U.S. flag An official website of the United States government.
Official websites use .gov

A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS

A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

i

Breeding season distribution and population grow of California sea lions, Zalphus californianus, in the United States druing 1964-2014



Details

  • Personal Author:
  • Corporate Authors:
    Southwest Fisheries Science Center (U.S.)
  • NOAA Program & Office:
  • Description:
    Breeding-season distribution and population growth rate of California sea lions (Zalophus californianus) in the U.S. population are estimated from counts of pups and non-pups collected during 1964 to 2014. Pup and non-pup count data were compiled from published and unpublished sources. These data showed that during this period the U.S. count of live-pups increased at an average annual rate of 4.7% per year (L95% CI=4.2%, U95% CI=5.2%). Average annual growth rates of live-pup counts at the four main island-rookeries in southern California (Santa Barbara Island, San Clemente Island, San Nicolas Island, and San Miguel Island; hence fore referred to as the Main Channel Islands) ranged from 4.2% to 5.5% from 1964 to 2014. The Channel Islands count of non-pups (non-pup counts were unavailable for the entire U.S. population prior to 2003) increased at an average annual growth rate of 2.8% per year (L95% CI=2.4%, U95% CI=3.4%). San Nicolas Island and San Miguel Island were the largest rookeries in the U.S. population, both having the most pups and non-pups. Prior to 1990, 59.2% of live pups counted in the Channel Islands were on San Miguel Island, and 32.4% were on San Nicolas Island. After 1990, these islands constituted 44.9% and 45.6% of Channel Island pups, respectively. California-wide surveys conducted during 2003-2005, 2007, and 2011-2013 indicated that the Main Channel Islands rookeries accounted for 99.71% of live pups counted in California and 77.35% of hauled-out non-pups in California during the breeding season. Sea lion counts were modeled (using generalized linear modeling) as a function of sea level height at Los Angeles, California (SLH-LA), Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO), and Multivariate El Niño Index (MEI). This model indicated that more pups were produced during cold-water conditions and fewer pups were produced during warmwater conditions, and that fewer non-pups were present at southern California rookeries during warm-water conditions and more were present during cold-water conditions.
  • Content Notes:
    Mark S. Lowry, Sharon R. Melin, and Jeffrey L. Laake

    "April 2017."

    System requirements: Adobe Acrobat Reader.

    Includes bibliographical references (pages 20-29).

  • Keywords:
  • Series:
    NOAA-TM-NMFS-SWFSC   574
  • DOI:
  • Document Type:
    Technical Memorandum
  • Place as Subject:
    California
  • Rights Information:
    Public Domain
  • Compliance:
    Submitted
  • Main Document Checksum:
    urn:sha-512:3514db8ec04bd078eecb267d98620175e5e961f6eed0668d144efd997b99116372a6f20300c1cdb7a0764bde25d233129618d1e4bfa6d712cccb0be068ccae5c
  • Download URL:
  • File Type:
    Filetype[PDF - 2.43 MB ]
PREVIOUS
ON THIS PAGE
Details
The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners. As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
BACK TO TOP