Recent Submissions

  • Aquatic habitat of the Tiekel River, southcentral Alaska, and its utilization by resident Dolly Varden (Salvelinus malma)

    Martin, Donald C. (1988-05)
    The Tiekel River is a third order stream in southcentral Alaska and contains stream-resident Dolly Varden (Salvelinus malma) that are small in size. The purpose of this project was to compile baseline aquatic habitat data, determine which habitats were the most important to the Dolly Varden and should be protected from future development, and develop management recommendations. Habitat data suggested that the Tiekel River drainage contained a wide variety of habitats that could fulfill the life requirements for a number of fish species. Habitat suitability index graphs were constructed for the important habitat variables and should be used in the planning of future habitat alterations to assure that habitat quality does not suffer. The beaver ponds were found to have a greater probability of producing large fish than the stream habitats. Fish size was positively correlated with August water temperatures and chlorophyll a concentrations.
  • Growth patterns of juvenile sockeye salmon in different thermal environments of Alaskan lakes

    Edmundson, Jim A. (1997-12)
    Rearing conditions imposed on juvenile salmonids in lakes are important determinants of freshwater growth patterns. In Alaska, sockeye salmon (Oncorhynchus nerka) nursery lakes exhibit a wide range in thermal characteristics. Compared to clear lakes, stained lakes are warmer and have longer growing seasons, whereas glacial lakes are colder and have shorter growing seasons. In stained lakes, a shallow thermocline restricts most of the heat to the surface layers. Deep mixing in glacial lakes, concomitant with meltwater intrusion, keep much of the water column near 4 °C. Mean depth accounts for 77% of the among-lake variation in the seasonal average water temperature (TS). Length of growing season is dependent on latitude and altitude; however, water temperature is not. Taken together, the factors TS, zooplankton biomass, and sockeye fry density accounted for 70% of the variation in age-1 sockeye smolt size. This limnological information can be included in stock-recruit models of sockeye salmon to improve assessments for management.
  • Dynamics of a super-population of dolly varden in the Chiniak Bay system, Kodiak Island, Alaska

    Whalen, Mary E. (1993-05)
    A weir was operated at Buskin Lake, Kodiak Island, Alaska in the spring of 1990, 1991 and 1992 to study the stock structure of a super­population of Dolly Varden (Salvelinus malma) in Chiniak Bay. In 1991, Jolly-Seber estimates of abundance (60,585) and survival (29.3%) were higher than the weir estimates of 30,725 and 6.3%. Growth parameter estimates were 0.23 for the Brody coefficient and 522 mm as the largest fish in the population. Age 4-7 fish dominated the spring emigration from Buskin Lake. Dolly Varden found in the fall at the American and Olds rivers and Buskin Lake constitute the main spawning stocks for the Chiniak Bay super-population at 3,375, 2,669 and 3,711 fish respectively in 1991. A dynamic pool model used in conjunction with Relative Stock Density was effective in detecting increases in length-specific exploitation of larger fish, but not for detecting increasing fishing mortality in the mature stock.
  • Evaluation of Arctic grayling enhancement: a cost per survivor analysis

    Skaugstad, Calvin Loren (1989-05)
    Age-O Arctic grayling Thymallus arcticus were stocked as sac fry and fingerlings in lakes in interior and south central Alaska to evaluate cost per survivor at age 1. When sac fry, 4-g, and 6-g fingerlings were stocked in the same lakes in 1986, estimates of the mean rate of survival at age 1 were 0.08, 0.63, and 0.75. The differences were significant. The mean costs per survivor at age 1 were $1.58, $0.24, and $0.21. The differences were significant between sac fry and both sizes of fingerlings. However, the difference was not significant between 4-g and 6-g fingerlings. When sac fry and 4-g fingerlings were stocked in different lakes in 1986 and again in 1987, estimates of the mean rate of survival to age 1 were 0.11 and 0.34. The difference was significant. The mean costs per survivor at age 1 were $0.82 and $0.70. The difference was not significant. I recommend stocking 4-g fingerlings because they require less rearing in a hatchery than 6-g fingerlings and the cost per survivor is usually less than that for sac fry.
  • Effects of placer mining sedimentation on Arctic graying of interior Alaska

