Special Status Species
Guadalupe fur seal Photo: NOAA Fisheries OPR Common name: Guadalupe fur seal
Scientific name: Arctocephalus townsendi
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Range Habitat Movements
Abundance Natural History Threats
Conservation Research Gaps Recommended Actions
References Resources

Listing Status
Endangered Species Act (?)
Status: Threatened
Critical Habitat: None
Recovery Plan: None
Five Year Status Review: None

California Endangered Species Act (?)
Status: Threatened

Marine Mammal Protection Act (?)
Status: Depleted; strategic stock
Stock Assessment: Revised in 20001

California Department of Fish and Game (?)
Status: Fully Protected

The World Conservation Union (IUCN) (?)
Status: Vulnerable

Convention on International Trade in Endangered Species (CITES) (?)
  Appendix I

Geographic Range

Prior to exploitation, Guadalupe fur seals ranged from the Farallon Islands in central California to the Islas Revillagigedo, Mexico and into the southern Gulf of California. Bones from this species have been found in archeological sites in Yachats, Oregon and along the Olympic peninsula, suggesting that this species ventured, at least occasionally, farther north along the coast of Oregon and Washington.2 Currently the only large breeding colony is located on Isla Guadalupe off Baja California, Mexico (Figure 1). A very small breeding group was identified in 1997 on Isla Benito del Este.3 The geographic range of this species during the non-breeding season is not well understood. Recently, individuals have been sighted between Zihuatenejo, Mexico and Bodega Head, California (Figure 1).4 This species may venture even further north to waters off Oregon and Washington; one dead stranded Guadalupe fur seal was collected in the Columbia River, Washington in 1992.2 The Farallon Islands (off central California) and the Channel Islands (off southern California, including San Miguel, San Nicolas, Santa Barbara and San Clemente Islands) are used as haul outs.5,6 A mother and young pup were sighted on San Miguel Island in 1997.7 This pup may to be the first pup born in California waters this century.


Guadalupe fur seals have been sighted in the water and stranded ashore in every county in the MBNMS (Figure 2, Table 1). The discovery of bones from this species in middens near Monterey Bay shows that this species has been occurring, to some extent, in the MBNMS for centuries.8

Geographic distribution of Guadalupe fur seal Figure 1. The geographic distribution of the Guadalupe fur seal Arctocephalus townsendi.6

Location of sightings and strands of Guadalupe fur seals Figure 2. Location of sightings and strandings of Guadalupe fur seals in central California. (See Table 1 for sources of data used to make this map).
Download full-size figure (1.2 MB JPG).

Table 1. Date and location of sightings and strandings of Guadalupe fur seals in central California. Age group and sex are provided if such information was available.

Location Age Group, Sex Source
Monterey Bay   6
Southeast Farallon Island Juvenile 5
6 km west of Bodega Head, Sonoma County Juvenile 5
Southeast Farallon Island Adult, Male 5
Southeast Farallon Island Juvenile 5
Southeast Farallon Island Adult, Male 5
South of Fort Ord, Monterey County Juvenile, Male 27
Princeton Harbor, San Mateo County Female 27
Blind Beach, Sonoma County Juvenile, Female 5
Sanddollar Beach Monterey County Juvenile, Male 5
Santa Cruz Wharf, Santa Cruz County Juvenile, Female 5
Año Nuevo Island, San Mateo County Adult, Female 5
Half Moon Bay, San Mateo County Juvenile, Female 5
Salinas River, Monterey County Juvenile, Female 5
Fort Funston, San Francisco County Juvenile, Female 5
Sutro Baths, San Francisco County Juvenile, Female 5
Port San Luis, San Luis Obispo County Juvenile, Female 5
Pescadero Beach, San Mateo County Juvenile, Male 12
Bean Hollow, San Mateo County Pup, Female 12
Pt. Lobos, Monterey County Adult, Female 12
N. end of Bolinas Beach, Marin County Juvenile, Male 12
Pomponio State Beach, San Mateo County Juvenile, Male 12
Pajaro Dunes, Santa Cruz County Pup, Male 12
Oceano Dunes, San Luis Obispo County Juvenile, Male 12
Asilomar State Beach, Monterey County Adult, Female 12
Half Moon Bay, San Mateo County Juvenile, Female 12
Moonstone Beach, San Luis Obispo County Pup, Male 12
Stinson Beach, Marin County Juvenile, Male 12
La Selva Beach, Santa Cruz County Juvenile, Female 12
South Beach, PRNS, Marin County Juvenile, Female 12
Morro Strand (N), San Luis Obispo County Juvenile, Male 12
Moss Beach, San Mateo County Juvenile, Female 12
It's Beach, Santa Cruz County Juvenile, Female 12
Davenport Beach, Santa Cruz County Juvenile, Male 12

