Hawaiian Monk Seal Myths Vs. Facts

  1. Myth:

    Seals only forage at night.

    Fact:

    Seals feed both during the day and at night, although this varies depending on age/sex class.

    More Information

    Monk seals as a whole do not appear to prefer feeding at specific times of the day. This misperception is derived from dietary and behavioral observations. Historical dietary information indicates seal diet is a mixture of diurnal and nocturnal species (Goodman-Lowe 1998). Though seals are consuming nocturnal species, they are not necessarily consuming them only at night. Nocturnal prey such as eels and cephalopods like to hide in crevices and rocks during the day and seals have been documented probing and overturning rocks to flush and capture prey (Parrish et al. 2008). Behavioral observations of seals by Kenyon and Rice (1959) noted that seals were not as plentiful on beaches in the early morning hours, but presence increased as the day went on and then decreased again before sunset leading to the assumption that seals were nocturnal foragers. However, new technology such as dive recorders and satellite tags are showing no significant difference between day and night feedings (Parrish et al. 2005).

    Further Reading:

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  2. Myth:

    Monk seals consume large amounts of lobster.

    Fact:

    Lobster is not a critical prey item of the monk seal diet.

    More Information

    Observations of lobster in the diet of monk seals are rare. In fact, in only a few occasions has lobster been documented in the diet. One lobster was found in the stomach of a dead monk seal (DeLong et al. 1984) and one seal was observed consuming two lobsters (MacDonald 1982). Two dietary studies, one in the NWHI (Goodman-Lowe 1998) and one in the MHI (Cahoon 2011) did not identify lobster in fecal samples, though biases may influence the likelihood of seeing lobster remains in samples. Even more advanced dietary techniques using fatty acid analysis do not indicate lobster as an important prey item for the population, though a few individuals did prefer it (Iverson et al. 2010).

    Further Reading:

    Cahoon MK
    2011. The Foraging Ecology of Monk Seals in the Main Hawaiian Islands. MS Thesis. University of Hawaii at Manoa, Honolulu. 172 p.
    MacDonald C
    1982. Predation by Hawaiian monk seals on spiny lobsters. Journal of Mammalogy 63: 700.
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  3. Myth:

    Seals eat too much of the fish targeted by fishermen. This poses a problem if the MHI seal population grows or if seals are translocated from the NWHI to the MHI.

    Fact:

    Considering what science tells us about monk seal foraging, the overall impact of seals on fishing in Hawai'i (recreational, subsistence, and commercial) is small.

    Myth 1 image
    Photo courtesy of Lesley Macpearson.

    The potential impact of seals on fishing in Hawai‘i is influenced by several factors:

    • There are a small number of seals in the MHI (~200 seals)
    • Seals consume a wide variety of marine organisms (not just fish), and many are species not targeted by fishers
    • Seals forage over wide areas, including habitats and depths not targeted by fishers

    Even as the MHI seal population grows or if some seals are temporarily translocated from the NWHI, impacts on fisheries are expected to be very small because seals eat so many different types of organisms and forage over such large areas. Even with the extra seals added via natural population growth or temporary translocation, the overall MHI population will still be relatively small.

    However, there could be impacts to individual fishermen when seals interact with their gear or catch. Guidelines (0.8 MB PDF) have been developed to minimize these impacts. Additionally, NOAA Fisheries is working with fishers (1.4 MB PDF) to characterize the number and types of seal-fisheries interactions to come up with solutions for seals and fishermen.

    More Information

    Hawaiian monk seal diet is very diverse and some prey items consumed by monk seals are also caught by recreational and commercial fishers. This overlap will continue as monk seal numbers increase. However, many prey items that monk seals target, such as small wrasses, flatfishes, shrimps, etc., are rarely targeted by the fishing community. Further, monk seals spend much of their time foraging in habitats deeper (some as deep as 1,600 ft) and further offshore than most recreational fishers target - some seals travel as far as 70 miles out. Additionally, monk seals distribute their efforts over a large area, minimizing their impact on any one place. The average home range (marine habitat utilized by a seal) is 119 square miles, but many seals use areas larger than the island of Kaua'i (550 square miles).

    In terms of seals and fishers occupying the same area, there is a high degree of overlap when the seals are leaving and returning to shore, which is when most direct interactions occur. This has led to the false, but understandable perception that seals only use shallow habitats. This is a result of the "driveway effect" – meaning all seals must use the shallows when going and coming from their resting spots, just like everyone has to use their driveway or street when they go to and from their home. Although seals are most often seen in the shallow near shore waters, this does not mean that seals spend most of their time there; even when the seals are near the shore, their presence does not mean they are feeding in that location.

