake, 1973-2014. Similar patterns of abundance were seen in electrofishing catch rates (Table 9; Figure 17). No Walleye were caught in >50 h of shocking from 1973-1976, with adult catch rates of 6-15 Walleye/h in 1978-1984 from stocked fish. Natural recruitment contributed to high electrofishing catch rates of 30-60 adult Walleye/h from 1985-1989. Catch rates remained around 15-30 adult Walleye/h from 1991 through 2006 (considered high for NY waters; Forney et al. 1994), with a significant decline from 2004-2014 (linear regression: r 2 = 0.75; df =10; P < 0.01), similar to the pattern seen in gillnet catch rates. By 2014, the adult Walleye electrofishing catch rate had declined to 4.7 Walleye/h, considered low for NY waters (Forney et al. 1994). The electrofishing catch rate of adult Walleye was significantly lower during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). 25
CPUE (#/h) 70 60 50 40 30 20 10 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year Figure 17. Catch per unit effort (CPUE) of adult Walleye in fall night electrofishing at Canadarago Lake, 1973-2014. Based on mark-recapture, the Walleye population was estimated at 15,797 adult Walleye in 2008 (+/-794, 95% confidence interval) and 18,667 (+/-830) adult Walleye in 2004. This equates to a density of 21-24 Walleye per hectare (17-21 kg/ha). For comparison, Walleye populations in Oneida Lake have averaged 10-24 adults/ha (9-19 kg/ha) from 1993-2013 (Jackson et al. 2014, Rudstam and Jackson 2014). Walleye mark-recapture estimates at Cayuta Lake found 12-14 fish/ha (19-23 kg/ha) in 2002-2009. The Walleye biomass in Canadarago Lake in the 2000s was higher than total predator biomass estimated in the 1970s and 1980s. (Table 10; Figure 18; t-test, unequal variance; t = -6.63; df = 1; P = 0.05). 26
Predator biomass (kg/ha) Oneida Lake, 1993-2013 Cayuta Lake, 2002-2009 25 20 15 10 5 0 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 Year Figure 18. Predator biomass (kg/ha) estimated by mark-recapture at Canadarago Lake from 1973-2008. Estimates in earlier years include all predators, but in 2004 and 2008 estimates were only for Walleye. Walleye mean biomass estimates at Cayuta Lake and Oneida Lake are included for comparison. Walleye Recruitment A high percentage of Walleye caught in standard gears were <400 mm prior to the early 1990s, with a decline in the percentage of Walleye <400 mm beginning after 1995 (Figure 19; electrofishing linear regression, 1995-2014: r 2 = 0.79; df =18; P < 0.01; gillnet linear regression, 1995-2014: r 2 = 0.86; df =10; P < 0.01). The number of Walleye <400 mm became very low in the mid-late 2000s, indicating a lack of recruitment. Proportional Stock Density (PSD) of Walleye in both gears reached 93-100 beginning in the mid-2000s (Table 11 and 12; Figure 20), with a significant increase in both gears from 1995-2014 (electrofishing linear regression: r 2 = 0.59; df =18; P < 0.01; gillnet linear regression: r 2 = 0.86; df = 10; P < 0.01). These values in size structure indices often indicate poor recruitment (Gablehouse 1984). 27
Proportional Stock Density % of catch <400 mm 100 90 80 70 60 50 40 30 20 10 Gillnet Electrofishing 0 1978 1982 1986 1990 1994 1998 2002 2006 2010 2014 Year Figure 19. Percent of adult Walleye catch <400 mm in standard gillnetting and fall night electrofishing catch at Canadarago Lake, 1978-2014. 100 90 80 70 60 50 40 30 20 10 Electrofishing Gillnet 0 1978 1982 1986 1990 1994 1998 2002 2006 2010 2014 Year Figure 20. Walleye Proportional Stock density from fall night electrofishing and standard gillnetting in Canadarago Lake, 1978-2014. Larval fish sampling from 2005-2014 caught only 3 Walleye in 432 larval fish tows (Table 13). Previous sampling in 1987-1988 caught significantly more Walleye (131 Walleye larvae in 192 tows; t- test on mean annual catch: t = 5.55; df = 9; P < 0.01). Age-0 Walleye catch rates from electrofishing 28
CPUE (#/h) also confirmed the lack of recruitment (Figure 21). From 1990 to 2004, age-0 Walleye catch rates surpassed 8 fish/h every 2-4 years, with at least a few age-0 caught every year. From 2005 to 2014, Walleye age-0 catch rates were significantly lower, and never surpassed 3 fish/h (t-test, unequal variance; t = 2.02; df = 22; P = 0.03). The reduced survival of age-0 is consistent with trends observed in adult catch rates and size structure. The electrofishing catch rate of age-0 Walleye was significantly lower during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). 50 45 40 35 30 25 20 15 10 5 0 1990 1993 1996 1999 2002 Year 2005 2008 2011 2014 Figure 21. Age-0 Walleye catch per unit effort (CPUE) from fall night electrofishing in Canadarago Lake, 1990-2014. Composition of age classes in the fall electrofishing catch indicated that percent of age-2 Walleye decreased from 2005-2014 (linear regression: r 2 = 0.65; df =9; P < 0.01), with a concurrent increase in the percent of fish that were age-7 and older (Figure 22; linear regression: r 2 = 0.48; df =9; P = 0.03). This shift from a younger to an older Walleye population is consistent with poor recruitment. By 2014, all Walleye in the electrofishing catch and most Walleye from the gillnet catch were age-7 and older. 29
