Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California
© 2014 The Authors. Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004-November 2013. From sightings of the six most common...
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ftcdlib:qt5fr4x1d6 2023-05-15T15:36:25+02:00 Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California Campbell, GS Thomas, L Whitaker, K Douglas, AB Calambokidis, J Hildebrand, JA 143 - 157 2015-01-01 application/pdf http://www.escholarship.org/uc/item/5fr4x1d6 english eng eScholarship, University of California qt5fr4x1d6 http://www.escholarship.org/uc/item/5fr4x1d6 public Campbell, GS; Thomas, L; Whitaker, K; Douglas, AB; Calambokidis, J; & Hildebrand, JA. (2015). Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California. Deep-Sea Research Part II: Topical Studies in Oceanography, 112, 143 - 157. doi:10.1016/j.dsr2.2014.10.008. UC San Diego: Retrieved from: http://www.escholarship.org/uc/item/5fr4x1d6 article 2015 ftcdlib https://doi.org/10.1016/j.dsr2.2014.10.008 2018-06-22T22:52:09Z © 2014 The Authors. Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004-November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) were the most frequently sighted baleen whales with overall densities of 0.91/1000km2(CV=0.27), 2.73/1000km2(CV=0.19), and 1.17/1000km2(CV=0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a generalized additive model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (Delphinus delphis), Pacific white-sided dolphins (Lagenorhynchus obliquidens) and Dall's porpoise (Phocoenoidesdalli) were the most frequently encountered small cetaceans with overall densities of 705.83/1000km2(CV=0.22), 51.98/1000km2(CV=0.27), and 21.37/1000km2(CV=0.19) respectively. Seasonally, short-beaked common dolphins were most abundant in winter whereas Pacific white-sided dolphins and Dall's porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short-beaked common dolphin or Dall's porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution. Article in Journal/Newspaper Balaenoptera musculus Balaenoptera physalus baleen whales Blue whale Fin whale Humpback Whale Megaptera novaeangliae University of California: eScholarship Pacific Deep Sea Research Part II: Topical Studies in Oceanography 112 143 157 |
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University of California: eScholarship |
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English |
description |
© 2014 The Authors. Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004-November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) were the most frequently sighted baleen whales with overall densities of 0.91/1000km2(CV=0.27), 2.73/1000km2(CV=0.19), and 1.17/1000km2(CV=0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a generalized additive model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (Delphinus delphis), Pacific white-sided dolphins (Lagenorhynchus obliquidens) and Dall's porpoise (Phocoenoidesdalli) were the most frequently encountered small cetaceans with overall densities of 705.83/1000km2(CV=0.22), 51.98/1000km2(CV=0.27), and 21.37/1000km2(CV=0.19) respectively. Seasonally, short-beaked common dolphins were most abundant in winter whereas Pacific white-sided dolphins and Dall's porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short-beaked common dolphin or Dall's porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution. |
format |
Article in Journal/Newspaper |
author |
Campbell, GS Thomas, L Whitaker, K Douglas, AB Calambokidis, J Hildebrand, JA |
spellingShingle |
Campbell, GS Thomas, L Whitaker, K Douglas, AB Calambokidis, J Hildebrand, JA Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
author_facet |
Campbell, GS Thomas, L Whitaker, K Douglas, AB Calambokidis, J Hildebrand, JA |
author_sort |
Campbell, GS |
title |
Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
title_short |
Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
title_full |
Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
title_fullStr |
Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
title_full_unstemmed |
Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California |
title_sort |
inter-annual and seasonal trends in cetacean distribution, density and abundance off southern california |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
http://www.escholarship.org/uc/item/5fr4x1d6 |
op_coverage |
143 - 157 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Balaenoptera musculus Balaenoptera physalus baleen whales Blue whale Fin whale Humpback Whale Megaptera novaeangliae |
genre_facet |
Balaenoptera musculus Balaenoptera physalus baleen whales Blue whale Fin whale Humpback Whale Megaptera novaeangliae |
op_source |
Campbell, GS; Thomas, L; Whitaker, K; Douglas, AB; Calambokidis, J; & Hildebrand, JA. (2015). Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California. Deep-Sea Research Part II: Topical Studies in Oceanography, 112, 143 - 157. doi:10.1016/j.dsr2.2014.10.008. UC San Diego: Retrieved from: http://www.escholarship.org/uc/item/5fr4x1d6 |
op_relation |
qt5fr4x1d6 http://www.escholarship.org/uc/item/5fr4x1d6 |
op_rights |
public |
op_doi |
https://doi.org/10.1016/j.dsr2.2014.10.008 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
112 |
container_start_page |
143 |
op_container_end_page |
157 |
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1766366765275676672 |