Ten years ago, Kentucky native Chris Fischer learned two things that inspired him to leave his job as a fishing show host and create a nonprofit devoted to tracking the migration and breeding patterns of the world’s largest sharks.

The first came from the scientists that Fischer took out on his boat for episodes of the cable TV show “Offshore Adventures.”

Whether they were experts on marlins, tuna, sailfin or any other fish, they all said the same thing: “If we continue to lose our sharks, there will be no fish for our kids to eat.”

Then he discovered that efforts to reverse the alarming decline in the ocean’s largest shark species were often hampered by a lack of data on their migration and behavioral habits.

So Fischer set out to find a way to safely catch, test, tag and release several species of the ocean’s so-called apex predator, which led to the creation of his nonprofit Ocearch four years ago. Today, the tracking information the group acquires on great whites, hammerheads, makos and other sharks from around the world is available to any researchers who want to use it.

Ocearch and its work are featured this week at the Audubon Aquarium of the AmericasShark Research Exhibit, which runs through Sunday. On Friday, Fischer will discuss the team’s recent work in the Gulf of Mexico during a free presentation from 5 p.m. to 8 p.m.

Sitting on the deck of the MV Ocearch vessel docked just outside the aquarium this week, Fischer said as many as 200,000 sharks are killed per day, mostly through “finning” operations that capture sharks and cut off their fins for shark-fin soup. The carcasses are then dumped overboard.

The reason the survival and health of large sharks is so important is that — like lions and wolves on land — they sit atop the food chain, and a disruption to their numbers has an impact on everything below.

“It creates an overabundance of second-tier predators,” Fischer explained. Squid populations explode, and they come up from the depths where they would normally hide from sharks and decimate species such as tuna and mahi by eating the young. Eventually, they will even start to cannibalize themselves.

Around reefs, second-tier predators like groupers and red snapper can quickly upset the natural order.

“Sharks are the great balance-keeper,” he said.

Fischer said knowing where sharks spend their early years, mate and give birth allows conservation efforts to protect sharks when they are most vulnerable.

“Every region is its own puzzle,” he said, noting that Ocearch has been on 23 expeditions around the world, including South Africa, Australia and the Americas.

There are problem spots around the globe, with finning operations prevalent in the Pacific and in areas where there are no laws or no resources to enforce them, Fischer said. On the high seas, it’s often anything goes.

“We’re doing pretty good in America,” he said. “We have legitimate management and enforcement and real science. I’m really excited about what’s going on on the East Coast, the West Coast and in the Gulf of Mexico in general. We’re starting to see a return to abundance of our sharks. People get it.”

Ocearch developed its own method for capturing sharks for study, pulling in its first in 2007 — a 12-foot shark off the Baja Peninsula — after many broken lines and hooks.

The crew uses a 28-foot fishing boat called Contender to chum the waters and set a barbless hook in the corner of a shark’s mouth when it comes up to feed. The shark swims off but is then gradually pulled back in by hand as the crew uses the cleats along the edge of the boat and the craft itself as leverage.

The shark, which can be up to 4,000 pounds and 18 feet long, is then led to a platform that has been lowered from the MV Ocearch into the water.

First mate Todd Goggins said hoses are used to irrigate the sharks through their gills while they are on deck, while blood samples, ultrasounds and other tests are run and the dorsal fin is tagged. The process is typically done in eight minutes. Fifteen minutes is the drop-dead limit Ocearch has set.

Goggins said blood tests taken to measure stress levels before and after the tagging process show it is not detrimental to the sharks.

The tags that are attached to the sharks ping off a satellite every time the sharks break the surface, providing information about where they migrate, when and where males and females congregate to mate and where the females give birth 18 months later.

In the Gulf of Mexico during October and November, Ocearch was able to get blood samples from male and female tiger sharks, and hormone levels and an ultrasound from a pregnant female sandbar shark. It also increased the number of scalloped hammerheads being monitored off the coast of Texas.

Fischer said he was most struck by the importance of the roughly 4,000 active and inactive drilling rigs that serve as artificial reefs, with much of the water between them acting essentially as a desert.

“I don’t think the general public understands how significant all of the rigs are to the future abundance of the Gulf of Mexico,” he said.

Fischer said all of Ocearch’s data are made publicly available, allowing it to partner with as many as 80 researchers at 40 institutions worldwide.

The sharks Ocearch has tagged and given names like Mary Lee, Katherine and Betsy can be tracked on the nonprofit’s website, and Fischer said one great white was found to have migrated down the east coast all the way to the mouth of the Mississippi River.

He said the MV Ocearch and its crew are scheduled to pull out of New Orleans on Sunday, headed for more work off the coast of Miami.

Over the long term, he hopes to see the group’s “shark-first, ocean-first” methodology take hold beyond its own work.

“This is bigger than any individual,” he said.

Follow Chad Calder on Twitter @Chad_Calder