RSS 1.0Theses supervised by AKCFWRU
Recent Submissions
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Resource partitioning and behavioral interactions among young-of-the-year salmonids, Chena River, AlaskaThe partitioning of habitat and food and the behavioral interactions of young-of-the-year Arctic grayling (Thymallus arcticus), Chinook salmon (Oncorhynchus tshawytscha), and round whitefish (Prosopium cylindraceum) were studied in the laboratory and in their natural habitat. Individuals of all three species defended territories. Arctic grayling were the most aggressive of the three and appear to displace round whitefish from their preferred habitat. In sympatry, there is a segregation of habitat use between Arctic grayling and chinook salmon. Stomach content analysis showed an overlap in diet among the three species. Larvae of the three species emerged at different times and sizes, resulting in a size divergence among coexisting species during their first summer. The three species were found to inhabit faster moving and deeper water as they grew, resulting in a spatial separation of the species and a reduced probability of interactions and competition among them.
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Phylogeographic variation and the island syndrome in holarctic tundra voles (Microtus oeconomus)Phylogeographic patterns of genetic and morphologic variation were explored among six subspecies of the Holarctic tundra vole (Microtus oeconomus). but focused on those populations occurring in southcoastal Alaska. Allozyme electrophoresis and karyotyping revealed that, although levels of intraspecific variation were low compared to other species of Microtus. allozymic divergence was concordant with regional glacial history. Tundra voles from interior Alaska became established prior to the last glacial retreat. However, populations from southcoastal Alaska were founded more recently. Tundra voles from Montague Island, an endemic subspecies, exhibited features of the island syndrome (i. e., gigantism, older age structure). Factors potentially responsible for insular gigantism were assessed. The findings of this study fail to support the hypothesis that the island syndrome is a direct result of interspecific competition. Other density-dependent factors, such as predation, may be responsible for body size and demographic changes in these insular rodents.
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Diet and nestling growth of red-legged and black-legged kittiwakes: an interspecies cross-fostering experimentI conducted an interspecific cross-fostering experiment to investigate how diet composition and feeding rates affected nestling survival, growth, and gastrointestinal development of Red-legged and Black-legged kittiwakes on St. George Island, Alaska. Red-legged Kittiwakes (Rissa brevirostris) fed nestlings primarily lanternfish (Myctophidae), a high-lipid diet, whereas Black-legged Kittiwakes (R. tridactyla) fed nestlings mostly walleye pollock (Theragra chalcogramma), a low-lipid diet. Nestling meal size was similar for the two species, but Red-legged Kittiwakes fed nestlings at about half the rate of Black-legged Kittiwakes. Interspecific differences in nestling growth were explained by differences in adult body mass. Survival rates and lean body mass did not differ between fostered nestlings and conspecific controls. Nestlings raised by Red-legged Kittiwakes had 50% larger fat reserves than those raised by Black-legged Kittiwakes. Thus growth rates of lean tissue were genetically constrained, while rates of fat deposition were determined by diet Interspecific differences in gastrointestinal anatomy were partly genetic and partly dietary in origin.
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Evaluation of models and assumptions for closed population abundance estimators from from cutthroat trout mark-recapture dataThe goal of this project was to improve cutthroat trout Oncorhynchus clarki mark-recapture experiments in southeast Alaska lakes. A mark-recapture experiment was conducted at Hasselborg Lake, Admiralty Island, southeast Alaska. The sampling design, nine abundance models and their assumptions were evaluated. Evaluation of model assumptions led to conclusions that the population was closed and no tag loss occurred. Probability of capture varied due to effects of time (sampling occasion) and heterogeneity (differences among individual fish) during 1992, and time and behavior (capture effects) during 1993. Chao M(h) was selected as the best abundance estimator for 1992, and Chao M(t) for 1993. Evaluation of sampling design led to several conclusions: angling was the most effective gear type; catch per unit effort decreased with depth; dispersal distance was not related to time; length distributions were depth specific; and gear selectivity took place.
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Life-history consequences of maternal condition in Alaskan mooseWe studied characteristics of life-history of Alaskan moose (Alces alces gigas) including the effects of maternal condition of adult females on survival and physical condition of young during their first year-of-life. We also examined the relation between maternal condition and reproductive parameters of individual adult moose. We found that females in better physical condition, as indexed by rump-fat thickness, had higher rates of pregnancy, gave birth to more twins, and produced young with higher birth masses than did females with less rump fat. Expected time-to-death for individual young increased as birth mass increased and decreased with increasing birth date and litter size. Our results indicated maternal condition influenced subsequent variables associated with birth, which ultimately influenced future survival of offspring. Timing of parturition also occurred earlier for individual females with greater rump-fat thickness. That outcome suggested that timing of parturition was the result of environmental factors acting on females prior to birth.
