Sanctuary Integrated Monitoring Network
Monitoring Project

Coastal Ocean Mammal and Bird Education and Research Surveys (Beach COMBERS)

Principal Investigator(s)

  • Jim Harvey
    Moss Landing Marine Laboratories, California State University
  • Scott Benson
    National Oceanic and Atmospheric Administration (NOAA)
  • Hannah Nevins
    California Department of Fish and Wildlife
  • Erica Donnelly
    Moss Landing Marine Laboratories, California State University
  • Andrew DeVogelaere
    Monterey Bay National Marine Sanctuary


  • SIMoN
  • Save The Earth
Start Date: May 01, 1997

In 1997, we began a beach survey program called Coastal Ocean Mammal and Bird Education and Research Surveys (Beach COMBERS). The specific objectives of the Beach COMBERS program are to:

1) Provide baseline information on the average presence of beachcast marine birds and mammals;
2) Assess causes of seabird and marine mammal mortality;
3) Assist the sanctuary and other resource management agencies in the early detection of unusual mortality events triggered by natural and anthropogenic environmental perturbations (such as red tides and oil spills);
4) Assess abundance of tar balls (oil patches) on beaches;
5) Build a network of interacting citizens, scientists, and resource managers; and
6) Disseminate information to the resource managers, public, and educational institutions.

The main premise behind the program is that variations from long-term trends can serve as an index of the health of MBNMS, allowing managers to “keep a finger on the pulse of the sanctuary.”

The program is a collaborative effort between Moss Landing Marine Laboratories and Monterey Bay National Marine Sanctuary, along with other state and research institutions including the California Department of Fish and Game, the Marine Wildlife Veterinary Care and Research Center, and the University of California Davis. During the first week of every month, trained volunteers survey beached marine birds and mammals at selected beach sections from Wadell Creek in the north to Morro Bay in the south (Figures 2 and 3). Since 1997, over 190 volunteers have been trained in conservation science during trainings of at least 20 hours. Currently, COMBERS volunteers survey 79 km of MBNMS beaches each month (Figure 1).

Summary to Date

Access the latest report about Beach COMBERS!

During the first years of the program we saw extremely high deposition as a cumulative result of mortality from natural die-offs attributed to domoic acid, starvation (El Niño), and human-related mortality attributed to oil spills and gillnet fishery by-catch (Figure 4). Trends in deposition were also related to the individual species’ specific susceptibility to mortality (e.g. many young common murres are deposited at the end of summer), and occurrence patterns in the area. Migratory species such as loons, grebes, sea ducks and shearwaters, exhibit peaks in mortality corresponding to the times they are most abundant in the MBNMS region (Figure 5). Auks and tubenoses have comprised the most abundant beachcast marine bird species over time (Figure 6). Chronic and major oil spillage continues to be a source of mortality for marine birds in the sanctuary (Figure 7).

Marine mammals also exhibited monthly variation in deposition (Figure 8). Northern elephant seal deposition may be correlated with varying presence of the species in sanctuary waters throughout the year. Beachcast sea lions, harbor seals, and harbor porpoises were less common in the winter months and more common in the summer months. Sea otter deposition was relatively stable from month to month. California sea lions were the most frequently encountered marine mammal, with sea lion carcasses comprising 50% or more of beachcast marine mammals almost every year between 1997-2006 (Figure 9).

From 1997 to 2007, we identified 28 mortality events involving seabirds and marine mammals indicated by increased deposition. Overall, nine of these events were attributed to changes in environmental conditions, nine were attributed to oiling, three were due to harmful algal blooms, three were related to population increases, two were related to fishery interactions, one was due to natural predation, and one was due to unknown circumstances. The fifteen mortality events that exceeded the threshold limit are shown in Figure 10.

The Beach COMBERS program has been hugely successful in documenting trends in mortality of marine birds and mammals. Several events documented by the Beach COMBERS program were determined to be of significance throughout the North America West Coast region (e.g., 1997-98 El Niño, 2003 fulmar die-off). The documentation of other events made important contributions to science (e.g., 1998 Domoic Acid Bloom, 2007 Mystery Spill). In addition to inclusion in a number of scientific papers and journals, Beach COMBERS data have been used to initiate resource protection actions that have contributed to the conservation of sanctuary resources. As an example, Forney et al. (2001) used Beach COMBERS data to show that gillnet fisheries were killing large numbers of nearshore species. This information led to modified California Fish and Game regulations. Another example is detection of wildlife oiled by the S.S Luckenbach oil spill.

