ICYMI: Don’t Feed The Dolphins

SARASOTA, FL — Well-meaning humans who just can’t resist throwing fish overboard to attract wild bottlenose dolphins may be doing the creatures more harm than good. A recent study that draws on data collected in Sarasota Bay in cooperation with Mote Marine Laboratory cast light on the dangers, even when inadvertent and accidental feedings are involved.

“This is the first study that directly links human-related feeding of wild dolphins – intentional or not – with increase risks of injury from human interactions such as boat strikes, entanglement in fishing gear or ingestion of hooks and line,” said Dr. Katie McHugh, staff scientist of the Chicago Zoological Society’s Sarasota Dolphin Research Program. That program is a collaboration with Mote Marine.

The study was designed to investigate just why bottlenose dolphins seek out human-provided food and if this behavior could increase risk of injury. Data analyzed in the study was collected between 1993 and 2014 by the Chicago Zoological Society/Brookfield Zoo’s Sarasota Dolphin Research Program, along with members of Mote’s stranding investigations program. That data collected was subsequently analyzed by Murdoch University in Western Australia and researchers from Scotland’s University of Aberdeen to produce the study that was recently published in the peer-reviewed journal “Royal Society Open Science.”

While Mote and others have long worked to discourage people from feeding or harassing wild marine animals for safety and legal reasons – doing so is illegal under the U.S. Marine Mammal Protection Act – the research backs up the advice, Mote said in a Monday statement about the study’s release.

“Animals can die from human interactions — for instance, we examined a dolphin known as FB93 who was recovered dead with a fish hook embedded in her head leading to fishing line around her larynx, strangling her,” said Gretchen Lovewell, manager of Mote’s Stranding Investigations Program. “Even if an animal survives with a wound or entanglement, it might be less able to survive the next challenge.”

Prior to the study’s release, cautionary tales tended to be anecdotal, Mote noted in its statement. The case of “Beggar,” a long-time resident of Sarasota Bay, for example, served as a warning. Beggar earned his name because of his propensity to beg people to feed him. Beggar was found dead in 2012 with broken bones, signs of old wounds, fish hooks in his stomach and other concerns.

For the newly released study, researchers analyzed data related to 1,142 bottlenose dolphins identified in Sarasota Bay, including 190 who were described as “conditioned.” The dolphins who were deemed “conditioned” earned that classification because they accepted human handouts, targeted bait or had been seen patrolling between boats, lines or fishing piers, Mote officials said. By the end of the study period in 2014, 84 of the dolphins had suffered human-related injuries.

“In a well-documented subset of the dolphins — 366 individuals observed in multiple seasons — 43.7 percent were dubbed ‘conditioned’ and 20 percent had human-related injuries. Among the injured dolphins, more than a third died or required rescue by trained responders from Mote, SDRP and partners,” Mote’s statement said.

Just how dolphin learn unhealthy eating habits is a question still out to the jury, researchers say. Initial analyses, however, suggest they may learn the hazardous practice from each other.

“A dolphin had a higher probability of human interactions if its close associates during the past two years did those behaviors,” McHugh said. “It’s possible that some dolphins were driven to food from humans by a lack of prey historically, but once enough animals became conditioned, social learning took over.”

McHugh pointed to a particular female dolphin named Vespa that researchers encounter about once a month as an example of one dolphin teaching others to feed unnaturally.

“We see her doing unnatural feeding behavior about twice a year,” McHugh said. “She’s not necessarily doing it all the time, but she’s taught it to her calves, and they’ve taught it to their grandcalves, and multiple animals in their family have died from human interactions.”

Once dolphins start seeing humans, their boats and traps as sources for food, they generally don't stop, according to another study in Georgia that was led by Mote biologist Rebeccah Hazelkorn.

Both studies lead to the same bottom-line conclusion: don’t encourage dolphins by feeding them.

“About 25-30 percent of dolphins and whales that we respond to at Mote have some sign of human interaction,” Lovewell said. “This new study has put the issue in context and allowed us to work with a great team to illustrate how humans can affect these animals.”

“Anything you can do to avoid feeding dolphins, to avoid rewarding risky unnatural behavior, really does help,” McHugh said. “They’ll eventually stop if you don’t feed them at all – not even one shrimp.”

To report feeding or harassment of wild dolphins, contact NOAA Fisheries Southeast’s enforcement division at 1-800-853-1964. To report injured, stranded or entangled marine animals in Sarasota or Manatee counties, call Mote’s Stranding Investigation’s Program at 941-988-0212. To report such sightings elsewhere in Florida, contact the Florida Fish and Wildlife Conservation Commission at 1-888-404-3922.

The full study can be viewed online via the Royal Society’s website.

Image by Sarasota Dolphin Research Program/CZS. Photo taken under NMFS Scientific Research Permit No. 15543.