SIMoN
  Sanctuary Integrated Monitoring Network
Monitoring Project

Cordell Bank Ocean Monitoring Program

Principal Investigator(s)

  • Lisa Etherington
    Cordell Bank National Marine Sanctuary
  • Kaitlin Graiff
    Cordell Bank National Marine Sanctuary
  • Michael Carver
    Cordell Bank National Marine Sanctuary
Start Date: January 01, 2004

The goal of the Cordell Bank Ocean Monitoring Program (CBOMP) is to characterize and monitor the spatial and temporal variability in the physical and biological components of the pelagic ecosystem in the region surrounding Cordell Bank, a prominent and productive submerged island located at the heart of the Cordell Bank National Marine Sanctuary (CBNMS) off central California. This assessment of the pelagic system specifically meets the Sanctuaryís mandate to conduct long-term monitoring of the resources within the Sanctuary and provides important information for resource protection and management.

Weather and ocean conditions permitting, single-day monitoring cruises over Cordell Bank were conducted monthly (sometimes seasonally) from 2004 to 2010 on R/V C. Magister or R/V Fulmar. Data on the distribution of seabirds, marine mammals, and other vertebrates were collected by trained observers along six 12 km long east-west transects centered around Cordell Bank. In addition, observers scored abundance of Velella velella, three jellyfish species, kelp, various types of marine debris and vessels. Physical and biological characteristics of the pelagic system were measured, including: water temperature, salinity, chlorophyll-a fluorescence, photosynthetically active radiation, and zooplankton abundance. Oceanographic data were collected continuously along the transects using underway data collection systems, as well as at seven locations with a CTD.

Data are used to relate the spatial patterns of bird and mammal distribution with oceanographic patterns on a seasonal and annual basis. These data will also be integrated with other west coast sanctuary monitoring programs to understand changes in the central California ocean environment.

Summary to Date

Cordell Bank provides optimal conditions for ocean productivity and seabird and marine mammal foraging: a shallow bank situated on the edge of the continental shelf, located in a strong upwelling zone within the California Current System (CCS). Within the CCS, 2005 and 2006 represent unique years, with late onset of upwelling, followed by weak and intermittent upwelling. The resulting response of the marine ecosystem to these changes in atmospheric and oceanographic conditions is reflected in seabird patterns observed as part of a monthly monitoring program of the Cordell Bank system.

Preliminary examination of data suggests a shift in distribution and abundance of seabirds, with responses varying depending on foraging strategy. Cassinís auklets (Ptychoramphus aleuticus) are one of the most abundant species found in the waters surrounding Cordell Bank; however, the abundance of this planktivorous specialist decreased in 2005-2006, likely due to a lack of krill prey. Abundance of blue whales, which feed almost exclusively on krill, also decreased during this time period. In contrast, abundances of some foraging generalist species (e.g., shearwaters, albatrosses) did not appear to have changed between years in the Cordell Bank region. In 2006, we observed a change in the distribution of some piscivorous species (Common murre, Uria aalge, Brown pelican, Pelecanus occidentalis) from nearshore to offshore environments. These observations suggest suites of species may be responding differently to changes in the pelagic prey community in these offshore waters. These results indicate that regional changes in atmospheric and oceanographic conditions are reflected in local changes in seabird distribution and abundance in the region of Cordell Bank, which can provide insight into the overall abundance and re-distribution patterns of seabirds within the CCS.

Work is in progress to examine patterns of seabird abundance on a finer spatial scale and to understand their distribution relative to oceanographic features. Similar analyses are needed to understand spatial and temporal patterns of marine mammals. Future work will also involve a detailed analysis of spatial and temporal variability in oceanographic conditions in the region of Cordell Bank and how these patterns relate to regional oceanographic conditions. This effort will also involve comparison of oceanographic patterns from the monthly data collected as part of the Cordell Bank Ocean Monitoring Program with the fine temporal resolution of data being collected by the Cordell Bank oceanographic buoy.

Study Parameters

  • Salinity
  • Density
  • Optical properties
  • Temperature
  • Distribution
  • Abundance
  • Habitat association
  • Marine debris
  • Density
  • Chl A
  • Vessels
  • Salinity
  • Density
  • Optical properties
  • Temperature
  • Distribution
  • Abundance
  • Habitat association
  • Marine debris
  • Density
  • Chl A
  • Vessels

Study Methods

Data on the distribution of seabirds, marine mammals, and other vertebrates (including sharks, turtles, and ocean sunfish) are collected by trained observers using standard strip-survey methodology along six 12 km long east-west transects centered around Cordell Bank. From the observation deck, trained observers survey quarter-circular and semi-circular areas, of varying radius, forward and abeam to one side of the observer's location. In addition, observers score abundance of Velella velella, three jellyfish species, and the presence of kelp using a categorical scoring system. Data on the presence of various types of marine debris as well as vessels are also recorded. For each transect, a quality of visibility score, which represents a subjective assessment by the observer of observation conditions, is determined separately for birds and mammals. Weather and ocean conditions, including visibility, cloud cover, ocean swell, and wind speed, are recorded for each transect. Zooplankton abundance is estimated along the transects with a Simrad EK60 echosounder with a single 120 kHz split-beam transducer. Data on oceanographic conditions of surface waters are collected continuously along the transects using underway data collection systems, including a SBE-45 instrument measuring temperature and salinity, as well as a fluorometer measuring chlorophyll-a. CTD casts are performed at 7 locations during each cruise using a SEACAT-SBE-19 instrument, measuring vertical profiles of water temperature, salinity, fluorescence of chlorophyll-a, and photosynthetically active radiation. Starting in 2005, a monthly plankton sample has been collected as part of the California Department of Health Services, Marine Biotoxin Monitoring and Control Program.

Figures and Images

Northern Fulmars are pelagic seabirds that are commonly encountered in monthly surveys of the Cordell Bank environment during winter and spring months. Photo: Sophie Webb


Pacific white-sided dolphins are one of the most abundant marine mammals in the Cordell Bank sanctuary. Photo: Michael Richlen


Monthly sampling with a CTD is one method of characterizing and monitoring the oceanographic conditions within Cordell Bank sanctuary. Photo: Michael Carver/CBNMS


Survey area for the Cordell Bank Ocean Monitoring Program. Dashed east-west lines centered over Cordell Bank represent the six transects conducted. Dots represent CTD sampling locations. Image created by Pam van der Leeden.


Documents

  • Cordell Bank Seabird Community
    Seabird community composition at Cordell Bank from 2004-2006, as assessed by monthly at-sea monitoring. Proportion of total observations per month are presented for the most common species during the time period 2004-2006.

  • CBOMP seabird presentation
    Seabird abundance at Cordell Bank, CA associated with changes in regional oceanographic conditions. Talk presented at 2007 Pacific Seabird Group Meeting in Asilomar, California.

  • Standardizing West Coast At-Sea Monitoring Programs
    2007 report by Peter Pyle on standardizing at-sea monitoring programs for marine birds, mammals, other organisms, debris, and vessels, including recommendations for West Coast National Marine Sanctuaries.

  • 2005 Sanctuary Currents Poster
    Poster presented at 2005 Sanctuary Currents conference summarizing preliminary results from data collected by the Cordell Bank Ocean Monitoring Program in 2004.

  • 2004 CBOMP Annual Report
    2005 report that summarizes the establishment of the Cordell Bank Ocean Monitoring Program, details survey design and data collection methodology, and briefly presents observation results from 2004.