Age frequency (%) 100 90 80 70 60 50 40 30 20 10 Age-2 Age-7 and older 0 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 22. Percent of age-2 and age-7 and older Walleye in the fall night electrofishing catch at Canadarago Lake, 1978-2014. Walleye - Growth rate and condition Lengths-at-age of Walleye from fall electrofishing and June gillnet surveys are reflective of Walleye abundance trends discussed earlier. Length-at-age of age-2 to age-5 Walleye was initially high from 1978-1984, but decreased from 1985-1987 as Walleye abundance increased (Tables 14 and 15; Figures 23 and 24). Electrofishing catches of age-2 thru age-5 Walleye all showed a significant or marginally significant increase in length-at-age from 1994-2014 (linear regression: all P between 0.002-0.07). In the gillnet catches, age-3 through age-5 Walleye all showed a significant increase in length-at-age from 1994-2014 (linear regression: all P between 0.001-0.02). Length at age-2 and age-5 Walleye from the electrofishing surveys were significantly higher during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). Mean length of walleye at age-4 from fall night electrofishing in 2000-2014 was 453 mm, considered to be high growth for NY waters (Forney at al. 1994). 30
Length (mm) Length (mm) 600 550 500 Age-5 Age-4 Age-3 Age-2 450 400 350 300 250 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 23. Observed mean length-at-age of Walleye from fall night electrofishing surveys at Canadarago Lake, 1978-2014. 500 450 Age-5 Age-4 Age-3 Age-2 400 350 300 250 1973 1977 1983 1987 1991 1995 1999 2003 2006 2010 2014 Year Figure 24. Observed mean length-at-age of Walleye from June standard gillnet surveys at Canadarago Lake, 1983-2014. Relative weight (W r ) of Walleye has also varied through time at Canadarago Lake (Tables 11 and 12; Figure 25). W r was high initially with the low population, then decreased during the 1970s and 1980s with values often below 85 as the Walleye population expanded (1974-1990 electrofishing linear regression: r 2 = 0.75; df =11; P < 0.01). From 1990-2007, W r averaged 85 but no trend was apparent (linear regression: r 2 = 0.05; df =12; P = 0.47). When Alewife became abundant, W r increased 31
Relative weight (%) significantly to the highest values seen since 1980 (2006-2014 gillnet linear regression: r 2 = 0.95; df =5; P < 0.01). Changes in W r were apparent throughout the range of Walleye sizes. 105 100 95 Electrofishing Gillnet 90 85 80 75 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 2013 Year Figure 25. Relative weight of Walleye from fall night electrofishing and standard gillnet surveys in Canadarago Lake, 1974-2014. Yellow Perch Abundance Yellow Perch were historically abundant in Canadarago Lake (Greeley 1936). Electrofishing catch rates of adult perch (about 100 mm or larger in most years) averaged 146 adult perch/h from 1973-1985 (Table 9; Figure 26). From 1986-2001, adult catch rates averaged significantly lower at 39 perch/h and never exceeded 100 fish/h (t-test, unequal variance on mean annual catch 1973-1985 vs 1986-2001: t = 3.94; df = 21; P < 0.01). From 2001-2008, adult perch catch rates increased significantly to as many as 1,270 adult perch/h (linear regression: r 2 = 0.62; df =7; P = 0.02) which is considered high for NY waters (Forney et al. 1994). The electrofishing catch rate of adult Yellow Perch was significantly higher during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). These high adult catch rates were consistent with the high catches of age-0 perch during the same period (see below). 32
CPUE (#/h) 1400 1200 1000 800 600 400 200 0 1970 1975 1980 1985 1990 1995 Year 2000 2005 2010 2015 Figure 26. Fall night electrofishing catch per unit effort (CPUE) of adult Yellow Perch in Canadarago Lake, 1973-2014. Gillnet catch rates of Yellow Perch were generally low from 1973-1980. Even after gillnet catches for Yellow Perch were corrected for mesh selectivity (Olson et al. 2001), it was determined that gillnets did not provide an accurate index of the Yellow Perch population prior to 1980 because the perch were simply too small to be caught in the mesh sizes used. For this reason, the pre-1980 gillnet catches for Yellow Perch (Table 8; Figure 27) should be interpreted with caution. From 1987-2014, gillnet catch rates varied from 32-157 adults/net, which is considered high for NY waters (Forney et al. 1994). A significant difference in the gillnet catch rate of adult Yellow Perch between the Walleye/Yellow Perch time period and the Alewife/zebra mussel time period was not detected (Table 4). It is possible that the gillnet catch rates in 2010-2014 could be affected by a similar situation as 1973-1980, since many small fish were again present. 33
