It is interesting to note that the ancient Greeks worshiped
the dolphin. Killing of dolphins was punishable by death in ancient Greek society. The people of ancient Crete believed
dolphins were gods.
The natural predators of the dolphin are tiger sharks, great white sharks,
and bull sharks as well as Orcas, commonly known as killer whales (although the Orca is really another species of
marine dolphin). Generally, these predators prey on weak or injured dolphins. When a shark attacks a dolphin it will
often tear off the flukes, disabling the animal and causing it to swim in circles, bleeding and exhausted. It then becomes
an easy meal for the predator with little risk of fighting back. Dolphins tend to move out of areas in which sharks are abundant.
Sharks and orcas account for a number of dolphin kills each year, but far
more dolphins are killed by man through destruction of the dolphin's habitat, incidental catch, and harassment of wild animals.
Today, the Bottlenose is threatened by a number of factors. These include
injury and death due to inappropriate fishing practices with gillnets, crab pots, shrimp trawling and seining. Long
line fishing is also a major threat to this animal. Of these fishing practices, gillnetting causes the largest mortality in
dolphin populations.
Following commercial fishing vessels, dolphins are able to increase their opportunity to find tuna and other
fish in high concentrations. When the gill nets and seines used by these vessels trap the desired schools of fish, they also
trap the dolphins feeding on them. As dolphins must surface to breathe air, they will drown if they are not quickly released
from these nets and seines.
Efforts by some major commercial fishing industries to avoid inadvertant capture of dolphins as "by-catch" (such
as in tuna fishing) have helped to reduce the accidental killing of dolphins.
The Bottlenose is protected by the Marine Mammal Protection Act of
1972 and is listed by this organization as "depleted". The passing of this act is largely responsible for the designation
of "Dolphin Safe" tuna (tuna caught without the netting of dolphins as by-catch). As a result, dolphin deaths due to inappropriate
fishing practices have declined from over 5,000 in 1990 to 0 in 1996. As a result of this act, in 1991 the United Nations
adopted a resolution very similar to the MMPA, establishing a global moratorium on the reduction of dolphin populations. This
has been effective in reducing the dolphin death rate, particularly in the eastern Pacific Ocean.
Pollution, parasites, naturally occurring biological toxins, and viruses are also responsible
for dolphin deaths. 63,000 chemicals are in use worldwide, many reaching our oceans. Materials such as pesticides
and heavy metals are dangerous to the dolphin, concentrate in its blubber and enter the milk fed to its calves. The health
of our oceans is crucial to man's survival and the dolphin may well serve as an "indicator
species" of impending changes in our marine environment, both chemical and physical. Improvements in our environment
may relate to changes researchers are able to observe in the lives of dolphins.
In July, 2009 is was reported that there are
approximately 3,000 discarded and lost fishing nets underwater in Puget Sound, Washington. Some of these nets are as large
as a football field. They continue to inadvertently snag marine wildlife, including dolphins. Unable to surface for air, these
dolphins drown within a few minutes. As part of the federal economic stimulus package, $5 million has been provided to hire
local divers to retrieve these nets, but months will be required to complete this important conservation effort.
NOAA (the National Oceanographic and Atmospheric Association) in March,
2009, issued an alert, warning of fines up to $20,000.00, imprisonment up to 1 year, and potential bite danger to
humans when approaching, feeding or harassing dolphins. Intentional human contact with wild dolphins reduces their fear of
people and can negatively alter their natural feeding instincts and reduce the ability of dolphin cows to teach their calves
to hunt for food.
Since 2006 there has been a reported increase in dolphin deaths due to "depredatory" behavior. Depredation is
when another aquatic animal steals an anglers' bait during recreational fishing. In Florida it is common for alligators,
sharks and dolphins to do this. The waters off the coast of Florida support a great number of recreational anglers. Dolphins
will attempt to steal bait or hooked sport fish from anglers' gear. The dolphin will become entangled in the fishing
line or more often will swallow the fishing hook and attached monofilament line in the "stealing" process, causing injury
or death to the dolphin. Oftentimes the injured dolphin will strand and die. Increased stranding due to depredatory behavior
has been noted in the Indian River Lagoon and Southwest Florida areas the last 4 years. To date over the last 4 years, NOAA
reports 13 Bottlenose dolphins have been found stranded due to such behavior in this area of Florida. Although this number
may seem small, it is significant. The Atlantic Bottlenose stock in this area does not migrate and any loss of members is
not replaced by new members immigrating to the Southwest Florida area.
What can you do? If you are fishing and see dolphins near your gear, retrieve your gear and move elsewhere to
fish. Do not cast fishing gear near visible dolphins. If you hook a dolphin accidently, provide slack in the line to allow
the dolphin to release itself. If this does not work, cut the line off as near the hook as possible to release the animal.
Use hooks that are NOT stainless steel and will corrode, eventually dropping out of the dolphin's mouth. Do not release caught
fish near an area inhabited by dolphins. That practice will attract more dolphins and will teach them they will
be fed near fishing vessels. Avoid tossing overboard any leftover bait for the same reasons.
The International Whaling Commission is another organization founded to
protect the future of, among other animals, the Bottlenose dolphin. Members of the IWC are asked to report inappropriate catching
of dolphins, including the accidental entanglement of these animals in fishing gear.
The Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES) includes Bottlenose dolphins as a species which is threatened and likely to become endangered if it is not
appropriately protected.
Some dolphin experts are becoming increasingly concerned over the "swim with" programs now so popular in certain
parts of the world. They feel these programs may negatively alter the behavioral patterns of wild dolphins, causing them
to become more dependent upon man for providing their food. Increased wild dolphin aggression may also occur as a result of
these programs. A doubling in the rate of calf mortality has been observed in areas where wild dolphin populations are
associated with these "swim with" programs.
Unfortunately, Japan, Taiwan, Peru and Sri Lanka continue to harvest dolphins for human consumption,
leather, oil and fertilizer production, even though this is in violation of international law. Thousands of dolphins
are taken each year in Japan for consumption. Although, according to the latest statistics, the numbers of dolphins being
captured by the Japanese appears to be down, the majority of these captured animals are still being killed (as illustrated
in the following graph).
"Drive hunts", used by the Japanese to capture and/or kill dophins continue to occur (see the dramatic video
below).
Site Content
Understanddolphins.com contains information condensed from a number of reputable technical sources,
peer reviewed journal articles, and respected dolphin research facilities, as well as from my personal experiences and
observations as a dolphin VIP Tour Guide and Educator.
I have made every attempt to support the information presented in this site with video and still
photographic images. On a regular basis I plan to produce more of these images and will continue to update the site with these
as well as with any new and scientifically verified information which becomes available.
