For four months each year, thousands of whale sharks migrate to the Gulf of Mexico to feed on abundant food. And over the past several years, there have been sightings of whale sharks in the zone now devastated by the Deepwater Horizon oil blowout. As these waters are a critical whale shark feeding habitat during the summer months, how will the oil ultimately affect this population?
Oil can harm whale sharks in a variety of ways – it spoils water, reduces oxygen levels and kills fish. And as several fish species spawn off the U.S. coast at the mouth of the Mississippi, fish eggs might be polluted. Should a whale shark feed on affected tuna or its roe, prey will infect predator. “It’s the contamination of their food web… even if they [whale sharks] survive this oil disaster themselves,” Dr. Robert Hueter, Director of the Center for Shark Research at Mote Marine Laboratory in Sarasota, Florida, recently shared at the annual Whale Shark Festival.
Whale sharks are filter feeders, and swallowed oil can also potentially get into their mouths and on the top of their filters. “That means no feeding – and probably no breathing – and the animal will most likely die,” says Hueter.
Whale sharks migrate great distances, making the spilled oil an international problem. “Even though it happened in U.S. waters, it can affect these animals in the Yucatan Peninsula because of their wide range,” says Dr. Alistair Dove, Senior Scientist at the Georgia Aquarium. “They go where they want to go… that makes the oil spill everybody’s problem.”
Tagging devices on some of the Gulf’s whale sharks are helping to monitor the moving behaviors of this particular poulation. “We are currently tracking [whale shark] Sara, and she moved north from Sarasota and then turned around in the Northern Gulf of Mexico… This has led us to hypothesize that the spilled oil is causing sharks to move elsewhere,” says Dr. Hueter.
He and his team have also reported seeing unusual sightings of all types of fish species – including tuna, mahi mahi and sailfish – off the Sarasota coast that don’t usually swim into waters that shallow.
Saved from the Spill premieres Tuesday October 5 at 9P et/pt on Nat Geo Wild.
Learn all about whale sharks.
Photo Credit: Georgia Aquarium