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Science Feature
The Science Feature describes important research and monitoring programs or projects occurring in the sanctuaries. The current Feature presents
a volunteer program conducted in and around the
Gulf of the Farallones National Marine
Sanctuary.
SEALS: Sanctuary Education Awareness and Long-term Stewardship
by Joseph Mortenson, Maria Brown, Jan Roletto, Leslie Grella, and Leah Culp
Introduction
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A
motor boat cruises past the seal haul-out.
(Photo credit: Bob Wilson)
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In the Gulf of the Farallones National Marine Sanctuary, adjacent Point Reyes National Seashore, and the Sonoma Coast State Beaches, there is a long history of concern that humans are disturbing resting harbor seals (Allen et al. 1984). Observations at Tomales Bay, Bolinas Lagoon, and the Russian River spits showed the highest rates of disturbance in comparison to other haul-outs sites along the central and northern California coast (Mortenson 1996). It was noted that many of the disturbances were associated with human recreational activities such clam digging, kayaking, canoeing, and motor boats.
The conflict between increased recreational use of the coast and undisturbed resting areas for wildlife is worldwide. Already half the people in the country and the world (Weber, 1994) live along the coasts. By 2050, it is projected that more than 70% of the nearly 400 million Americans (U.S. Bureau of the Census, 1995) will live near the ocean. How will coastal species tolerate the millions of new shoreline dwellers?
With the growing number of Californians, how many disturbances can harbor seals tolerate along the shoreline, especially at heavily visited haul-outs? How can recreational use be managed so that people and seals can share the coast? Perhaps successful programs to conserve seal colonies can help guide us in protecting all coastal species in the future.
In 1996, The GFNMS in collaboration with the Farallones Marine Sanctuary Association (FMSA) initiated the Sanctuary Education, Awareness, and Long-term Stewardship (SEALS) program, a harbor seal monitoring and interpretation program along the central California coast. The SEALS program was developed to respond to high levels of disturbance to harbor seals and strives to achieve the following goals:
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SEALS volunteers document activity patterns of humans and seals near Seal and Clam Islands in Tomales Bay. (Photo credit: Leah Culp)
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- Minimize disturbance to harbor seals and maintain the integrity of rookery sites in the Gulf of the Farallones National Marine Sanctuary;
- Preserve the harbor seal colony size in the Gulf of the Farallones National Marine Sanctuary;
- Increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and
- Educate the general public about harbor seals and their habitat in the Gulf of the Farallones National Marine Sanctuary.
In order to achieve these goals, the Sanctuary and FMSA train local citizens to interpret and monitor harbor seals. Volunteers complete an intensive 33-hour training course on harbor seal natural history, bay and lagoon ecology, interpretation and monitoring t
echniques, research protocols, and the history of the GFNMS.
Since 1997, the Sanctuary and FMSA have managed a harbor seal interpretation and disturbance assessment program at two harbor seal haul-outs in Tomales Bay and Bolinas Lagoon. Volunteers with staff supervision conduct the interpretation of the wildlife on the haul-outs and document human activities as they relate to harbor seal behaviors.
Beginning in 1998, central California seal censuses were added to the program (Figure 1). This census data assures the Sanctuary of sustained information on the regional population and distribution of harbor seals. Volunteers and staff from Point Reyes National Seashore, Golden Gate National Recreation Area, the Sanctuary, FMSA, Fitzgerald Marine Reserve, CalTrans, San Francisco State University, Seal Watch Jenner, and Seal Watch Sea Ranch simultaneously count seals at a number of haul-outs from the southern border of San Mateo County to the northern border of Sonoma County, including San Francisco Bay.
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Study Design
Tomales Bay: Clam & Seal Island Haul-outs. During previous harbor seal studies in the Point Reyes National Seashore area it was found that the seals on Clam and Seal Islands were disturbed on 81% of the observation days&emdash;almost double the percent noted a decade earlier. Clam diggers and fishers were associated with 51% of the disturbances (Allen and King 1992). Overall, humans were associated with 1.33 disturbances per hour in 1991, which was the highest rate of disturbance ever reported on the West Coast (Mortenson, 1996). In response to the high level of disturbance of seals and their pups, the Sanctuary initiated an interpretation program on Clam and Seal Islands, in Tomales Bay. Flags were placed 300 feet from seal haul-outs and docents positioned themselves at the flags in order to answer questions, offer views through spotting scopes of the seals and provide information on why they were present.
