• Relationships between brown bears and chum salmon at McNeil River, Alaska

      Peirce, Joshua McAllister (2007-08)
      Since 1967, the McNeil River State Game Sanctuary (MRSGS) has been managed by the Alaska Department of Fish and Game to 'provide permanent protection for brown bears'. Up to 144 bears have been identified in a summer at MRSGS, and 72 bears at once have been observed in the vicinity of McNeil Falls. In this study, 155 chum salmon were radio tagged as they entered McNeil River and monitored daily. In 2005 and 2006 bears killed 48% of pre-spawning tagged chum salmon and consumed 99% of all tagged chums below McNeil Falls where most of the run occurs. A retrospective analysis of 31 years of run data using a new stream life, and a correction for observer efficiency, revealed that the current escapement goal of 13,750-25,750 actually represents 34,375-64,375 chum salmon. Considering the large removal of pre-spawning chum salmon, I recommend an additional 23,000 chum salmon be added to the escapement goal. Additionally, an annual escapement of 4,000-6,000 chum salmon above McNeil Falls should be set as an objective. These recommendations should encourage increased chum salmon returns, providing both food for McNeil bears, as well as benefiting the commercial fishery with increased harvest opportunities.
    • Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-Arctic Alaskan river

      Benson, Emily R. (2010-08)
      The aim of this study was to investigate the environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. Ecosystem metabolism is the combination of gross primary production and ecosystem respiration within a river. Aquatic macroinvertebrates link primary producers at the base of the food web with secondary consumers. The extent to which photosynthetically active radiation, discharge, and nutrients influence metabolism rates and how primary production and river discharge rates influence benthic macroinvertebrate densities in sub-arctic rivers is not clear. These processes ultimately help regulate prey resources available for upper level consumers such as juvenile salmon. I employed Random Forests model analyses to identify important predictor variables for primary production and respiration rates (estimated using the single-station diel oxygen method) at four sites in the Chena River, sub-arctic Alaska, throughout the summers of 2008 and 2009. I calculated Spearman correlations between nutrient levels and metabolism rates. I used Random Forests models to identify the variables important for predicting benthic macroinvertebrate density and biomass at the study sites. The models indicated that discharge and length of time between high water events were the most important variables measured for predicting metabolism rates. Discharge was identified as the most important variable for predicting benthic macroinvertebrate density and biomass. Phosphorus concentration was low (at times below the detection limit), while nitrogen concentration was more variable; the ratio of nitrogen to phosphorus was above the threshold for phosphorus limitation, suggesting that phosphorus may have been limiting primary production.
    • A remote sensing-GIS based approach for assessment of chinook salmon rearing habitat in the Unuk river floodplain

      Smikrud, Kathy M. (2007-05)
      Remote sensing offers an alternative method to managers in mapping and monitoring the habitat within large rivers. Large rivers are not accommodating for traditional (foot) fish habitat surveys due to their size and typically complex habitat. This study investigates the use of digital aerial photos and thermal infrared images acquired in spring 2003-2005 to map and quantify juvenile chinook salmon (Oncorhynchus tshawytscha) habitat in a 12-river km section of the Unuk River floodplain in Southeast Alaska. Images were processed and analyzed to produce a fluvial landscape classification (7 landcover classes with an overall classification accuracy of ~84%) using a combination of aerial and thermal images. Change detection of large woody debris (LWD) was also examined and revealed both quantitative and distributional changes during the 3 years. A GIS-based habitat suitability analysis was used to identify potential chinook salmon rearing habitats including: river channel edges, sloughs, braids, pools associated with LWD and primary river channels. Overall 77.82 hectares of potentially medium/high chinook rearing habitats were identified. Results from this study provide a promising foundation towards mapping and monitoring salmon habitat in large river systems for purposes of protection, conservation and monitoring to ensure sustainable stocks of salmon.
    • Reproductive behavior and related social organization of the muskox on Nunivak Island

