Gulf Of Mexico Sharks Are Shrinking ... Fast [UNC Study]

Sep 17, 2014

A champion tiger shark at a fish rodeo in 1988
Credit Joel Fodrie / UNC IMS

Over the past 30 years, the size of sharks in the Gulf of Mexico has been shrinking. Drastically. Some sharks are 70 percent smaller.

The findings come from the University of Alabama and the University of North Carolina's Institute of Marine Sciences.

Researchers came up with a novel way of gathering the historical data. While there wasn't any academic database that collected such information, local newspapers in the Gulf region have been publishing the results of fishing competitions for years.

What they found was that between the 1920s and 1980s, the size of trophy sharks being caught was getting larger and larger.

"Boats were getting bigger, rods were getting better," said Dr. Joel Fodrie of the UNC IMS.

But by the 90s, average shark sizes began to drop. Today, not only are smaller sharks being caught, but smaller species of sharks are being reeled in. While sportsmen used to land an 800 pound tiger or bull shark, they're now more likely to pull in a 250 pound hammerhead.

The average size of trophy sharks in the Gulf of Mexico rose for nearly 60 years before beginning a steep drop downward.
Credit Eric Mennel. Data provided by Joel Fodrie / WUNC

"We're often limited by our temporal scope when it comes to how we see the world," said Fodrie. "Some of the pictures from the papers show kids in [the year] 2000, 2008, staring in awe of a 225 pound tiger shark. What those kids don't realize is that 30 years ago, there were sharks four times that size. There were sharks that could literally bite that 225 pound fish in half."

A tiger shark caught in 1990 (top) and a tiger shark caught in 2008.
Credit Joel Fodrie / UNC IMS

Fodrie says the drop in size correlates to an increase in the commercial fishing of sharks.

Through the 90s, sharks were often used as imitation fish product, and the fins were sold to Asian markets.

But as conservation efforts have picked up in recent years, the amount of commercial shark fishing has dropped drastically, from about 6,000 tons per year, to closer to 1,000.

It's hard to say what affect this might have on the ecosystem of the Gulf of Mexico. A study in North Carolina showed the decreasing size of sharks allowed ray populations to explode, upsetting the food chain of other fish.