Florida International University researchers are hopeful about great hammerhead sharks outsmarting ocean temperature swings.
More than one-third of all shark species are threatened with extinction.
“Great hammerheads are definitely a species that we’re really concerned with, and the reason that they have done poorly compared to some other sharks is that they are very sensitive to stress,” said Yannis Papastamatiou, a professor of biological sciences at FIU.
Papastamatiou is part of a team researching the life patterns of this elusive shark that we still know so little about.
It is illegal to kill the shark in state waters, but even catch-and-release is a death sentence for the powerful but delicate fish.
“If we could understand how shark behavior changes with temperature, then maybe we could predict where they are going to go as the temperatures change due to changing climates,” Papastamatiou said.
Most cold-blooded predators slow down when ocean temperatures shift. For some reason, hammeheads do not.
“The great hammerheads are a critically endangered species and understanding their thermal tolerance, their temperature tolerance, their preferred temperature is a really important element of trying to protect them in the future,” said Erin Spencer, an expert on hammerheads.
Spencer, who earned a doctorate, focused her dissertation on the sharks maintaining peak hunting performance of fast-moving prey like tarpon in the Summer and blacktip sharks in the Winter.
Meaning, this top predator has an edge over other species in tolerating changing climates.
“We get really a ton of data on the behavior of the animals in the wild, both what habitats they are using, how deep they are, and then how they are behaving in those habitats. How active are they? How fast are they swimming? And then from this, we can also then say, how does their behavior change based on what the water temperature is,” Spencer said.
For the study, researchers tagged hammerheads with bio markers similar to a FitBit.
“We have been using this clamp system, and basically our tag with the speed sensors can fit,” Spencer said.
After a few days, a portion of it dissolves and the tag floats to the surface to be retrieved. The clamp falls off the fin. The data stored is downloaded.
The research showed the hammerheads performed well in waters as warm as 93 degrees and as cold as 62 degrees, but the sweet spot was about 85 degrees.
“Understanding more about these animals and how they move and how they behave is power in designing ways to protect them that are going to be really effective,” Spencer said.
It’s unclear how many great hammerheads swim in our waters, but studies like this aim to understand and protect them.
“We can coexist with these predators,” Spencer said. “I think we still have got some ways to go, but I do have hope, compared to what things might have been like 20 to 30 years ago.”
