La Jornada: Alert about alopecia in Guadalupe fur seals

More than a quarter of the Guadalupe fur seals in the San Benito archipelago, in Baja California, have alopecia, a condition that has raised alarm among researchers, as it could be a sign of environmental deterioration in the marine ecosystem.

During monitoring carried out in 2024, the results of which were published in the journal Frontiers in Marine Sciencespecialists documented hair loss in 53 of 208 individuals evaluated, equivalent to 25.5 percent of the observed population. A photographic analysis determined that young people or those with poorer physical or nutritional condition were more likely to present this condition.

In interview with The DayPriscilla Casandra Gutiérrez, researcher at the Interdisciplinary Center for Marine Sciences of the National Polytechnic Institute (IPN) and leader of the study, explained that this finding is relevant, since it could reflect broader alterations in the marine ecosystem.

“Beyond the fur seal, this phenomenon could be a sign of changes in the environmental conditions of the region,” he noted.

This marine mammal has a coat made up of two different layers: the primary hair, which is characterized by long, thick and shiny strands, which gives the animal its characteristic brown color, and the secondary hair, a dense layer of fine, woolly hair, which prevents water from coming into contact with its skin.

“The hair that falls out is the primary hair, that’s why when we look at photographs of alopecic wolves they look white, because the secondary hair is exposed.”

This outer layer, added the specialist, “is the sunscreen” of the wolves, because it captures UV rays, “by losing this cover, they lose that protection.”

The Guadalupe fur seal is a species endemic to Mexico. Its main reproductive colony is located on Guadalupe Island, while a colony made up mainly of young specimens lives in the San Benito archipelago. It feeds on squid and spends much of its life in the open sea.

For now, scientists do not have a definitive answer about the causes of alopecia in this species. Casandra Gutiérrez considered that multiple factors could be involved: ocean warming, sea pollution or nutritional problems.

Tests carried out on the fur and blood samples of the affected individuals ruled out that this condition was associated with an infectious process caused by fungi, bacteria or parasites.

“What we know is that hair fragility exists. What is the factor that causes hair to weaken? That is the million-dollar question that we still cannot answer.”

After documenting the magnitude of the problem and the groups most affected, the next step will be to identify the possible causes.

“Alopecia in marine mammals has a history in the polar bear, the gray seal and the northern elephant seal, but the worst of all is this case, because it occurs in individuals from three months old to adult males and females.”

Casandra Gutiérrez said that in the coming months a student will analyze the presence of possible contaminants in the water, in order to identify some that may have effects on her endocrine system. “In the sea there are persistent organic materials, heavy metals that have the ability to affect the thyroid hormone.”

The scientist called on the community of veterinary doctors, biologists, and ecologists to get involved in this line of research. “We need to strengthen conservation medicine, the study of emerging diseases and mortality in marine mammals because very little work has been done.”

For the expert in medicine and conservation ecology, identifying what causes alopecia is a priority not only for the conservation of these animals, but also for understanding the alterations that could occur in marine ecosystems.

“It is very good to create protected natural areas and expand them, but we must ensure that the quality of these areas is adequate,” he concluded.