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  4. Myth:

    Monk seals eat 400 lbs of fish per seal per day. Or, monk seals eat their weight in fish every day.

    Fact:

    This is impossible. No large carnivore (meat eating animal) consumes the equivalent of its body weight in a day.

    Very small animals like shrews, hummingbirds, and some insects, etc. must consume large amounts of food relative to their size, but not marine mammals, including monk seals. Given the size of the monk seals stomach (only slightly larger than our own) it is actually IMPOSSIBLE for monk seals to consume and digest that quantity of food. We cannot say for certain what % of their weight wild monk seals consume each day, but for most large carnivores it is about 4-10% of the predator’s biomass. One study of a captive monk seal estimated consumption to be about 5% of its weight per day. Waikiki Aquarium feeds its seals about 2-3% of the seal's body mass per day.

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  5. Myth:

    Seals damage coral reefs as they hunt for food and thus damage fish habitat. This will get worse as the MHI population grows and/or if seals are translocated to the MHI from the NWHI.

    Fact:

    Seals rarely damage live coral while they forage - they do sometimes lift or turn over rocks and root around in rubble and sand, but this material is not live coral, and this activity does not damage the ecosystem nor reduce the productivity of the fishery.

    The reefs in Papahānaumokuākea Marine National Monument (PMNM) are numerous and healthy. They are also home to more than 900 monk seals. There is no evidence, including many of hours of footage from seal-mounted video cameras, indicating that monk seals damage coral reefs.

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  6. Myth:

    Seals will attract sharks, which will put people at risk of shark attacks.

    Fact:

    All information to date indicates that more monk seals in the MHI has not, and will not, lead to more shark attacks on humans.

    While the monk seal population has increased in the MHI over the past 10 years, incidents of shark attacks on people have shown no corresponding increase.

    More Information

    According to the International Shark Attack File, there have been a total of only 102 documented shark attacks on people in Hawai'i from 1828-2010, and 8 of these were fatal. The most recent fatal attack in Hawai'i was in 2004. From 2000 – 2010, no upward trend in shark attacks was reported in Hawai'i, while at the same time the monk seal population was apparently growing. Thus, shark attacks in Hawai'i are extremely rare occurrences in general, and do not appear to be increasing due to the increasing MHI monk seal population.

    Tiger sharks are overwhelmingly considered responsible for shark attacks on humans in Hawai'i, and tiger sharks do in fact also attack monk seals. However, there are several lines of evidence that suggest an increase in the number of seals in Hawai'i would not likely increase incidence of shark attack. First, while there have been studies that support the idea that there are more white shark attacks on people (especially surfers) near seal colonies (for example, in California and South Africa), these colonies typically involve predictable and seasonal aggregations of tens of thousands of seals, and white sharks focus on these areas when seals are present. In contrast, there are presently around 200 seals in the MHI. These seals are scattered throughout the islands and do not aggregate in dense colonies. These small numbers mean that monk seals cannot be a significant source of food for sharks, because there are not nearly enough seals to sustain the sharks. A similar concern is often heard about the abundance of green turtles and shark attacks in Hawai'i. However, despite the fact that green turtle abundance has been growing in Hawai'i for decades, there has been no apparent increase in shark attacks on humans during this time.

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  7. Myth:

    Seals are a human safety risk because they will attack people.

    Fact:

    Most monk seals are not aggressive toward people, unless they feel threatened (such as when a person gets between a mother seal and her pup).

    Some seals that have been fed by (intentionally or unintentionally) or have been interacting with ("played with") people may become dangerous when they grow up to be large, mature seals that persistently seek out human interaction.

    Following laws and guidelines that promote public safety around seals and prevent human-seal interactions is the best way to minimize the relatively small public safety risk posed by seals.

    More Information

    Normal "wild" monk seals almost never attack or seek interactions with humans. There have been only a few known cases of aggressive interactions between seals and people. These have occurred either when a person has gotten too close to a protective mother’s pup or when a seal has become conditioned to associate humans with food or socialization and later became too “rough” with unsuspecting swimmers or divers. With effective outreach and education, both of these situations can, and should be, avoided. As a rule, it is not a good idea to undertake activities that may be interpreted as a threat to a mother or her young of most wild species, and some domesticated species as well. Following basic Hawaiian Monk Seal Viewing Guidelines and guidelines for fishers (0.8 MB PDF) will prevent or greatly reduce public safety risks associated with the occurrence of conditioned or habituated seals.

    Additional Information:

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  8. Myth:

    Monk seals are not from Hawaii and they are being brought in by government agencies.

    Fact:

    Monk seals are native to the Hawaiian Islands and the main Hawaiian Island subpopulation is growing naturally, with or without translocation.

