Lake trout (Salvelinus namaycush) otoliths as indicators of past climate patterns and growth in Arctic lakes

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Show simple item record Torvinen, Eric S. 2017-06-13T01:37:19Z 2017-06-13T01:37:19Z 2017-05
dc.description Thesis (M.S.) University of Alaska Fairbanks, 2017 en_US
dc.description.tableofcontents The effects of climate change on freshwater ecosystems are amplified in high-latitude regions, however, Alaska climate data are limited due to the remote location of the Arctic. Predictions have indicated that warming temperatures owing to climate change could increase fish growth, but the magnitude and factors influencing these changes remain uncertain. Here I investigated the relationship between Lake Trout Salvelinus namaycush growth and physical and biological characteristics, fish community structure and climate patterns. I applied biochronology techniques to predict recent climate patterns from annual growth increments recorded on Lake Trout otoliths. Growth increments were also used to perform length-at-age back-calculations and to estimate the growth coefficient K, as described by a von Bertalanffy growth model. Lake Trout were captured from 13 climate-sensitive lakes in the Fish Creek watershed in Arctic Alaska during 2014 and 2015. Individual Lake Trout (N = 53) ranged from 471--903 mm fork length (FL; mean = 589.3 mm) and their readable annuli, representative of age, ranged from 9--55 annual growth increments. I constructed a growth chronology for the period 1977--2014 and used model selection to identify the best predictive model of relative Lake Trout growth (ring width index; RWI) as a function of climate descriptors. A single covariate model was the best predictor and indicated that RWI tracked mean August air temperature recorded at a local weather station from 1998--2013 (P < 0.001; R2adj = 0.55; RMSE = 0.048). Lake Trout growth (K) was subsequently modeled as a function of physical and biological characteristics, and fish community structure, using multiple linear regression. The highest ranked model included physical (i.e., depth, distance to river and coast, connectivity class, and number of stream intersections) and biological (sex) covariates. Model averaging indicated K was higher in deeper, well connected lakes, located further from the coast and was lower with increasing distance from a large river, though the relationship with depth was found to be the single significant covariate. This study demonstrated the utility of biochronology techniques to estimate past climate patterns in remote regions, and provided valuable knowledge regarding growth-environment relationships for Lake Trout. In turn, this information can be used to better understand the effects of a changing environment in sensitive Arctic lake ecosystems. en_US
dc.language.iso en_US en_US
dc.subject Otoliths en_US
dc.subject Lake trout en_US
dc.subject Growth en_US
dc.subject Climatic factors en_US
dc.subject Arctic regions en_US
dc.title Lake trout (Salvelinus namaycush) otoliths as indicators of past climate patterns and growth in Arctic lakes en_US
dc.type Thesis en_US ms en_US
dc.identifier.department Department of Fisheries en_US
dc.contributor.chair Falke, Jeffrey
dc.contributor.committee Arp, Christopher
dc.contributor.committee Zimmerman, Christian
dc.contributor.committee Sutton, Trent

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