Rookeries and hauls-outs are located on islands with rocky shorelines often along the base of large cliffs. Males establish territories in or near sea caves, tide pools, or other recessed areas that offer relief from the sun, wind, and surf and provide easy access to the ocean. Not much is known about this species habitat preferences while at sea.


This species is not known to haul out or breed in the MBNMS, but a number of individuals have been sighted in Sanctuary waters or have stranded on Sanctuary beaches (Figure 1). Very little is known about the distribution of this species in offshore habitats of the Sanctuary.

Migration and Movements

Adult males and some juveniles leave island rookeries during the non-breeding season (September-May) while adult females, pups and some juveniles are found on islands for most of the year. Many females leave the rookery in April and May (after weaning pups) and return in June to give birth.9 It is not known where most individuals go while at sea, but most sightings occur to the north of Guadalupe Island, Mexico.

Information collected from two recent tagging studies give some information regarding movement patterns while at sea. In the first study, nursing females were tagged on Guadalupe Island.10 The females left the rookery on foraging trips with round-trip distances ranging from 704 to 4,000 km. Foraging occurred to the northwest and southeast of Isla Guadalupe and occurred over 200 km offshore of the Baja coast. The mean travel velocity was 7.1 km/hr. In the second study, an adult female was released in 1998 after rehabilitation at the Marine Mammal Center in central California.11 After release at Point Piedras Blancas in central California, she traveled at an average speed of 3.2 km/hr south to Isla Guadalupe before heading north again. Her last recorded position was 315 km offshore of Mendocino County. In general, she maintained a distance from shore of over 200 km.


The movement patterns of Guadalupe fur seals in the MBNMS is not well understood, but most individuals are sighted or strand along the central California coast in the summer and early-fall (May-August) (Table 1). Many, but not all, sighting and strandings in the Sanctuary have occurred during El Niño events (e.g., 1991-1993) suggesting that this species may exploit warm water conditions to extend its range to the north.5 However, satellite tagged yearlings released in the central California remained off the northern and central California coast for the three months that their tags were transmitting information.12 These data raise the possibility that Guadalupe fur seals occur off the central California coast more frequently than the sighting and stranding data indicate, and that stranding rates of these animals increase during El Niño events.


Pre-exploitation abundance estimates range between 20,000 and 200,000.13 Extensive sealing in the 1800s reduced the population down to probably a few dozen individuals. The species was believed to be extinct in the early 1900s until 1928 when a breeding group was discovered at Isla de Guadalupe.14 The colony was exterminated by museum collectors soon after its discovery and thought to be extinct again until a small breeding group was rediscovered in 1954.15,16 This small breeding colony is estimated to have been growing at an annual rate of 13.7% (Figure 3).10 The most recent estimate of the size of the population on Isla Guadalupe was 7,408 individuals in 1993.10 There is some evidence that this species has recently re-colonized a former rookery on Isla Benito del Este, Baja California.3


The number of Guadalupe fur seals that use the MBNMS on a regular basis has not been estimated. The number of strandings has been increasing along the central California coast (Figure 4), a trend that is likely to continue if the population maintains its current growth rate.12

Figure 3. Estimated population size of the Guadalupe fur seal based on counts at the main rookery on Isla Guadalupe, Mexico.10
Download full-size figure (XXX KB PDF).

Figure 4. The number of Guadalupe fur seals stranded per year along the central California coast 1977-2004.25
Natural History
Click here to view the natural history information of this species.


