Crowdsourcing Sharks: a citizen science success story

Source: Paxton ,A.B., E.Blair, C.Blawas, M.H. Fatzinger, M. Marens, J. Holmberg, C. Kingen, T. Houppermans, M. Keusenkothen, J. McCord, B. R. Silliman, and L. M. Penfold. 2019. Citizen science reveals female sand tiger sharks (Carcharias taurus) exhibit signs of site fidelity on shipwrecks. Ecology 100(8): e02687. 10.1002/ecy.2687

Conserving the environment and its organisms works most effectively when managers and scientists have a lot of environmental information. However, some of the world’s most vulnerable animals, like the sand tiger shark, are also the most secretive. Luckily for these scary looking predators, amateur scientists can be an agent of change.

Photo submitted to of Sand Tiger Shark swimming above artificial reef off North Carolina Coast used in study by Paxton et al. 2019

#Crowdsourced #Science

Crowdsourcing websites such as are powerful tools where internet users can come together to fund great ideas or to help out people in need. Citizen science relies on these same principles but instead of money, people are pitching in to contribute data. 

By pooling the efforts of many outdoor enthusiasts and amateur conservationists we have created online communities where people share observations or information and build large databases of environmental information that can be used in scientific research.

With citizen science opportunities like these on or National Geographic Resource Library, scientists are quickly accessing new and interesting data that can help explain some of nature’s difficult questions. 

Sand Tiger Sharks

Growing from 7-10 feet long, these large (and scary looking) sharks inhabit shallow reefs along many coastlines around the world. On the east coast of the US, they seem to aggregate at shipwreck sites, or artificial reefs, acting as slow moving but voracious predators. 

Like many top predators, sand tiger sharks are instrumental in maintaining normal ecology in coastal marine ecosystems, however, are more vulnerable to extinction than species at other trophic levels. 

A species in danger

Sand tiger shark numbers have declined by more than 75% since the 1980s due to unregulated fishing. They’ve been named “vulnerable” by the International Union for Conservation of Nature red list of threatened species (IUCN 2009). 

Sand tiger sharks would greatly benefit from further protection, but this is easier said than done as scientists do not entirely understand which habitats are important to this animal at different times of their lives. 

Deep diving for answers

However, there is a source of shark information that was, until recently, untapped. Recreational SCUBA divers have been documenting shipwreck or artificial reef sites for decades, and they love to take photos of large sand tiger sharks. 

Photos taken of single female sand tiger shark taken 10 months apart on the same reef by a citizen scientist. From Paxton et al., 2019.

Divers from all over the world can visit citizen science website and submit their shark photos into a huge database. Each shark has their own pattern of distinct brown spots along their sides that can identify specific individuals. The Spot a Shark database compares the patterns from each photo with other previously submitted sharks, hopefully matching pictures of the same sharks taken by different people.

When shark researchers looked further into information collected by the database in coastal North Carolina, they found an exciting trend. Photos submitted from different divers show that a total of 6 female sand tiger sharks were spotted multiple times on the same reefs, or the same areas, at different times. 

Recreational diver takes photos and enjoys an artificial reef. Photo by: Romeroc, 2016.

Unfortunately, these photos cannot tell us how the sharks were using the artificial reef habitats. The occasions were separated by anywhere from 1 month up to 6 years so it is unclear if they were simply passing through or if these wrecks are important places for them. 

Spot a Shark = Save a Shark ?

The researchers believe the photos are preliminary proof that female sand tiger sharks of the Atlantic will return to the same artificial reef habitats over time. These areas are likely important for shark conservation and should be included in future plans to protect vulnerable shark species.

This is one success story, among many, where citizen scientists can contribute to our collective knowledge and make a difference in conserving some of the world’s most mysterious and important habitats for animals.

Are you interested in being a part of one of these success stories? You can start with the’s Catalog to learn about various citizen science projects across the country and start your search for local scientists that may need your help.


Share this:

Alina Spera

I am a second year PhD student at the University of Texas at El Paso. I study how climate change is impacting coastal Arctic biogeochemistry and ecology. When I'm not in the field or lab I'm probably running or hanging with my hamster!

Leave a Reply