AFSC/NMML/CCEP: Channel Islands Pinniped Census

The National Marine Mammal Laboratories' California Current Ecosystem Program (AFSC/NOAA) initiated and maintains census programs for California sea lions (Zalophus californianus) and northern fur seals (Callorhinus ursinus) at San Miguel and San Nicolas Islands, California. The program documents annual pup births, pup mortality, and temporal patterns in adult and juvenile presence at San Miguel Island. For both species, the database contains field data on the annual number of live pups and dead pups by location. At San Miguel Island, daily counts of adults, pups, and juveniles in a sample area are also available. The data are used to describe population trends and changes in land resource use among the species.

The census data are used in models to estimate the size of the populations based on pup production as an index of the population as whole. These data contribute to the NMFS Stock Assessment Reports that are used to monitor the status of marine mammal species under the Marine Mammal Protection Act of 1972.

Cite data as: Melin, S. R., DeLong, R. L., Orr, A. J., Laake, J. L. 2016. California sea lion and northern fur seal censuses conducted at Channel Islands, California by Alaska Fisheries Science Center from 1969-07-31 to 2015-08-08 (NCEI Accession 0145165). NOAA National Centers for Environmental Information.

Tables include information (counts) of California sea lions and northern fur seals during daily censuses (all age/sex classes) and for yearly production estimates (pups only). See "Child Items" for more detailed information.

The user is responsible for the results of any application of this data for other than its intended purpose. NOAA denies liability if the data are misused. Applications or inferences derived from the data should be carefully considered for accuracy. Whereas every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

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The dataset is archived with the NOAA National Centers for Environmental Information (NCEI). Acknowledgement of NOAA/NMFS/AFSC, as the source from which these data were obtained in any publications and/or other representations of these data is suggested. Communication and collaboration with dataset authors is strongly encouraged prior to use.

The dataset is available for download via the NCEI Ocean Archive System at http://accession.nodc.noaa.gov/0145165.

There are no legal restrictions on access to the data. They reside in public domain and can be freely distributed.

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. Acknowledgement of NOAA/NMFS/AFSC, as the source from which these data were obtained in any publications and/or other representations of these, data is suggested. Data should be cited as: Melin, S. R., DeLong, R. L., Orr, A. J., Laake, J. L. 2016. California sea lion and northern fur seal censuses conducted at Channel Islands, California by Alaska Fisheries Science Center from 1969-07-31 to 2015-08-08 (NCEI Accession 0145165). NOAA National Centers for Environmental Information.

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Metadata are subject to revision at any time and information within the metadata record should not be cited without author consent. Whereas every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

MS Access

At San Miguel Island, live pup surveys include the entire colony. Pup mortality surveys do not include areas outside the Point Bennett rookery on the west end of the island. Northern fur seal pup mortality surveys are conducted regularly only in the west half of Adams Cove; the east half is surveyed after 1 August to avoid disturbance to breeding California sea lions. A few years are missing data for Castle Rock, a small offshore colony, because of weather that prevented landing on the rock for counts.

At San Nicolas Island, live and dead pup surveys are conducted only on the southwest end of the island and do not represent the entire San Nicolas colony.

Until 1991, only one or two counts of dead pups were conducted after the live pup count in most years. After 1991, the current methodology of multiple surveys every 15 days was employed. Point Bennett Point (2007) and Northeast Point (2010) were dropped from the pup mortality sample area because of seabird nesting and access problems.

Data are edited in the field and entered into the database by the person who collected the data. The data managers make sure all the data are entered in the same format and check and correct for inconsistencies in the data.

Data not automatically processed

IT Security and Contingency Plan for the system establishes procedures and applies to the functions, operations, and resources necessary to recover and restore data as hosted in the Western Regional Support Center in Seattle, Washington, following a disruption.

Pup Birth Census:

1. All pups are counted by two or more observers that walk through the colony, along bluffs or from a blind counting all live pups observed. Counters use hand tallies and record their counts individually in their data books. Observers do not discuss individual counts while in the field.

2. For California sea lions, the entire colony at San Miguel is counted over 4-5 days; at San Nicolas Island a sample area is counted over 2 days. For northern fur seals, all pups are counted on a single survey. When counts span several days, distinct break points in the topography (usually headlands or large breaks in the distribution of animals such that is unlikely that adjacent areas mix) are used to provide markers to avoid counting the same pups on different days.

3. Counts are entered into the Microsoft Access database each night and error checked by the observers. When the census is complete, the average number of pups is computed for the colony or sample area.

Pup Mortality Survey:

1. Pup mortality surveys for California sea lions are conducted in sample areas on San Miguel and San Nicolas Islands. At San Miguel Island, the area is the Point Bennett rookery located on the west end of the island and represents about 45% of the total population. At San Nicolas Island, the area includes the southwest end of the island and represents about 33% of the population. Pup mortality surveys for northern fur seals are conducted in Adams Cove on the mainland of San Miguel throughout the reproductive season and only once on Castle Rock.

2. At San Miguel Island, pup mortality surveys are conducted at 10-15 day intervals beginning the first week of July and ending the middle of August. Surveys conducted after the end of the reproductive season may be at 15 day intervals or up to 1-2 months. At Castle Rock, a single mortality survey is conducted at the same time as the live pup survey for each species. At San Nicolas Island, one to three surveys are conducted over the reproductive season.

3. When surveys are conducted over the season, observers search the sample areas and collect and count each dead pup they encounter. The data includes: island, date, area on the island, species, beach location, substrate type, and carcass condition. The carcasses are then stacked into piles throughout the rookery to avoid counting individual carcasses more than once. In a few years, carcasses were tagged with individual numbers for a mark-recapture study to estimate disappearance rates of carcasses. Each carcass was tagged with two uniquely numbered tags and left on the beach. On the subsequent surveys, the tags and carcass condition were recorded when tagged carcasses were encountered creating a capture history for each carcass over the season.

4. Counts are entered into the Microsoft Access database and edited by the observer that collected the data. The total number of dead pups over the season for each species at each colony provides an index of the annual pup mortality.