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Earth Island Institute, Spring, 2003
IMMP has obtained a secret research report on dolphins and posted a copy on EII’s website. Prepared by scientists in the Bush administration’s
National Marine Fisheries Service (NMFS), the report reveals that thousands of dolphins are still dying in tuna nets in the Eastern Tropical Pacific (ETP), largely in tuna fleets owned by millionaires in Mexico, Venezuela, Colombia, and other tuna fishing nations.
“This report on NMFS scientists’ dolphin research clearly shows that the technique favored by the Mexican fleet and other nations to catch tuna harms dolphins,” says David Phillips, IMMP director. “The Secretary of Commerce has until the end of December 2002 to determine if he will weaken the US federal standards for the use of the ‘Dolphin Safe’ tuna label in order to allow Mexican and other tuna importers to falsely claim their tuna does no harm to dolphins. This secret report shows that dolphins are still dying in tuna nets and that weakening the ‘Dolphin Safe’ tuna label would increase the slaughter.”
The report, the result of NMFS research conducted from 1997 to 2002, includes many shocking statistics:
Despite low “reported” dolphin kills from the tuna fleets, dolphin populations remain seriously depleted. Eastern spinner dolphins remain at only 35 percent of their former numbers, while northeastern offshore spotted dolphins are at only 20 percent. Either the dolphin mortality reports are false, or dolphins are dying in tuna nets out of sight of onboard observers. More importantly, the research shows that dolphins are not recovering as expected. By some calculations, the populations may still be declining. By one analysis, it will take 65 years for depleted eastern spinner dolphins to recover, while depleted northeastern offshore spotted dolphins would take 78 years to recover. Another analysis supported by the data projects that neither species would recover after 200 years. According to calculations based on NMFS populations models, 43,590 dolphins are dying in tuna nets each year.
Nets are set on dolphins 5,000 times annually, resulting in the chasing of 9.6 million dolphins and the capture in nets of 2.3 million dolphins each year. Individual eastern spinner dolphins in the ETP are chased an average of 5.6 times each year, and two out of three captured annually. Individual northeastern offshore spotted dolphins average 10.6 chases and 3.2 captures each year. The report states that physiological stress- resulting in low birth rate, ill health, and early death-is a plausible explanation for the lack of recovery of dolphins.
At least an additional 6-10 percent of eastern spinner dolphin mortality and an additional 10-15 percent of northeastern offshore spotted dolphin mortality occurs when dependent calves become separated from their mothers during the chasing and netting process, and the percentage is likely higher.
There is no evidence of any environmental changes that could account for the magnitude of the lack of recovery of dolphin populations. Indeed, the carrying capacity of the ETP for dolphins would have to decrease three-to four-fold in order to account for the lack of recovery of dolphins.
In short, the practice of chasing and netting dolphins to catch the tuna that swim beneath is clearly the reason for the dolphins’ lack of recovery. No other explanation fits the research data or the facts.
“The American public deserves to know the truth about how tuna is caught,” says Phillips. “The Bush administration is sitting on this explosive report that details the dangers of chasing and netting dolphins. The Secretary of Commerce is poised to decide to deliberately lie to American consumers to benefit a small handful of Mexican tuna millionaires and drug lords, who would be able import tuna to the US using a phony “Dolphin Safe” label. All of the major US and European tuna processors have pledged not to buy or sell such tuna. American consumers won’t buy tuna stained by the blood of dolphins!”
from : thirdworldtraveler.com
A very small form of the spinner dolphin has been found to inhabit the Gulf of Thailand.
Ten specimens taken incidentally in a local shrimp fishery differ from specimens of this species collected elsewhere in body size and shape, skull size and shape, number of teeth and numbers of thoracic and lumbar vertebrae. Four cranially adult males were 129–137 cm long, well below the ranges for the Indian Ocean, western Pacific, central Pacific, eastern Pacific and Atlantic.
The skull is also very small. Tooth counts and vertebral counts average lower than in other series. The color pattern is not significantly different from that of spinner dolphins in the central and western Pacific, Atlantic and Indian Oceans but differs from that of the small eastern spinner of the eastern Pacific. The Gulf of Thailand specimens are morphologically separable from all other specimens, but it is to be expected that when larger samples are available there will be some overlap.
