This book serves as a comprehensive identification guide to the cetaceans inhabiting the eastern North Pacific Ocean and adjacent Arctic waters. It aims to provide detailed information for researchers, students, and enthusiasts to distinguish between various whale, dolphin, and porpoise species found in this region. The text focuses on the physical characteristics, distribution, and behavior of these marine mammals, drawing upon scientific literature and field observations.

This work is recognized as a foundational text for identifying cetaceans in its specified geographic area. Its detailed approach and focus on observable characteristics make it a valuable resource for field researchers and marine biologists. The book's utility lies in its systematic presentation of data, enabling accurate species differentiation. It is likely regarded as a standard reference for anyone studying or observing marine mammals in the eastern North Pacific and Arctic.