Seals are wild marine mammals. While they may appear docile, they can harm humans under specific conditions. Understanding these risks is important for safe interactions and respecting their natural behaviors, as they are not domesticated and retain innate instincts for self-preservation.
Why Seals Might Harm Humans
Seals are not inherently aggressive towards humans. Most instances of harm stem from defensive reactions or misinterpretations of human behavior. A seal may bite or scratch if it perceives a direct threat to its safety or its young. Mother seals, especially during pupping season, exhibit strong protective instincts if humans approach their pups too closely. Disturbing a resting or sleeping seal can also provoke a defensive response, as a sudden disruption can startle the animal.
An injured or ill seal can behave unpredictably. Seals might also mistake a human in the water for prey, particularly if swimming or surfing, leading to investigatory bites. Though rare, this highlights the need for caution in their natural habitat.
A significant factor contributing to aggressive encounters is the habituation of seals to human presence, often due to intentional feeding. Seals that grow accustomed to being fed by humans can lose their natural wariness and may become bold or even aggressive if food is not offered or if their personal space is encroached upon. This altered behavior can lead to serious bites, as seals possess powerful jaws and sharp teeth designed for catching prey. Bites from seals can be severe, causing deep wounds, and scratches can also occur during defensive encounters.
Health Risks from Seal Encounters
Beyond direct physical injury, seal encounters pose significant health risks due to zoonotic disease transmission. Seals carry bacteria that can cause serious infections if transmitted through bites or scratches. One notable risk is “seal finger,” a painful and debilitating bacterial infection often caused by Mycoplasma spp. or Erysipelothrix rhusiopathiae. This condition, also known as “blubber finger,” can lead to severe tissue damage, chronic pain, and permanent disability if not treated promptly.
Another bacterial threat is Mycobacterium marinum, which can cause skin lesions, nodules, or ulcers, commonly on hands and fingers, through contact with contaminated water or direct exposure. This infection can be challenging to diagnose due to its slow-growing nature and can progress to deeper tissues, affecting tendons, bones, and joints. Additionally, seals can carry other bacteria like Streptococcus phocae, which has been associated with infections in marine mammals and could potentially be transmitted to humans through wounds.
Parasites also represent a potential health concern, though they are generally less common or less severe in transmission to humans compared to bacterial infections. Seals can host various parasites, including roundworms (anisakid nematodes) and hookworms. While some parasites like Toxoplasma gondii can be found in seal tissues, posing a risk if raw or undercooked meat is consumed, direct transmission of external parasites like seal lice to humans is unlikely as they are highly host-specific. Any injury from a seal necessitates immediate medical attention due to the high risk of infection from these pathogens.
Staying Safe Around Seals
Maintaining a respectful distance is the most important safety measure around seals. NOAA Fisheries recommends staying at least 50 yards (about 150 feet) away from seals and sea lions on shore or in the water. Some guidelines suggest 100 yards, emphasizing that if a seal stares, fidgets, vocalizes, or flees, you are too close. Disturbing their natural behavior can cause stress, potentially leading them to abandon pups or flee into the water, injuring themselves.
Never attempt to approach, touch, or feed seals; these actions are dangerous and illegal under marine mammal protection laws. Feeding alters their natural foraging behaviors and makes them less wary of humans, increasing the risk of bites and other negative interactions. Keeping pets on leashes around seal habitats is also important, as seals may perceive unleashed animals as a threat, potentially leading to defensive reactions or injury to the pet.
If a seal appears distressed, injured, or abandoned, do not intervene. Instead, contact local wildlife authorities or marine mammal rescue organizations. These professionals are equipped to handle such situations safely and effectively. If a seal approaches you or an encounter turns aggressive, slowly and calmly back away without sudden movements, allowing the animal space to retreat. Remember that seals are wild animals deserving of respect.