"The thing about these shows is that they target the animals that are already not doing well," Dr. Neil Hammerschlag, research scientist at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, told The Dodo, adding that the compounded pressures of commercial overfishing, bycatch and other factors have contributed to a global decline in sharks over the past 50 years.
Hammerschlag added it also matters which individual shark is being caught. For instance, sharks take a relatively long time to sexually mature - usually about ten years. Sharks also continue to grow their entire lives, and become more effective reproducers as they get older and larger. What's more, older fish tend to produce larger and healthier offspring.
"So if you're catching a shark, it makes more of a big deal if you're catching one thats mature," he said. "These trophy shows target the biggest ones - meaning the mature, most reproductively active ones."
Because the cash prize is awarded to the fisher with the biggest catch, the fishermen favor the most ecologically valuable individuals. To make matters worse, many species will either be injured or die after they are caught - then they're thrown back in search of a bigger catch. It depends on the species, because some are more resistant to being caught than others, but for many sharks, two hours of struggling on a fishing line will usually lead to death.