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Aquatic ecology of two subarctic lakes: Big and Little Minto Lakes, AlaskaDuring 1988, three sampling trips were made to Big and Little Minto Lakes to study their limnological features. Physical and chemical measurements were made of both lakes, while the invertebrate community and habitat characteristics were investigated along Big Minto Lake's shoreline (5-35cm water depth) . Both lakes are shallow and eutrophic, with high dissolved oxygen and pH, and moderate alkalinity. Invertebrate abundance averaged 7,352/m2 (±SE = 406, n = 60) , and was dominated by Diptera (38%) . Gastropoda comprised the largest portion (41%) of total biovolume (11.28 mL/m2, ±SE = 1.28, n = 60). Diptera and Coleoptera contained the majority of invertebrate families. Scrapers (41%) and collectors (23%) dominated the food web in biovolume. Overall, invertebrate abundance was significantly correlated with low detritus biomass; however, Trichoptera abundance was significantly correlated with low vegetation biomass, shallow water, and the August sample period; and both diversity indices, were significantly correlated with aquatic plant biomass (AFDW).
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Life histories and community structure of the caddisflies (Trichoptera) of two Alaskan subarctic streamsThe ecology of Trichoptera was studied in two streams in interior Alaska. Monument Creek and West Fork are characterized by cold water temperatures, low allochthonous input and periphyton biomass, and lengthy ice cover. Nine species were found, Rhyacophila vofixa ? (Rhyacophilidae), Glossosoma verdona, G. alascense (Glossosomatidae), Brachycentrus americanus (Brachycentridae), Hydatophylax variabilis, Ecclisomyia conspersa, Onocosmoecus unicolor, Chyranda centralis and Apatania crymophila (Limnephilidae). There were four shredders, three scrapers, one omnivore, and one predator. Within shredders and scrapers, species had sequentially overlapping life histories, perhaps allowing functionally similar species to use the same food resources. Latitudinal gradients in the North American Trichoptera fauna were investigated using approximately 90 studies from the literature and unpublished Alaskan data. Taxonomic richness showed a weak negative correlation with latitude in light trap studies. Hydropsychoidea showed an inverse correlation, while Limnephiloidea and Limnephilidae showed positive correlations with latitude. Density and biomass were also negatively correlated to latitude.
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Life histories and community structure of Ephemeroptera and Plecoptera in two Alaskan subarctic streamsDevelopment of water quality and quantity standards required for improved management of stream fisheries depends on understanding life cycles of the major benthic components. Because temperature is a major factor influencing aquatic insect life histories, subarctic streams provide excellent opportunities to examine organisms existing under extreme environmental conditions. Life histories and community structure of Ephemeroptera and Plecoptera were examined in two Alaskan subarctic streams during 1979 and 1980. Biweekly benthos samples were collected during the ice-free period in a second and a fourth order stream. Seventeen stonefly species and at least seven mayfly species were collected as nymphs or adults. Nymphal abundance and biomass were greater for all taxa in erosional zones (P < 0.05). Coexistance of systematically-related species occurred because of seasonal separation of life histories, or differences in food exploitation patterns.
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Stock identification and homing of arctic grayling, Thymallus arcticus (Pallas), in interior AlaskaThe objectives were to determine techniques for identification of Arctic grayling Thymallus arcticus (Pallas) stocks in interior Alaska and evaluate homing. Starch gel electrophoresis was used to identify three stocks in the Tanana River and the upper Koyukuk River drainage. Photoidentification could not be used to separate these stocks based on the number of spots on their sides. The spot pattern seemed to have potential for identification of individual grayling. It was feasible to tag young-of-the-year grayling with coded micro-wire tags. The 30-day tag loss was high (27.8%) for the smallest, but significantly lower (7.7%) for the largest size group. Analysis of back-calculated fork lengths at first annulus indicated that Badger Slough and Chena River grayling represent separate stocks. Mature Badger Slough grayling had similar numbers of whole circuli to young-of-the-year grayling from Badger Slough, suggesting that they were homing to their natal stream.
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Angler effort, exploitation, and values on the upper Chena River, AlaskaMethods of improving accuracy and efficiency of creel census estimates were tested during the summers of 1979 and 1980 on the grayling (Thymallus arcticus) fishery of the upper Chena River. Roving counts of fishermen accurately (within 10%) reflected angler use. Incomplete trip catch-per-unit-effort estimates obtained from a roving creel census were free from sampling bias. Stratification (weekends vs. weekdays) resulted in a twofold increase in precision of use estimates. A two-stage sampling design (time periods within days) improved efficiency of sampling. Motivations and values of interior Alaskan anglers were evaluated using survey questionnaires. Aspects of the fishing experience not related to catching fish, such as companionship, outdoor enjoyment, and relaxation, were primary motivations for most (94%) anglers. The catch-related motivations were also important to a large portion (63%) of anglers. The upper Chena River fishery had many attributes which, when taken together, provided satisfactory fishing experiences to a wide range of angler types.
