Sarasota dolphins are “urban dolphins.” As such, they face many threats living in an environment heavily affected by human activities.
The dolphins must share the waterways with thousands of motor boats. The boats range from jet skis and small runabouts to large cabin cruisers, yachts and barges.
Motor boats create a noisy environment, potentially noisy enough to interfere with the dolphins’ echolocation, the sounds they make to communicate with one another, or the sounds of the fish they are seeking for food.
Recreational fishing also may create a hazard for the dolphins. Dolphins are sometimes hooked or entangled in fishing line.
Human pollution creates other hazards for dolphins. Chemicals in the water can contaminate fish eaten by wild dolphins. This contamination, from a variety of sources threatens the health of dolphins.
Some boaters feed wild dolphins, not knowing that this creates a threat to both the dolphins and the humans, and that it is illegal.
In Sarasota, bottlenose dolphins share the waterways with thousands of small motor boats, yachts, barges, jet skis, and sailboats.
Because little is known about how boats affect dolphins, Sarasota is an ideal place to study how boats affect dolphin behavior.
Every six minutes during daylight hours, dolphins had motor boats pass within 100 meters
These are “urban dolphins” that are well familiar with heavy boat traffic. One Sarasota Bay study showed that the dolphins had motor boats pass within 100 meters every six minutes during daylight hours.
Noise produced by boat traffic can effect dolphin communication. We have found that as boats approach, dolphins whistle more frequently.
We don’t know yet whether boat noise interferes with dolphin communication and echolocation, or whether the dolphins might be signaling to others nearby to bunch together for protection.
Support for this project has come from, NOAA Fisheries, Earthwatch Institute, a GAANN Fellowship, the University of California Santa Cruz Ocean Sciences Department, and Chicago Zoological Society.
Human pollution, which can remain in the ecosystem for decades creates serious health hazards for dolphins.
SDRP collaborators have been assessing contaminant loads in Sarasota dolphins since the 1990s. High contaminant loads in localized are create health threats to the local population of dolphins.
Dive deeper: Read about contaminants in a local dolphin population
Chemicals in the water can contaminate fish; dolphins eating these fish then concentrate these contaminants.
Some of these contaminants build up over time threatening the health of dolphins, and especially the survival of young calves.
Sometimes humans try to give food to wild dolphins. This poses a threat to the dolphins. It’s illegal, and it’s dangerous for the humans too.
Dolphins are born to be hunters, not beggars. When people feed them, it can teach the dolphin bad habits. Mother dolphins that beg may fail to teach their young how to forage for food.
Sometimes, begging for food becomes a way of survival for dolphins, and they become dependent on human handouts. Begging dolphins often are not healthy.
Dive deeper. See dolphin animated video
A child feeds a wild dolphin. This activity creates health risks for the dolphin and is dangerous for the humans too.
In some cases, the dolphins lose their fear of people while begging. Sometimes, begging dolphins are hurt when they get too close to a boat’s propeller.
Sometimes, hanging around boats causes a dolphin to be tangled in fishing hooks and line, and this can be fatal. In at least one case, a dolphin taking discarded fish thrown to them by anglers was attacked and killed by a shark.
People are at risk too. It is not uncommon for begging dolphins to get aggressive when they don’t receive the hand-out they expect.
People have been bitten by begging dolphins. People have also been fined for feeding and harassing the animals.
You can help dolphins by educating others. Many people do not know about the laws that protect dolphins. Feeding dolphins breaks the law. By sharing this information with your friends and boaters, we are all helping protect dolphins.
Click here to download a pdf with Dolphin Friendly Fishing & Viewing Tips
While the problem of dolphin mortality in some commercial fishing gear is well known, dolphins are also known to entangle and die in recreational fishing gear as well.
Dolphins that approach anglers run the risk of getting tangled in lines, hooked by fish-like lures, or ingesting baited hooks or lures.
Three types of interactions between dolphins and anglers are on the increase:
1. Scavenging: dolphins take fish or bait discarded by anglers in boats or on piers. Wild dolphins are thus not eating wild-caught prey. Instead they develop the bad habit of approaching humans. Human discards can be very unhealthy for dolphins.
2. Depredation: dolphins remove caught-fish from fishing lines. This puts the dolphin too close to the hook(s) that caught the fish. Dolphins have been hooked and injured this way. And the injuries can prove fatal.
3. Tangling: dolphins can become tangled in the line. Tangling can restrict the dolphin’s movements and ability or fish or escape predators. Tangling can lead to skin sores and infection, which threatens the dolphin’s health. Several Sarasota dolphins had to be rescued after become wrapped in fishing line that threatened their lives.
What You Can Do:
1) Never feed wild dolphins – it’s harmful and illegal.
2) Reuse or share leftover bait.
3) Reel in your line if dolphins approach it.
4) Change locations if dolphins show interest in your bait or catch.
5) Release your catch quietly away from dolphins.
6) Check your gear and tackle: prevent breakage and losing gear.
7) Use circle and corrodible hooks.
8) Stay at least 50 yards away from wild dolphins.
9) Don’t discard your fishing line overboard. Recycle it instead.
10) Stash your trash: wild dolphins might eat pieces of it.
All photos © Sarasota Dolphin Research Program under NMFS permit #522-1785