Posted on October 23, 2001

Human Disturbances Affect Harbor Seal Haul-Out Behavior:  Can the Law Protect These Seals From Boaters?

Barbara Lelli and David E. Harris*

*University of Southern Maine
Lewiston-Auburn College
55 Westminster Street
Lewiston, Maine 04240
USA

*deharris@usm.maine.edu to whom correspondence should be sent.

Abstract

Over 30,000 harbor seals inhabit the near shore waters of the Gulf of Maine. They leave the water (haul-out) primarily onto rock ledges to rest, sleep, give birth and nurse their young.  Federal legislation, the Marine Mammal Protection Act of 1972 (MMPA), protects harbor seals from human disturbance, including non-lethal disturbances that disrupt normal behavior.

We observed the harbor seal population that hauls-out at low tide on two rock ledges in Gun Point Cove, Casco Bay, in the southern Gulf of Maine.  Throughout four consecutive Augusts (1997 - 2000) we counted the number of harbor seals hauled out at each low tide between 7 AM and 7 PM.  We also determined the level and type of boat traffic passing the ledge, the off shore weather conditions (temperature, wave height and % possible sunshine - from the nearest weather buoy), as well as the current status and enforcement of the MMPA (from statutory law, case law and the agency responsible for enforcing this law).

Using multivariate analysis, we found that the number of seals hauled out correlated positively with off shore wave height but negatively with % possible sunshine.  We also found that the level of boat traffic in the cove was, by far, the single strongest predictor of harbor seal haul-out number, accounting for 27% of its variability.  In 122 days of observation, we observed 85 incidents in which the harbor seals were flushed off their haul-out ledges.  Of these, 93% were caused by boats.  Because most (526/565=93%) of the boats passing the ledge were motor boats, this boat type caused the majority of flushing events.  However, 55% of paddled boats caused flushing events whereas only 11% of motor boats did so.  We also observed no enforcement of the MMPA in Gun Point Cove.  Our legal research determined that the MMPA has been used to prosecute lethal harassment of seals, but we could find no indication that the MMPA has ever been used to deter disturbances of the type we observed.

We have found that human disturbance by boat traffic has a large impact on harbor seal haul-out behavior on near-shore ledges in the Gulf of Maine.  However, while the MMPA has been used successfully to deter human activity that directly and immediately harms seals, penalties have not been imposed to prevent harassment by boaters.  This suggests that education of boaters and clear regulations may be a reasonable first step in reducing the impact of boaters on harbor seals in the Gulf of Maine.

INTRODUCTION

The harbor seal (Phoca vitulina concolor, Figure 1) is the most abundant pinniped in the Gulf of Maine.¹ Concentrated in coastal, near-shore waters, harbor seals forage for food, mate, and rest in the water.  However, harbor seals also leave the water (haul-out) to rest, sleep, give birth,² nurse, save energy and regulate body temperature, and molt³ (Terhune & Almon, 1983; Katona et al., 1993).  On the Maine coast, these seals commonly haul-out onto rock ledges that are exposed at and around low tide.  Although it is not clear why harbor seals prefer some ledges to others, factors such as ease of access to the water, proximity to food sources and minimal disturbance levels may impact harbor seal haul-out site choice (Krieber and Barrette, 1984).

Figure 1:  Phoca vitulina concolor. Marine Animal Lifeline photo.

A variety of temporal (i.e. time of day and time of tide cycle), seasonal, weather (i.e. air temperature, wind speed, and cloud cover) and sea condition (i.e. offshore wave height and surf height) variables can impact harbor seal haul-out behavior (see Watts, 1996 for review).  Disturbances resulting from human activity and other causes can also impact haul-out behavior (Renouf et al., 1981; Schneider and Payne, 1983; Terhune and Almon, 1983; Allen et al., 1984; Stewart, 1984; Suryan and Harvey, 1999; Mortenson et al., 2000).  In some study locations, harbor seals were disturbed on two_thirds or more of days, most commonly by human activity (Allen et al., 1984; Suryan and Harvey, 1999).  In at least one instance, persistent disturbances may have caused harbor seals to permanently abandon a haul-out site (see Allen et al., 1984 for discussion).

The Mammal Protection Act of 1972⁴ ("MMPA") was enacted in response to concerns that human activities can be harmful to marine mammals.  The MMPA makes any act of pursuit, torment or annoyance that has the potential to injure a harbor seal illegal even though the species as a whole is not depleted or defined as a "strategic stock"⁵ under the MMPA, and is not listed as "threatened" or "endangered" under the Endangered Species Act.⁶  It is also illegal, albeit with lower penalties, to do anything that has the potential to disturb a harbor seal in the wild by causing disruption of its behavior patterns.  Because the primary habitat of the harbor seal is near-shore waters frequented by commercial and recreational boaters, there is frequent contact between harbor seals and people.  Thus, the MMPA may be violated by boaters who cause seals to return to the water from a haul-out ledge.

