Hatchling turtles are cute, small and inexpensive. Handled improperly, they also can make you sick.

Turtles are well-known carriers of salmonella, a common bacterial disease that causes fever, stomach cramps and dehydration and can lead to severe illness, especially in young children and elderly people. In August 2023, the Centers for Disease Control and Prevention released an advisory about an 11-state outbreak of salmonella bacteria linked to pet turtles.

“Don’t kiss or snuggle your turtle, and don’t eat or drink around it. This can spread Salmonella germs to your mouth and make you sick,” the agency warned.

Global trade in turtles is big business, and the U.S. is a leading source, destination and transit country. Some of this commerce is legal, some is not. For example, it has been illegal in the U.S. since 1975 to sell turtles with shells less than 4 inches (10 centimeters) in diameter because young children often contract salmonella from them. But it’s easy to find them for sale nonetheless.

However, humans are a much bigger threat to turtles than vice versa. Over half of the world’s turtle species are classified as threatened or endangered, and overharvesting of wild turtles is a major cause. Turtles also face other threats, including habitat loss, climate change, pollution, diseases, invasive species and death or injury while trying to cross roads.

As a conservation biologist, I work with colleagues from academia, nonprofit organizations and state and federal agencies to protect threatened species and combat wildlife trafficking. I also use the global wildlife trade to teach important ecological concepts and research skills. Here’s what we know about trade in turtles and how it threatens their survival.

It’s hard to harvest turtles sustainably because they are so long-lived. Individual turtles of some species can survive for more than 100 years. Most turtles reach reproductive maturity late in life and have relatively few eggs, not all of which produce successful offspring.

To put this in context, compare a common female snapping turtle from the northern U.S. with a female white-tailed deer. Begin at the start of their lives and fast-forward 17 years. At this point, the snapping turtle will just be ready to reproduce for the first time; the deer will already be dead, but it may have produced over 600 descendants. It can take a female turtle her entire life to generate one or two offspring that in turn reach adulthood and replace her in the population.

Turtles are valuable because they play diverse roles in land, freshwater and ocean ecosystems. For example, tortoise burrows provide refuge for hundreds of other species, including birds, mice, snakes and rabbits. Box turtles – the type you may encounter in your garden – consume practically any kind of plant material and excrete the seeds as they move around, helping plants spread. Some seeds even germinate more readily after passing through a box turtle’s gut.

In lakes and ponds, freshwater turtles serve as both predator and prey, and they help maintain good water quality by consuming decaying organisms. Terrapins reside in brackish water zones, where rivers flow into oceans and bays, and feed heavily on snails. Without terrapins present, the snails would quickly consume all underwater seagrasses, which would harm fish, shellfish, sea urchins and other organisms that rely on seagrasses for their survival.

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