Progress 10/01/08 to 09/30/11
Outputs
OUTPUTS: We completed three years of data collection designed to document annual variation in brook trout (Salvelinus fontinalis) population metrics (density, reproduction, growth, survival, emigration, and condition) and key habitat variables (temperature, pH, monomeric aluminum, dissolved oxygen, ground water) in six Adirondack lakes (Lower Sylvan Pond, East Lake, Panther Lake, Honnedaga Lake, Rock Lake, Wilmurt Lake). A sub-sample of brook trout (10-20 fish per sampling effort) were kept from spring-summer gill net and fall trap net surveys in each lake to assess age and growth, diet composition, and fish condition. Surface water temperature was monitored in all lakes and bottom temperature was monitored in unstratified lakes using automated temperature data loggers. Backpack electrofishing surveys of tributaries, seeps, and non-habitats (those not providing a thermal refuge) were conducted in all lakes in mid-August to provide a measure of relative abundance of young-of-the-year fish resulting from spawning the previous fall. A key project result was determining that elevated summer temperatures delay spawning and reduce redd (spawning nest) construction for resident brook trout. Repeated surveys throughout the spawning season allowed us to fit an individually-based parametric model and estimate the day of year on which spawning initiated, reached its midpoint, and ended in each year. Spawning phenology was then assessed relative to: 1) mean of maximum daily air temperature and 2) mean of maximum daily water temperature at the lake bottom through the summer in each year using a linear model. Elevated temperatures in summer were correlated with a delay in spawning and a reduction the total number of redds constructed. Increasing the summer mean of maximum daily air temperatures by one degree C delayed spawning by about a week and decreased the total number of redds constructed by about 65. We assessed the relationship between a commonly used index for lake brook trout population density (gillnet CPUE ) and brook trout densities derived from directly estimated populations and used data from capture-mark-recapture tagging efforts in 2010 and 2011 to estimate adult brook trout abundance and gill net capture probability in two study lakes with contrasting environmental conditions. We compared densities derived from these population estimates to catch rates in gill nets and trap nets, after correcting these catch rates for size-based selectivity (when possible). We also assessed brook trout growth rates (estimates and variance) in six Adirondack lakes to investigate age- and year-specific variation in growth rates with two approaches: 1) Von Bertalanffy models and 2) multilevel models. We then compared growth estimates to observations of incremental somatic growth. Written reports regarding our project efforts were provided to private landowners associated with these study lakes (Adirondack League Club, Wilmurt Lake Club, Rock Lake Club), as well as annual meetings of these private cooperators. Additional presentations regarding project results and methods were provided to staff of the New York State Department of Environmental Conservation. PARTICIPANTS: Individuals who worked on this project included Clifford Kraft, Principal Investigator (project design and implementation), Daniel Josephson, Research Associate (project design and implementation), Jason Robinson, former graduate student (project design and implementation), Justin Chiotti, Research Aid IV (project design and implementation), Kurt Jirka, Research Support Specialist, (project design and implementation). Partner organizations included the Adirondack Lake Survey Corporation, New York State Department of Environmental Conservation (NYSDEC), Adirondack League Club, Rock Lake Club, Wilmurt Lake Club and Bay Pond Park. Collaborators and contacts included Barry Baldigo, Watersheds Research Section, US Geological Survey, Troy, NY; Rich Preall, Bureau of Fisheries, NYSDEC (Ray Brook); Chris VanMarren, Bureau of Fisheries, NYSDEC (Watertown); Jim Daley, Bureau of Fisheries, NYSDEC (Albany). TARGET AUDIENCES: Angler (e.g. Trout Unlimited) and conservation (e.g. Nature Conservancy) organizations, plus state (NYSDEC), private landowners, and local bodies of government (e.g. Town of Webb, Herkimer County) responsible for managing Adirondack lake fisheries. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
