Too Many Turtles In The Ocean?

Tiger shark bite on a board. Photo courtesy Jesse Kunewa

There aren’t many guarantees in life. Some say even death and taxes can be avoided. Lord knows many have tried.

But there is one thing that I can guarantee. I guarantee if you jump in a canoe with me and we paddle from one end of Kailua Bay to the other, we will see a Hawaiian green sea turtle. No question.

World-renowned green sea turtle expert George Balazs of NOAA says the green sea turtle population has steadily grown over the past 20 years. It is estimated Hawaii’s green sea turtle population is between 30,000 and 50,000, growing at about 7 percent every year.

“They are well on the road to a healthy biological recovery,” says Balazs.

But is that recovery contributing to more tiger sharks coming closer to shore?

Surfers, fishermen, divers and paddlers will tell you absolutely yes. The green sea turtle feeds on marine vegetation and rich algae beds in shallow water. The tiger shark’s diet includes the green sea turtle. So it’s no surprise with more turtles in the water, there’s an increase in tigers feeding closer to shore.

“In my opinion, it’s not that they’re more actively seeking turtles, there’s just a lot more turtles,” says shark expert John Naughton, now retired from National Marine Fisheries. “They’re the natural predator of the green sea turtle and they’re just doing their thing. We had a number of incidents in Kailua a couple of years ago where turtles were hauling up on the beach and lifeguards were seeing big tigers swimming by, and actually witnessed a couple of attacks on turtles.”

Two recent tiger shark attacks on two Kailua-Kona surfers have renewed discussion of Hawaii’s booming green sea turtle population. Both Theresa Fernandez and Alayna DeBina thought they were hit by turtles at Lyman’s Beach, but quickly realized it was a tiger shark.

“I was starting to paddle, then I felt my board kind of lunge forward and grabbed back and under, and I said oh, this is not a turtle,” recalls Fernandez.

“Some people think it’s because the honu population has really grown since they’ve become so protected, and that’s their choice of food,” says DeBina. “There’s a lot more of them abundantly near the shoreline, which brings them closer.”

Fernandez agrees.

“I think the turtle population has exploded along our coastline, and you know sharks love turtles and they know where to find them,” says Fernandez. “I think that’s the main reason they’re so close. They just come in to eat and it’s easy pickings.”

Both women escaped injury. The shark was estimated to be at least 10 feet long. It’s still unclear if the attacks involved the same shark.

No one in Kailua-Kona, or anywhere around the state, for that matter, is suggesting the need for turtle eradication – not publicly, at least. Truth is the emotionally charged subject is quietly discussed, especially after tiger shark sightings and more so after an attack on humans. Experts say eradication is not an option.

“Hopefully we won’t see too many of these incidents (shark attacks) because it obviously brings up the call for turtle eradications or opening up turtle fisheries, and personally I just don’t think that’s right,” says Naughton. “It’s a good thing to see the population of green sea turtles come back the way they are.”

Turtles are a part of a tiger shark’s diet, but it is not the animal’s only choice. Tiger sharks are opportunistic feeders. They also feed on monk seals, mahimahi and even puffer fish, and their diet expands beyond the ocean.

“When we’ve caught them they’ve had things like pigs and goats, and I remember once we had an entire horse’s head in the stomach of a big tiger,” recalls Naughton. “They’re clearly not actively hunting humans. I mean, with the number of people in the water here we’d be in huge trouble if that was the case.”

But that’s not the case. Not by a long shot. Yes, there are more turtles in the ocean, but too many? As visitors in their home, how dare we even ask?