      Smith, Timothy E. (1976-05)
      The sexual behavior and social organization of the muskox (Ovibos moschatus wardi Zimmerman) were studied on Nunivak Island, Alaska, in fall 1972 and summer and fall 1973. Observation effort was concentrated on a single harem group for two months, during the height of courtship activity. Movements and fluctuations in the structure of this group are documented. There was no significant change in mean herd size as a result of the rut, suggesting the existence of a basic social unit independent of the influence of harem bulls. Harem bulls were in the 6-10 year age class. They exerted a stabilizing influence on the harem but did not direct its movements. The rut extended from early July to mid-October. Copulation occurred on September 4 and 5. General patterns of sexual and agonistic behavior are described. Changes in activity patterns as a result of the rut are shown. Bulls displayed more marked changes than cows or juveniles. The proportion of time allocated to sexual and agonistic behavior increased at the expense of maintenance activity as the rut progressed.
    • Reproductive patterns in king eiders

      Bentzen, Rebecca L.; Powell, A. N.; Thomas, D. L.; Kitaysky, A. S.; Flint, P. L. (2009-12)
      Mammalian predation, avian predation, female body condition and food availability on the breeding ground are likely the main factors influencing nesting success in tundra-nesting waterfowl. These driving factors are mediated by the primary life history characteristics; incubation behavior, female body size, nesting associations, and nest site selection. I created a conceptual model illustrating how these factors are interrelated and how they impact nest success through a variety of pathways to better understand the evolution of a species' nesting strategy and patterns observed in the field. The importance of the driving factors likely varies between sites and with the species nesting strategy. Given the conceptual model, I predicted the difference in life history characteristics and nesting success at two sites that vary in any of the four driving factors. I tested the model and associated predictions using King Eider females (Somateria spectabilis) breeding on Alaska's coastal plain by comparing selective forces influencing nesting strategies at two sites, Teshekpuk and Kuparuk, between 2002 and 2006. King Eiders fit the model with some modifications to the mediating pathways. Site differences were found in many of the reproductive parameters which matched the prediction of more available forage at Kuparuk than at Teshekpuk. No differences in either avian or mammalian predation pressure were evident between sites. Eiders at Kuparuk had higher nest survival and incubation constancy than at Teshekpuk. Body mass and nest selection were similar between sites. Although questions concerning the nesting strategies of King Eider remain, I feel that this was a valid approach to identifying selective forces impacting nesting strategies and applicable to tundra nesting waterfowl in general.
    • Resilience of a deer hunting system in Southeast Alaska: integrating social, ecological, and genetic dimensions

      Brinkman, Todd J. (2009-08)
      I examined the interactions of key components of a hunting system of Sitka black-tailed deer (Odocoileus hemionus sitkensis) on Prince of Wales Island, Alaska to address concerns of subsistence hunters and to provide a new tool to more effectively monitor deer populations. To address hunter concerns, I documented local knowledge and perceptions of changes in harvest opportunities of deer over the last 50 years as a result of landscape change (e.g., logging, roads). To improve deer monitoring, I designed an efficient method to sample and survey deer pellets, tested the feasibility of identifying individual deer from fecal DNA, and used DNA-based mark and recapture techniques to estimate population trends of deer. I determined that intensive logging from 1950 into the 1990s provided better hunter access to deer and habitat that facilitated deer hunting. However, recent declines in logging activity and successional changes in logged forests have reduced access to deer and increased undesirable habitat for deer hunting. My findings suggested that using DNA from fecal pellets is an effective method for monitoring deer in southeast Alaska. My sampling protocol optimized encounter rates with pellet groups allowing feasible and efficient estimates of deer abundance. I estimated deer abundance with precision (±20%) each year in 3 distinct watersheds, and identified a 30% decline in the deer population between 2006-2008. My data suggested that 3 consecutive severe winters caused the decline. Further, I determined that managed forest harvested>30 years ago supported fewer deer relative to young-managed forest and unmanaged forest. I provided empirical data to support both the theory that changes in plant composition because of succession of logged forest may reduce habitat carrying capacity of deer over the long-term (i.e., decades), and that severity of winter weather may be the most significant force behind annual changes in deer population size in southeast Alaska. Adaptation at an individual and institutional level may be needed to build resilience into the hunting system as most (>90%) of logged forest in southeast Alaska transitions over the next couple of decades into a successional stage that sustains fewer deer and deer hunting opportunities.
    • Response of northern red-backed vole (Clethrionomys rutilus) populations to a major spruce beetle infestation in the Copper River Basin, Alaska