Catch per 150 foot net 180 160 140 120 100 80 60 40 20 Catches unreliable from 1973-1980 See text 0 1973 1975 1977 1979 1981 1985 1989 1993 1997 2001 2004 2008 2012 Year Figure 27. Standard gillnet catch rates of Yellow Perch in Canadarago Lake, 1973-2014. Yellow Perch Recruitment From 1997-2007, age-0 Yellow Perch catch rates from electrofishing increased significantly to 500-1,900 age-0 perch/h (Table 9; Figure 28; linear regression: r 2 = 0.73; df =8; P <0.01). From 2007-2014, catch rates exhibited a significant decrease (linear regression: r 2 = 0.40; df =7; P =0.05). This change was even more pronounced in 2012-2014 when catch rates averaged 13/h, a significant reduction from 1999-2007 catch rates that averaged 717/h (t-test, unequal variance: t = 2.11; df = 9; P = 0.03). Reasons for this decrease in age-0 perch are unknown, but may have been due to the combined effects of Alewife predation on larvae, water clarity changes, reduced reproductive capacity of slow growing adult perch, and reduction in zooplankton food for young perch. A significant difference in the electrofishing catch rate of age-0 Yellow Perch during the Walleye/Yellow Perch time period and the Alewife/zebra mussel time period was not detected (Table 4). 34
% of catch >200 mm CPUE (#/h) 2,000 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 28. Fall night electrofishing catch per unit effort (CPUE) of age-0 Yellow Perch in Canadarago Lake, 1990-2014. Size structure of Yellow Perch from electrofishing and gillnet surveys (Figure 29) indicate that from 1973-1980, few perch were over 200 mm. From 1980-1987, there was a significant increase in the percent of perch > 200 mm in the gillnet catch (linear regression: r 2 = 0.87; df =4; P = 0.02). From 1993-2014, the percent of perch > 200 mm decreased significantly in both gears (electrofishing linear regression: r 2 = 0.34; df =18; P < 0.01; gillnet linear regression: r 2 = 0.48; df =11; P = 0.01). 120 100 Gillnet Electrofishing 80 60 40 20 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year Figure 29. Percent of standard gillnet catch and fall night electrofishing catch of Yellow Perch >200 mm in Canadarago Lake, 1972-2014. 35
Proportional Stock Density Yellow Perch PSD from electrofishing and gillnet surveys followed similar overall trends, though some years were dramatically different between the two sampling gears (Tables 11 and 12; Figure 30). PSD from the gillnet tended to be biased towards larger fish, likely due to gear selectivity. PSD of perch from electrofishing increased significantly from 1972-1984 (linear regression: r 2 = 0.69; df = 10; P < 0.01), with a significant decrease in the proportion of larger perch in the population from 1984-2014 (linear regression: r 2 = 0.22; df = 25; P = 0.01). By 2014, PSD of Yellow Perch was below 20 in both gears, indicating a population dominated by small individuals. This was in the same range as PSD values seen from 1973-1980 in both gears. 120 100 Electrofishing Gillnet 80 60 40 20 0 1970 1974 1978 1982 1986 1990 1994 1998 2002 2006 2010 2014 Year Figure 30. Proportional Stock Density of Yellow Perch from fall night electrofishing and standard gillnetting at Canadarago Lake, 1972-2014. Larval fish sampling from 2005-2014 (Table 13) indicated larval perch were abundant (20-100/sample) in most years from 2005-2011, however significantly lower numbers (1-11/sample) were found in 2012-2014 (t-test, unequal variance: t = 2.12; df = 5; P = 0.04). This trend also is consistent with age-0 catches in electrofishing. 36
Length (mm) Yellow Perch - Growth rate Greeley (1936) found a very slow growing Yellow Perch population, which is consistent with our observations from 1972-1981. Observed length-at-age of age-0 through age-4 Yellow Perch from fall electrofishing all increased significantly from 1972-1991 (linear regression: all P < 0.01), and all decreased significantly from 1991-2014 (linear regression: all P < 0.04; Table 17; Figure 31). Mean length-at-age from 2000-2014 was considered high for NY waters (Forney et al. 1994). Likewise in the June gillnet sample, length-at-age of age-3 through age-5 Yellow Perch all increased significantly from 1976-1991 (linear regression: all P < 0.01), and age-2 through age-5 length-at-age decreased significantly from 1991-2014 (linear regression: all P < 0.01; Table 16; Figure 32). Since 2011, lengthat-age has declined to levels seen in the 1970s. Yellow Perch mean length-at-age-3 was significantly lower during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period, however length-at-age-1 was not (Table 4). 350 300 250 Age-4 Age-3 Age-2 Age-1 Age-0 200 150 100 50 0 1970 1974 1978 1982 1986 1990 1994 1998 2002 2006 2010 2014 Year Figure 31. Observed mean length-at-age of Yellow Perch from fall night electrofishing in Canadarago Lake, 1972-2014. 37
Length (mm) 1936 NY Biological Survey 350 300 Age-5 Age-4 Age-3 Age-2 250 200 150 100 1970 1974 1978 1982 1986 1990 1994 Year 1998 2002 2006 2010 2014 Figure 32. Observed mean length-at-age of Yellow Perch from standard gillnetting in Canadarago Lake, 1976-2014. Also included for reference is length-at-age from 1936 (Greeley 1936). Smallmouth Bass The Smallmouth Bass adult catch rate in gillnet surveys was 2-3 bass/net in the 1980s, and decreased significantly from 1983-1997 (Table 8; Figure 33; linear regression: r 2 = 0.72; df = 7; P = 0.01). A significant increase was seen from 2003-2014 (linear regression: r 2 = 0.67; df = 6; P = 0.02). The gillnet catch rate of adult Smallmouth Bass was significantly higher during the Alewife/zebra mussel time period than during the Walleye/Yellow Perch time period (Table 4). The electrofishing catch rate of adult