An unexpected and important knowledge outcome of this project was determining that elevated summer temperatures delay the timing of spawning and reduce fall redd (spawning nest) construction for resident lake-dwelling brook trout. Lake-spawning brook trout select redd sites based on the presence of discharging groundwater that is relatively constant in temperature within and across years, leading to relatively consistent egg incubation times. Therefore, delayed spawning is likely to delay fry emergence, which could influence emergence synchrony with prey items.This work highlights non-lethal effects of elevated summer temperatures on native resident salmonids in aquatic environments with limited thermal refugia. Global and regional climate models predict increases in temperature across the north temperate eco-region over the next century, and these changing climate conditions are expect to lead to associated increases in stream and lake temperatures. The influence of changing climate on the timing of life-history events (phenology) has been well established for a wide variety of organisms, with clear links between temperature and phenologic events such as bud-break, first flower, insect emergence, or migration timing for birds and butterflies. Our project is the first to document such impacts on resident coldwater fish, which often have limited capacity to move away or migrate long distances in response to thermally stressful conditions. A change in action occurred when New York State Department of Environmental Conservation staff conducted a survey of brook trout condition in more that 60 western Adirondack lakes during summer 2009, using methods developed as part of our project. Management practices for several of our study lake populations of brook trout were adjusted based on project results confirming the presence of a large enough population to sustain increased harvest rates in these lakes.
Publications
- Josephson, D.C., Lepak, J.M., Robinson, J.M., and C.E. Kraft. 2012 (In press). Rainbow trout performance in food-limited environments: Implications for future assessment and management. Journal of Freshwater Ecology.
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: We completed the second year of a data collection effort designed to evaluate the influence of key habitat variables (temperature, pH, monomeric aluminum, dissolved oxygen, ground water) on population metrics (density, reproduction, growth, survival, emigration, and condition) of brook trout in six Adirondack lakes (Lower Sylvan Pond, East Lake, Panther Lake, Honnedaga Lake, Rock Lake, Wilmurt Lake). A sub-sample of brook trout (10-20 fish per sampling effort) were kept from spring-summer gill net and fall trap net surveys in each lake to assess age and growth, diet composition, and fish condition. In both 2009 and 2010 water chemistry surveys were conducted at deep sites in all study lakes in July, August, and September, and water chemistry surveys were conducted in all lake tributaries in mid-August. Surface water temperature was monitored in study lakes (at 2 m depth) and bottom temperature was monitored in unstratified lakes using automated temperature data loggers. Backpack electrofishing surveys of tributaries, seeps, and non-habitats (those not providing a thermal refuge) were conducted in all lakes in mid-August to provide a measure of the relative abundance of young-of-the-year fish resulting from spawning the previous fall. During the past year we evaluated previously collected (from 2008) samples of eggs from spawning brook trout, and these results indicated that substantial differences in population characteristics were reflected in brook trout egg size. We therefore again collected eggs from spawning brook trout in all study lakes in fall 2010 in order to confirm whether these differences are consistent from year to year. Written reports on our survey efforts were provided to private landowners associated with these study lakes (Adirondack League Club, Wilmurt Lake Club, Rock Lake Club), as well as annual meetings of these private cooperators. Additional presentations