      McDonough, Thomas (2000-08)
      A spruce bark beetle (Dendroctonus rufipennis) epidemic in the Copper Basin of Alaska beginning in the late 1980's has infested over 200,000 ha of white spruce forests in the region. The impact of spruce beetle-induced habitat changes on the northern red-backed vole (Clethrionomys rutilus) was investigated using mark/recapture techniques for 2 field seasons. Vole abundance and recruitment was significantly greater on low versus heavily infested sites but a large vole survival response was lacking. Vole food resources and protective vegetative cover did not vary substantially in areas with different levels of spruce mortality. Male movement distances were influenced by sex ratio, and females appeared to respond to food resources (epigeous sporocarps). Beetle infestations alone did not influence vole movements, but female movement distances decreased when heavy infestation levels were coupled with female age and sporocarp availability. The impact of beetle infestations on red-backed vole populations in the Copper Basin appears to be relatively small.
    • Responses of captive common eiders to implanted satellite transmitters with percutaneous antennas

      Latty, Christopher J. (2008-05)
      Implanted transmitters have been used for over a decade to track the migrations and habitat use of many sea duck species, but their effects remain largely unstudied. To address this, I assessed the physiological and behavioral responses and characterized the clinical responses of six Common Eiders implanted with a transmitter with a percutaneous antenna. To maintain a semi-natural feeding regime, I fed birds benthicly in a 4.9 m deep dive column. I collected blood, feces, mass, and video data prior to surgery to establish baselines and at staggered intervals for 3.5 months post surgery to determine responses. All birds had some clinical complications, but most abated within 2 weeks of surgery. Mass increased in the first two weeks, but no trend was evident thereafter. Most biomarkers and dive performance metrics were altered at some point after surgery. While most biochemical values returned to baseline within weeks of surgery, a few remained deviated for longer. Additionally, dive speeds were slower for up to 3.5 months after implantation. Although it is uncertain how these changes would ultimately affect birds in the wild, effects on physiological condition and behavior seem likely in the first few weeks after surgery with longer-term effects also possible. Scientists should consider these responses and possible effects on the validity of PIT data when designing studies and analyzing information from implanted transmitters in sea ducks.
    • A review of waterfowl investigations and a comparison of aerial and ground censusing of waterfowl at Minto Flats, Alaska

      Rowinski, Ludwig J. (1958)
      The Minto Flats is one of the important waterfowl concentration areas of interior Alaska. Aerial surveys and ground studies were initiated in this area in 1950 and have continued in succeeding years. This study began in September, 1955, as a research project of the Alaska Cooperative Wildlife Research Unit. The study was financed largely by Pitman-Robertson Project Alaska W-3-R. The Minto Flats is an area of about 450 square miles, located about 35 miles west of Fairbanks. The important nesting species are scaup, pintail and widgeon. The Minto Lakes area serves as an important molting and flocking area for these and other species. Climatically the Minto Flats resemble the rest of interior Alaska. Water levels in the area are highly variable and influence the vegetation and breeding. Minto Lakes, Big Lake, and the Tolovana Flats were selected for concentrated study in 1956. During the 1956 field studies, data were collected for comparison with data available from previous years. Waterfowl production in the Minto Flats area is affected principally by weather, changes in water level, and predation. Among the factors influencing censusing are the census methods, stratification, and sample size. Enumeration of waterfowl is affected by differences in the visibility of birds, population composition, environmental conditions, and the accuracy of observers in relation to the other variables and in regard to individual partiality and talent. The difference between observers, when analyzed statistically points out the need for continuity of observers with known levels of ability. Breeding bird census figures from aerial surveys from 1950 t o 1956 are not comparable due to differences in census methods. Aerial brood surveys are valuable for determining year to year production trends while ground surveys provide data on brood species composition. Together they are the best guide to waterfowl production. Nesting studies have provided some data on nesting terrain, clutch size, and nesting success. The effect of nest hunting on the breeding population and the time necessary for obtaining an adequate sample indicates that nest hunting is not an economical or accurate means of measuring yearly productive success. Aerial surveys are recognized as the most feasible way of measuring production if the accuracy of the information gathered from the air can be increased.
    • River features associated with chinook salmon spawning habitat in Southwest Alaska