This study explores the relationship between boating activity and harbor seal haul-out behavior and examines the governmental response to human disturbances of harbor seals under the MMPA.  To do this, we used a multivariate model to determine the predictive power of temporal (time of day), weather (air temperature and % possible sunshine), and sea condition (off-shore wave height) variables, as well as the amount of human activity (boat traffic) over harbor seal haul-out number on two near-shore ledges in Casco Bay, Gulf of Maine.  We also researched the MMPA and its enforcement history relative to pinnipeds. Our results suggest that human activity may have a large effect on harbor seal haul-out behavior compared to known natural variables. Boater education may be the most pragmatic mechanism for reducing the impact of this activity.

METHODS

Site Description: We observed the harbor seal population that hauls out on two near-shore low tide ledges in Gun Point Cove, Casco Bay, Gulf of Maine (43E47'N, 69E57'W). The cove is 3 km long by 325 m wide.  It runs north to south. At its south end the cove opens to Casco Bay, while at its north end it narrows to a <10 m wide passage between two islands.  Bridges connect these islands to each other and to the mainland.

The two ledges on which the seals haul-out are located in mid-channel approximately 200 m from land on the west and 125 m from land on the east, and lie parallel to the channel.  Boats passing through the cove pass parallel to the ledges.  Depending on tide height, the ledges are above the water surface for as much as six hours centered on low tide.  At dead low tide, they are each approximately 35 m long by 2 m wide. Because both slope gradually to the water even at low tide, seals that are flushed off the ledges can regain them.  This site is protected from wind and waves, and according to local residents, harbor seals have hauled out here for many years.  There are a number of similar ledges in the general vicinity of Gun Point Cove that are not common haul-out sites. The reason that the seals preferentially access these particular ledges is unknown.

Our observation point was located on the land to the west of the ledges, 200 m from the south and 250 m from the north ledge.  At this distance, the seals do not respond to the presence of the observers by raising their heads to look or by entering the water.  From this position, all seals hauled out on the west side and crest of the ledges are visible.  Only the middle one-third of the ledges is high enough to block the view of the east side of the ledges.

Data Collection Technique:  We observed the seals for at least 30 minutes within 30 minutes of each low tide that occurred between 7 AM and 7 PM during the calendar month of August 1997 - 2000 (n=122 days).  On 20 August 1997 there was no low tide at our study location between 7 AM and 7 PM, while on 3 August 2000 thick fog prevented an accurate count of seals. Using a 15X-45X spotting scope (Bushnell, Denver, CO), we made three counts of the seals, at 10-minute intervals, and averaged the counts to obtain the haul-out number for that day.  To avoid over counting under conditions when the seals were lying close together, only the number of individuals that we could clearly distinguish (i.e. head clearly visible) were counted.  Using this counting procedure, count numbers by different observers varied by 3% or less.

Because individuals and small groups of seals gain and leave the ledge periodically over the haul-out period, we arbitrarily defined a "flushing event" as any time that 10% or more of the hauled-out seals left the ledge as a group.  This criterion limits the likelihood that normal seal behavior will be counted as a flushing event but may undercount smaller disturbances.  We chose August for our data collection period because year round observations at this site have shown that harbor seals use this location in greatest numbers during August (unpublished data) and recreational boat traffic is high during this period as well.

We also counted the number of times that boats passed the ledges during a period of not less than 30 minutes before and during the seal counting period and calculated the number of boat passages per hour.  Only boats that passed completely through the cove by the ledges were counted.

Our observations were conducted in a small sheltered cove that experiences sea conditions far different from those offshore.  Thus, we compared haul-out number to weather and sea condition data from the nearest NOAA Moored Buoy Station (the Portland, Maine weather buoy, Station #44007, located at 43E31'53"N, 70E08'39"W, approximately 6 km offshore) rather than measuring conditions in the cove itself.  This allowed us to analyze the relationship between haul-out number in the cove and the conditions the seals would have experienced if they had remained offshore.  We chose the air temperature and wave height values recorded in the hour previous to the low tide time and the % possible sunshine for the day.  These data were available on the National Weather Service Gray/Portland, Maine website (http://www.nws.noaa.gov/er/gyx/).

Statistical Analysis:  To determine how well the haul-out number (dependent variable) could be predicted by the values of the independent variables (boat traffic, offshore wave height, % possible sunshine, time of day, and air temperature) we first used univariate analysis and then a stepwise regression analysis.  In the multivariate analysis, variables were added to the model in order of greatest F value.  The criterion for variable entry was probability of F < 0.50, and for variable removal it was probability of F > 0.100.  We compared the event counts of motor vs. paddled boats causing flushing events by Chi-Square analysis.

Enforcement of MMPA:  Over the course of our project, we observed recreational and commercial boaters disturbing the natural behavior of seals with no apparent law enforcement response.  To determine whether and how the MMPA is applied to the type of disturbances we observed, we studied the text of the law and researched case law to determine how courts have interpreted this legislation.  We also obtained enforcement data from NOAA Fisheries Office of Law Enforcement (http://www.nmfs.noaa.gov/ole/fen.html), which is the sole agency responsible for enforcing the MMPA on the Maine coast.⁷

RESULTS

Statistical Summary:  Because there were no obvious year-to-year temporal trends in any of the variables over the study period (Table 1), we analyzed the four years as a single data set.  Over 122 days, we observed an average of 42.0±5.2 (mean ± 95% C.I.) seals at low tide and 4.0±0.7 boats per hour.  There was an average of 60.5 ± 5.7% of the possible sunshine and mean offshore wave height was 0.71± 0.07 meters (Table 1).  In 141 total hours of observation time, we saw 565 boats pass the haul-out ledges.  Of these boats, 526 were power boats, 38 were paddled boats (canoes and kayaks) and one was a sail boat.  We observed 85 flushing events.  Of these events, 79 (93%) were caused by boats, 2 by dogs barking, one each by an airplane, a swimmer, and a lawnmower starting.  In one case there was no apparent cause for the flushing event.  These flushing events occurred in 38 of 122 observation days (31%).