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Spawning substrate and adequate escapement for coho salmon in the Ayakulik river, Kodiak National Wildlife Refuge, AlaskaEscapement information for management of coho salmon, (Oncorhynchus kisutch), is lacking in some drainages on Kodiak National Wildlife Refuge. In 1993 and 1994,1 assessed availability of spawning substrate for coho salmon in the Ayakulik River, a major drainage of the Refuge, as a potential cost-effective method for setting escapement goals. Spawning substrate was divided into three categories: optimal, suboptimal and marginally usable. I conducted a foot survey to count coho salmon spawners in 10 river sections during late October 1994 in three of four strata comprising the Ayakulik River. I found a significant relationship between numbers of spawners and availability of optimal substrate in two of the strata combined (r2=0.28, p=0.04); with optimal and suboptimal substrate combined the significance increased (r2=0.39, p=0.01). When I pooled optimal, suboptimal, and marginally usable substrate I found no significant relationship (r2=0.21, p=0.08). Adequate escapement of coho salmon may be predicted by the amount of optimal and suboptimal substrate available.
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Population characteristics of Dolly Varden in the Tiekel River, AlaskaLength and age data were collected from a population of stream resident Dolly Varden (Salveilnus malma) in the Tiekel River in southcentral Alaska during the summers of 1985 and 1986. In addition to stream-dwelling individuals, fish inhabiting beaver ponds in the Tiekel River drainage and the nearby Little Tonsina River were also sampled. From these data, a description of some basic characteristics of the Tiekel River population was developed. The Tiekel River Dolly Varden population is young, with high natural mortality after age 4, especially in the mainstem Tiekel. Fish in this drainage mature at young ages and small sizes. Although they do not reach lengths or ages as great as anadromous char, Dolly Varden of the Tiekel River drainage are similar in both length and age to resident char reported in other studies. Habitat plays an important role in determining both growth and life span of these fish. Beaver ponds are capable of producing larger fish than the mainstem, and some beaver ponds are more productive than others.
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Seasonal proximate composition and food source comparisons of Dolly Varden char in the Kugururok River, AlaskaThe Kugururok River on the Noatak River System is an important spawning tributary for Dolly Varden char (Salvelinus malma), an important subsistence resource, occur bycatch in commercial fisheries, and are the basis of a sport fishery. The feeding habits and energetic condition of two spawning run patterns in the Noatak River Drainage were studied. Isotope ratio analysis revealed a predominantly marine carbon and nitrogen composition in all adult char. No internal isotopic fractionations were found either between tissues or seasons in any tissue. Proximate analysis revealed patterns of lipid and protein utilization characteristic of periodic starvation in fishes. Significant shifts of energy between key tissues were noted during the production of gonads. Data suggest that energetic minimums must be reached at sea before char can enter freshwater and successfully spawn.
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Effects of spawning run delay on spawning migration of Arctic graylingThe effects of delays on the spawning run of Arctic grayling in Fish Creek, a tributary of the Jack River, near Cantwell, Alaska were examined. Tagged grayling were delayed for 3, 6, or 12 days, and then released; control fish were released within 12 hours of capture. During the delays, a high proportion of females became ripe; most males were ripe before the delays and remained ripe over a longer period than females. Delayed and control fish were monitored by the recapture of tagged fish in upstream traps. Females released in a "running-ripe" condition migrated at higher rates, but failed to reach upstream areas in similar proportions as those of "less ripe" females. Reduction in distances traveled by grayling as a result of longer delays may lead to the use of non-preferred spawning habitats, underuse of spawning areas upstream, and decreases in recruitment. I recommend that spawning delays for Arctic grayling not exceed 3 days.
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Fourier analysis of otolith banding patterns to discriminate among hatchery, tributary, and lake shore incubated sockeye salmon (Oncorhynchus nerka) juveniles in Tustumena Lake, AlaskaOtolith banding patterns formed during incubation were used to discriminate among hatchery and wild sockeye salmon (Oncorhynchus nerka) fry from Tustumena Lake, Alaska. Banding patterns were described by Fourier analysis of otolith luminance profiles. Amplitudes of individual Fourier harmonics were used as discriminant variables. Estimates of total correct classification of otoliths to hatchery or wild origin were as high as 83.1% using quadratic discriminant function analysis on 10 Fourier amplitudes. The maximum total classification rate estimate among hatchery and five wild groups was 45.7% using linear discriminant function analysis on 14 Fourier amplitudes. Although classification rates for any individual group of wild incubated fry never exceeded 64%, site specific information was evident for all groups because the probability of classifying an individual to its true incubation location was significantly greater than chance. Results indicate phenotypic differences in otolith microstructure amongst incubation sites separated by < 10 km.