Smallmouth Bass decreased from 1989-2014 (Table 9; Figure 34; linear regression: r 2 = 0.47; df = 20; P < 0.01) though fall electrofishing catch rates can be variable for Smallmouth Bass (Green 1989). The spring electrofishing survey in 2010 had higher catch rates than fall 2010 (see Table 9). In 14 of 15 years since 1993, the electrofishing catch rate of adult Smallmouth Bass at Canadarago Lake was less than the statewide average of 7 fish > 254 mm/h (Perry et al. 2014). Smallmouth Bass recruitment measured by the fall age-0 electrofishing catch rate decreased significantly from 1989-2014 (linear regression: r 2 = 0.28; df = 19; P = 0.02). Relative weight of Smallmouth Bass averaged 93 from 1972-1989 (Figure 35) which is equal to the statewide average, and mean PSD from 1972-1989 was 56, again equal to the state average (Table 18; Figure 36). Smallmouth Bass length-at-age from fall 38
CPUE (#/h) CPUE (#/150 foot net night) electrofishing was higher than the statewide average in most years for age-5 bass, and equal or below the average for age-2 bass (Table 19; Figure 37). 3.0 2.5 2.0 1.5 1.0 0.5 0.0 1983 1987 1991 1995 1999 Year 2003 2006 2010 2014 Figure 33. Smallmouth Bass catch per unit effort (CPUE) in standard gillnetting at Canadarago Lake, 1983-2014. 45 40 35 30 25 20 15 10 5 NYS Average Smallmouth Bass electrofishing catch rate: Adults = 7 fish/h (Perry et al. 2014) Adult Age-0 0 1970 1975 1980 1985 1990 1995 Year 2000 2005 2010 2015 Figure 34. Smallmouth Bass catch per unit effort (CPUE) of adults and age-0 from fall night electrofishing at Canadarago Lake, 1973-2014. 39
Proportional Stock Density Relative weight 130 125 120 115 NY Statewide Average Wr Largemouth Bass = 103 Smallmouth Bass = 93 (Perry et al. 2014) Largemouth Bass Smallmouth Bass 110 105 100 95 90 85 80 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 35. Relative weight (W r ) of Smallmouth Bass and Largemouth Bass from fall night electrofishing at Canadarago Lake, 1972-2014. 100 90 80 70 60 50 40 30 20 10 NY Statewide Average PSD Largemouth Bass = 55 Smallmouth Bass = 56 (Perry et al. 2014) Largemouth Bass Smallmouth Bass 0 1972 1974 1976 1978 1980 1982 1989 1991 1993 1996 1998 2001 2003 2005 2007 2009 2011 2013 Year Figure 36. Proportional Stock Density (PSD) of Smallmouth Bass and Largemouth Bass from fall night electrofishing at Canadarago Lake, 1972-2014. 40
Length (mm) 400 375 350 325 300 275 250 Age-5 from Canadarago Lake Age-5 average from Perry et al. 2014 Age-2 from Canadarago Lake Age-2 average from Perry et al. 2014 225 200 175 150 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 37. Mean observed length-at-age of Smallmouth Bass age-2 and age-5 from fall night electrofishing at Canadarago Lake, 1972-2014. Comparison to average of other NY waters is shown from Perry et al. (2014). Few bass were aged after 1993. Largemouth Bass The fall electrofishing catch rate of adult Largemouth Bass averaged 9.2 fish/h, with no significant change over the entire period (Table 9; Figure 38; linear regression: r 2 = 0.05; df = 22; 2- tailed P = 0.31). This catch rate was below the NYS average (18 adults >254 mm/h; Perry et al. 2014) in 21 of 23 years. A high age-0 catch rate was found in 1991 (41 age-0/h), with additional large year classes in 2006 and 2008. The age-0 catch rates suggest that the lake may be shifting more towards Largemouth Bass than Smallmouth Bass. Jackson et al. (2015) looked at bass recruitment and the effects of spring fishing at Canadarago Lake. Largemouth Bass mean relative weight from 1999-2014 was 111, which was much higher than the NY statewide average of 103 (Figure 35). PSD of Largemouth Bass from fall electrofishing ranged widely among years, from a low of 19 in 1974 to a high of 92 in 2007 (Table 18; Figure 36). Length-at-age of Largemouth Bass for age-2 and age-5 was higher than the NY statewide averages from 1972-1980 (Table 19; Figure 39). 41
Length (mm) CPUE (#/h) 80 70 60 50 40 NYS Average Largemouth Bass electrofishing catch rate: Adults = 18 fish/h (Perry et al. 2014) Adult Age-0 30 20 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 2015 Year Figure 38. Largemouth Bass catch per unit effort (CPUE) of adults and age-0 from fall night electrofishing at Canadarago Lake, 1973-2014. 400 375 350 Age-5 from Canadarago Lake Age-5 average from Perry et al. 2014 Age-2 from Canadarago Lake Age-2 average from Perry et al. 2014 325 300 275 250 225 200 175 150 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year Figure 39. Mean observed length-at-age of Largemouth Bass age-2 and age-5 from fall night electrofishing at Canadarago Lake, 1973-2014. Comparison to average of other NY waters is shown from Perry et al. (2014). Few bass were aged after 1990. 42
