Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska
Until translocation efforts in the 1960s, sea otters (Enhydra lutris) were absent from Southeast Alaska due to extirpation by the fur trade in the 18th and 19th centuries. About 400 sea otters were reintroduced to six Southeast Alaska locations, including two sites near Prince of Wales Island in sou...
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University of Alaska Fairbanks
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ftproquest:oai:pqdtoai.proquest.com:28155799 2023-05-15T18:03:32+02:00 Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska LaRoche, Nicole 2020-01-01 00:00:01.0 http://pqdtopen.proquest.com/#viewpdf?dispub=28155799 ENG eng University of Alaska Fairbanks http://pqdtopen.proquest.com/#viewpdf?dispub=28155799 Ecology|Limnology|Nutrition|Sustainability|Animal sciences|Behavioral Sciences|Conservation biology thesis 2020 ftproquest 2021-03-13T17:38:55Z Until translocation efforts in the 1960s, sea otters (Enhydra lutris) were absent from Southeast Alaska due to extirpation by the fur trade in the 18th and 19th centuries. About 400 sea otters were reintroduced to six Southeast Alaska locations, including two sites near Prince of Wales Island in southern Southeast Alaska. The most recent US Fish and Wildlife Service population count, completed in 2012, estimated that about 25,000 sea otters inhabited Southeast Alaska. Sea otters will reduce invertebrate prey biomass when recolonizing an area. By quantifying sea otter diets and caloric intake according to recolonization patterns, we can better understand the ecosystem impacts of sea otter population increase and range expansion. The goal of this study was to quantify changes in seasonal diet composition and assess the energetic quality of sea otter prey in southern Southeast Alaska. I made visual foraging observations of 3,385 sea otter dives around Prince of Wales Island (POW) to determine diet composition during the spring and summer months. I then collected vibrissae from 45 sea otters obtained from subsistence hunters to assess year-round sea otter diets using stable isotopes. I collected sea otter prey items throughout POW in three seasons (May 2018, August 2018, and February 2019) to measure energy, lipid and protein content, and δ13C (carbon) and δ15N (nitrogen) values. Sea otter diets mainly consisted of clams, as quantified both from visual observations and stable isotope analysis. However, there was more variation in the diet estimates from stable isotope analysis. Stable isotope analysis revealed variation among individual diets of sea otters and individuality in diet within the POW region of sea otters. Sea otters seasonally increased consumption of some prey when the prey was highest in lipid and overall caloric content. Sea otters switched prey types when the prey was more energetically valuable. The results of this study will aid in future management of shellfisheries, subsistence hunting, and implementing co-management of a protected species by providing quantitative diet composition data for stakeholders. This work is a part of a large-scale project examining how the recovery of sea otters structures nearshore marine ecosystems, provides ecosystem services, and affects community sustainability. Thesis Prince of Wales Island Alaska PQDT Open: Open Access Dissertations and Theses (ProQuest) Prince of Wales Island ENVELOPE(-99.001,-99.001,72.668,72.668) |
institution |
Open Polar |
collection |
PQDT Open: Open Access Dissertations and Theses (ProQuest) |
op_collection_id |
ftproquest |
language |
English |
topic |
Ecology|Limnology|Nutrition|Sustainability|Animal sciences|Behavioral Sciences|Conservation biology |
spellingShingle |
Ecology|Limnology|Nutrition|Sustainability|Animal sciences|Behavioral Sciences|Conservation biology LaRoche, Nicole Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
topic_facet |
Ecology|Limnology|Nutrition|Sustainability|Animal sciences|Behavioral Sciences|Conservation biology |
description |
Until translocation efforts in the 1960s, sea otters (Enhydra lutris) were absent from Southeast Alaska due to extirpation by the fur trade in the 18th and 19th centuries. About 400 sea otters were reintroduced to six Southeast Alaska locations, including two sites near Prince of Wales Island in southern Southeast Alaska. The most recent US Fish and Wildlife Service population count, completed in 2012, estimated that about 25,000 sea otters inhabited Southeast Alaska. Sea otters will reduce invertebrate prey biomass when recolonizing an area. By quantifying sea otter diets and caloric intake according to recolonization patterns, we can better understand the ecosystem impacts of sea otter population increase and range expansion. The goal of this study was to quantify changes in seasonal diet composition and assess the energetic quality of sea otter prey in southern Southeast Alaska. I made visual foraging observations of 3,385 sea otter dives around Prince of Wales Island (POW) to determine diet composition during the spring and summer months. I then collected vibrissae from 45 sea otters obtained from subsistence hunters to assess year-round sea otter diets using stable isotopes. I collected sea otter prey items throughout POW in three seasons (May 2018, August 2018, and February 2019) to measure energy, lipid and protein content, and δ13C (carbon) and δ15N (nitrogen) values. Sea otter diets mainly consisted of clams, as quantified both from visual observations and stable isotope analysis. However, there was more variation in the diet estimates from stable isotope analysis. Stable isotope analysis revealed variation among individual diets of sea otters and individuality in diet within the POW region of sea otters. Sea otters seasonally increased consumption of some prey when the prey was highest in lipid and overall caloric content. Sea otters switched prey types when the prey was more energetically valuable. The results of this study will aid in future management of shellfisheries, subsistence hunting, and implementing co-management of a protected species by providing quantitative diet composition data for stakeholders. This work is a part of a large-scale project examining how the recovery of sea otters structures nearshore marine ecosystems, provides ecosystem services, and affects community sustainability. |
format |
Thesis |
author |
LaRoche, Nicole |
author_facet |
LaRoche, Nicole |
author_sort |
LaRoche, Nicole |
title |
Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
title_short |
Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
title_full |
Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
title_fullStr |
Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
title_full_unstemmed |
Sea Otter Diet Composition with Respect to Recolonization, Life History, and Season in Southern Southeast Alaska |
title_sort |
sea otter diet composition with respect to recolonization, life history, and season in southern southeast alaska |
publisher |
University of Alaska Fairbanks |
publishDate |
2020 |
url |
http://pqdtopen.proquest.com/#viewpdf?dispub=28155799 |
long_lat |
ENVELOPE(-99.001,-99.001,72.668,72.668) |
geographic |
Prince of Wales Island |
geographic_facet |
Prince of Wales Island |
genre |
Prince of Wales Island Alaska |
genre_facet |
Prince of Wales Island Alaska |
op_relation |
http://pqdtopen.proquest.com/#viewpdf?dispub=28155799 |
_version_ |
1766174406276546560 |