Entanglement in fishing gear: Though there have been no reports by on-board observers of fishery-related mortality of this species, drift and set gillnet fisheries may cause incidental mortality of this species along the coast of California and Mexico (little is known about fisheries-related mortality or injury in Mexico). Two of the 13 Guadalupe fur seals that stranded along the central California coast between 1988 and 1995 had injuries caused by entanglement in fishing gear.19

Acoustic disturbance (e.g., noise from ships, aircraft, research boats, and military and industrial activities): There is concern about the potential negative impacts of human-induced noise on pinnipeds though there is no evidence of impacts on Guadalupe fur seals.20

Habitat degradation (e.g., chemical pollution, oil pollution, coastal development, marine debris): Any increase in oil and gas development offshore of California and the west coast of Baja California, Mexico would increase both the potential of an oil or chemical spill and the amount of shipping traffic in and adjacent to Guadalupe fur seal habitat.

Competition for prey resources: Guadalupe fur seals may be competing with commercial fisheries for declining stocks of some prey species.


No threats are unique to the MBNMS.

Conservation and Research

In 1985 the Guadalupe fur seal was listed as “threatened” under the Endangered Species Act (ESA). In addition, it is considered to be "depleted" and a "strategic stock" under the Marine Mammal Protection Act (MMPA). Under the ESA and MMPA, the National Marine Fisheries Service (NMFS) is responsible for the management and recovery of most marine mammal species including the Guadalupe fur seal. Even though it is required under the ESA, no recovery plan for this species has been prepared, nor has a recovery team been established.

As required under the MMPA, NMFS updates the Stock Assessment Reports for all marine mammal stocks at least once every three years. The most recent update occurred in 2003. Current Stock Assessment Reports are available on the NOAA Office of Protected Resources website.

Under the ESA and MMPA, this species is protected from commercial sealing, which was the principal cause of the species’ decline. In the portion of the Guadalupe fur seal's range that is under U.S. jurisdiction, no human activities are known to be adversely impacting recovery of this species. No specific actions necessary for the recovery of the species have been identified and no direct recovery actions are being implemented by NMFS.

The health of the Guadalupe fur seals in California will be monitored, in part, by the following programs:

Marine Mammal Health and Stranding Response Program Network (Joe Cordaro, Southwest Regional Stranding Coordinator, NMFS/SWFSC). The network consists of volunteer groups that respond to marine mammal strandings in California. Samples from stranded animals provide information on sex, length, age, reproductive condition, contaminant loads, stock discreteness, parasites, diseases, and cause of death. In addition to collecting data from stranded animals, this program assesses health trends, correlates health with available data on physical, chemical, environmental, and biological parameters, and coordinates effective responses to unusual mortality events.

Pinniped Monitoring at Point Reyes National Seashore (PRNS) (Principal Investigator: Sarah Allen, PRNS). Harbor seals, northern elephant seals, California sea lions, Steller sea lions, Guadalupe fur seals, and Northern fur seals have been censused bi-weekly at the Point Reyes Headlands since 1995. The main objective of the study is to determine long-term trends in annual population size and annual and seasonal distribution of pinnipeds at PRNS and Golden Gate National Recreational Area. The primary data collected are counts of species on land by age class (as appropriate) and spatial distribution. Tissue and blood samples are collected sporadically. Sightings of Guadalupe fur seals, Steller sea lions, and Northern fur seals are rare.

Pinniped monitoring at San Miguel Island (Principal Investigator: Bob DeLong, NMFS National Marine Mammal Lab): The numbers of California sea lions, northern elephant seals, northern fur seals and Guadalupe fur seals on San Miguel Island are monitored on a regular basis.


Beach COMBERS - Coastal Ocean Mammal and Bird Education and Research Surveys (Project Leader: Hannah Nevins, Moss Landing Marine Laboratories). In 1997 the MBNMS began a beach survey program using trained volunteers to survey beached marine birds and mammals monthly at selected sections of beaches throughout the Monterey Bay area. Currently, the program monitors 45 km of beaches in the MBNMS. The program is a collaborative project between MLML, MBNMS, and other state and research institutions, with the specific goal of using deposition of beach cast carcasses as an index of the health of the sanctuary. The Marine Mammal Health and Stranding Response Program Network is notified of all stranded or dead cetaceans so that data can be collected and the cause of the stranding event determined. Within the MBNMS, live strandings are handled by The Marine Mammal Center in Sausalito and dead stranding are handled by Moss Landing Marine Laboratories (Monterey Co.), University of California Santa Cruz (Santa Cruz Co.), and the California Academy of Sciences (San Mateo Co.).