      Jallen, Deena M.; Margraf, F. Joseph; Adkison, Milo (2009-08)
      Chinook salmon (Oncorhynchus tshawytscha) is a highly valued traditional, subsistence, and commercial resource in Southwest Alaska. Stream habitat availability is a major component influencing salmon productivity. The objective of this study is to identify river features associated with spawning habitat, and describe upper and lower boundaries of chinook salmon spawning on the Tuluksak River. River distances, elevation, salmon locations, spawning sites, and habitat observations were collected along 75 river kilometers of the Tuluksak River primarily within the Yukon Delta National Wildlife Refuge. Habitat and salmon observations were grouped into strata along the length of the river for comparison and analysis. Chinook salmon were observed spawning in the upper 45 river kilometers of the study area. Map-based observations of elevation and channel sinuosity correlate better with chinook salmon spawning than in stream habitat measurements along the Tuluksak River. The upper boundary of chinook salmon spawning in the Tuluksak River was outside of our study area. The lower boundary for chinook salmon spawning habitat on similar rivers might be determined by examining elevation, sinuosity, and channel features from remote images or maps prior to conducting field studies.
    • River features associated with chum salmon spawning areas: a method to estimate habitat capacity

      O'Brien, John P. (2006-05)
      Diminishing returns of salmon and years of poor commercial and subsistence fishing in western Alaska are a cause for concern. Management tools which recognize the intricate life histories of salmon and incorporate environmental conditions at each particular life stage are needed. Toward that goal a study of spawning habitat for chum salmon Oncorhynchus keta was conducted from 2002 to 2005 on the Tuluksak River in western Alaska. Small-scale river features were measured during two summers of field work. Large-scale river features were identified using remote sensing. Principal components analysis (PCA) denoted an association between spawning sites and channel intersections, gravel bars, islands, and areas of accelerated channel change, forming the basis for a predictive habitat model. Two models were developed that combined them habitat assessment with chum salmon redd size and spatial requirements at three spawning densities. The first model, based on field observations in 2002 and 2003, estimated a greater spawning capacity than the second model, based on large-scale river features. Spawning capacity estimates from both models were consistent with historic escapement data and should be used as a starting point for further research. This study represents progress toward a management strategy that is sensitive to habitat-dependent production potential.
    • The role of fire in the carbon dynamics of the boreal forest

      Balshi, Michael S. (2007-12)
      The boreal forest contains large reserves of carbon, and across this region wildfire is a common occurrence. To improve the understanding of how wildfire influences the carbon dynamics of this region, methods were developed to incorporate the spatial and temporal effects of fire into the Terrestrial Ecosystem Model (TEM). The historical role of fire on carbon dynamics of the boreal region was evaluated within the context of ecosystem responses to changing atmospheric CO₂ and climate. These results show that the role of historical fire on boreal carbon dynamics resulted in a net carbon sink; however, fire plays a major role in the interannual and decadal scale variation of source/sink relationships. To estimate the effects of future fire on boreal carbon dynamics, spatially and temporally explicit empirical relationships between climate and fire were quantified. Fuel moisture, monthly severity rating, and air temperature explained a significant proportion of observed variability in annual area burned. These relationships were used to estimate annual area burned for future scenarios of climate change and were coupled to TEM to evaluate the role of future fire on the carbon dynamics of the North American boreal region for the 21st Century. Simulations with TEM indicate that boreal North America is a carbon sink in response to CO₂ fertilization, climate variability, and fire, but an increase in fire leads to a decrease in the sink strength. While this study highlights the importance of fire on carbon dynamics in the boreal region, there are uncertainties in the effects of fire in TEM simulations. These uncertainties are associated with sparse fire data for northern Eurasia, uncertainty in estimating carbon consumption, and difficulty in verifying assumptions about the representation of fires that occurred prior to the start of the historical fire record. Future studies should incorporate the role of dynamic vegetation to more accurately represent post-fire successional processes, incorporate fire severity parameters that change in time and space, and integrate the role of other disturbances and their interactions with future fire regimes.
    • Seasonal diets of mink and martens: Effects of spatial and temporal changes in resource abundance

