DESTIN, Fla. (AP) — On a blistering day in June, more than 100 people stood in line to board the Hannah Marie dolphin cruise on Destin Harbor.

One of several dolphin cruise boats in Destin, the Hannah Marie offers five dolphin cruises a day during peak season, shuttling hundreds of tourists through East Pass and down the coastline to catch a glimpse of one of the Emerald Coast's original settlers: bottlenose dolphins.

"People are fascinated by dolphins because most of them don't ever see them where they live," said Bobby Montz, a deckhand aboard the Hannah Marie. "We tell them that we train them, but of course we don't. They're wild animals. They do whatever they want to do, and we just watch."

The National Oceanic and Atmospheric Administration estimates about 175 bottlenose dolphins live in Choctawhatchee Bay and about 51,000 live along northern Gulf of Mexico continental shelf, which runs from Texas to the southern tip of Florida.

But while tourists pay big bucks to catch a glimpse of one on a sightseeing trip, locals have built relationships with the playful marine mammals over the past century — for better and for worse.

Andy Horn, a supervisor of marine mammals at the Gulfarium Marine Adventure Park on Okaloosa Island, works with dolphins at the park and studies them in their natural habitat. He said he's seen a troubling trend of dolphins that live in and near waterways frequented by humans — Destin's East Pass and Harbor area, for example — become a bit too socialized to people.

"Dolphins are opportunistic feeders, so they might get into trouble with the shrimp boats or the fishermen, going up and stealing their bait or their fish," Horn said. "That behavior is not really something you want to see in the wild population, because when they learn to interact with people for their survival needs, that changes their natural behavior."

Stacey Horstman, a bottlenose dolphin conservation coordinator with NOAA, agrees. She says she's seen an increase in human-caused deaths in the dolphin population in recent years, including dolphins that die by ingesting items such as plastic bags or fish hooks and others that die when humans intentionally and unintentionally harm them.

"We have enough information from different population studies to know that animals that learn to beg from people are at a higher rate of concern from being injured by humans and boats," she said.

NOAA said in 2016 that rates of violent incidents involving dolphins appeared to be increasing. Between 2002 and 2016, 23 dolphins had stranded themselves with evidence of being shot with a gun or an arrow, the agency said. Fifteen of those occurred since 2010 — an alarming upward trend, officials said.

Allison Garrett, a spokeswoman for NOAA, said there have been no known cases in the past year or so.

The most recent suspicious dolphin stranding in Northwest Florida occurred in May 2016 when an older male dolphin was found dead from an apparent gunshot wound on the beach on Okaloosa Island.

There was no sign of animosity toward dolphins on the Hannah Marie, as nearly all of the boat's 100-plus passengers swarmed to the ship's port side to catch a glimpse of the first pod of the day. A trio of bottlenose dolphins spotted about 100 yards from shore on Okaloosa Island dipped in and out of the water, chasing a school of fish nearing the boat.

Seven-year-old Gavin Busby of Texas stood clutching the guardrail and squealing in delight as the dolphins moved closer and closer to the boat.

"I think he really likes dolphins," said his dad, Chase. "He really likes marine life and dolphins. I don't think he's ever seen them this close."

While bottlenose dolphins are the most common dolphins in Northwest Florida waters, they're not the only ones.

Todd Watkins, a local photographer, was boating with friends on Memorial Day weekend about 3 miles southwest of the East Pass. He came across a pod of what he thought were bottlenose dolphins, but when he looked closer he noticed a few of them appeared to have polka-dot pattern on their skin.

"We came across the pod and slowed down because they swam right across the bow of my boat," Watkins said. "There were more bottlenose than spotted. I had never seen spotted dolphins here before."

Atlantic spotted dolphins, also called "stenellas" because of their scientific name Stenella frontalis, are the polka-dot patterned twins of the Atlantic bottlenose dolphins. They're the second most common type of dolphin found in the Gulf of Mexico, according to Horn, the marine mammal supervisor at the Gulfarium. They typically stay in water deeper than 60 feet, which keeps them away from the coastline.

"Some species make their movements in the summer months closer to shore, and they can be found in groups in as little as 20 to 40 feet of water," Horn said.

Watkins put his GoPro camera in the water and caught a few photos of the spotted dolphins as they swam with bottlenose dolphins. He said the dolphins were swimming along the boat and acting playful.

"A few of them were swimming with the front of the boat, like they wanted to play and wanted me to go faster," he said.

Dolphins are protected under the Marine Mammal Protection Act (MMPA) of 1972, which prohibits harassing or coming within 50 yards of dolphins in the wild.

The act was put in place for several reasons, including limiting human-to-animal interactions in the wild, which could be dangerous for all involved.

"If dolphins are readily approaching boats and you see them with their heads popping up out of the water and their mouths open, or if they're peeking at you with one eye, that's not a natural wild dolphin behavior," Horstman said. "It's illegal to feed, or attempt to feed, a dolphin. It sparks a whole host of challenges for the animals, and for people, too."

Horstman said dolphins can be aggressive, and those that appear to interact with humans have likely been conditioned with food or bait before. She's heard stories of dolphins biting humans off Florida and Alabama, mostly because people were trying to feed them.

"The one thing about dolphins that people forget when they're trying to swim with them or touch or pet them or feed them is that they are wild animals," she said. "They are big and powerful and they can inflict harm to us just as much as we can to them."

Additionally, dolphin feeding can be harmful because a dolphin who learns to beg for food from people may pass that trait on to her calf, leading to a disruption in the food chain and normalizing human interaction behavior with a new generation of dolphins.

Roy DiVincenti, the captain of the Hannah Marie, tells his boat guests at the start of each dolphin cruise about the laws and guidelines for viewing dolphins in the wild.

Still, as the Hannah Marie was floating near a pod of dolphins on a recent cruise, another boat appeared nearby, closer to the dolphins. Its passengers reached their hands under the water to try to pet the dolphins as they swam under the boat.

That's a definite no-no, says Horn.

"Boating around dolphins can be done very safely, and there are MMPA guidelines," he said. "Getting too close to dolphins in a boat can lead to the dolphin being seriously injured."