Invader in red: the impacts of the red-eared slider turtle across the globe

Magnitude of the Freshwater Turtle Exports from the US: Long Term Trends and Early Effects of Newly Implemented Harvest Management Regimes:

Header image by: Sheila Sund: (Flickr)

Fostering the troops 

Pet stores are a great place to learn about animals and foster curiosity, respect, and responsibility for the natural world through the care of animals. However, pet trade has also led to the widespread introduction of exotic animals to many ecosystems. In the United States, one of the most exported animals are red-eared sliders (Trachemys scripta elegans). In fact, between 1989 and 1997 more than 50,000,000 individuals were exported out of the United States and export numbers remained high in 2012.

Terrorizing terrapins

Not all species introductions result in negative effects for wildlife. In general, harmful impacts occur when invaders have a competitive advantage over native species. For example, in the UK many ponds are home to one species of turtles. This means that the red-eared slider, which often co-occurs with up to six species may have a competitive edge. In 2004,  a study  showed that native UK turtles were healthier and larger in ponds without red eared sliders than native turtles in ponds where they had to share their habitat with the invaders. Media reports describe red-eared sliders as terrorizers that drown waterfowl and link their popularity as pets with the cartoon Teenage Mutant Ninja Turtles. Similar findings have been reported from Japan, where red-eared sliders reach sexual maturity faster and have competitive advantage over native Japanese turtles. 

Figure 1: Red eared slider in Minoru Park, Richmond, BC, Canada photo by Rhondle

First line of defense 

A cohesive management plan with regulation on harvesting (collecting turtles from the wild) and farming is needed to mitigate the harvesting and consequent exportation of wildlife. In their study, Dr. Ivanna Mali (Biology Professor at Eastern New Mexico University) and colleagues found that in the United States regulation to control harvesting, farming and exporting turtles can vary by states. In fact, their findings suggest that export of turtles increased in Louisiana after stricter turtle harvesting regulations were established in the surrounding states (Figure 2). The authors suggest that states should work together and establish regulation in tandem and with the same legal language to aid in a united regional management policy. 

Figure 2: The top panel shows the major exporters of turtles in the United states. The bottom panel shows that harvesting regulations vary from state to state. Note that Florida and Alabama have strict no harvesting regulation, while there is no regulation in the nearby state of Louisiana which is a major export. (Graphic by authors of study)


Turtles in 2020 

Although authors made a call for more united regional turtle harvesting management policies, six years later the 2020 report of the Center for Biological Diversity details that policy still varies greatly by states in the United States. Although 29 states have completely prohibited commercial harvesting, 11 states still uphold weak trapping laws that allow unlimited harvesting of turtles. These states are Arkansas, Delaware, Louisiana, Maryland, Minnesota, Ohio, Oklahoma, South Carolina, Tennessee, Vermont, and Wyoming. If you are a resident of these states be sure to contact your local representatives with your concern on the state position on the trapping and export of wildlife. Presently, many species in the United States have been affected by harvesting policies and the export of red-eared sliders have contributed to species decline across the globe.    

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Kevin Aviles Rodriguez

I am in the process of completing my PhD in Ecology and Evolutionary Biology at the University of Massachusetts in Boston. I am interested in human environmental changes as natural experiments to test hypothesis about the evolution of animals. Specifically, I study small lizards known as anoles and how living near human households impacts their ecology and behavior. I love fieldwork because often it takes me away from the cold and towards the sunny beachy islands that I love the most.

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