Table 1:  Summary statistics show mean values (± 95% C.I.) for each
year and for all study years combined; n is the number of observations.

Impact of Boat Traffic:  In univariate analysis, the level of boat traffic and the % possible sunshine correlated negatively with haul-out number. Offshore wave height correlated positively with haul-out number (Table 2). Among the independent variables, the level of boat traffic showed the highest correlation with haul-out number.

Table 2:  Univariate Pearson correlations between each of the independent variables
and the number of seals hauled out; n is the number of observations.

 
Figure 2:  Bar graph shows the number of flushing
events caused by motor vs. paddled boats.

 
Figure 3:  Bar graph shows the % of paddled and motor boats that cause flushing events.
A paddled boat is significantly more likely than a motor boat to flush seals (P < 0.05).
(Comparison of event counts performed by Chi-Square analysis.)

Because 93% (526/565) of the boats passing the ledge were power boats, it is not surprising that over 2/3 (58/85 = 68%) of flushing events were caused by power boats (Figure 2).  However, 55% (21/38) of paddled boats caused flushing events while only 11% (58/526) of motor boats did so (Figure 3).  These event counts are significantly different (P < 0.001).  Thus, when a boat enters the cove it is significantly more likely to cause a flushing event if it is a paddled boat rather than a motor boat.  One possible explanation for this finding is that paddled boats might have approached the ledges more closely than did motor boats.  We were not able to make accurate absolute measurements of the distances of boats from the ledges.  However, we did observe that the seals commonly left the ledge in response to paddled boats over 300 m away while this was virtually never the case with motor boats.

Multiple Regression Analysis:  In the completed multivariate model (Table 3) boat traffic, offshore wave height, and % possible sunshine were included as significant predictors of haul-out number while time of day (F = 3.24, p = 0.075) and air temperature (F = 0.004, p = 0.95) were not significant and thus not included. Table 4 summarizes model construction.  This process shows that the level of boat traffic alone explains 27% of the variability in harbor seal haul-out number, adding wave height improves the prediction by 8%, and adding % possible sunshine improves it by another 4%.  The completed model that includes all three variables thus explains 39% of the variability in haul-out number (F= 24.73, P < 0.001).  In this model, haul-out number decreases by 3 for every additional boat per hour passing the ledge, increases by 17 for every additional one meter of wave height and decreases by one for every additional 5% of possible sunshine (Table 3).

Table 3: Completed multivariate model shows F value,
Beta and significance (p value) of each variable.

Table 4:  Stepwise model construction shows progressive addition of significant
variables; R² indicates cumulative variation in haul-out number explained;
D indicates change in a variable, p indicates significance level.

The Marine Mammal Protection Act:  The MMPA established a moratorium, with certain exceptions, on the "taking" of marine mammals in all U.S. waters without a permit issued at the discretion of the Secretary of Commerce.⁸  The 1994 Amendments of the MMPA (Pub.L. 103-238) defined the term "to take" as meaning "to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal".⁹  To "harass" means any act of pursuit, torment or annoyance that has the potential to injure a marine mammal, or any act that has the potential to disturb a marine mammal by causing disruption of behavioral patterns including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering.¹⁰  Human actions that merely have the potential to disturb a seal are defined as an unlawful "taking".¹¹

The Secretary of Commerce is responsible for the conservation and management of pinnipeds (other than walruses) and cetaceans.  The Secretary of Commerce delegated MMPA enforcement authority to the National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NOAA/NMFS).  The Office for Law Enforcement is the compliance office for NOAA/NMFS and is the only Federal agency that is fully dedicated to the protection and conservation of U.S. marine resources.  It is headquartered in Silver Springs, Maryland and operates out of five Division areas. Maine is part of the Northeast Division.

The Secretary has adopted regulations that specifically address how the MMPA relates to boating.  The term "take" is defined by regulation to include, among other things, "...the negligent or intentional operation of an aircraft or vessel, or the doing of any other negligent or intentional act which results in disturbing or molesting a marine mammal."¹²

There are both civil and criminal remedies available under the MMPA.  The Office of General Counsel of NOAA Fisheries is authorized to seek civil penalties of not more than $10,000, with each unlawful taking counted as a separate offence.¹³  Knowing violations of the Act are subject to criminal prosecution by the Department of Justice, with penalties upon conviction of not more than $20,000, imprisoned for not more than one year, or both.¹⁴

Most of the flushing events that we observed appeared unintentional.  In some cases, flushing events were triggered by commercial fishers and recreational boaters simply traveling through the Cove.  In other cases, boaters entered the Cove and approached the haul-out site, sometimes within a few feet, for the obvious purpose of viewing seals.  This almost always caused the seals to become noticeably agitated and, in many cases, to flee into the water.  Because there is no basis for concluding that any of these boaters intended to harass seals, these apparent violations of the MMPA would incur civil, not criminal, penalties.