The dwarf form may overlap in body and skull size with small spinner dolphins taken incidentally in a gillnet fishery for sharks off northern Australia. The geographic range of the dwarf spinner may be restricted. The size and status of the population and the impact of the shrimp fishery are unknown and should be investigated. The dwarf spinner may have an ecology different from that of other spinners, feeding mainly on reef-associated and benthic organisms rather than mesopelagic animals.
by : William F. perrin, Nobuyuki Miyazaki, Toshio Kasuya
Marine Mammal Science
Volume 5 Issue 3 Page 213 – July 1989
Spinner Dolphin Pictures, Behaviors and Information (provided by the Wild Dolphin Foundation)
The Hawaiian Spinner Dolphins are under threat from unrestricted and unregulated growth of tourism. Please sign our petition to help them.
There are many species of dolphins (nai’a) swimming in the tepid waters of Hawaii, the most common are the Hawaiian spinner, spotted (kiko), bottlenose and roughtooth dolphins. Other often seen members of the dolphin family – although termed as whales (kohola)- are pilot and false killer whales. Dolphins in Hawaii are commonly termed as “porpoise” by local folks, especially fishermen, who use the word “dolphin” when referring to the dolphin fish, or mahi mahi.
So called for their high, spinning leaps, spinner dolphins are known as playful, eager bow-riders throughout much of their range. But in the eastern tropical Pacific, where tuna fishermen have killed millions of spinners since 1959, the dolphins no longer approach ships. In Hawaii, they not only approach ships, but could be termed the oceanic “Ambassadors of Aloha” (aloha – recognition of the god of life within another, a combination of joy, harmony, gentleness, compassion, humility, generosity and patience). There is some belief that Native Hawaiians (Kanaka Maoli) deemed porpoise to be a oceanic tribe with equal rights as human villagers. They worked cooperatively with porpoise to fish then and do to this day.
This may still ring true today as modern fisher-people enlist the dolphins help in finding prime food fish. Probably since the islands have formed, the Hawaiian spinner dolphins have come into nearshore daytime habitats along the west coast of Oahu. We have traced it back to 800 years, hard to go back further given that Hawaiian was not a written language (oral history) until post western contact.
In the near-coastal waters of Oahu, spinner dolphins are seen on an almost daily basis in near shore waters. Hawaiian Spinner dolphins are shaped and colored somewhat differently from other spinner dolphins.
Our wildlife tours focus on education and conservation so that an interactive relationship can be maintained in the best interest of both humans and dolphins. We teach admiration and deep respect for these wonderful mammals. Below are descriptions of daytime behaviors spinners frequently engage in. Pictures were taken during our dolphin encounter charters.
Stenella longirostris “Nai’a”- PHYSICAL TRAITS
Size :
1.7 to 2.2 m, 75 kg. Males slightly larger than females
Calves at birth :
77 cm
Teeth :
45 to 65 sharp-pointed teeth on each side of upper and lower jaw
Food :
Fish (small deep-ocean species) and squid
Habitat :
Mainly offshore
Range :
Tropical, subtropical and warm temperate world ocean
Status:
Population unknown, but common in most parts of its range. Substantial declines have occurred in the easter tropical Pacific
To see the enlarged pictures, please click on the desired picture. Double click to open movies.
Spins
The Spinner dolphins are famous for their fantastic jumps high out of the water. They can leap into the air and make as many as 7 complete spins before diving back into the ocean again! Few dolphins are known to leap as high as the Spinner and except for the Clymene dolphin, no others can spin. Why Do Spinner Dolphins Spin?
Note: Click on the picture to the right to see good spin video >>
Head-Over-Tail
This aerial behavior is probably the most energetic. While the spin is more like a top, this leap is a series of mid-air somersaults.
Note: Click on the picture to the right to see head over video >>
Head Slaps
This very young spinner has already learned a way to get mom’s attention. Repeated head slaps send an acoustical message. Notice the pinkish underside, normally white, this could mean excitement or the product of vigorous slapping!
Tail or Peduncle Slaps
Often seen before a change in the pods behavior. Most often, immediately after we see this behavior, the pod will change its traveling direction. Tail slap video and how it looks from underwater. The dolphin is excited about his “play toy!”
Nose-Outs
Often seen before going into a rest mode, or when they seem to have interest in us. These, although still classified as aerial behaviors are the least energy taxing.
Fluke-up Dive
Dives with the tail (flukes) raised in the air seem to signal deep dives. This a borderline aerial behavior – as it still happens above the water line, but is not very active.
Playing Behavior
Spinners often make “play-toys” of objects in their environment. In our area, the tradewinds blow lightweight plastic grocery bags into the ocean. The dolphins drape these over their fins and pass them back and forth.
