Giant apple snails found in the San Antonio River

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Hand extended holds an adult apple snail.

In the past few years, the San Antonio River has faced a new threat to its ecosystem. San Antonio River Authority (River Authority) biologists first responded to the observation of Giant apple snails (Pomacea maculata) along the Museum Reach of the San Antonio River Walk in October 2019. Now that the weather is warming up, observations of apple snails are on the rise again. Read below to learn about this invasive species and how the River Authority is addressing this threat.

What are apple snails?

Apple snail egg casing found on wall.

Left: Adult apple snails found in the San Antonio River. Right: You could easily mistake the egg casings laid by female apple snails for wads of bright pink bubble gum!

Apple snails are large snails native to South America. They get their namesake from their size – when fully mature, they can grow up to the size of a large apple (6 inches in diameter). They are a highly destructive invasive species throughout Texas and are currently on the Texas Parks and Wildlife (TPWD) Invasive, Prohibited, and Exotic Species list.

Why are apple snails a threat?

  1. Apple snails are voracious eaters of aquatic plants. Basically, they are the hungry, hungry hippos of the river. Unfortunately, they eat the plants that our river’s native organisms rely on for food and habitats. This presents a big problem for our local creeks and the San Antonio River.
  2. Apple snails have LOTS of babies. Female apple snails lay weekly clutches containing between 500-1000 eggs once they reach maturity. Some can even lay up to 2,000 eggs!
  3. Apple snails have no predators in the San Antonio River Watershed because they are a non-native species from South America.

How did they get into the river?

Typically sold at pet shops, it is likely that these snails outgrew their owners’ aquariums and were released into the river. You should never dump your aquarium into the river or any other freshwater or saltwater body!

How is the River Authority addressing this threat?

River Warrior collects apple snail egg casing in a kayak.

Collected adult apple snails.

The River Authority is proactive in protecting our natural resources. This is why our staff has been working hard to address invasive species in our commitment to safe, clean, and enjoyable creeks and rivers. 

Since the River Authority and its partners started coordinated removals in late April 2020, 4,217 adult snails and 22,154 egg cases have been removed. The scheduled river draining in January 2022 by the City of San Antonio also provided River Authority crews an opportunity to remove over 500 adult snails from the river. Staff routinely monitor the Museum Reach, Downtown, and King William sections of the San Antonio River Walk to search for and remove new findings.

How can you help?

River Warrior apple snail removal

You can report any sighting of egg cases or adult apple snails by calling toll-free at (866) 345-7272 or contact us through our website. Your help with reporting this invasive species will assist our Environmental Sciences team in further studying and removing these snails along our creeks and rivers.

Finally, we invite you to join our River Warriors! These dedicated volunteers help to track and remove Giant apple snail egg cases. “Having the River Warriors out there on the water, as much as they have been, has been a tremendous help,” said Chris Vaughn, Senior Aquatic Biologist. To date, River Warrior volunteers have removed 48 apple snails and 1,260 egg casings.

Ready to jump right in? Join us at the upcoming Apple Snail Training on Thursday, May 26, from 12pm – 1pm. You will learn all about apple snails and how to help remove them from our waterways. Email to RSVP.

Want the latest information on Apple Snail removal and other River Authority initiatives?

 The River Authority blog gives you an insider’s view of the initiatives and projects at the River Authority. Sign up to receive this bi-weekly blog to learn about upcoming events like the grand opening of the newest phases of the San Pedro Creek Culture Park. Other topics include the vital work our staff, including scientists and engineers, do every day to help keep our local waterways safe, clean, and enjoyable for everyone. Don’t miss out!

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Acequia Trail Notice

The Acequia trail will have heavy traffic near MROC starting May 22nd until further notice. The SAWS Acequia project will be bringing in crews to work on the lift station site and across the street. There will have flaggers to stop traffic, please use caution. 

SASPAMCO Paddling Trail

The SASPAMCO paddling trail is open from River Crossing Park to Helton Nature Park.
*Please Note: Paddling Trail from Helton Nature Park to HWY 97 is still closed due to blockages. 

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