CPUE (#/h) Sunfish and other species In the last decade, adult Pumpkinseed have been more abundant in electrofishing samples than Bluegill (2-tailed t-test: t = -2.45; df = 9; P = 0.04). Adult Pumpkinseed catch rates have ranged from 20-100 adults/h, while Bluegill have generally ranged from 10-40 adults/h (Table 9; Figure 40). Pumpkinseed electrofishing catch rates have been higher in recent years but not significantly (2001-2014, linear regression: r 2 = 0.14; df = 13; P = 0.10), while Bluegill have shown no trend (2001-2014, linear regression: r 2 = 0.12; df = 13; P = 0.22). Age-0 Lepomis spp. have had large year classes every 2-3 years, with 60-80 fish/h in 2001 and 2006. Gillnet catches likewise indicate higher catches of Pumpkinseed than Bluegill from 1983-2014 (Table 8; Figure 41; 2-tailed t-test: t = -3.97; df = 17; P < 0.01). No significant differences during the Walleye/Yellow Perch time period and the Alewife/zebra mussel time period were detectable for either sunfish species in the gillnet (Table 4). 160 140 120 100 Bluegill Pumpkinseed 80 60 40 20 0 1990 1994 1998 2002 2006 2010 2014 Year Figure 40. Bluegill and Pumpkinseed catch per unit effort from fall night electrofishing at Canadarago Lake, 1990-2014. 43
Catch per 150 foot net 12 10 8 Bluegill Pumpkinseed 6 4 2 0 1983 1987 1991 1995 1999 2003 2006 2010 2014 Year Figure 41. Bluegill and Pumpkinseed catch per unit effort from standard gillnetting at Canadarago Lake, 1983-2014. Rock Bass have been the second most abundant fish in Canadarago Lake electrofishing catches, with catch rates varying from 22-250 adults/h (mean 99/h; Table 9). White Sucker are also common (39/h), followed by Brown Bullhead (15/h) and Bluntnose Minnow (10/h). In the gillnet catch, Pumpkinseed, White Sucker, and Rock Bass are also common species, followed by Golden Shiner, Rudd, Brown Bullhead, and Chain Pickerel. Summary and Discussion Canadarago Lake has been an important natural resource since as early as 3,500-1,300 B.C. Herring and American Shad reportedly ascended the Susquehanna River before the first dams were constructed around 1825. By the 1930s, the lake was described as eutrophic and dominated by Yellow Perch, bass, Chain Pickerel, and sunfish. Nutrient reduction from sewage treatment and phosphorus bans improved water quality starting in 1972 through bottom-up control of the food web. Through stocking, Walleye and tiger muskellunge became important predators in the lake around 1978 and initiated top-down control of the food web in the 1980s. Natural reproduction sustained a large Walleye population for several decades. The results were improved water quality, better growth rates of fish, and a prized fishery resource through the 1990s and 2000s. 44
Canadarago Lake was largely un-impacted by exotic species until 1999, when Alewife were first found. Predators such as Walleye, bass, tiger muskellunge, and Chain Pickerel did not prevent the Alewife expansion in Canadarago Lake, but may have substantially slowed the expansion. Colonization by zebra mussels further impacted lower trophic levels beginning in 2001. These non-native species set the stage for large changes in the ecosystem over the next decade, and it appears many of the anticipated changes have occurred. Alewife first reached high abundance around 2006 based on net catches and acoustic estimates. Following a peak in 2010, Alewife abundance decreased sharply in 2011 but rebounded in 2012-2014. This sharp drop in 2011 and rebound in 2012-2014 was reflected by changes in several variables during that same time period such as water clarity, zooplankton size, Alewife growth, and Yellow Perch growth. Alewife populations often go through large fluctuations from year to year, with overwinter dieoffs common (Colby 1971; Lepak and Kraft 2008). A winter die off of an estimated 5,000 alewife was recorded by NYSDEC in 2009 (Preddice 2009). Winter temperature data indicate Canadarago Lake is intermediate in terms of thermal conditions for Alewife survival, but Alewife have now persisted for 16 years in Canadarago Lake, and remain abundant. We have shown significant changes in 11 variables between the Walleye/Yellow Perch time period and the Alewife/zebra mussel time period, such as water clarity, zooplankton size and abundance, Alewife growth, Walleye recruitment and growth, and Yellow Perch recruitment and growth (Tables 4 and 7). The average size of zooplankton has declined in Canadarago Lake, as might be expected when Alewife become abundant. Alewife abundance from 2003-2014 was significantly related to mean zooplankton size, mean zooplankton density, and Daphnia spp. biomass. Similar changes have been observed in Otsego Lake (Harman et al. 2003), Onondaga Lake (Wang et al. 2010), and Cayuta Lake (Rudstam et al. 2011). Zooplankton, and especially Daphnia spp., showed marked rebounds in 2012 after the sharp Alewife decrease in 2011. Declines in zooplankton can cause an increase in phytoplankton, and a decrease in water clarity. Improvements in water clarity may be limited by Alewife effects even when phosphorus loading declines. Alewife age-0 length-at-age was negatively correlated with Alewife abundance, likely through food limitation. Both zebra mussels and Alewife have increased in the last decade in Canadarago Lake, and have the potential to alter ecosystem function, including composition and abundance of fish. Zebra mussels increase water clarity by filtering phytoplankton. A significant correlation between Alewife 45