Note: Click on the picture to the right to see dolphins play video >>
Echelon Swimming
Newborn calves can be seen swimming near their mothers head for about a week before they swim nearer to her dorsal fin. This is termed as echelon swimming. Dolphins carry their young inside their womb and gestation is about 12 months for a bottlenose. The baby emerges tail first, and will suckle from its mother for up to 4 years.
Breathing
Oceanic dolphins have evolved a method of breathing without surfacing from the water. They blow a bubble when near the water surface and then quickly draw breath in when the bubble forms a bridge 
between the blowhole and the air, through the water. Dolphins breathe through their blowhole located at the top of their head. A dolphin may empty and refill its lungs in less than a fifth of second. As the dolphin breathes the air leaves the blowhole at speeds of over 100mph. To sleep, a dolphin must shut down only half of its brain, as its breathing is under voluntary control.
Social Behavior
Spinner dolphin’s pectoral flippers are used to steer them through the water, and they also use them to stroke one another, increasing the social bond between them. Dolphin “friends” may swim along face to face touching flippers. Dolphins that appear to be closely bonded may swim in synchrony, twisting, turning and swimming in perfect harmony together.
Whistles
Spinner Dolphins can be very noisy under and above water, click here to hear for underwater video and sound of spinner dolphins vocalizing and a signature whistle.
from : sailhawaii.com
1. Dolphins are mammals; they nurse their young from mammary glands.
2. Dolphins can swim up to 260 m. below the surface of the ocean, although they are mainly shallow divers.
3. Dolphins can stay up to 15 minutes under water although they usually stay only a few minutes diving.
4. Dolphins use a technique called echolocation to find food and navigate.
5. Dolphins are social beings which live in groups and cooperate among each other for activities like getting food and calf rising.
6. There are 32 species of ocean dolphins and 5 species of river dolphins.
7. The largest dolphin is the “killer whale” (orca), which can grow to 6.1 meters long.
8. The most known dolphin is the “bottlenose dolphin” which can grow to 2.5-2.8 meters.
9. Dolphins are warm-blooded and their internal temperature is around 36 degrees. To conserve this temperature they are surrounded by a thick layer of fat called “blubber” just below the skin.
10. The average botllenose dolphin brain weighs 1500-1600 grams, while average human brain weighs 1200-1300 grs. This is not a conclusive evidence of dolphin intelligence as many other factors might be the cause of intelligence according to scientists.
11. Dolphins can make a unique signature whistle that may help individual dolphins recognize each other or perform any other kind of communication still unknown.
12. Bottlenose dolphins can swim 5 to 12 kilometers per hour, although they can reach up to 32 km/h.
by : Laurent Mikhail
Laurent Mikhail is a dolphin fan. You can find all the information about dolphins in his site :
http://www.dolphins-world.com/
Swimming with dolphins in the wild is an amazing experience because you get the opportunity to interact with these incredibly friendly and intelligent animals on their own turf.
Unlike captive dolphins who have no choice but to interact with human beings whether they want to or not, wild dolphins can choose whether they want to stick around and swim with you and if they don’t they have the freedom to simply disappear into the deep blue sea which makes it all the more special when they do decide to stay (which occurs on a frequent basis).
There is a huge debate raging about the ethics of swimming with captive dolphins and even though there are definite benefits for humans (treatment for depression and disabilities) captivity is harmful to the dolphins as they suffer from stress and illness and have a much shorter life expectancy than similar dolphins in the wild. The demand to swim with captive
dolphins also encourages capture from wild populations that are already under threat which is very detrimental to the environment.
On the other hand, studies conducted on the effects of humans swimming with dolphins in the wild have shown that there seem to be no ill effects to the animals if it is done responsibly and sensibly (not by chasing and herding them or noisy splashing in the water).
The jury is still out because long term trends need to be taken into consideration but until such time as the scientific uncertainty is cleared up or the dolphins move away because they are feeling harassed, responsible swimming with wild dolphins is an ethical way to interact with them and tourism revenues generated provide a strong incentive for dolphin conservation.
So if you have a dream is to go swimming with dolphins, going the wild route with an ethical and responsible operator is the way to do it. Here are the top five places in the world to swim with wild dolphins …
1. Kaikoura, New Zealand
The best place in the world to swim with wild dusky dolphins because the success rate of finding and swimming with the pods is very high. The dolphins are attracted to the nutrients in the
water that are available due to a 1200 meter trench situated just off the coast.
2. Oahu and Kona, Hawaii
You will find spinner and spotted dolphin here and some of the boat operators boast a 99% success rate of finding the pods on day trips.
