Document Type

Article

Publication Date

6-5-2007

Keywords

Callorhinus ursinus, Historic ecology, Stable isotopes, Zooarchaeology, Ancient DNA

Abstract

Historical data provide a baseline against which to judge the significance of recent ecological shifts and guide conservation strategies, especially for species decimated by pre-20th century harvesting. Northern fur seals (NFS; Callorhinus ursinus) are a common pinniped species in archaeological sites from southern California to the Aleutian Islands, yet today they breed almost exclusively on offshore islands at high latitudes. Harvest profiles from archaeological sites contain many unweaned pups, confirming the presence of temperate-latitude breeding colonies in California, the Pacific Northwest, and the eastern Aleutian Islands. Isotopic results suggest that prehistoric NFS fed offshore across their entire range, that California populations were distinct from populations to the north, and that populations breeding at temperate latitudes in the past used a different reproductive strategy than modern populations. The extinction of temperate-latitude breeding populations was asynchronous geographically. In southern California, the Pacific Northwest, and the eastern Aleutians, NFS remained abundant in the archaeological record up to the historical period ≈200 years B.P.; thus their regional collapse is plausibly attributed to historical hunting or some other anthropogenic ecosystem disturbance. In contrast, NFS populations in central and northern California collapsed at ≈800 years B.P., long before European contact. The relative roles of human hunting versus climatic factors in explaining this ecological shift are unclear, as more paleoclimate information is needed from the coastal zone.

Publication Title

PNAS: Proceedings of the National Academy of Sciences of the United States of America

Volume

104

Issue

23

First Page

9709

Last Page

9714

DOI

10.1073/pnas.061098104

Required Publisher's Statement

Copyright the Authors, Published by PNAS

PNAS June 5, 2007 104 (23) 9709-9714; https://doi.org/10.1073/pnas.0610986104

Comments

This article contains supporting information online at www.pnas.org/cgi/content/full/0610986104/DC1.

Subjects - Topical (LCSH)

Northern fur seal--Research--Pacific Coast (North America); Marine mammals--Effect of human beings on--Pacific Coast (North America); Animal populations--Effect of human beings on--Pacific Coast (North America)

Geographic Coverage

Pacific Coast (North America)

Genre/Form

articles

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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