Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system
The energy needs of rorqual whales (f. Balaenopteridae) govern their relationship to marine habitats during the foraging season. However, their cryptic foraging strategies and extreme feeding behaviors complicate our effort to identify and protect habitats “critical” for rorquals. What is the relati...
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ftcdlib:qt52f602q1 2023-05-15T15:36:43+02:00 Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system Keen, Eric 470 2017-01-01 application/pdf http://www.escholarship.org/uc/item/52f602q1 en eng eScholarship, University of California http://www.escholarship.org/uc/item/52f602q1 qt52f602q1 public Keen, Eric. (2017). Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/52f602q1 Ecology Behavioral sciences Environmental science British Columbia fjord foraging strategy habitat use whales dissertation 2017 ftcdlib 2017-04-07T22:49:56Z The energy needs of rorqual whales (f. Balaenopteridae) govern their relationship to marine habitats during the foraging season. However, their cryptic foraging strategies and extreme feeding behaviors complicate our effort to identify and protect habitats “critical” for rorquals. What is the relationship between rorquals and their habitat, and how must that shape conservation strategies? I addressed this question in the case of sympatric humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) in the marine territory of the Gitga’at First Nation in the Kitimat Fjord System of British Columbia. For three summers (2013-2015) I studied whales, their prey, and their environment aboard the RV Bangarang using oceanographic station sampling, systematic transect surveys, and opportunistic focal follows of whales (Chapter 1). Ocean sampling demonstrated the strong coupling of water features with offshore patterns in storm forcing and regional meteorology (Chapter 2). By combining these surveys with a long-term Gitga’at dataset, area humpback whales were found to practice a structured and persistent pattern in seasonal habitat use, which demonstrates how complex and habitat-specific a rorqual’s habitat use can be (Chapter 3). Both humpback and fin whales were found to respond to changes in krill supply in aggregative and behavioral thresholds that are set by a combination of intrinsic energetic needs and the context of local prey supply (Chapter 4). Associations with non-prey habitat features were markedly different in the two species (Chapter 5). Humpback distribution was more closely coupled to that of their prey and other habitat features, while fin whale distribution was driven broadly by site fidelity. Novel spatial analytics were used to identify the most probable environmental cues used by foraging whales (Chapter 6). Both species were found to be particularly sensitive to the depth of prey layers, which is governed largely by oceanographic features (Chapter 7). This coupling of habitat features and feeding performance influences the competitive dynamics of rorqual whales. The findings in this case study advance general theories on marine predator ecology and conservation, and have direct implications for the management of Gitga’at territory and the identification of fin whale critical habitat in Pacific Canada. Doctoral or Postdoctoral Thesis Balaenoptera physalus Fin whale Megaptera novaeangliae University of California: eScholarship British Columbia ENVELOPE(-125.003,-125.003,54.000,54.000) Canada Kitimat ENVELOPE(-128.714,-128.714,53.989,53.989) Pacific Rorqual ENVELOPE(-62.311,-62.311,-65.648,-65.648) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Ecology Behavioral sciences Environmental science British Columbia fjord foraging strategy habitat use whales |
spellingShingle |
Ecology Behavioral sciences Environmental science British Columbia fjord foraging strategy habitat use whales Keen, Eric Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
topic_facet |
Ecology Behavioral sciences Environmental science British Columbia fjord foraging strategy habitat use whales |
description |
The energy needs of rorqual whales (f. Balaenopteridae) govern their relationship to marine habitats during the foraging season. However, their cryptic foraging strategies and extreme feeding behaviors complicate our effort to identify and protect habitats “critical” for rorquals. What is the relationship between rorquals and their habitat, and how must that shape conservation strategies? I addressed this question in the case of sympatric humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) in the marine territory of the Gitga’at First Nation in the Kitimat Fjord System of British Columbia. For three summers (2013-2015) I studied whales, their prey, and their environment aboard the RV Bangarang using oceanographic station sampling, systematic transect surveys, and opportunistic focal follows of whales (Chapter 1). Ocean sampling demonstrated the strong coupling of water features with offshore patterns in storm forcing and regional meteorology (Chapter 2). By combining these surveys with a long-term Gitga’at dataset, area humpback whales were found to practice a structured and persistent pattern in seasonal habitat use, which demonstrates how complex and habitat-specific a rorqual’s habitat use can be (Chapter 3). Both humpback and fin whales were found to respond to changes in krill supply in aggregative and behavioral thresholds that are set by a combination of intrinsic energetic needs and the context of local prey supply (Chapter 4). Associations with non-prey habitat features were markedly different in the two species (Chapter 5). Humpback distribution was more closely coupled to that of their prey and other habitat features, while fin whale distribution was driven broadly by site fidelity. Novel spatial analytics were used to identify the most probable environmental cues used by foraging whales (Chapter 6). Both species were found to be particularly sensitive to the depth of prey layers, which is governed largely by oceanographic features (Chapter 7). This coupling of habitat features and feeding performance influences the competitive dynamics of rorqual whales. The findings in this case study advance general theories on marine predator ecology and conservation, and have direct implications for the management of Gitga’at territory and the identification of fin whale critical habitat in Pacific Canada. |
format |
Doctoral or Postdoctoral Thesis |
author |
Keen, Eric |
author_facet |
Keen, Eric |
author_sort |
Keen, Eric |
title |
Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
title_short |
Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
title_full |
Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
title_fullStr |
Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
title_full_unstemmed |
Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
title_sort |
whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system |
publisher |
eScholarship, University of California |
publishDate |
2017 |
url |
http://www.escholarship.org/uc/item/52f602q1 |
op_coverage |
470 |
long_lat |
ENVELOPE(-125.003,-125.003,54.000,54.000) ENVELOPE(-128.714,-128.714,53.989,53.989) ENVELOPE(-62.311,-62.311,-65.648,-65.648) |
geographic |
British Columbia Canada Kitimat Pacific Rorqual |
geographic_facet |
British Columbia Canada Kitimat Pacific Rorqual |
genre |
Balaenoptera physalus Fin whale Megaptera novaeangliae |
genre_facet |
Balaenoptera physalus Fin whale Megaptera novaeangliae |
op_source |
Keen, Eric. (2017). Whales of the rainforest: habitat use strategies of sympatric rorqual whales within a fjord system. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/52f602q1 |
op_relation |
http://www.escholarship.org/uc/item/52f602q1 qt52f602q1 |
op_rights |
public |
_version_ |
1766367086638006272 |