This species is “fully protected” under the Fish and Game Code (§4700), which means that this species cannot be taken or possessed in California without a permit from the Fish and Game Commission. In addition, this species is protected under the California Endangered Species Act (CESA). Under CESA, the California Department of Fish and Game (CDFG) is responsible for conserving, protecting, restoring, and enhancing endangered and threatened species and their habitat. Currently, no state managed fisheries are known to be negatively impacting this species. CDFG does not have any active research, management, or conservation programs for the Guadalupe fur seal.


The Mexican government designated Isla Guadalupe as a wildlife sanctuary in 1922 and a pinniped sanctuary in 1975. The species is also protected from take by Mexican law. However, disturbance and some poaching may still occur.

Research Gaps

Not much is known about the distribution, abundance, foraging behavior or movement patterns of Guadalupe fur seals in the MBNMS. However, this species is in very low abundance in the area, which makes research dedicated to this species difficult and expensive. Researchers studying other marine mammals and birds should be coordinated to collect data (e.g., distribution, abundance, behavior, genetic samples, etc.) from any Guadalupe fur seals sighted along the southern and central California coast. Tagging studies should continue on both wild and rehabilitated animals.

Recommended Actions
  • Support observer programs for U.S. and Mexican commercial fisheries that are potential entanglement risks for this species.21
  • Support a continued ban on intentional take of this species in U.S. and Mexican waters.
  • Work to reduce or eliminate future oil and natural gas extraction projects along the California and Mexican coast (exploring for, developing, or producing oil or gas reserves is prohibited inside the MBNMS by the National Marine Sanctuary Act).
  • Support the management of fisheries that target the prey species of the Guadalupe fur seal. The goal of management should be a balance between human use and maintaining adequate prey resources for this growing population.
MBNMS: Enforce Sanctuary regulations that help prevent disturbance to Guadalupe fur seals including:
  • Existing “Restricted Overflight” zones prohibit low flying aircraft (<1,000 ft) over many potential haulout sites in the Sanctuary.22
  • Prohibitions on intentional take or injury to animals protected under the MMPA.23
  • Prohibitions on discharging or depositing any material in or near Sanctuary boundaries that injures a Sanctuary resource. Reduce injury and mortality from entanglement in marine debris, particularly fishing gear, through education outreach to fishing industry, abandoned gear recovery, and entanglement/stranding response teams. Improve water quality by reducing entry of possible infectious agents and chemical pollutants (e.g., organochlorines, butyltins, heavy metal) into Sanctuary waters.24
  • Review, update and implement a vessel traffic management system in and around Sanctuary waters to ensure the safe transport of petroleum and other hazardous materials along the coast.
Cited References
1. Carretta JV, Forney KA, Muto MM, Barlow J, Baker J, Lowry M (2004) U.S. Pacific Marine Mammal Stock Assessments: 2003. NOAA Technical Memorandum NMFS-SWFSC-358, U.S. Department of Commerce.
2. Etnier M (2002) Occurrences of Guadalupe fur seals (Arctocephalus townsendi) on the Washington coast over the past 500 years. Marine Mammal Science 18:551-557.
3. Maravilla-Chavez M, Lowry M (1999) Incipient breeding colony of Guadalupe fur seals at Isla Benito Del Este, Baja California, Mexico. Marine Mammal Science 15:239-241.
4. Aurioles-Gamboa D, Hernandez-Camacho C, Rodriguez-Krebs E (1999) Notes on the southernmost records of the Guadalupe fur seal, Arctocephalus townsendi, in Mexico. Marine Mammal Science 15:581-583.
5. Hanni K, Long D, Jones R, Pyle P, Morgan L (1997) Sightings and strandings of Guadalupe fur seals in central and northern California, 1988-1995. Journal of Mammalogy 78:684-690.