    Simmons, Rodney C. (1984-05)
    During summer 1982 and 1983, I assessed the effects of placer mining sedimentation on Arctic grayling, Thymallus arcticus, in the headwaters of the Birch Creek and Chatanika River drainages, northeast of Fairbanks, Alaska. In each drainage I compared the differences between two streams near their confluence, one that was undisturbed and one with mining activity upstream. Although many age-0 and adult grayling used unmined streams for summer habitat, I found no grayling in the mined streams except during periods of migration. Apparently, grayling consistently chose clearwater streams for summer residence. Caged fish studies demonstrated that if grayling could not escape from streams carrying mining sediments, they would suffer direct, chronic effects, including gill damage, dietary deficiencies, and slowed maturation. The indirect effects of sedimentation on grayling populations, through loss of summer habitat for feeding and reproduction, are more severe than the direct ones.
  • Estimation of angler harvest, catch and effort in the Swanson River canoe trails system, Kenai National Wildlife Refuge, Alaska

    Shiffer, Mary P. (1989-08)
    Methods of estimating harvest, catch, angler effort and quality of catch were tested during the summer of 1988 on the Swanson River Canoe Trails System, Kenai National Wildlife Refuge, Alaska. Angler interviews at Trails System access points provided the best estimates of these sport fishing variables. Rainbow trout dominated the catch (95%); about three-fourths were less than 254 mm long and most were released. Total estimated catch of trout was 18,448 (10,221-26,675; ρ=0.95); estimated harvest was 25 percent of the catch: 4,651 (2,722-6,580; p=0.95). Aerial surveys (counts of cars and boats) and the trail head registers provided seasonal use trends for the Trails System, but there was no relationship between these indices and the variables of the fishery. Anglers must be personally interviewed in order to acquire data to evaluate the fishery.
  • Injury and survival of northern pike captured by electrofishing

    Roach, Stafford M. (1992-05)
    I exposed 240 northern pike Esox lucius to four levels of pulsed direct current (PDC). Incidence of spinal injury for 30 Hz was 5.0% at 100 V and 10.0% at 400 V; and for 60 Hz was 8.3% at 100 V and 11.7% at 400 V. Injury rates were not significantly different among treatments (P=0, 58) . I also electroshocked 140 fish with 120-Hz PDC at 300-600 V; spinal injury increased to 29% (P<0.01). These fish were held for 1 month in ponds to compare survival with 70 unshocked fish; survival was 91-92% for both groups (P=0.57). During field trials I captured about three northern pike with 60-Hz PDC for every one caught with DC and 30-Hz PDC (P=0.08). Conventional electrofishing (i.e., 60-Hz PDC at 100-400 V) did not cause significant injury in adult northern pike but did capture them efficiently. PDC at frequencies above 60 Hz should be avoided.
  • Seasonal allocation of energy in four tissues of northern pike from Minto Flats, Alaska

    Murphy, Robert Leo (1989-12)
    The seasonal changes in energy content of the gastrointestinal tract, gonad, liver, and muscle of 120 mature northern pike (Esox lucius Linnaeus) from Minto Flats, Alaska were estimated (bomb calorimetry) during winter, early spring (prespawning), late spring (postspawning), and fall 1988. Increases in the specific energy contnet of testes was completed by September, and did not change from September to March. Ovarian specific energy content remained unchanged between the postspawning (21.78 kJ/g) and fall (21.89 kJ/g) periods, then accumulated during the winter (24.80 kJ/g). Gastrointestinal tract specific energy content decreased in fish of both sexes during spawning, and increased during winter. Liver specific energy content occurred in females during summer, and in males during winter. Winter is a critical period for males and females; gonadal energy requirements in females must be met to assure reproductive success the following spring, and, important energy reserves necessary for survival are accumulated in males.
  • Stock assessment of arctic grayling at Ugashik Lakes, Alaska

    Meyer, Scott C. (1990-12)
    Arctic grayling (Thymallus arcticus) stocks were assessed at Ugashik Narrows and Outlet in Southwest Alaska during the open-water periods of 1987, 1988, and 1989. Abundance, size, and age data were collected, which were then compared with historical data for 1968-1984. The Narrows is the stream between Upper Ugashik Lake and Lower Ugashik Lake, and the Outlet is the source of the Ugashik River from Lower Ugashik Lake.
  • Habitat utilization by fishes in the Tanana River near Fairbanks, Alaska