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Figure 1. Average distance between flushing seals and associated human activities in Tomales Bay. Kayaks may flush seals at a distance of approximately 200 m from the seals.
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A monitoring and behavioral assessment project was established to measure the effectiveness of the interpretation program and the visible buffer at the seal haul-outs. Data are collected on seal counts, location and dispersal of seals, vigilance behavior, flushing behavior and approaches to the water, pupping rates, all human activities and all associated harbor seal behavior/response to activities, distance between the human activities and seals, as well as flushes and disturbances when there is no apparent associated human or natural activity.
Bolinas Lagoon: Channel, Pickleweed, and Kent Haul-outs. Similar circumstances occurred at the harbor seal haul-outs in Bolinas Lagoon; harbor seals were disturbed from kayaking and canoeing. Thus, a similar monitoring and behavioral assessment project was established to determine which activities are associated with harbor seal disturbances, document distances between activities and harbor seals, determine if the rate of disturbance is increasing and from which activities, and to monitor harbor seal population changes.
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Results
Tomales Bay. Flushing rates have appeared to decrease since the placement of docents on the mudflats near the seal haul-outs in Tomales Bay. Most of the historic disturbances to the seals were from clam diggers that approached the haul-outs on foot, at a rate of 1.33 flushes per hour during the early 1990's (Allen and King 1992). With the placement of docents near the haul-outs, the rate of disturbances from clam diggers has remained very low (< 0.10 flushes per hour). The human activity patterns have changed over the years. Now motor boats and kayakers are initiating more flushes (Table 1). However, while the rate of disturbance from motorboats has been fourfold over the course of the study, the rate of disturbance from kayakers has fallen to less than a third of its original rate.
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Table 1. Total number of activities and occurrences, occurrence rate (number per hour), number of associated flushes, associated flush rate (number per hour), and percentage of activity occurrences associated with flushes for all activity types observed at Tomales Bay, Clam and Seal Islands haul-outs, 2000.
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Activity
Type
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Number of Occurrences
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Occurrence Rate
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Number of Associated Flushes
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Associated Flush Rate
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% Occurrence Associated with Flushes
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Aircraft
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2
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0.04
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2
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0.04
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100%
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Clammer
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1,833
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38.49
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4
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0.08
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< 1%
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Docent
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29
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0.61
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1
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0.02
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3%
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Dog
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9
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0.19
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0
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0.00
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0%
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Fisher
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1
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0.02
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0
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0.00
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0%
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Kayak
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17
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0.36
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5
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0.11
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29%
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Motorboat
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653
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13.71
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59
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1.24
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9%
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Rowboat
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2
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0.04
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1
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0.02
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50%
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Sailboat
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1
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0.02
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0
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0.00
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0%
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Unknown
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12
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0.25
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10
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0.21
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83%
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Totals
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2559
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53.15
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82
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1.72
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3%
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Bolinas Lagoon. During the mid to late 1970s harbor seals in Bolinas Lagoon were disturbed 0.05-0.09 times per hour (Allen et al. 1984). During the early 1990's flushing rates increased to 0.41 flushes per hour (Morgan and Swift 1992). These earlier investigations did not always delineate which human activities were associated with flushes nor did they include an assessment of the level of all activities in the Lagoon. The SEALS project includes counts of all activities regardless of the associated seal behavior. SEALS data has revealed that in some years, nearly 30% of the flushes were not associated with any human activity. This indicates that there may be an elevated level of vigilance behavior by seals in the Lagoon and that the seals retreat to the water on a more frequent basis, possibly due to temperature, tide height, or other environmental factors that may be unique to a Lagoon haul-out.
Observers recorded 15 different activities within the lagoon (Table 2). Most activities were along the shoreline and away from the seal haul-outs and were not associated with many disturbances. Infrequent aquatic activities such as kayaking and canoeing were associated with more disturbances. The overall disturbance rate was much lower than what was documented by Morgan and Swift. It appears that the presence of the SEALS volunteers may have had an effect on reducing the number of flushes at the Bolinas Lagoon haul-outs.
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Table 2. Total number of activities and occurrences, occurrence rate (number per hour), number of associated flushes, associated flush rate (number per hour), and percentage of occurrences associated with flushes for all activity types observed at Bolinas Lagoon, Channel and Pickleweed haul-outs, 2000.
