SEASONAL PATTERNS IN THE ABUNDANCE AND DISTRIBUTION OF CALIFORNIA CETACEANS, 1991–1992

A bstract This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100‐150 nmi (185‐278 km) of the California coast during 1991 and 1992. The results of a shipboard line‐transect survey conducted in July‐November 1991 (“summer”) were compared to those...

Full description

Bibliographic Details
Published in:Marine Mammal Science
Main Authors: Forney, Karin A., Barlow, Jay
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 1998
Subjects:
Aquatic Science
Ecology, Evolution, Behavior and Systematics
Pacific
Megaptera novaeangliae
Orca
Orcinus orca
Physeter macrocephalus
Online Access:http://dx.doi.org/10.1111/j.1748-7692.1998.tb00737.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1748-7692.1998.tb00737.x
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1748-7692.1998.tb00737.x
Description
Summary:A bstract This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100‐150 nmi (185‐278 km) of the California coast during 1991 and 1992. The results of a shipboard line‐transect survey conducted in July‐November 1991 (“summer”) were compared to those from aerial line‐transect surveys conducted in March‐April 1991 and February‐April 1992 (“winter”). Using a confidence‐interval‐based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white‐sided dolphins ( Lagenorhynchus obliquidens ), Risso's dolphins ( Grampus griseus ), common dolphins ( Delphinus spp.), and northern right whale dolphins ( Lissodelphis borealis ) were significantly more abundant in winter. The abundance of blue whales ( Balaenoptera musculuss ) and gray whales ( Eschrichtius robustus ) reflected well‐documented migratory patterns. Fin whales ( B. physalus ) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises ( Phocoenoides dalli ), bottlenose dolphins ( Tursiops truncatus ), killer whales ( Orcinus orca ), sperm whales ( Physeter macrocephalus ), or humpback whales ( Megaptera novaeangliae ). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white‐sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.

Similar Items