Bottle nosed dolphins living along the coast of Florida are getting used to supplement their diet by snatching bait from fishing lines or circle recreational anglers practising catch-and-release. Some dolphins have even made a habit out of routinely approaching humans to beg for food.

Scientists at the National Marine Fisheries Service have now been able to show that this behaviour is spread down through generations of dolphins.

“We are able to document lineage, from grandmother to mother to calf, all following fishing boats and taking thrown-back fish,” says Jessica Powell, a National Marine Fisheries Service biologist.

Dolphins begging for food might be an endearing sight, but approaching humans in this fashion means taking a great risk. In 2006, three dead Sarasota Bay dolphins turned out to have fishing lures stuck inside them.

“Whenever animals become reliant on humans for food, it puts them at jeopardy,” says Dr. Randy Wells, director of dolphin research at Sarasota’s Mote Marine Laboratory. “If they are coming to boats or piers to get fish, they are swimming through a maze of lines, hooks and lures and those lines are designed to be invisible under water.”

Some dolphins do however seem to have figure out how to stay clear of harms way. A bottlenose dolphin nicknamed “Beggar” has been soliciting free meals in a narrow stretch of Intracoastal Waterway near Nokomis Beach since he was a juvenile 20 years ago. Despite routinely swimming just inches from boat propellers, the skin of Beggar’s 8 feet long body is free of major scars. Hopefully, the same is true for the inside of his 400 pound body.

As if the menace of razor sharp propeller blades, invisible fishing lines and jagged double hooks weren’t enough, bottlenose dolphins also stand the risk of encountering anglers who may not appreciate having their bait or catch snatched away by a hungry cetacean. A commercial fisherman out of Panama City, Florida has been sentenced to two years in prison after throwing pipe bombs at dolphins trying to steal his catch. Off Panama City, tour operators have been feeding dolphins for years to assure their presence at the popular “swim-with-the-dolphins” tours.

Feeding the Florida dolphins is illegal under both state and federal law, with federal law banning wild dolphin feeding in the early 1990s. Feeding wild dolphins can also be dangerous and the abovementioned “Beggar” dolphin has for instance sent dozens of overfriendly patters to the hospital for stitches and antibiotics.

Hand-feeding aside, a severe red tide in 2005 seems to have made the habit of interacting with humans for food much more widespread than before among the Florida dolphins. The red tide wiped out 75-95 percent of the dolphin’s usual prey fish and the hungry dolphins eventually realised that they could fill their bellies by picking bait fish off fishing lines.

“We suspect that the dolphins were
hungry,” Wells explains. “Their main prey
base was gone. Seeing a fresh pin fish
dangling from a line might look pretty
good to them. And once they learned
that anglers are a source of food, they
don’t forget that very quickly.”

Commercial, recreational and party/charter boat fishermen from Maine to North Carolina have all rallied together to deal with an out-of-balance population of predatory spiny dogfish sharks that threatens the recovery of New England groundfish and several others fish stocks living along the U.S. East Coast.

The newly formed Fishermen Organized for Rational Dogfish Management (FORDM) has requested the assistance of Dr. Jane Lubchenco, newly appointed National Oceanic and Atmospheric Administration head, in dealing with the predator.

Spiny dogfish

The disproportionate abundance of dogfish is not a new problem; as early as 1992 Dr. Steven Murawski, now chief scientist of the National Marine Fisheries Service’s, wrote “Given the current high abundance of skates and dogfish, it may not be possible to increase gadoid (cod and haddock) and flounder abundance without ‘extracting’ some of the current standing stock.”

That was over 15 years ago and the situation has not improved. On the contrary, the amount of dogfish now exceeds that of skates, and dogfish comprises over half of all fish taken in the annual trawl surveys carried out by the Northeast Fisheries Science Center.

The spiny dogfish can exceed 150 cm in length and preys on virtually all species of fish smaller than itself. Dogfishes can also create a problem for other species by competing with them for prey fish.

This remarkable abundance of dogfish is most likely the result of countless years of ever increasing over-fishing. Spiny dogfish is not an appreciated food fish and the depletion of other species seems to have favoured it greatly in these waters.