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Activity Type
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Number of Occurrences
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Occurrence Rate
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Number of Associated Flushes
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Associated Flush Rate
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% Occurrence Associated with Flushes
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Aircraft
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3
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0.02
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0
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0.00
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0%
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Ambulance
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1
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0.01
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0
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0.00
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0%
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Automobile
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37
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0.23
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0
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0.00
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0%
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Bird
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2
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0.01
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0
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0.00
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0%
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Canoe
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9
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0.06
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4
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0.02
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44%
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Chainsaw
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7
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0.04
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0
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0.00
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0%
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Dog
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14
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0.09
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0
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0.00
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0%
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Fisher
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38
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0.23
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1
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0.01
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3%
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Harbor Seal
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2
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0.01
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0
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0.00
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0%
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Hiker
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366
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2.25
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3
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0.02
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1%
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Horn
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28
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0.17
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0
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0.00
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0%
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Kayak
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8
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0.05
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1
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0.01
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12%
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Loud Noise
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1
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0.01
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0
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0.00
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0%
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Motorcycle
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43
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0.26
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0
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0.00
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0%
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Unknown
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13
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0.08
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5
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0.03
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38%
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Total
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572
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3.51
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14
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0.09
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0.98
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Discussion
Wildlife Viewing Guidelines. In an effort to develop recommended viewing distances for seals and other wildlife, the SEALS project assesses the distance between all human activities and seals. The average number of flushes were associated with activities 300 to 400 feet away, and the range of flushes were associated with activities from 0 to over 1,200 feet away (Figure 2). In order to develop guidelines for the public, we determined that the minimal viewing and activity distance of one football field length (300 feet) would be adequate to reduce most flushing events that would occur unintentionally from recreationists. The length of a football field was selected because most flushes occurred at distances closer than 300 feet and because many people can easily gauge the approximate length of a football field.
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Figure 2. Map of Gulf of the farallones National Marine Sanctuary. Stars indicate location of SEALS monitoring projects.
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Education and Stewardship. Education and stewardship are the best avenues to further reduce disturbances to wildlife while continuing to have multi-recreational uses within the Sanctuary . The information collected from the SEALS program has been used to develop educational materials for kayakers and boaters. FMSA, in cooperation with the Sanctuary, Marin County Open Space District, Sierra Club, California Department of Fish and Game, and Bay Area Sea Kayakers, has developed a Paddler's Etiquette placard that outlines responsible wildlife viewing guidelines . The goal is to have the placard distributed with all kayaks sold in the San Francisco Bay area. FMSA is also working with kayaking outfitters and recreational groups to spread the message of responsible wildlife viewing. The falling rate of disturbances associated with kayakers in Tomales Bay may reflect the Sanctuary's and FMSA's educational efforts on how to recreate without disturbing wildlife. The Sanctuary's new challenge is to reduce the rate of disturbance to harbor seals from motorboats in Tomales Bay. The Sanctuary, Point Reyes National Seashore, and FMSA will be forming a committee to develop a plan on how to address the increase in disturbance from motorboats and to evaluate how increased marine patrols, on-the-water docents, and continued education programs might play a role in the reduction of disturbance to wildlife of the Sanctuary.
Literature Cited
Allen, S. G., D. G. Ainley, and G. W. Page. 1984. Haul out patterns of harbor seals in Bolinas Lagoon, California. Fishery Bulletin, 82 (3): 4900.
Allen, S. G., and M. E. King. 1992. Tomales Bay Harbor Seals: A Colony at Risk. Proceedings form the 3rd Biennial State of Tomales Bay Conference, pp. 33-37.
Morgan, L., and R. Swift. 1992. The effect of disturbance on harbor seal haul-outs in Bolinas Lagoon, California. Marine Mammal Center Marin Headlands GGNRA Sausalito, CA 94965.
Mortenson, J. 1996. Human Interference with Harbor Seals at Jenner, CA 1994-1995. Stewards of Slavianka, Sonoma Coast State Beaches, Russian River/Mendocino Park District, California State Parks. Duncan's Mills, CA, 48 pp.
U.S. Bureau of the Census. 1996. Population Projections of the United States by Age, Sex, Race, and Hispanic Origin: 1995 to 2050. Current Population Reports, Series P25-1130.
Weber, P. 1994. It comes down the coasts. Washington, D. C., World Watch. March/April, pp 20-29.
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