      Ben-David, Merav (1996)
      Seasonal changes in food availability and feeding habits of mink (Mustela vison) and martens (Martes americana) on Chichagof Island, Southeast Alaska, were studied through the analysis of natural abundance of stable isotopes. Dependence of the two species on marine-derived nutrients, carried to the terrestrial system via the upstream migration of spawning Pacific salmon (Onchorhynchus sp.), was investigated. Twenty-four mink and 75 martens were live-trapped repeatedly in early summer (prior to salmon runs), early autumn (post salmon runs), late winter, and in spring (during the mating season). A blood sample was obtained from each individual. In addition, 25 mink and 165 marten carcasses were obtained from trappers during late autumn 1991-1994. Concurrently, prey availability was monitored, and tissues from prey were collected. The abundance of stable isotopes in prey tissues and blood samples were compared, indicating that riverine mink depended on salmon (carcasses and fry), with little seasonal or individual variation, whereas coastal mink relied on intertidal organisms in spring and summer, but fed on salmon carcasses when they became available in autumn. In addition, analysis of blood progesterone revealed that timing of reproduction in female mink appear to be shifted, so that lactation coincided with the availability of salmon carcasses. In contrast, martens showed individual variation in their diets, with some individuals feeding exclusively on terrestrial organisms, while the diets of others include salmon carcasses. Incorporation of salmon in the diet depended largely on availability of small rodents and location of the martens home range on the landscape. Although salmon carcasses are not a preferred food item for martens, they act as a suitable alternative to maintain body condition and allow successful reproduction even in years when preferred food is not readily available.
    • Seasonal movement patterns and habitat occupancy of Kotzebue region inconnu

      Smith, Nicholas J.; Sutton, Trent; Seitz, Andrew; Zimmerman, Christian (2013-12)
      Inconnu Stenodus leucichthys are large, long-lived piscivorous whitefish harvested in subsistence and sport fisheries in Alaska. My study was conducted to describe the seasonal movements and habitat occupancy of inconnu in the Selawik and Kobuk River drainages, Alaska, from 2010 through 2012. Methods consisted of surgically implanting acoustic telemetry tags in 80 fish from both rivers in 2010 and 2011 (n = 320), and deploying a fixed array of 20 Vemco VR2W acoustic receiving stations affixed with archival tags throughout Selawik Lake and Hotham Inlet. Tagged inconnu detections revealed that Selawik and Kobuk River inconnu displayed a high degree of spatial and temporal overlap while co-located in the Hotham Inlet/Selawik Lake complex. During the winter period, tagged fish predominately occupied the northern end of Hotham Inlet. In the summer period, fish transitioned from the northern end of Hotham Inlet to Selawik Lake and also the southern end of Hotham Inlet. Average daily displacements for Selawik and Kobuk River inconnu ranged from 2,000 to 10,000 m/day. Water temperature and salinity occupancy ranged from -1.39 to 18.69°C and 0 to 31.3 psu, respectively. No stock-specific or temporal trends in temperature and salinity occupancy by inconnu from the Selawik and Kobuk rivers were detected during my study. In addition to providing a more complete account of the life history of inconnu, these results will aid managers in developing future management strategies.
    • Seasonal movements and habitat use of rainbow trout in the Susitna River basin, southcentral Alaska

      Fraley, Kevin Marshall; Falke, Jeffrey; McPhee, Megan; Prakash, Anupma (2015-12)
      Potamodromous Rainbow Trout are an important ecological and recreational resource in freshwater systems of Alaska, and increased human development, hydroelectric projects, declining Pacific salmon stocks, and climate change may threaten their populations. We used aerial and on-the-ground telemetry tracking, field-measured and remotely-sensed aquatic habitat characteristics, snorkel surveys, and resource selection and occupancy models to characterize seasonal movements and habitat use of adult Rainbow Trout (>400 mm FL) at multiple spatial and temporal scales across the large (31,221 km²) and complex Susitna River basin of southcentral Alaska during 2003-2004 and 2013-2014. We found that trout overwintered in mainstem habitats near tributary mouths from November to April. After ice-out in May, trout ascended tributaries up to 51 km to spawn, and afterward moved downstream to lower tributary reaches to intercept egg and flesh subsidies provided by spawning salmon in July and August. Trout transitioned back to mainstem overwintering habitats at the onset of autumn when salmon spawning activity waned. Fidelity to tributary of capture varied across seasons, but was high in three out of four drainages. Different habitat characteristics influenced Rainbow Trout habitat use during each season, including stream gradient and sinuosity in the winter, substrate suitability and sinuosity during spawning, mean annual flow during the pre-salmon feeding season, and Chinook salmon spawning potential after the arrival of adult salmon in freshwater. We found that during the ice-free feeding season trout responded to fine-scale (channel unit) characteristics rather than more coarse-scale (stream reach) variables. Weekly movements were significantly longer when spawning salmon were present compared to pre-arrival. We found no difference in movements and habitat use for a subset of fish for which sex was identified using genetic analysis. However, the observed sex ratio was heavily female-biased, which contrasts with what has been observed in other non-anadromous salmonid populations. As most trout undertake extensive movements within and among tributaries and make use of a variety of seasonal habitats to complete their life histories, it will be critical to take a broad and multiscale approach to their management in light of anticipated future land use and climate change.
    • Seasonal movements of arctic grayling in a small stream on the Arctic Coastal Plain, Alaska