regarding project results and methods were provided to staff of the New York State Department of Environmental Conservation. PARTICIPANTS: Individuals who worked on this project included Clifford Kraft, Principal Investigator (project design and implementation), Daniel Josephson, Research Associate (project design and implementation), Jason Robinson, former graduate student (project design and implementation), Justin Chiotti, Research Aid IV (project design and implementation), Kurt Jirka, Research Support Specialist, (project design and implementation). Partner organizations included the Adirondack Lake Survey Corporation, New York State Department of Environmental Conservation (NYSDEC), Adirondack League Club, Rock Lake Club, Wilmurt Lake Club and Bay Pond Park. Collaborators and contacts included Barry Baldigo, Watersheds Research Section, US Geological Survey, Troy, NY; Rich Preall, Bureau of Fisheries, NYSDEC (Ray Brook); Chris VanMarren, Bureau of Fisheries, NYSDEC (Watertown); Jim Daley, Bureau of Fisheries, NYSDEC (Albany). TARGET AUDIENCES: Angler (e.g. Trout Unlimited) and conservation (e.g. Adirondack Nature Conservancy) organizations, plus state (NYSDEC), private landowners, and local bodies of government (e.g. Town of Webb, Herkimer County) responsible for managing Adirondack lake fisheries. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The first two project years have provided a welcome contrast in climate conditions. Summer 2009 was relatively cool, and stressful thermal conditions only existed for a short period of time during that year. By contrast, summer 2010 was consistently warm and wet, which provided a useful contrast with the prior year in which data was collected for this project. In addition, a wide range of pH and ANC (acid neutralizing capacity) levels were found in surface waters and tributaries of the six study lakes. One of the most noteworthy observations to date has been that seasonal diet composition of brook trout was generally consistent within each lake in both 2008 and 2009, even though lake-to-lake differences in diet were substantial. It's possible that the similarity between diet data collected in 2008 and 2009 reflects similar environmental conditions in these two years, therefore we expect that additional diet data collected in 2010 (a year with very different climate conditions) will be informative in determining whether conditions of food availability are consistent within particular lakes in warm and cool summers. In addition, in both study years the greatest brook trout densities were consistently found in spring gill net surveys of East Lake, with lower densities found in Panther and Wilmurt Lakes. Lower Sylvan Pond and Rock Lake had densities from 1-5 fish/hour, and the lowest density was found in Honnedaga Lake (<1.0 fish/hour). Percent water in tissue of brook trout showed similar seasonal trends among study lakes in both study years, indicating that brook trout build up lipid levels during a period of suitable water temperatures and food availability prior to the development of warm summer thermal conditions. Fish tissue lipid levels prior to fall also seem to provide a useful indicator of reproductive output during fall spawning. In the final project year we will confirm whether water content provides a good proxy for brook trout lipid levels by analyzing both lipids and water content from tissue samples collected in 2010. We will also implement a laboratory study evaluating how food consumption influences tissue lipid levels and water content in brook trout, while also evaluating the use of bioelectrical impedance analysis (BIA) as a method to non-destructively measure fat content in trout tissues. BIA measurements were collected when conducting fall trap net surveys in Fall 2010 as a preliminary attempt to determine whether this technique could be used to evaluate fish condition without killing fish. Discussions of this project with New York State Department of Environmental Conservation staff led to their evaluation of brook trout condition and wild reproduction in more than 60 western Adirondack lakes during summer 2009, and DEC staff now plan to continue conducting ongoing surveys of brook trout condition and reproduction in a small number of public lakes.
