Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California
Daytime feeding behavior of humpback whales (Megaptera novaeangliae) in Gulf of the Farallones, California, and adjacent waters was observed during autumn of 1988 to 1990. Bodega Canyon, Cordell Bank, and the Farallon Islands were the primary sites of feeding activity. Fecal samples of whales and zo...
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
1992
|
Subjects: | |
Online Access: | http://aquaticcommons.org/2665/ http://aquaticcommons.org/2665/2/Kieckhefer_MS_Thesis_OCR.pdf |
id |
ftaquaticcommons:oai:generic.eprints.org:2665 |
---|---|
record_format |
openpolar |
spelling |
ftaquaticcommons:oai:generic.eprints.org:2665 2023-05-15T16:36:10+02:00 Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California Kieckhefer, Thomas R. 1992 application/pdf http://aquaticcommons.org/2665/ http://aquaticcommons.org/2665/2/Kieckhefer_MS_Thesis_OCR.pdf en eng http://aquaticcommons.org/2665/2/Kieckhefer_MS_Thesis_OCR.pdf Kieckhefer, Thomas R. (1992) Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California. Masters Thesis, San Jose State University, 86pp. Biology Thesis NonPeerReviewed 1992 ftaquaticcommons 2020-02-27T09:19:48Z Daytime feeding behavior of humpback whales (Megaptera novaeangliae) in Gulf of the Farallones, California, and adjacent waters was observed during autumn of 1988 to 1990. Bodega Canyon, Cordell Bank, and the Farallon Islands were the primary sites of feeding activity. Fecal samples of whales and zooplankton tows contained euphausiids exclusively, dominated by Thysanoessa spinifera (79%), with lesser amounts of Euphausia pacifica (14%), Nyctiphanes simplex (4%), and Nematoscelis difficilis (3%). In 1988 and 1990, whales also were infrequently observed feeding on small schooling fish, presumably Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and juvenile rockfish (Sebastes spp.). Feeding was the most common behavior observed (52%), and less frequently traveling (23%), milling (21 %), and resting (4%). Whales used different methods to consume euphausiid prey at the surface (0-10 m), in shallow water (11-60 m), and deep water (61-140 m). Humpback whales fed at the surface 56% of time in 1988 and 32% of time in 1990, using primarily lateral lunges to capture swarms of euphausiids. In 1989, no surface feeding was observed; however, deep, long-duration dives were followed by extended surface intervals with many respirations. These 1989 observations coincided with increased prey depth as indicated by depth sounder records of diving whales and prey scattering layers. In 1989, increased prey depth and associated feeding behaviors were strongly associated with unusually high surface temperatures, calm seas, and changes in water circulation. Environmental conditions in 1989 triggered the most intense and wide-spread occurrence of red tide in this region since 1980. Red tide samples collected throughout this period contained Alexandrium (=Gonyaulax) catenella and Noctiluca scintillans. Surface feeding was observed only in 1988 and 1990, when surface prey were available and red tides were very limited in extent, duration, and intensity. Annual variations in humpback whale feeding behavior were related to prey availability which is affected by corresponding environmental conditions. (PDF contains 94 pages) Thesis Humpback Whale Megaptera novaeangliae International Association of Aquatic and Marine Science Libraries and Information Centers (IAMSLIC): Aquatic Commons Pacific |
institution |
Open Polar |
collection |
International Association of Aquatic and Marine Science Libraries and Information Centers (IAMSLIC): Aquatic Commons |
op_collection_id |
ftaquaticcommons |
language |
English |
topic |
Biology |
spellingShingle |
Biology Kieckhefer, Thomas R. Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
topic_facet |
Biology |
description |
Daytime feeding behavior of humpback whales (Megaptera novaeangliae) in Gulf of the Farallones, California, and adjacent waters was observed during autumn of 1988 to 1990. Bodega Canyon, Cordell Bank, and the Farallon Islands were the primary sites of feeding activity. Fecal samples of whales and zooplankton tows contained euphausiids exclusively, dominated by Thysanoessa spinifera (79%), with lesser amounts of Euphausia pacifica (14%), Nyctiphanes simplex (4%), and Nematoscelis difficilis (3%). In 1988 and 1990, whales also were infrequently observed feeding on small schooling fish, presumably Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and juvenile rockfish (Sebastes spp.). Feeding was the most common behavior observed (52%), and less frequently traveling (23%), milling (21 %), and resting (4%). Whales used different methods to consume euphausiid prey at the surface (0-10 m), in shallow water (11-60 m), and deep water (61-140 m). Humpback whales fed at the surface 56% of time in 1988 and 32% of time in 1990, using primarily lateral lunges to capture swarms of euphausiids. In 1989, no surface feeding was observed; however, deep, long-duration dives were followed by extended surface intervals with many respirations. These 1989 observations coincided with increased prey depth as indicated by depth sounder records of diving whales and prey scattering layers. In 1989, increased prey depth and associated feeding behaviors were strongly associated with unusually high surface temperatures, calm seas, and changes in water circulation. Environmental conditions in 1989 triggered the most intense and wide-spread occurrence of red tide in this region since 1980. Red tide samples collected throughout this period contained Alexandrium (=Gonyaulax) catenella and Noctiluca scintillans. Surface feeding was observed only in 1988 and 1990, when surface prey were available and red tides were very limited in extent, duration, and intensity. Annual variations in humpback whale feeding behavior were related to prey availability which is affected by corresponding environmental conditions. (PDF contains 94 pages) |
format |
Thesis |
author |
Kieckhefer, Thomas R. |
author_facet |
Kieckhefer, Thomas R. |
author_sort |
Kieckhefer, Thomas R. |
title |
Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
title_short |
Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
title_full |
Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
title_fullStr |
Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
title_full_unstemmed |
Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California |
title_sort |
feeding ecology of humpback whales in continental shelf waters near cordell bank, california |
publishDate |
1992 |
url |
http://aquaticcommons.org/2665/ http://aquaticcommons.org/2665/2/Kieckhefer_MS_Thesis_OCR.pdf |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Humpback Whale Megaptera novaeangliae |
genre_facet |
Humpback Whale Megaptera novaeangliae |
op_relation |
http://aquaticcommons.org/2665/2/Kieckhefer_MS_Thesis_OCR.pdf Kieckhefer, Thomas R. (1992) Feeding Ecology of Humpback Whales in Continental Shelf Waters near Cordell Bank, California. Masters Thesis, San Jose State University, 86pp. |
_version_ |
1766026476274057216 |