    Mecum, Robert D. (1984-05)
    This study evaluated summer habitat utilization of fishes and the effects of floodplain developments on fish and aquatic habitat in the glacially-fed Tanana River near Fairbanks, Alaska. Aquatic habitats were quantitatively described on the basis of water velocity, depth, and clarity, and substrate, cover and vegetation. Lake chub and longnose sucker were abundant in all habitats. Whitefishes, juvenile salmon, and northern pike were captured most frequently in areas with high water clarity. Burbot preferred deeper, turbid waters. Young-of-the-year of lake chub and longnose sucker preferred shallow, silty backwaters; juvenile lake chub demonstrated no habitat preferences; and adult lake chub, juvenile longnose sucker, and juvenile/adult slimy sculpin preferred gravel riffles. Bank stabilization activities have significantly modified aquatic habitat and fish communities of Tanana River backwaters. In general, free-flowing sidechannels have become blocked-off sloughs resulting in reduced turbidities and lower flows.
  • Evaluation of some factors affecting food conversion by age-0 arctic grayling reared in floating net-pens

    McKinley, Timothy R. (1992-05)
    Two experiments were repeated three times to evaluate the effects of feeding frequency, loading density, and food particle size on food conversion of age-0 Arctic grayling Thymallus arcticus reared in floating net-pens. Growth in length or weight could not be evaluated because of the short (11 - 12 days) feeding trials. When fed to satiation, the optimal interval between feedings was 3 hours. The highest initial loading density used (5.6 kg/m3) consistently produced the best food conversions (1.10 - 1.51 g food/g weight gain). Food particles several sizes larger than those generally recommended were used with less waste and without adverse effects. Optimal food size for 60 - 73 mm Arctic grayling was 1.3 - 1.5 mm (2.1 - 2.5% fork length).
  • Evaluation of sampling gears for fish population assessment in Alaskan streams and rivers

    Lorenz, William Reed (1984-12)
    During summers, 1982 and 1983, a variety of habitats were sampled on the Tanana and Kenai River drainages to evaluate sampling gears used for fish population assessment in Alaskan streams and rivers. Experiments were conducted to investigate sampling efficiency, length and species selectivity, and injuries to fish by three active (backpack electroshocker, electrofishing boat, seine), and two passive (minnow trap, fyke net) gear types. Gears were compared using a common set of attributes: accuracy, portability, scope or species detection, labor required, fishing power, fish savings (low mortality), and initial cost. Electrofishing systems were best for species detection and fishing power, while passive gears had higher catch per hour of labor. Large fyke nets and seines were effective under limited environmental conditions. A linear model was developed to assist in selecting an optimum fishing gear, or array of gears, for any level of fisheries population assessment, considering all applicable sampling constraints.
  • Resource partitioning and behavioral interactions among young-of-the-year salmonids, Chena River, Alaska

    Lee, Kristine M.; Reynolds, James B. (1985-09)
    The 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.
  • Evaluation of models and assumptions for closed population abundance estimators from from cutthroat trout mark-recapture data

    Laker, Mark William; Reynolds, James B. (1994-09)
    The 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.
  • Life histories and community structure of the caddisflies (Trichoptera) of two Alaskan subarctic streams

    Irons, John G., III (1985-05)
    The 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.
  • Life histories and community structure of Ephemeroptera and Plecoptera in two Alaskan subarctic streams

    Howe, Allen L. (1981-05)
    Development 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.
  • Stock identification and homing of arctic grayling, Thymallus arcticus (Pallas), in interior Alaska

    Hop, Haakon; Reynolds, James B. (1985-12)
    The 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.
  • Spawning substrate and adequate escapement for coho salmon in the Ayakulik river, Kodiak National Wildlife Refuge, Alaska

    Hander, Raymond F. (1997-05)
    Escapement 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.
  • Population characteristics of Dolly Varden in the Tiekel River, Alaska

    Gregory, L. Saree (1988-09)
    Length 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.
  • Seasonal proximate composition and food source comparisons of Dolly Varden char in the Kugururok River, Alaska

    Foy, Robert James; Smith, Ronald L.; Reynolds, James B. (1996-12)
    The 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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