The mere existence of the MMPA does not appear to deter boaters from harassing and disturbing harbor seals.  We did not observe any law enforcement officials monitoring boat activity in Gun Point Cove or otherwise responding to any violations.

DISCUSSION

Increasing Human Use of the Maine Coast:  The linear measure of Maine's mainland shoreline is only about 230 miles, but when all of its bays, inlets, coves and other features are included, the shoreline reaches 4,568 miles.  Maine also has 4,613 coastal islands of one acre or more in size as well as numerous smaller islands and tidal ledges.  There are 144 towns on the coast and islands, comprising only 12 percent of the State's land area but providing residences for 43 percent of the population.  In 1790, about 59,000 people lived in coastal areas while today over 532,800 people live there.  The vast majority of Maine's eight million annual visitors spend time on the coast.  The number of registered boats using Maine's coastal waters has more than tripled since 1970 (State Planning Office, Maine Coastal Program, http://www.state.me.us/spo/mcp/facts.htm).  Thus, people use the Maine coast for industrial, commercial, agricultural, aquacultural, residential and recreational reasons and are doing so in substantially larger numbers than in the past.

Increasing Harbor Seal Population on the Maine Coast:  Adult male harbor seals average 5 feet (153 cm) and 200 pounds (91kg) while the average adult female is slightly smaller (Katona et al., 1993).  Because of their relatively small size, harbor seals were not commercially exploited for oil, ivory, hide or meat, as were whales and large pinnipeds, such as walruses.  However, prior to 1972, shooting and killing seals for sport, personal consumption, or as nuisances was legal. In one notable exception, there was a ban on shooting seals in Casco Bay during the summer months, a restriction that was for the protection of humans working and recreating on the Bay, not for the benefit of seals.  In the early 20th century, harbor seals were seen as a threat to fish stocks and, as a result, Maine¹⁵ and other U.S. coastal states as well as the Canadian government offered bounties to reduce the population.¹⁶

The Gulf of Maine harbor seal population has grown dramatically since the first survey¹⁷ in 1973 revealed fewer than 6,000 animals.  Aerial surveys have since recorded 10,540 (1981), 9,331 (1982), 12,940 (1986), and 28,810 (1993) seals.  The most recent aerial survey, conducted in 1997, provided a minimum population estimate of 30,900 (Gilbert and Guldager, 1998).  Most observers agree that the MMPA has played a crucial role in the recovery of this population.

Impact of Weather and Sea Conditions on Harbor Seal Haul-out Behavior:  In this study, we found a positive correlation between offshore wave height and haul-out number at locations so well protected (see Methods) that wave height at our study site rarely exceeded 0.3 meters during the study period.  This result is in agreement with Pauli and Terhune (1987) who also found that haul-out number increased when offshore wave height was high. It supports the idea that harbor seals may preferentially haul-out at sheltered locations when offshore wave height makes resting in the water difficult (Pauli and Terhune, 1987), making undisturbed access to haul-out ledges particularly important at these times.  The predictive value of our multivariate model improved by 8% when offshore wave height was considered (Table 4).

The impact of cloud cover on harbor seal haul-out number is complex.  One study found a weak negative relationship between cloud cover and haul-out number (Grellier et al., 1996) while this study and others (Schneider and Payne, 1983) found a positive correlation, and yet another study found no relationship (Kovacs et al., 1990).  Even the reason that cloud cover might impact haul-out behavior is unknown.

Impact of Human Activity:  It is well known that human activity can flush harbor seals off haul-out sites (Allen et al., 1984; Calambokidis et al., 1991; Suryan and Harvey, 1999, Mortenson et al., 2000).  After a flushing event, haul-out numbers infrequently (Suryan and Harvey, 1999) or never (Allen et al., 1984) recover fully.  However, in some locations, harbor seals may remain close to a haul-out site after being disturbed (Renouf et al. 1981; Schneider and Payne, 1983).  In the wild, harbor seals treat haul-out space as a contested resource (Neumann, 1999) and studies on captive animals suggest that harbor seals need haul-out time year round (Brasseur et. al., 1996).

Not all harbor seals respond identically to a disturbance.  Some studies have noted behavior differences between groups (Terhune and Almon, 1984), while others have found that some animals within a group are more resistant to disturbance than others (Suryan and Harvey, 1999).  We have also noted that a few individuals may remain hauled out even when the level of boat traffic is very high (data not shown).  These animals are apparently resistant to disturbances that affected other seals.

A few previous studies have attempted to quantify the impact of human activity relative to natural factors.  When Schneider and Payne (1983) entered disturbance as a dichotomous variable in a multivariable model that included weather conditions and time relative to low tide, they increased the ability of their model to predict the fraction of harbor seals hauled out by 14%.  Here, we found the level of boat traffic passing a ledge predicted 27% of the variability in haul-out number (Table 4).

