Program: Bachelor of Science in Marine Biology
Home State: Oregon
Faculty Mentor: Heidi Pearson
Kierstin was an REU student during Summer 2012. She conducted a pilot study of sea otter foraging behavior in Sitka Sound. Below is the abstract she wrote for her REU presentation.
Abstract: The sea otter (Enhydra lutris) is a keystone species that instigates large-scale alterations to the structure of marine habitats. The impact sea otter activity has to Sitka Sound, AK, has been relatively unexplored in recent years, despite the heated debates surrounding the sea otters’ economic and ecological worth in the area. This study examined activity budgets and foraging behavior of sea otters in Sitka Sound through shore-based observations. It was hypothesized that foraging would be the most common behavioral state recorded, that dive duration would be positively related to dive depth, and surface duration would be positively related to dive duration and tool use.Ten- minute instantaneous point sampling was used to generate an activity budget. Sea otters did not spend equal amounts of time in each behavioral state (p < 0.05), spending the majority of their time foraging and resting, followed by grooming, traveling, and interacting. Foraging data was gathered through 15 focal-animal samples, from which a Generalized Estimating Equations (GEE) model was used to test correlations between dive durations, surface durations, time of day, tidal state, success of dive, depth category, and rock use. The tests showed a significant positive correlation between surface durations and rock use (p < 0.001), but no significant correlations between any other variables for both dive and surface durations (all p > 0.05). As such, the test results implied that prey selection is a possible determining factor influencing sea otter dive durations and that foraging dive durations remain within sea otters’ aerobic dive threshold. To further understand the transformation of a habitat occupied by sea otters, future studies will evaluate dive depths, prey items, and correlations between sea otter foraging behavior and the increased biomass of Macrocystis kelp in Sitka Sound.
Data collection: June-August, 2012
Presentation at REU symposium, August 2012
Poster presentation at Sitka WhaleFest, Nov. 2012
Poster presentation at the Science of Southeast Alaska’s Sea Otters symposium, UAS, Feb. 2013
Kierstin continued her research as a Directed Research student during Fall 2012. She analyzed the rest of her data and produced a 42-page synthesis paper on sea otter ecology. Her abstract is pasted below. We have already discussed plans for her to submit a URECA application to collect additional data during Summer 2014.
Abstract: The sea otter (Enhydra lutris) is a keystone species that instigates large scale
alterations to the structure of coastal marine habitats. A period of overhunting by Russian, Spanish, and American fur traders that began in the late 18th century resulted in the sea otter’s near extinction until their protection in 1911. Since then, sea otters have rapidly spread throughout their historic range along the North Pacific rim. Sea otters from southeast Alaska are now making their way into the food-rich habitats of the inside passage, moving closer to Juneau from the Icy Strait. The objective of this study was to indicate potential foraging habitat in the Juneau area and discuss how economically valuable resources in the region might be affected by sea otters. Baseline criteria for evaluating the Juneau coast was established through habitat conditions defined in previous literature and foraging site data gathered during a pilot study in Sitka. Depth was the main criteria used for analyzing habitat, from which it was found that sea otters can potentially forage from roughly 80% of the defined study area based on their 100 meter dive limit. Roughly 36% of the study area is within sea otter’s preferred foraging range of <40 meters. These accessibility estimations, along with environmental comparisons between the Juneau area and regions with similar environmental conditions that have established sea otter populations, allowed conjectures to be made regarding the ecological and economic pressures Juneau could expect from sea otters.