    All evidence indicates that Hawaiian monk seals are native (indigenous) to the Hawaiian Islands, including the MHI. Hawaiian monk seals are endemic to Hawaii, meaning they are only found in Hawai'i and nowhere else in the world. We have documented reports of monk seals sighted in the MHI going back to the 1800's, and archeological remains of monk seals dating to AD 1400-1700 were found on the Island of Hawai'i.

    More Information

    The Hawaiian monk seal likely reached the Pacific Ocean through the Central American Seaway (now blocked by the Isthmus of Panama), and that closed approximately 3 million years ago. There is no fossil or reported evidence of Hawaiian monk seals anywhere else other than the Hawaiian archipelago.

    Although not as prominent in Native Hawaiian culture as other sea creatures, like sea turtles, recent research reveals that some Hawaiian families have traditional ties to monk seals and there are some historical Hawaiian cultural references to monk seals. Many folks have not seen or heard much about monk seals in the MHI in the past few generations because they have only recently become more numerous again in the MHI. For more information visit: http://nameahulu.org/cultural-research/.

    The MHI seal population is naturally increasing because of high reproductive success of the seals already here, not because seals are moving here from the NWHI. NOAA Fisheries moved 21 adult male seals to the MHI in 1994 to correct an unbalanced sex ratio at Laysan Island (NWHI). However, those males cannot account for the natural, unassisted population growth that is now underway.

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  9. Myth:

    NOAA Fisheries seems to be responsible for seal population decline in the NWHI; NOAA Fisheries research and enhancement activities have/will hurt seal recovery.

    Fact:

    Monk seal recovery is a high priority for NOAA Fisheries and sometimes research and enhancement activities do involve some risk. However, risk is only taken if analysis has shown that those risks are outweighed by benefits to the species.

    All NOAA Fisheries activities that involve "take" of monk seals must be permitted under the Endangered Species Act (ESA) and Marine Mammal Protection Act (MMPA), which prohibits authorization of any activity that might cause a population decline. NOAA Fisheries has conducted controlled studies to prove that its activities are safe for monk seals and do not cause adverse impacts on the monk seal population.

    More Information

    To better understand the behavior and biology of monk seals, various studies are conducted where handling and instrumentation of seals occurs. To ensure the welfare of seals during these handling events, NOAA Fisheries has conducted studies to assess the effects of handling events. Two noteworthy studies indicate that seals are not negatively affected by handling activities such as tagging and attachment of telemetry or camera devices ( Baker and Johanos 2002; Littnan et al. 2004).

    During field activities, NOAA scientists follow numerous protocols to minimize risk and disturbance to seals such as keeping a low profile when observing seals by hiding behind vegetation or marine debris. If there is a chance seals will be unnecessarily disturbed, activities are modified or postponed. Any disturbances that do occur are documented.

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  10. Myth:

    NOAA Fisheries doesn’t seem to have the resources or capacity to effectively track and manage seals in the MHI.

    Fact:

    Our growing volunteer network, combined with the latest tracking technology, including satellite and VHF radio tags, gives NOAA Fisheries the ability to track and re-sight seals in the MHI.

    Many seals in the MHI are visually identifiable either using plastic tags applied to their rear flippers, temporary "bleach" marks applied to their fur, and through distinctive natural scars and other markings. Further, various electronic telemetry tags can be used to monitor movements and dive behavior of individual seals of interest at near real-time. These tags allow monitoring as long as the battery lasts or until the device molts off, with the longest duration being about a year. NOAA Fisheries will continue to develop our tracking technologies and management strategies, and continue to work with coastal community members to maintain and improve our seal tracking and management abilities.

    More Information

    In recent years, NOAA Fisheries has been working on methods and tools to best assess and track the monk seal population in the main islands. Through our efforts over the last several years, and with the help of a growing volunteer sightings network, we are able to monitor most of the population of seals on Kaua'i, O'ahu, Maui, and Moloka'i (West Moloka'i and Kalaupapa). Currently there are few seals that utilize the shores of Lana'i and Island of Hawai'i (based on aerial surveys, site visits, and general sighting reports). We realize that there are gaps in information from areas that are more remote or have limited accessibility such as Ka'ula, Ni'ihau, Lehua, and Kaho'olawe, and we are working on ways to gain better information about seals in these areas by conducting focused surveys. NOAA Fisheries has increased its temporary seal bleach marking effort in order to aid in accurate identification of seals and increase public reporting of MHI sightings. As the Hawaiian Monk Seal population grows or if seals are temporarily brought down the MHI chain, efforts to increase awareness and reporting of seals on these islands will be undertaken.