Several factors may contribute to this difference.  Assessing boat traffic as a continuous variable may add to its predictive power.  Also, the narrow channel at our study site may bring boats close to the seals, producing a larger impact on their behavior.  Because the main channel past the haul-out ledges at our study site is 200 m wide (see Methods), boats passing the ledges in mid-channel are well within the distance at which disturbances occur in other studies (Allen et al., 1984; Calambokidis et al., 1991; Suryan and Harvey, 1999; Mortenson et al., 2000).  It is also possible that the presence of frequent boat traffic decreases haul-out number via mechanisms in addition to flushing them from haul-out ledges.  Allen et al. (1984) have shown that harbor seals were more likely to re-haul when a disturbance was of short duration.  At high levels, boat traffic may act as a continuous disturbance and prevented re-hauling.

Previous researchers have observed that human disturbances in the form of boat and aircraft traffic, as well as from people walking on the beach, can flush seals into the water from haul-out sites and thus negatively impact seal haul-out numbers (Renouf et al., 1981; Schneider & Payne, 1983; Terhune & Almon, 1983; Ecological Research Associates, Inc., 1989).  Our results confirm these impressions and demonstrate that human activity is the major predictor of seal haul-out number at a site where these disturbances are common.

Our finding that harbor seals react more strongly to the presence of paddled boats than to the presence of motor boats is also in agreement with previous studies.  Observations from the Pacific coast of the U.S. have shown that harbor seals are more likely to enter the water in response to a paddled boat than to a motor boat (Suryan and Harvey, 1999) and enter the water at greater distances in response to a paddled boat than in response to a motor boat (Calambokidis et al., 1991).  The reason that paddled boats produce such an exaggerated response from seals is not known.  However, these results suggest that efforts to reduce the impact of paddled boats on harbor seals may be particularly important.

NOAA/NMFS's Enforcement Strategy vis-à-vis Seals:  The government has sought and obtained both civil and criminal penalties for shooting at and/or killing pinnipeds.  In recent years, several cases have been brought against individuals for shooting Stellar sea lions (Eumetopias jubatus).  This species is endangered and is afforded additional legal protection under the Endangered Species Act.  In November 1998, two Kodiak Alaska residents pleaded guilty to shooting Stellar seal lions.  In the summer of 1999, an Alaskan salmon fisher named Stanley Roy Pedersen fired at Stellar sea lions 30 times in separate incidents, according to deckhands.  Members of the local fishing association testified that all fishers, including Pedersen, knew better than to harass sea lions.  In January 2001, after a 4 day trial, Pedersen was found guilty of shooting sea lions and of violating firearms laws.  In April 2001, he was sentenced to 46 months for the firearms violations and a one year concurrent sentence for "taking" a sea lion.¹⁸

NOAA Fisheries has also successfully prosecuted individuals for shooting and killing non-endangered harbor seals.  In a recent case, the government charged Gunner Noreen, the operator of an Alaskan gill netting vessel, under the MMPA.  Crew members reported to authorities that Noreen shot and killed a harbor seal (Phoca vitulina richardsi), and Noreen ultimately admitted the act.  The case was settled in February 2001 with Noreen agreeing to pay at $5,000 penalty and forfeit the .270-caliber rifle he used in the incident.¹⁹

There are no reported cases of the government prosecuting individuals for non-lethal harassment of pinnipeds.  However, a case from the 5th Circuit Court of Appeals deals with this type of harassment of a cetacean.  In Strong v. United States, 5 F.3d 905 (5th Cir. 1993), the operators of a business that transports tourists by boat to feed wild dolphins sought to overturn 50 C.F.R. 216.3, which prohibits feeding marine mammals in the wild.  The court held that 'disturb' is synonymous with 'harass' and thus constitutes an unlawful taking. The court observed that:

"...the agency has been given substantial scientific evidence that feeding wild dolphins disturbs their normal behavior and may make them less able to search for food on their own. It is therefore clearly reasonable to restrict or prohibit the feeding of dolphins as a potential hazard to them." Id., at 906-907.

Thus, NOAA Fisheries has the authority to take enforcement actions to restrict human activities that do not directly injure or kill marine mammals, including seals.  In the Strong case, it was helpful that the Secretary had adopted a specific regulation that pertained to feeding and that there was credible scientific evidence to show that this activity posed a potential harm to the animals.

Over the course of our study of harbor seals in Gun Point Cove, we observed repeated incidents in which human activity disturbed harbor seals but no law enforcement presence in the cove.  We are unaware of any enforcement action against boaters for flushing seals from haul-out ledges in Gun Point Cove or anywhere else on the Maine coast during the study period.  Thus, we conclude that the MMPA is at not being used effectively to eliminate boat disturbances of harbor seals in Maine.