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Stock assessment of rainbow trout in a Southeast Alaska impoundmentBlue Lake is a multiple-use reservoir near Sitka, Alaska that supports an important sport fishery sustained by a reproducing population of rainbow trout Oncorhynchus mykiss. Although harvest levels appeared high, the effects of exploitation were unknown before this study took place. Mark-recapture, size-age-sex, maturity, and harvest data were collected during 1991 and 1992 to assess stock status. Closed population abundance estimators proved more useful than open population models. Abundance in spring 1992 was estimated at 4708 fish >180 mm FL with a coefficient of variation of 17.0%. Maximum scale age was 7, age- and length-at-maturity at the 50% level were 3.4 years and 233 mm FL, natural mortality was 0.26, and full recruitment occurred at age 5. The critical exploitation rate beyond which sustained yield may not be possible was estimated at 0.32. The estimated 1992 exploitation rate with hooking mortality taken into account was 0.26.
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Evaluation of sampling gears for fish population assessment in Alaskan lakesThree lakes in Alaska's Interior and Kenai Peninsula were sampled during summers, 1982 and 1983, to evaluate sampling gears used for fish population assessment in Alaskan lakes. Two active gears (electrofishing boat and seines) and two passive gears (fyke nets and minnow trap) were evaluated for performance in catching power, size selectivity, species detection, fish destruction, manpower requirement, cost, portability, and field repairability. Three different electrofishing boat currents (AC, DC, and pulsed-DC) were also evaluated. The electro fishing boat had highest catching power, while fyke nets and minnow trap had highest catch per man-hour of labor. Seines had variable catching power, dependent upon shoreline substrate and sites to haul the seine to shore. Night electrofishing had higher catching power than day electrofishing when fished in a clear water lake, as opposed to equal catching power in a brown water lake. All three electrofishing currents exhibited a consistent pattern of length selectivity for coho salmon (Oncorhynchus kisutch). Planning of fish population assessment projects involves (1) clearly stated objectives, (2) knowledge of project constraints, physical or economic, and (3) knowledge of the sampling attributes of gears to be used.
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Spawning run characteristics of Dolly Varden in the Kugururok River, Noatak Drainage, AlaskaBiological information was collected on fall and summer spawning runs of Dolly Varden in the Kugururok River, in northwest Alaska. Partial weirs, angling, and beach seining were used to capture fish in 1993; angling was used in 1994. Run timing of both spawning groups was similar to other northern Dolly Varden populations. Males of both summer and fall spawners had higher mean lengths and greater length ranges than females. Lengths of migrating summer spawners in 1994 were larger than those in 1993. Weight-length relationships among the groups for both years were equal. Condition factors of spawners were lower than migrants; migrating fall spawners had the highest condition. The proportion of female summer spawners (82%) on the spawning grounds in 1993 was unusually high. Recommendations are to continue to monitor harvests and escapements and maintain at historic levels, determine implications of skewed sex ratios on spawning success, and genetically identify stocks.
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Effects of gill net selectivity on sockeye salmon in the Egegik and Naknek-Kvichak districts, Bristol Bay, AlaskaGill nets have been used to harvest sockeye salmon (Oncorhynchus nerka) in Bristol Bay since 1884. Minimum mesh size restrictions have been in effect since 1926 to alter size composition of the commercial catch. The most recent restriction (5-3/8 inches, stretched) was selected to maximize catch of males, the larger of the sexes, while allowing more females to spawn. Analysis of historical data indicated that minimum mesh size regulations were effective in increasing the catch of larger sockeye salmon while allowing smaller fish to escape. Also, multistrand monofilament gill nets, a recent technological development, caught more small sockeye salmon than did traditional multifilament nylon gear. Test fishing studies using multistrand monofilament and multifilament nylon gill nets showed that mesh size influenced mean length as well as sex and age composition of catches for both types of web. However, catch per unit effort was greater for multistrand monofilament than for multifilament nylon gill nets.
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Summer habitat relationships and foraging ecology of the Delta bison herdInvestigations of habitat use, diet composition and diet selection of introduced plains bison (Bison bison bison) in interior Alaska in summer were conducted during 1989 through 1991. Bison used early- and mid-successional plant communities on the floodplain of the Delta River and wetlands above the floodplain. Grasses predominated in summer diets of bison, but substantial amounts of willow (Saiix) were included. Other shrubs were used much less than available, as were sedges. The role of sedges in bison diets may be changing as bison increasingly have exploited sedge-dominated wetland habitats. Experimental studies of the effects of bison grazing on forage productivity, forage quality and plant species composition were conducted in the mid-successional graminoid meadow, the traditional summer range of Delta bison. Bison grazing had no effect on productivity but did increase nitrogen concentration of graminoids. Changes in plant species composition occurred in response to protection from grazing for 9 years.