abundance and water clarity was not found over the period 2003-2014, or between the means for the two time periods (Table 4 and 7), likely complicated by the many factors that influenced water transparency over this time. Data suggest Alewife effects on plankton offset some of the expected mussel effects on water clarity. Large age-0 Yellow Perch year classes were seen in the early 2000s, which probably reduced water clarity through predation on zooplankton, and zebra mussels were likely responsible for the high transparency readings in 2004-2009. Increased water clarity can often result in an increased shoreline zone of aquatic plants and algae on the lake bottom (Zhu et al. 2006). Markham (1978) observed increases in submerged aquatic vegetation in Canadarago Lake between 1968 and 1976, with further expansion of vegetation by 2010 (Brooking et al. 2010; see Appendix I Maps 7, 8 and 12). Increased water clarity may also increase predation on larval fish (Irwin et al. 2009). Alewife were predicted to impact fish recruitment through larval predation (Brooking et al. 2001) and have been shown to prey on larval fish elsewhere (Kohler and Ney 1980; Mason and Brandt 1996; Brooking et al. 1998). Sampling for larval fish indicated very low numbers of Walleye fry from 2005-2014. The low Walleye fry catches are also consistent with the low catch of young Walleye in electrofishing, and this reduced recruitment has led to reduced adult Walleye catch rates in recent years. Further evidence of reduced recruitment can be seen in the Walleye length frequency, age frequency, and size structure indices. In response to reduced recruitment of Walleye, NYSDEC initiated a Walleye stocking program in 2011. Approximately 40,000 Walleye fall fingerlings were stocked from 2011-2013, and the stocking program was switched to 50 d old fingerlings in 2014-2015. Stocking was intended to boost Walleye recruitment by offsetting some of the losses of young Walleye to Alewife predation. In 2014 gillnetting, 9 of 11 age-3 or younger Walleye were fin-clipped fish from stocking. Effectiveness of the stocking program will be reviewed after the 5 year period ending in 2015. Alewife predation effects on larval Yellow Perch are often similar to larval Walleye, though perch fry can reach much higher densities (>10/m 3 ) than Walleye and maintain moderate populations in some Alewife lakes in NY (Forney 1975; Forney et al. 1980). Walleye fry may be more vulnerable to Alewife predation than Yellow Perch because they are less abundant and are present earlier in the season when fewer other larval fish are available to buffer predation. Fry sampling found large numbers of larval perch in some years from 2005-2011 when they were only 8 mm long, but substantially reduced numbers 4-5 weeks later when they were 18 mm long. Based on fry catches and electrofishing catches of age-0 Yellow Perch from 2012-2014, recruitment of young Yellow Perch has been substantially reduced the past 3 years. 46
Alewife have likely had a positive impact on Walleye growth and condition. Walleye length-atage increased, and W r was positively correlated to Alewife abundance (Table 4 and 7). However effects on Yellow Perch growth between the two time periods were negative. The decrease in Yellow Perch growth began prior to 2006, likely related to density-dependent growth associated with high recruitment, and a further reduction in growth was seen after Alewife became abundant in 2006-2014, likely due to reduced zooplankton abundance. This slow growth combined with high recruitment has led to large reductions in Yellow Perch length frequency and size structure indices, approaching conditions found in the 1970s before Walleye stocking. Perch growth rates and size structure may rebound somewhat due to low recruitment of age-0 Yellow Perch in 2012-2014, but it s unknown whether this trend will continue. Alewife likely affect Largemouth Bass and Smallmouth Bass populations as well, and bass also were likely affected by changes in water clarity from zebra mussels. The fall electrofishing results indicated Smallmouth Bass have decreased in recent years, though this conclusion is brought into question based on higher catches in the 2010 spring electrofishing (see Green 1989) and continued high gillnet catches of adults. Smallmouth Bass age-0 were particularly low since 2006 when Alewife became abundant. Largemouth Bass age-0 had high catches through 2009, though the last 4 years were somewhat reduced. Relative weights of bass indicated Largemouth Bass were in above average condition, while Smallmouth Bass condition was average for NY (Perry et al. 2014). We would expect Largemouth Bass to benefit from mussel-induced increases in water clarity from 2004-2009 and associated increases in aquatic vegetation growth, though predation in recent years could be affecting age-0 as well. The combined effects of predation, along with water clarity and vegetation changes on pelagic versus inshore larvae may be difficult to separate. Bass populations in other lakes with alewife seem to fare well, such as Cayuta Lake (Rudstam et al. 2010), the Finger Lakes (Bloomfield 1978), and Lake Ontario embayments (Sanderson 2014). Long-term sampling of the fish populations and lower trophic levels in Canadarago Lake has enabled us to monitor changes in the fish populations, introduction of new species, and their impacts on the aquatic food web. This has allowed fisheries managers to enact changes in regulations, implement or remove stocking strategies as needed, and better advise the angling public about changes in Canadarago Lake. Fisheries and limnology surveys have documented past and present changes which have had large effects on the Walleye and Yellow Perch populations in Canadarago Lake. 47