    If moved, any translocated seals will be instrumented with a satellite and VHF radio tag for near-real time information of the animal's location. This will allow NOAA Fisheries to monitor the seal's welfare and behavior in its first several months in the main Hawaiian Islands. Subsequent monitoring will be done with the existing robust volunteer sighting network. However, translocation would not be implemented without sufficient funding, required ESA and MMPA permits, and extensive community outreach efforts.

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  11. Myth:

    The seal population in the MHI will explode like other invasive species (e.g. ta'ape).

    Fact:

    Many introduced species have indeed become problematic invasive species in Hawai'i. However, monk seals are not alien species and the biology of slow-growing native monk seals (a marine mammal) is very different than the biology of Hawai'i's alien species (fish, plants, and land mammals).

    All available scientific information indicates that the Hawaiian monk seal population could not "explode" like alien species have in Hawai'i, or even grow to populations comparable to other seals or sea lions in other locations. Female monk seals give birth to one pup and do not pup every year. Even with ideal conditions, the monk seal population is slow growing.

    The current best estimate is that there are about 200 seals in the MHI today, and even by the year 2030, the population will still be less than 700 seals in the MHI.

    More Information

    Monk seals are not an alien species in Hawai'i (see Myth 6 above), so they do not have the ecological advantage that some alien species, such as ta'ape or mongoose, have when they are introduced into new ecosystems. Female seals, on average, have less than one pup per year, compared to the thousands of offspring produced by alien fish species like ta'ape, and the 6 or more offspring per year produced by a small land mammal, like a mongoose. Even among all types of seals and sea lions, all of which are relatively slow reproducing species, the monk seal population appears to be among the slowest growing, even when conditions are favorable for population growth. This may be partly because Hawai'i's subtropical marine ecosystem is much less productive than the temperate and arctic ecosystems where the other seal and sea lion species live. Contrary to what it may seem, coral reef ecosystems have very low levels of nutrients in the water - that's why the water is so clear. Temperate and arctic ecosystems, on the other hand, have relatively high nutrient levels and thus can support higher biological production and higher populations of seals and sea lions.

    Currently there are at least 150 seals in the MHI, but because we don't have complete counts at all islands, the true number is probably closer to 200 seals. Based on other information (survival and birth rates), we believe the population could be growing at approximately 6% per year. If we assume the population to be 150 seals, then in 20 years the number of seals could grow to between 450 and 500 seals. (NOAA Fisheries uses a sophisticated computer-based modeling program to estimate future populations.) If the current population is actually closer to 200 seals and it continued to grow at 6% per year, the number of seals in the MHI would be closer to 700 seals in 20 years. However, large mammal populations, such as the monk seal, rarely continue to expand at the same rate as when the population is small. That is because when populations are small, there are abundant resources for each individual. As the population grows, sooner or later the availability of one or more resources is reduced and the growth rate declines. For monk seals in the MHI, the limiting factor might be the amount of preferred prey species, the availability of suitable haul out or pupping habitat, or perhaps some other factor. As we learn more about monk seal ecology in the MHI, we will have a better understanding of which factor may eventually limit their abundance.

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  12. Myth:

    NOAA Fisheries will be moving hundreds of seals from the NWHI to the MHI permanently.

    Fact:

    Currently, only 1 in 5 pups born in the NWHI survive to adulthood, and the proposed translocation effort is to improve the survival of these young animals, by bringing weaned pups to the MHI, where immature seals have substantially higher survival rates, and then returning them to the NWHI to rebuild the population there. Only a small number of pups will be temporarily moved, so they will have little effect on the seal population density at the nursery sites and little or no effect on ocean resources and fishing.

    Only a small number of seals will be involved in this effort, initially starting with a small number of pups (probably 5-10) to test the effectiveness and refine the techniques, with a maximum of 20 pups per year once the project is in full operation. Because the seals will be returned to their birth sites after three years (once they've survived the critical period when most of the pups die before age 3), the total number of translocated pups and juveniles at any one time is capped. The translocated seals may be distributed at one or several sites, depending on how many suitable recipient sites exist. This small number of translocated pup and juvenile seals will be a small proportion of the total population at any recipient site. Any seals translocated to the MHI would thus have negligible effect on recreational or commercial fisheries or other ocean users. NOAA Fisheries is also proposing to develop tools to minimize undesirable seal-human interactions (including fishery interactions) in the MHI. Translocated seals will be managed to mitigate such interactions just like any other MHI seal.

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  13. Myth:

    The seals brought down from the NWHI to the MHI will end up having more pups and cause additional problems.

    Fact:

    The main goal of this effort is to bring all the translocated seals back to the NWHI before they are old enough to have their own young so that these young, healthy seals (mostly females) will build up the population in the NWHI.

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