This may be attributable to several factors.  First, if a violation is not observed by or reported to the proper law enforcement agency, no civil or criminal enforcement action is possible.  (The NOAA Enforcement Hotline is 1-800-853-1964.)  Second, protecting harbor seals may be a lower institutional priority for NOAA Fisheries than some other marine mammal species, perhaps because harbor seals are not a threatened or endangered species under the ESA, or a depleted or strategic stock under the MMPA.  Third, courts may be reluctant to impose sanctions on boaters for activities that are not prohibited by a specific regulation, are not intentionally harmful, and do not ordinarily cause direct and immediate injury or death to any animal.  Additional research is needed to determine the long-term effects of such disturbances (Suryan and Harvey, 1999).

Environmentalists have turned to the courts for help in obtaining more aggressive enforcement of the MMPA, with mixed results.  For example, Earth Island Institute and others sued the government for issuing permits to tuna fishers in an effort to protect dolphins from the deadly side-effects of purse-seine and gill nets.²⁰  Successful plaintiffs in these cases have proven that the government violated a statutory mandate.  The problem of protecting seals from boaters is not readily solved by suing the government because the MMPA does not require that every boater who harasses and disturbs seals be prosecuted. Courts are reluctant to second-guess the government in the exercise of prosecutorial discretion.²¹

Public education is an alternative strategy that may succeed in changing the behavior of boaters around seals.²²  NOAA/NMFS uses public education and outreach for this purpose.  The Office of Law Enforcement (OLE) National Outreach Program targets specific constituent groups in need of information and education.  This includes public meetings to facilitate two-way communication between constituents and the agency, posters at launch sites and beaches, and presentations to student groups.  NOAA/NMFS publishes educational materials on the Internet, including a website (http://www.nmfs.noaa.gov/prot_res/MMWatch/MMViewing.html) for people who wish to view marine life in the wild.  The website contains viewing guidelines as well as information about the potential consequences to the animals.

In some places, citizens fill the enforcement void through volunteer efforts on behalf of seals.  Not-for-profit organizations that are dedicated to the rescue, rehabilitation and release of marine mammals (and sea turtles) conduct public education and media campaigns designed to educate the public.  In Maine, the Marine Animal Lifeline (http://www.stranding.org) and Allied Whale (http://www.coa.edu/alliedwhale/index.html) fulfill this role.

On the west coast, a number of marine conservation organizations are dedicated to the protection of seals and other marine wildlife.  For example, Sanctuary Education Awareness and Long-term Stewardship (SEALS) is a harbor seal monitoring and interpretation program of the Farallones Marine Sanctuary Association in collaboration with the Gulf of the Farallones National Marine Sanctuary.²³  SEALS was developed to respond to high levels of disturbance to harbor seals.  Its goals are to minimize disturbance to harbor seals and help maintain the integrity of rookery sites; to preserve the harbor seal colony size; and to educate the general public about harbor seals and their habitat.  Among other things, SEALS conducts a boater education campaign. It has developed and posted a placard that outlines responsible wildlife viewing guidelines at boat launch sites.

CONCLUSIONS AND RECOMMENDATIONS

We have found that human disturbance by boat traffic has a large impact on harbor seal haul-out behavior on near-shore ledges in the Gulf of Maine.  However, while the MMPA has been used successfully to deter human activity that directly and immediately harms seals (e.g. shooting them), it is not being used to prevent harassment by boaters.

To completely eliminate the effect of boats on harbor seals would require drastic legal measures.  For example, it might require a ban on all boat traffic in Gun Point Cove at times when the ledges are exposed at and around low tide.  Harbor seals would enjoy better protection if NOAA/NMFS adopted regulations that provided clear operational guidance.  To withstand a court challenge, such regulations should be based on solid scientific evidence on the impact of boaters on seals, and the potential harm this activity causes to these marine mammals.

ACKNOWLEDGMENTS

We thank Sweet Water Trust and Lewiston-Auburn College for financial support.  We also thank Mike DeSisto for assistance with the statistical analysis.  For assistance in field work and data analysis, we thank Beth Aponte, Jon Behling, Mary Bernier, Paul Carmichael, Lee Castonguay, Barbara Chadwick, Carlotta Drane, Nichole Gagne, Sean Hall, Catherine Hildonen, Elizabeth Madonick, Kellie Pelletier, Chris Pierre, Pauline Pierre, Rick Quaintance, Sarah Quaintance, and Heather Ward.  This research protocol was approved under Marine Mammal Protection Act permit #904-1460 issued to David E. Harris.

