Aerial surveys conducted in the North Sea have shown that seals practice social distancing, which could have significant implications for the spread of disease among these marine mammals. According to a study published by the Royal Society, researchers observed that grey and harbour seals maintain distances between individuals, unlike walruses that cluster together. This behavior may be an evolutionary response to viral susceptibility.
The study compared harbour seals with grey seals and found that harbour seals keep a greater distance from their neighbors. This finding is crucial as disease outbreaks, such as bird flu, are a serious concern in wildlife. The research was conducted in the wild coastal area of the Dutch Wadden Sea, where both species of seals gather on intertidal flats and beaches to rest, socialize, mate, and give birth.
Harbour seals have previously experienced devastating outbreaks of disease, such as the seal distemper virus in 1988 and 2002, which resulted in a significant reduction in their population. In contrast, grey seals remained relatively unaffected. The study suggests that grey seals may carry the virus but do not get as sick as harbour seals, possibly contributing to the spread of the virus. It is believed that the genetic makeup of grey seals provides them with greater resistance to respiratory viruses.
Interestingly, the observed social distancing among harbour seals may be a response to the memory of past outbreaks. This behavior is comparable to human responses during the Covid pandemic. Covid itself is a zoonotic disease, meaning it can be transmitted from animals to humans. There is evidence that Covid has affected marine mammals, and concerns exist about the potential spread of the virus among seals and whales through human sewage in the sea.
Lockdown measures due to Covid had unintended benefits for the natural world, including marine mammals like seals. Reduced disturbance and quieter seas provided a respite for these animals. It is also important for humans to maintain distance from seals for their own safety, as seal bites have been linked to potential zoonosis and infections that could lead to digit amputation.