      Heim, Kurt C.; Wipfli, Mark; Seitz, Andrew; Falke, Jeffrey (2014-08)
      In watersheds of the Arctic Coastal Plain (ACP) of Alaska, Arctic Grayling adopt a migratory life history strategy to persist in a landscape with long (~ 8 month), cold winters that cause shallow aquatic habitats to freeze solid. We investigated movement patterns of adult and juvenile Arctic Grayling in a shallow beaded stream (Crea Creek), a dominant headwater stream type on the ACP. From 2012–2013 Arctic Grayling (N = 1035) were tagged with passive integrated transponder tags and monitored using an array of stream-wide antennae. Migration into Crea Creek peaked immediately after ice break-up in the main channel of the study area. Fish caught within the stream in June were in relatively poor body condition compared to fish captured later in summer. In both years, fish entering the stream during high flow and colder temperatures swam farther upstream than those entering during low flow and warmer temperatures. Migration of adult fish out of the stream was most strongly correlated with decreasing stream discharge, whereas juvenile downstream migration occurred in two peaks and was negatively correlated to minimum stream temperature and discharge. Among juveniles, fish of larger size and higher body condition tended to emigrate earlier. These results indicate that the population level migratory response is strongly tied to seasonal changes in hydrology, though heterogeneity among individuals also influences the response to seasonal change. This work demonstrates the importance of environmental cues, and surface-water flow mediated connectivity during the open-water period, and provides information needed to identify susceptibilities of migratory fishes to climate change and petroleum development on the ACP.
    • Seasonal movements of broad whitefish (Coregonus nasus) in the freshwater systems of the Prudhoe Bay oil field

      Morris, William A. (2000-05)
      Adult broad whitefish were tagged with radio transmitters in the Little Putuligayuk and Putuligayuk rivers along the Beaufort Sea coast of the Prudhoe Bay area, Alaska. Thirty-two fish were tagged in Lake Judith, a shallow tundra lake in the Little Putuligayuk River system. An additional 5 fish were tagged in the Putuligayuk River near a suspected spawning and overwintering site. Many fish left the tundra system to overwinter in the west channel of the Sagavanirktok River, however, unexpected movements also occurred. Six (20%) of the fish found in overwintering areas moved to the east channel of the Sagavanirktok River, an area long disregarded as having much potential for overwintering fish. Additionally, 2 fish traveled west over 100 km along the coast to the Colville River. Broad whitefish in this study wintered in marginal habitat and exhibited the ability to travel between distant coastal river systems along the arctic coast of Alaska.
    • Seasonal movements of northern pike in Minto Flats, Alaska

      Albert, Matthew L.; Sutton, Trent M.; Evenson, Matthew J.; Margraf, F. Joseph; Verbyla, David (2016-08)
      Northern pike (Esox lucius) is a large, long-lived piscivorous species that are harvested in sport and subsistence fisheries in Alaska. My study described the seasonal movements of northern pike that inhabit the Minto Lakes portion (Goldstream Creek drainage) of the Minto Flats wetland complex, Alaska, from May 2008 through January 2010. Very high frequency (VHF) radio tags (n = 220) were surgically implanted in northern pike in Minto Flats in May 2007, 2008, and 2009, and fish were relocated with fixed telemetry stations and aerial- and boat-based telemetry surveys. Radio-tagged northern pike displayed a distinct spring pre-spawning migration into the Minto Lakes study area, where they remained for the duration of the open-water season. A protracted out-migration occurred between late September and early December, with downstream movements peaking in November and October of 2008 and 2009, respectively. Radio-tagged fish present in the Minto Lakes study area during the open-water season overwintered exclusively in a 26-km reach of the Chatanika River from its confluence with Goldstream Creek upstream to the Murphy Dome Road access point. Daily movement rates were greatest during May and August. In addition to providing a better understanding of northern pike life history in Minto Flats, these results will aid managers and researchers by identifying critical habitats and providing information to better design future population assessment experiments.