Future Fisheries Management Implications 1) Predator Biomass Maintaining the highest predator biomass possible would benefit the lake in its current state, by reducing abundant prey fish such as Alewife and age-0 Yellow Perch. With the changes observed since the introduction of Alewife and zebra mussels, it appears the Walleye population is unlikely to be sustained by natural reproduction. Stocking of fingerling Walleye will likely be necessary into the future, if the current stocking program proves successful. Increased predator biomass would also benefit Yellow Perch growth rates and size structure, which may rebound somewhat from low Yellow Perch recruitment found in 2012-2014. Continued monitoring of Walleye and Yellow Perch populations at some scale would benefit future management decisions. 2) Alewife abundance Some measure of Alewife abundance would also help guide fisheries management decisions in the future. Percid gillnets have provided a rough index of Alewife abundance, although they don t catch age-0 Alewife or smaller adults which could be a problem, especially if Alewife growth rates and size structure decrease. Smaller mesh nets could be set if Alewife numbers become questionable. Analysis of Walleye stomach contents from gillnet samples may also provide additional information on whether Alewife remain abundant. 3) Invasive species The recent introductions in this lake are an unfortunate example of what happens when invasive species alter a lake s ecosystem. Efforts to reduce or prevent the spread of additional new species cannot be emphasized enough. Nuisance species within ~100 miles of Canadarago Lake include the Round Goby, White Perch, many aquatic plants including hydrilla (Hydrilla verticillata) and water chestnut (Trapa natans), Asian clam (Corbicula fluminea), quagga mussel (Dreissena bugensis), spiny water flea (Bythotrephes longimanus), fishhook water flea (Cercopagis pengoi), hemimysis shrimp (Hemimysis anomala), didymo algae (Didymosphenia geminata), and many others. Acknowledgements The data contained in this report were primarily collected under the direction of Dr. David M. Green, who devoted much of his professional life to sampling the fish populations of Canadarago Lake. Folks who worked with Dr. Green included Dr. John Forney, Steve Smith, Bernie Schonhoff, Donald 48
Bunnell, John Farrell, Tom Greig, Dave Wickersham, Steve Nack, Brian Young, Mark Olson, Larry Nashett, Bill Youngs and many others. Many agency professionals assisted the authors with the collection of this data including Fred Linhart, Scott Wells, Norm McBride, Kay Sanford, Walt Keller and many other DEC Region 4 staff. This project was funded as part of New York Federal Aid in Sportfish Restoration Grants F-56-R, Job 1-2 and F-61-R, Study 2, Job 2-6. References Cited Note: Readers should be advised that to avoid unnecessary duplication, many of the Canadarago Lake reports cited in the text are referenced in Appendix III rather than duplicated in this References Cited section. Brandt, S. B, D. M. Mason, D. B. MacNeill, T. Coates, and J. E. Gannon. 1987. Predation by Alewife on Yellow Perch in Lake Ontario. Transactions of the American Fisheries Society 116:641-645. Bloomfield, J. A. 1978. Lakes of New York State Volume 1: Ecology of the Finger Lakes. Academic Press. New York, NY. Brooking, T. E., L. G. Rudstam, M. H. Olson, and A. J. VanDeValk. 1998. Size-dependent Alewife predation on larval Walleyes in laboratory experiments. North American Journal of Fisheries Management 18:960-965. Brooking, T. E. and L. G. Rudstam. 2009. Hydroacoustic target strength distributions of Alewives in a net-cage compared with field surveys: Deciphering target strength distributions and effect on density estimates. Transactions of the American Fisheries Society 138:471 486. Carlson, R. E. 1977. A trophic state index for lakes. Limnology and Oceanography 22:361-369. Colby, P. J. 1971. Alewife dieoffs: why do they occur? Limnos 4:18-27. Fetzer, W. W. 2009. Overwinter mortality of Gizzard Shad in Oneida Lake, NY. MS Thesis. Cornell University, Ithaca, NY. 88 pp. 49