Publications
- Robinson, J.M., D.C. Josephson, B.C. Weidel and C.E. Kraft. 2010. Influence of variable summer water temperatures on brook trout growth, consumption, reproduction and mortality in an unstratified Adirondack lake. Transactions of the American Fisheries Society 139:685-699.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: We completed the first year of a data collection program that is documenting annual variation in key habitat variables (temperature, pH, monomeric aluminum, dissolved oxygen, ground water) as well as population metrics (density, reproduction, growth, survival, emigration, and condition) of brook trout in six Adirondack lakes (Lower Sylvan Pond, East Lake, Panther Lake, Honnedaga Lake, Rock Lake, Wilmurt Lake). A sub-sample of brook trout (10-20 fish per sampling effort) were kept from spring-summer gill net and fall trap net surveys in each lake to assess age and growth, diet composition, and fish condition. Water chemistry surveys at deep sites were conducted on all study lakes in July, August, and September in 2009, and water chemistry surveys were conducted at all tributaries in mid-August. Surface water temperature was monitored in all lakes (at 2 m depth) and bottom temperature was monitored in unstratified lakes using automated temperature data loggers. Backpack electrofishing surveys of tributaries, seeps, and non-habitats (those not providing a thermal refuge) were conducted in all lakes in mid-August to provide a measure of relative abundance of young-of-the-year fish resulting from spawning the previous fall. In summer 2009 we also conducted surveys to quantify the amount of tributary habitat in each lake that is suitable and occupied by first-year brook trout. This was accomplished by conducting longitudinal surveys of all lake tributaries along their entire lengths, measuring physical and chemical habitat, and capturing brook trout in backpack electrofishing surveys. We also developed maps of predicted groundwater input locations along all study lake shorelines using a topographic index modeling approach. Written reports on our survey efforts were provided to private landowners owning property associated with these study lakes (Adirondack League Club, Wilmurt Lake Club, Rock Lake Club), as well as annual meetings of these private cooperators. Additional presentations regarding project results and methods were provided to staff of the New York State Department of Environmental Conservation. PARTICIPANTS: Individuals who worked on this project included Clifford Kraft, Principal Investigator (project design and implementation), Daniel Josephson, Research Associate (project design and implementation), Justin Chiotti, Research Aid IV (project design and implementation), Kurt Jirka, Research Support Specialist, (project design and implementation). Partner organizations included the Adirondack Lake Survey Corporation, New York State Department of Environmental Conservation (NYSDEC), Adirondack League Club, Rock Lake Club, Wilmurt Lake Club and Bay Pond Park. Collaborators and contacts included Barry Baldigo, Watersheds Research Section, US Geological Survey, Troy, NY; Rich Preall, Bureau of Fisheries, NYSDEC (Ray Brook); Chris VanMarren, Bureau of Fisheries, NYSDEC (Watertown); Jim Daley, Bureau of Fisheries, NYSDEC (Albany). TARGET AUDIENCES: Angler (e.g. Trout Unlimited) and conservation (e.g. Nature Conservancy) organizations, plus state (NYSDEC), private landowners, and local bodies of government (e.g. Town of Webb, Herkimer County) responsible for managing Adirondack lake fisheries. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Overall, it was a relatively cool summer in 2009, and stressful thermal conditions were only observed for a short period of time. In addition, a wide range of pH and ANC (acid neutralizing capacity) levels were found in surface waters and tributaries of the six study lakes. The greatest brook trout densities were found in spring gill net surveys of East Lake (15-38 fish/hour). Similar surveys of Panther and Wilmurt Lakes showed lower, but similar densities (5-14 fish/hour). Lower Sylvan Pond and Rock Lake had densities from 1-5 fish/hour, and the lowest density was found in Honnedaga Lake (<1.0 fish/hour). Percent water in tissue of brook trout showed similar seasonal trends among study lakes. Tissue water content was high in the May, then the tissue water content decreased for brook trout in all lakes as the summer progressed (June through August). The decreasing water content indicates that brook trout were building up lipid levels during a period of suitable water temperatures and active foraging in the lakes. By October, the tissue water content had increased to levels exceeding those observed in May, coinciding with the fall spawning season and lipids being depleted by fall spawning activities. Aquatic insects were frequent in diets of all size classes of brook trout in the study lakes, and zooplankton most frequently occurred in the diets of smaller (<300mm) brook trout. Isopods (a type of crustacean) were common in the diets of all size classes of fish in Honnedaga and Panther Lakes. Generally, stomach fullness for brook trout was greatest in the spring, declined in the summer, and increased again in the fall. The largest numbers of spawning redds were found in Panther Lake, Rock Lake, and Wilmurt Lake. Lower numbers of redds were observed in East Lake and Honnedaga Lake, and very few redds were found in Lower Sylvan Pond. Based on these early project results, New York State Department of Environmental Conservation staff conducted a survey of brook trout condition in more that 60 western Adirondack lakes during summer 2009, using methods developed as part of this project.
Publications
- No publications reported this period
|
|