You asked. We answered. In early June, FIU News invited our readers to submit their questions about sharks. We shared those questions with our shark researchers. Earlier this week, they answered your questions about shark attacks. Now, they are here to answer your questions about the current state of shark populations, conservation and what scientists do to keep track of the ocean’s great predator.
Substantial changes are in the works for shark conservation after decades of neglect.
The current state of shark populations is very poor, according to FIU marine biologist Demian Chapman, and much work remains to reverse that trend. Marine protection zones are a good place to start.
“This strategy tends to be most feasible in countries where there is limited capacity for monitoring fisheries and enforcing more complicated fisheries regulations,” Chapman said.
More developed nations, including the United States, Australia and New Zealand, are actually having success with managing fisheries. These countries have more resources and expertise to determine and oversee sustainable fishing practices. Chapman also points to species-specific protection, in which fishing is banned for endangered species. And at the international level, trade restrictions are now in place for eight species of sharks.
Predator in Peril
FIU research suggests as many as 100 million sharks are taken from the oceans every year, a pace sharks cannot keep up with. To advance conservation efforts, Chapman and a team of international researchers are conducting a global survey of shark and ray populations called Global FinPrint.
While fishing is a leading threat, scientists are becoming increasingly concerned about how sharks are responding to climate change and changes in ocean chemistry. Chapman fears some species — especially those living in colder water and those that rely on coral reef habitats — will be dramatically affected.
Yannis Papastamatiou shares this concern. An FIU marine biologist, Papastamatiou uses acoustic and satellite technologies to study black tip reef sharks, leopard sharks, great whites, tiger sharks, stingrays and more. He says evidence already exists to show that the distribution of sharks changes with warming temperatures.
FIU research scientist Jeremy Kiszka says most sharks are ectothermic predators, meaning their temperature varies with the temperature of the water. That’s why warming temperatures are of particular concern. And with the prediction that the ocean will become more acidic, Papastamatiou said certain species are known to change their feeding behaviors and physiology.
Education is one of the most important tools in the fight to save the world’s shark populations. Today, most sharks are killed as a commodity, traditionally for their fins, meat or use in products. Mike Heithaus, a marine scientist and dean of FIU’s College of Arts, Sciences & Education, says some shark products sold today are not even beneficial to people. He and the other FIU shark experts are conducting research to advance understanding of sharks and their habitats in an effort to improve policy and conservation.
Heithaus uses cutting-edge technology, including cameras worn by animals, to unravel the lives of hard-to-study marine creatures from whales and dolphins to sharks, seals and turtles. Much of his works relies on satellite transmitters attached to a shark, which records a shark’s position whenever it comes to the surface. An alternative type of tag, which is programmed to release from a shark after weeks or even months, can monitor water temperatures, light levels, salinity and depth. Data from these can be downloaded through satellites.
But when they need to know what is going on below the surface, scientists, including Papastamatiou, rely on acoustic transmitters. Using high frequency sound waves, acoustic transmitters can be tracked using underwater listening stations that help track movements of sharks.
Despite their fierce persona, the researchers want people to remember that sharks are actually extraordinary creatures that play critical roles in preserving the health of the oceans.
“Based on fossil records, it is estimated that sharks have been on Earth for about 450 million years,” Kiszka said. “With about 500 species of sharks recorded in the world, we see they have colonized most available marine habitats, from the open and deep ocean to coastal waters. Some species of sharks even feed and reproduce in freshwater habitats. There are a huge number of hypotheses explaining species richness. When sharks evolved, the availability of a range of ecological niches may have driven the incredible diversity of shark species known today.”