The thud on the dock got Jean Fruh's attention.
She turned and walked over to the family whose members were loading themselves into rental kayaks at Shelter Cove Marina.
As a tin of Beach Cliff sardines fell out of one family member's pocket.
"The family (of 10) literally had pockets of them," Fruh said Tuesday as she recounted the scene from last July. "They were visitors. They didn't know."
The family had intended to feed the sardines to dolphins, she said. Someone at a store had told them dolphins like sardines. That someone likely hadn't told the visitors that it was illegal to feed dolphins, that doing so could eventually kill them - and land the family a multi-thousand-dollar fine.
Fruh - a South Carolina Master Naturalist who works as a guide for Outside Hilton Head and directs The Outside Foundation, a local nonprofit that teaches kids to protect the environment - educated the family about the harmful effects of feeding wild dolphins. She regularly sees people feeding the mammals. Some are visitors, she said, but others are locals who should know better.
She can't say whether illegal feeding has increased, but she's noticed more dolphins approaching her boat as she's eased into the area's no wake zones. "Beggars," she calls them.
"First of all, feeding dolphins is a federal offense," said Wayne McFee, research wildlife biologist for the National Oceanic and Atmospheric Administration in Charleston. The Marine Mammal Protection Act - enacted in 1972 and amended a couple of decades later to prohibit the feeding of dolphins - specifies fines of up to $20,000 and one year in prison for illegal feeding.
Aside from being illegal, feeding can change dolphins' behavior, he said.
Dolphins accustomed to being fed can train their offspring to beg instead of hunt for their food. They might be more inclined to go after fishing bait, he said, which means they can swallow hooks that can lodge in their stomachs and cause fatal infections. Sometimes a hook will sever the trachea from the blow hole, which causes the animal to asphyxiate.
Dolphins who've become "beggars" can become aggressive, he said. "We've had numerous instances of people being bitten by them, and these animals have anywhere from 80 to 100 sharp, conical teeth that can do a lot of damage."
Above all else, illegal feeding encourages dolphins to approach boats, which is dangerous for them.
Amber Kuehn, who works for the Coastal Discovery Museum, and whose Spartina Marine Education Charters partners with USC Beaufort to lead dolphin research excursions, says some of the local dolphins she tracks have scars on their dorsal fins from propeller strikes.
The dorsal fin acts as a dolphin's fingerprint, she said. Unfortunately, a lot of those prints are more distinctive because of the boat strikes.
There are about 200 local dolphins who live in the area, she said. But the population roughly triples during the summer as animals travel south.
"Dolphins don't taste their food," Kuehn said. "They swallow it whole; they're lazy like people are."
The animals will eat anything, she said, so they'll fill up on hand-fed Twinkies and won't hunt for fish. Fish are their source of fresh water, she said, so dolphins that eat human food can become dehydrated and eventually die.
"You won't ever see the horribleness of this, because they get sick and they die," Kuehn said. "That's what kind of makes people like, 'What's the big deal?' It's over time where they're not eating like they should."
Hilton Head is a "hot spot" for illegal feeding, McFee said. "Most of our calls from feeding dolphins come from Hilton Head."
Ally Rogers, spokesperson for NOAA's Office of Law Enforcement, said there have been no complaints of dolphin feeding in the South Carolina area this year. The area averages about five cases per year, she said, which can range anywhere from a written warning to a "summary settlement" for a commercial vessel.
NOAA's agents have discretion on whether to warn or fine someone, she said, adding that first-time offenders typically receive a verbal or written warning. Part of the agents' job is education, she said, and encouraging policy compliance.
Fruh, a former college professor, is a proponent of education. Her nonprofit organization has developed coloring sheets to help educate children about wildlife. One of the sheets encourages kids to turn out the lights to protect nesting sea turtles. Another warns of the danger of feeding alligators. And then there's one about dolphins - which reminds us that the animals "are hunters, not beggars."
Last July, as the family members' sardines tins thudded on the dock, Fruh took a moment to talk to them.
Dolphins eat live food, she'd told them. This is dead food. And dolphins aren't used to the bacteria on our hands.
"I kept one of the (tins) to remind me that it's an everyday thing," she said.
"A reminder to teach people."
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For more information about the harmful effects of feeding wild dolphins, visit www.dontfeedwilddolphins.org.