NOTES

1. Grey seals (Halichoerus grypus), harp seals (Pagophilius groenlandica) and hooded seals (Cystophora cristata) are also present.  The number of harp and hooded seals has increased dramatically in recent years. (Katona et al., 1993).
2. Pups are born between mid-April and mid-June and nurse for 4 to 6 weeks before they are weaned.
3. Harbor seals molt (shed all of their fur) each year during July and August.
4. 16 U.S.C. 1361-1421; Pub.L. 92-522, as amended.
   URLs:  http://www.nmfs.noaa.gov/prot_res/laws/MMPA/MMPA.html
   http://www4.law.cornell.edu/uscode/16/ch31.html
5. The legal definition of ‘strategic stock' under the MMPA is a species that is or may soon be listed under the Endangered Species Act ("ESA")(see footnote 6), or a species for which the level of direct human-caused mortality exceeds a prescribed number. 16 U.S.C. 1362(19).  The term ‘stock’ has no agreed-upon biological definition.
6. The Endangered Species Act of 1973, 16 U.S.C. 1531, et seq., passed soon after the MMPA, provides additional protection for wildlife that is in danger of extinction, including marine mammals such as the North Atlantic Right whale (Eubalaena glacialis) and the Stellar (Northern) sea lion (Eumetopias jubatus).
   URLs:  http://www.nmfs.noaa.gov/prot_res/laws/ESA/ESA_Home.html
   http://www4.law.cornell.edu/uscode/16/1531.html
7. Section 107 of the MMPA (16 U.S.C. 1377) authorizes the Secretary of Commerce to designate officers and employees of any State to enforce the MMPA.  No law enforcement agency of the State of Maine has been so designated to date.
8. 16 U.S.C. 1371(a).  The MMPA also prohibits the taking of marine mammals by U.S. citizens on the high seas, and the importing of marine mammals and marine mammal products into the United States.
9. 16 U.S.C. 1362(13).
10. 16 U.S.C. 1362(18)(A).
11. Every question of statutory interpretation starts with the language of the statute.  "The primary indication of [Congress's] intent is the language of the statute." United States v. Aguilar, 21 F.3d 1475, 1480 (9th Cir. 1994), aff'd in part, rev'd in part on other grounds, 515 U.S. 593, 132 L.Ed.2d 520, 115 S.Ct. 2357 (1995).  As the Supreme Court has explained: "[I]n interpreting a statute a court should always turn to one cardinal canon before all others. . . .[C]ourts must presume that a legislature says in a statute what it means and means in a statute what it says there." Connecticut Nat'l Bank v. Germain, 503 U.S. 249, 117 L.Ed.2d 391, 112 S. Ct. 1146, 1149 (1992).  "When the words of a statute are unambiguous, then, this first canon is also the last: `judicial inquiry is complete.' " Id.
12. 50 C.F.R. 216.3.  This is the same regulation that prohibits feeding or attempting to feed a marine mammal in the wild.
13. 16 U.S.C. 1375(a)(1).
14. 16 U.S.C. 1375(b).
15. Pub. L., Chapter 284, section 57 (1901).
16. "By 1939 extensive stretches of the Canadian and adjacent U.S. coastline had been so denuded that some fishermen were actually complaining they could no longer find a seal to kill for the table" (Mowat).  Bounties were offered in Massachusetts until 1962 (Katona) and in Canada until 1976 (Mowat).
17. Seals are counted while they are resting on haul-out ledge.  No adjustment has been made for animals that are in the water or outside the survey area.  As such, all population numbers reported are minimal estimates (Waring, et al. 2000).
18. Alaska Daily News, 17 January 2001, 20 January 2001, and 6 April 201.
    The government has been under considerable pressure from environmental groups to take more aggressive steps to protect Stellar sea lions.  Greenpeace, American Oceans Campaign and the Sierra Club sued NMFS in 1998 to enjoin commercial groundfish (primarily Pollack) trawl fishing in the North Pacific ecosystem (Gulf of Alaska and the Bering Sea/Aleutian Islands region), a critical habitat for Stellar sea lions.  The U.S. District Judge Thomas S. Zilly found that the Pollock fishing regulations issued by NMFS do not protect endangered Stellar sea lions and violate the ESA and National Environmental Policy Act.  The Court found that NMFS failed to take the protective measures that were recommended by its own scientists, and ordered NMFS to re-examine the impacts of fisheries on sea lions. Greenpeace et al. v. NMFS et al., U.S. Dist. Ct., Western District of Washington, No. C98-49.
19. www.publicaffairs.noaa.gov/releases2001/feb01/noaanmfs0110akr.html
20. See, e.g., Committee for Humane Legislation, Inc. v. Richardson, 540 F.2d 1141 (D.C. Cir. 1976) (environmentalists successfully challenged permit issued by NMFS yet the effective date of the decision was stayed because "the immediate impact ... would be disastrous to the commercial fishermen...", id. at 1151; Earth Island Institute v. Mosbacher, 929 F.2d 1449 (9th Cir. 1991)(NMFS regulation violated the language and purpose of MMPA); Earth Island Institute v. Mosbacher, 785 F.Supp. 826 (N.D.Cal. 1992)(plaintiffs granted preliminary injunction requiring government to implement secondary embargo; other relief denied); Earth Island Institute v. Brown, 17 F.3d 1241 (9th Cir. 1994), opinion withdrawn, 28 F.3d 76 (9th Cir. 1994), cert. denied, 513 U.S. 999, 130 L.Ed.2d 417, 115 S.Ct. 509 (injunction vacated on jurisdictional grounds, case remanded for further proceedings).
21. "[L]itigation decisions are generally committed to agency discretion by law, and are not subject to judicial review...." Beck v. U.S. Dept of Commerce, 982 F.2d 1332 (9th Cir. 1992)(citing Heckler v. Chaney, 470 U.S. 821, 831, 84 L.Ed 2d 714, 723, 105 S.Ct 1649 [1985][This Court has recognized on several occasions over the years that an agency’s decision not to prosecute or enforce, whether through civil or criminal process, is a decision generally committed to an agency’s absolute discretion.]).
22. Earth Island Institute was in the forefront of the effort to educate the public and the government about the large number of dolphin deaths caused by tuna fishing.
23. Other non-profit organizations include the La Jolla Friends of the Seals (http://www.lajollaseals.org) and Friends of the Elephant Seals (http://www.elephantseal.org).