6. Belcher R, Lee TJ (2002) Arctocephalus townsendi. Mammalian Species 700:1-5.
7. Melin S, DeLong R (1999) Observations of a Guadalupe fur seal (Arctocephalus townsendi) female and pup at San Miguel Island, California. Marine Mammal Science 15:885-888.
8. Rice DW (1998) Marine mammals of the world: systematics and distribution. Society for Marine Mammalogy Special Publication No. 4.
9. Pierson MO (1978) A study of the population dynamics and breeding behavior of the Guadalupe fur seal, Arctocephalus townsendi. Ph.D. dissertation, University of California, Santa Cruz.
10. Gallo-Reynoso JP (1994) Factors affecting the population status of Guadalupe fur seal, Arctocephalus townsendi (Merriam, 1897), at Isla de Guadalupe, Baja California, Mexico. Ph.D. Dissertation, University of California, Santa Cruz.
11. Lander M, Gulland F, DeLong R (2000) Satellite tracking a rehabilitated Guadalupe fur seal (Arctocephalus townsendi). Aquatic Mammals 26:137-142.
12. D. Greig, The Marine Mammal Center, personal communication
13. Fleischer LA (1987) Guadalupe fur seal Arctocephalus townsendi. In: Croxall JP, Gentry RL (eds) Status, biology, and ecology of fur seals, Vol 51:1-212. National Oceanic and Atmospheric Administration, Technical Report, National Marine Fisheries Service, p 43-48.
14. Townsend CH (1928) Reappearance of the lower California fur seal. Bull NY Zool Soc 31:173–174.
15. Bartholomew GA, Jr. (1950) A male Guadalupe fur seal on San Nicolas Island, California. Journal of Mammalogy 31:175-180.
16. Hubbs CL (1956) Back from oblivion, Guadalupe fur seal: still a living species. Pacific Discovery 9:14-21.
17. Reynolds JE, III, Rommel SA (1999) Biology of Marine Mammals. Smithsonian Institution Press, Washington, D.C.
18. Bernardi G, Fain S, Gallo-Reynoso J, Figueroa-Carranza A, Le Boeuf B (1998) Genetic variability in Guadalupe fur seals. Journal of Heredity 89:301-305.
19. Goldstein T, Johnson SP, Phillips AV, Hanni KD, Fauquier DA, Gulland FMD (1999) Human-related injuries observed in live stranded pinnipeds along the central California coast 1986-1998. Aquatic Mammals 25:43-51.
20. National Research Council (2005) Marine Mammal Populations and Ocean Noise: Determining When Noise Causes Biologically Significant Effects. Committee on Characterizing Biologically Significant Marine Mammal Behavior. National Academies Press, Washington, DC. 142 pages.
21. Addressed in part by JMPRWildlife Disturbances Issues - Marine Mammal, Seabird and Turtle Disturbance Action Plan: Commercial Harvest Related Disturbance Strategy. Joint Management Plan Review (JMPR). Proposed Action Plans. Draft report. Monterey Bay National Marine Sanctuary.
22. Addressed in part by JMPR Ecosystem Protection Issues - Low Flying Aircraft Disturbance Strategy. Joint Management Plan Review (JMPR). Proposed Action Plans. Draft report. Monterey Bay National Marine Sanctuary.
23. Addressed in part by JMPR Wildlife Disturbance Issues - Marine Mammal, Seabird and Turtle Disturbance Action Plan: Enforcement Activity Disturbance Strategy. Joint Management Plan Review (JMPR). Proposed Action Plans. Draft report. Monterey Bay National Marine Sanctuary.
24. Addressed in part by JMPR Wildlife Disturbance Issues - Marine Mammal, Seabird and Turtle Disturbance Action Plan: Marine Debris Strategy. Joint Management Plan Review (JMPR). Proposed Action Plans. Draft report. Monterey Bay National Marine Sanctuary.
25. D. Greig, The Marine Mammal Center, unpublished data
26. Rice DW (1998) Marine mammals of the world: systematics and distribution. Society for Marine Mammalogy Special Publication No. 4.
27. Webber M, Roletto J (1987) Two recent occurrences of the Guadalupe fur seal Arctocephalus townsendi in central California. Bulletin of the Southern California Academy of Sciences 86:159-163.
References and Resources
Click here for images, reports, and links to other websites for this species.

Acknowledgement of Reviewers

Thank you to Denise Greig and Mike Weise for reviewing this report and providing helpful comments and corrections.

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