Forney, J. L. 1975. Contribution of stocked fry to Walleye fry populations in New York Lakes. Progressive Fish-Culturist 37:20-24. Forney, J. L. 1980. Evolution of a management strategy for the Walleye in Oneida Lake, New York. New York Fish and Game Journal 27:105-141. Foster, J.R. 1993. Alewife population dynamics in Otsego Lake. In 25th Annual Report, 1992. SUNY Oneonta Biological Field Station. SUNY Oneonta. Cooperstown, NY. Gablehouse, D. W. Jr. 1984. A length categorization system to assess fish stocks. North American Journal of Fisheries Management 4:273-285. Harman, W. N., M. F. Albright, and D. M. Warner. 2003. Trophic changes in Otsego Lake, NY following the introduction of the Alewife. Lake and Reservoir Management 18:215-226. Hartman, K.J., and S.B. Brandt. 1995. Estimating energy density of fish. Transactions of the American Fisheries Society 124: 347-355. Idrisi, N., E. L. Mills, L. G. Rudstam, and D. J. Stewart. 2001. Impact of zebra mussels, Dreissena polymorpha, on the pelagic lower trophic levels of Oneida Lake, New York. Canadian Journal of Fisheries and Aquatic Sciences 58:1430-1441. Irwin, B. J., L. G. Rudstam, J. R. Jackson, A. J. VanDeValk, J. L. Forney, and D. G. Fitzgerald. 2009. Depensatory mortality, density-dependent growth, and delayed compensation: disentangling the interplay of mortality, growth, and density during early life stages of Yellow Perch. Transactions of the American Fisheries Society 138:99-110. Jackson, J. R., T. E. Brooking, A. J. VanDeValk, and L. G. Rudstam. 2003. Factors affecting survival of stocked Walleye in New York lakes. Final Report. New York State Department of Environmental Conservation. Albany, NY. 67 pp. Jackson, J. R., L. G. Rudstam, A. J. VanDeValk, T. E. Brooking, K. T. Holeck, C. Hotaling, and J. L. Forney. 2014. The Fisheries and limnology of Oneida Lake 2013. New York Federal Aid in 50
Sport Fish Restoration Study 2 Job F-61-R. New York State Department of Environmental Conservation. Albany, NY. 63 pp. Kohler, C. C. and W. A. Hubert, 1999. Inland Fisheries Management in North America. American Fisheries Society. Bethesda, MD. Kohler, C. C. and J. J. Ney. 1980. Piscivory in a landlocked Alewife population. Canadian Journal of Fisheries and Aquatic Science 37:1314-1317. Lepak, J. M. and C. E. Kraft. 2008. Alewife mortality, condition, and immune response to prolonged cold temperatures. Journal of Great Lakes Research 34:134-142. Mason, D. M., and S. B. Brandt. 1996. Effect of Alewife predation on survival of larval Yellow Perch in an embayment of Lake Ontario. Canadian Journal of Fisheries and Aquatic Sciences 53:1609-1617. Mayer, C. M., A. J. VanDeValk, J. L. Forney, L. G. Rudstam, and E. L. Mills. 2000. The response of Yellow Perch in Oneida Lake, NY to the establishment of zebra mussels. Canadian Journal of Fisheries and Aquatic Sciences 57:742-754. Miller, D. 1961. A modification of the small Hardy plankton sampler for simultaneous high speed plankton hauls. Bulletin of Marine Ecology 45:165-172. Pennsylvania Fish Commission. 1896. Report of the State Commissioners of Fisheries for the year 1895. Clarence Busch, State printer of Pennsylvania. Harrisburg, PA. 245 pp. Rand, P.S., B.F. Lantry, R. O'Gorman, R.W. Owens, and D.J. Stewart. 1994. Energy density and size of pelagic prey fishes in Lake Ontario, 1978-1990 - Implications for salmonine energetics. Transactions of the American Fisheries Society 123: 519-534. Sanderson, M. 2014. A recreational fishery survey of Port, East, and Blind Sodus Bays. Federal Aid in Sportfish Restoration F-56-R Study 2 Job 2-2. New York State Department of Environmental Conservation. Avon, NY. 54 pp. 51
Wang, R. W., L. G. Rudstam, T. E. Brooking, D. J. Snyder, M. A. Arrigo, and E. L. Mills. 2010. Food web effects and the disappearance of the spring clear water phase in Onondaga Lake following nutrient loading reductions. Lake and Reservoir Management 26:169 177. Warner, D. M. 1999. Alewife in Otsego Lake: A comparison of their direct and indirect mechanisms of impact on transparency and chlorophyll a. 32nd Occasional Paper, SUNY Oneonta Biological Field Station, SUNY Oneonta. Oneonta, NY. Wells, L. 1970. Effects of Alewife predation on zooplankton populations in Lake Michigan. Limnology and Oceanography 15:556-565. Zhu, B., D. G. Fitzgerald, C. M. Mayer, L. G. Rudstam, and E. L. Mills. 2006. Alteration of ecosystem function by zebra mussels in Oneida lake, NY: Impacts on submerged macrophytes. Ecosystems 9:1017-1028. 52
Appendix I. Maps of Canadarago Lake Map 1. Map of Canadarago Lake watershed and surrounding property owners in 1847. 53
Map 2. Canadarago Lake map from 1935 New York Biological Survey (Wheeler and O Dell 1936). 54
Map 3. Map of Canadarago Lake in 1958 with depth soundings and netting locations from Shepherd (1959). 55
Map 4. Bathymetric map of Canadarago Lake from Fuhs (1973) showing lake divisions used for sampling in the 1960s thru the 1980s. 56
Map 5. Map of substrate types in Canadarago Lake from Green and Smith (1976). 57
Map 6. Map of Canadarago Lake with contours in feet showing sampling locations used in 1970s and 1980s Cornell University fisheries surveys; adapted from original by Harman and Weir (1974). 58
Map 7. Map of emergent, submerged, and floating aquatic vegetation in Canadarago Lake in 1968 from Markham (1978). 59
Map 8. Map of emergent, submerged, and floating aquatic vegetation in Canadarago Lake in 1976 from Markham (1978). 60
Map 9. Map showing artificial reef locations in Canadarago Lake from Sanford (1985). 61
Map 10. NYS DEC contour map of Canadarago Lake from 2015 (http://www.dec.ny.gov/docs/fish_marine_pdf/canlkmap.pdf). 62
Map 11. Map showing WIN numbers for Canadarago Lake and tributaries from GIS location information (Scott Wells, NYSDEC Region 4, October 2011). 63
Map 12. GIS extrapolation of submerged aquatic vegetation (% cover) from a lake-wide acoustic survey at Canadarago Lake on 8/25/2010 (Brooking et al. 2014). 64