Monitoring Trends

  • Seabirds were the most abundant animals encountered during beach surveys.
  • Seabird deposition was relatively stable leading into and following a sharp peak during August and September of 1997 that was dominated by Common Murres (Uria aalge). This deposition event was attributed to an increase in fishing effort and by-catch of Common Murres in fishing nets at this time.
  • California sea lions Zalophus californianus were the most frequently encountered marine mammal carcass found on surveys each year from 1997 to 2006.
  • Presence of beachcast pinnipeds exhibited a dramatic increase in June 1998 and remained high through September 1998. This trend was attributed to a toxic phytoplankton bloom (a.k.a Domoic acid event; Gulland 2000, Scholin et al. 2000).

Study Parameters

  • Mortality
  • Range/Biogeography
  • Diversity
  • Abundance
  • Distribution
  • Migration/movement patterns
  • Human impacts

Study Methods

A total of nine beaches within Monterey Bay and one in Carmel Bay, (47.4 km total length) have been monitored monthly since May 1997. A 3.7-km stretch of sandy beach along the outer coast, north of Santa Cruz, has been monitored since September 1998. Bi-monthly sampling began in October 1998 at beach segments 5 and 8 to provide better temporal resolution of carcass deposition. Each beach segment is approximately 3.7 - 5.2 km in length. Five beaches near Cambria (in the southern portion of the MBNMS) have been surveyed since May 2001. In 2003, a beach was added in Big Sur and two additional city beaches were added in Santa Cruz and Monterey. The average time to complete a survey is three hours. The basic method is similar to a strip transect, where all beachcast birds and mammals within the strip (i.e., the width of the beach being surveyed) are counted. Deposition rates of marine birds and mammals are then calculated as the number of new animals encountered per linear km of coastline surveyed. Using these methods we can compare deposition rates among beaches, seasons and years.

Collected data are documented on standardized data forms. Data collected include: date; name of the person(s) making the observations; beach name and segment number; northern and southern boundary; time survey began and ended; wind and sky conditions; and number of tar balls found or collected. In addition, for each carcass encountered, the following information is recorded: species; stage of decomposition; age and sex; evidence of scavenging; evidence for the cause of death; presence of oil; whether or not a photograph was obtained; and presence of identification tags or bands. The intended use of the "comments" section is for documentation of any tags present on the carcass, length measurements, photograph roll and frame numbers, or any notes that would aid in identification after the form is submitted. A toe is clipped from seabird carcasses to assess the length of time the carcass may remain on a beach. Before clipping a toe, the volunteer documents the number of toes previously removed. Marine mammals are marked likewise by attaching a piece of jute twine to the carcass.

Figures and Images

Figure 1: Map of COMBER beach segments in MBNMS. Volunteers survey 28 pre-defined segments of sandy beach during the first week of each month.

Figure 2: Each marine bird or mammal encountered is identified to the lowest taxonomic level by COMBERS volunteers. In this case, this bird is recognized as a loon by the spots on the scapular (back) feathers, and distinguished as a Common Loon by the large, thick bill.

Figure 3: COMBERS volunteers try to determine the extent of oiling or other probable causes of death. The probable cause of death for this Sooty Shearwater is most likely to be entanglement in fishing gear.

Figure 4: Monthly overall new deposition of all seabird species during Beach COMBER surveys from 1997 to 2007. Sharp peaks in deposition are suggestive of significant die-off events.

Figure 5: Monthly mean deposition of ten most abundant seabirds, 1997-2007. Data shown are for new deposition on 11 core beaches in the northern part of the MBNMS (sites #1-11, Figure 1). Bars represent one standard error (SE, n = 11 yrs.).

Figure 6: Yearly beachcast seabird species composition from 1997 to 2006. Auk and tubenose species tend to be the most frequently observed by COMBERS volunteers.

Figure 7: Total number of new beachcast seabirds (seabirds/km) and percent oiled, May 1997-August 2007. Significant oiling events were identified when the percent of oiled birds exceeded two percent monthly.

Figure 8: Monthly mean deposition of five most abundant marine mammals observed by COMBERS volunteers on MBNMS beach sections, 1997-2007. Bars represent one standard error (SE, n = 11 yrs.).

Figure 9: Yearly beachcast marine mammal species composition by taxonomic group from 1997 to 2006. Sea lions have been the most frequently observed mammals each year.

Figure 10: From 1997-2007, data from the Beach COMBERS program have been used to identify 15 mortality events. Significant events were defined by one or more species exceeding a calculated threshold limit. Column color represents the category of event cause: red columns indicate fishery interactions, purple columns indicate environmental conditions; blue columns indicate a single-species event; and green columns indicate a harmful algal bloom.