LITERATURE CITED

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Brasseur, S., J. Creuwels, B. Werf and P. Reijnders. 1996. Deprivation indicates necessity for haul-out in harbor seals. Marine Mammal Science 12(4):619-624.

Calambokidis, J., G.H. Steiger, J.R. Evenson and S.J. Jeffries. 1991. Censuses and disturbance of harbor seals at Woodard Bay and recommendations for protection. Final report to the Washington Department of Natural Resources, Olympia. 44 pp.

da Silva, J. and S.M. Terhune. 1988. Harbor seal grouping as an anti-predator strategy. Animal Behavior 36:1309-1316.

Ecological Research Associates, Inc. (Johnson, S.R., J.J. Burns, C.I. Malme, and R.A. Davis). 1989. Synthesis of information on the effects of noise and disturbance on major haulout concentrations of Bering Sea pinnipeds, for U.S. Minerals Management Services, Alaska Outer Continental Shelf Region, U.S. Department of Interior, Contract No. 14-12-0001-30361, LGL Rep. No. TA 828. 268 pp.

Gilbert, J.R. and N. Guldager. 1998. Status of harbor and gray seal populations in northern New England. Final Report to: National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, MA. Under NMFS/NER Cooperative Agreement 14-16-009-1557. 13 pp.

Grellier, K., P.M. Thompson and H.M. Corpe. 1996. The effect of weather conditions on harbour seal (Phoca vitulina) haulout behavior in the Moray Firth, northeast Scotland. Canadian Journal of Zoology 74:1806-1811.

Katona, S.K., V. Rough, and D.T. Richardson. 1993. A Field Guide to Whales, Porpoises, and Seals from Cape Cod to Newfoundland, Fourth Edition, Revised. Smithsonian Institution Press, Washington, D.C.

Kovacs, K.M., K.M. Jonas and S.E. Welke. 1990. Sex and age segregation by Phoca vitulina concolor at haul-out sites during the breeding season in the Passamaquoddy Bay region, New Brunswick. Marine Mammal Science 6(3):204-214.

Krieber, M. and C. Barrette. 1984. Aggregation behavior of harbor seals at Forillon National Park, Canada. Journal of Animal Ecology 53:913-928.

Kroll, A.M. 1993. haul-out patterns and behavior of harbor seals, Phoca vitulina, during the breeding season at Protection Island, Washington. M.S. thesis, University of Washington, Seattle, WA, 142 pp.

Mortenson, J., M. Brown, J. Roletto, L. Grella, L. Culp, and J. Kinman. SEALS Annual Report:1999. 2000. Unpublished Report, National Oceanic and Atmospheric Administration, Gulf of the Farallones National Marine Sanctuary, San Francisco, CA.

Moss, J. 1992. Environmental and biological factors that influence harbor seal (Phoca vitulina richardsi) haul-out behavior in Washington and their consequences for the design of population surveys. M.S. thesis, University of Washington. Seattle, WA, 127 pp.

Mowat, Farley. 1984. Sea of Slaughter. Chapters, Shelburne, VT. 446 pp.

Neumann, D.R. 1999. Agnostic behavior in harbor seals (Phoca vitulina) in relation to the availability of haul-out space. Marine Mammal Science 15(2):507-525.

Pauli, B.D. and J.M. Terhune. 1987. Meteorological influences on harbour seal haul-out. Aquatic Mammals 13(3):114-118.

Renouf, D., L. Gaborko, G. Galway, and R. Finlayson. 1981. The effect of disturbance on the daily movements of harbour seals and grey seals between the sea and their hauling grounds at Miquelon. Applied Animal Ethology 7:373-379.

Schneider, D.C. and P.M. Payne. 1983. Factors affecting haul-out of harbor seals at a site in southeastern Massachusetts. Journal of Mammalogy 64(3):518-520.

Stewart, B.S. 1984. Diurnal hauling patterns of harbor seals at San Miguel Island, California. Journal of Wildlife Management 48(4):1459-1461.

Suryan, R.M. and J.T. Harvey. 1999. Variability in reactions of Pacific harbor seals, Phoca vitulina richardsi, to disturbance. Fishery Bulletin 97:332-339.

Terhune, J.M. and M. Almon. 1983. Variability of harbour seal numbers on haul-out sites. Aquatic Mammals 10(3):71-78.

Waring, G.T., J.M. Quintal, and S.L. Swartz, Eds. 2000. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments-2000. NOAA Technical Memorandum NMFS-NE-162. 301 pp.

Watts, P. 1993. Possible lunar influence on hauling-out behavior by the pacific harbor seal (Phoca vitulina richardsi). Marine Mammal Science 9(1):68-76.

Watts, P. 1996. The diel hauling-out cycle of harbor seals in an open marine environment: correlates and constraints. Journal of Zoology, London 240:175-200.

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