3. Azores Archipelago
If you want dolphin variety then this is where you will find it as up to eight different
species call this home and it’s possible to see super pods of up to 1000 individuals here too.
4. Bimini, Bahamas
One of the advantages of swimming with dolphins here is the fact that the water is very warm, shallow and clear but it’s important to remember that these are wild creatures and 20% of the time they don’t come closer to the boat and rather swim away.
5. Red Sea, Egypt
Spinner and bottlenose dolphins can be found in these waters and travel operators have a very good record of finding dolphin pods in this area.
by : Bruce Whittaker
SPECIES :
Stenella Longirostris
DESCRIPTION :
Slender, with a long, thin beak, the Spinner Dolphin has a distinct stripe connecting the long, pointed flippers to the eyes.
SIZE :
Spinner Dolphins weigh 45kg – 75kg (100 – 165lbs) and measure 1.3m – 2..1m (4.25ft – 6.89ft)
POPULATION :
Unknown
RANGE :
Spinner Dolphins are found in tropical and subtropical oceans worldwide.
HABITAT :
Spinner Dolphins are found in tropical and subtropical oceans worldwide.
FOOD :
Spinner Dolphins take midwater fish and squid. They differ from other dolphins in that they feed at night.
BEHAVIOR :
Groups range from a few to a few thousand animals. Spinners often mix with pilot whales, spotted dolphins, yellowfin, and skipjack tuna. They rest in shallow waters and inlets, usually feeding after resting.
OFFSPRING :
Spinners mate once or twice a year. Adult females give live birth to one calf every 2 or 3 years.. Gestation period averages10.6 months, but the calf is usually weaned after 7 months.
THREATS :
Most significant threat to the Spinner Dolphin is getting caught in tuna nets. In 1990, “Dolphin Safe” labels (certifying that no dolphins were encircled to catch tuna) were placed on tuna cans, reducing dolphin deaths in tuna nets by 97 percent. Pressure from foreign trading nations has weakened the standards of the current label. Defenders of Wildlife has filed a lawsuit to help save the dolphins. Write to Secretary Donald L. Evans, Department of Commerce, Washington, DC 20230 and let him know how you feel about actions that may harm dolphins.
PROTECTION :
Protection: *CITES, Appendix II
*Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international treaty with more than 144 member countries. Appendix I species cannot be traded commercially. Appendix II species can be traded commercially only if it does not harm their survival.
from : kidsplanet.org
Kingdom :
Animalia
Phylum :
Chordata
Class :
Mammalia
Subclass :
Eutheria
Order :
Cetacea
Suborder :
Odontoceti
Family :
Delphinidae
Genus :
Stenella
Species :
Stenella longirostris
Range :
The Spinner Dolphin (Stenella longirostris) is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which they will spin longitudinally along their axis as they leap through the air.
:: TAXONOMY
The Spinner Dolphin is sometimes referred to as the Long-snouted Spinner Dolphin, particularly in older texts, to distinguish it from the similar Clymene Dolphin which is often called the Short-snouted Spinner Dolphin. The species was discovered by John Gray in 1828. There are four named subspecies:
- Eastern Spinner Dolphin (S. l. orientalis), found in the
tropical eastern Pacific. - Central American or Costa Rican Spinner Dolphin (S. l.
centroamericana), also found in the tropical eastern Pacific. - Gray’s or Hawaiian Spinner Dolphin (S. l.
longirostris), found in the central Pacific around Hawaii but represents a
mixed bag of broadly similar subtypes found throughout the world. - Dwarf Spinner Dolphin (S. l. roseiventris), first found in
the Gulf of Thailand.
However the species display a greater variety than these subspecies might indicate. A hybrid form characterized by its white belly is noted in the eastern Pacific. Other less distinct groupings have been identified in other oceans.
The specific name comes from the Latin for long-beaked.
:: PHYSICAL DESCRIPTION
The bulk of the dolphin is dark grey, with darker patches in the tail stock, back and throat. Usually it has creamy-white patch on the belly though this varies considerably. The beak is distinctively long and thin, with a dark tip. The fins too are lengthy for dolphins of this size. The dorsal fin is erect and even leans forward in older males found in the eastern Pacific. However this description has to be described as a little loose – Spinner Dolphins are the most variable in form of all cetaceans.
Adults have varied in size from 129 cm to 235 cm and weight from 23 kg to 78 kg. The gestation period is 10 months. Individuals reach maturity at 4-7 years (females) and 7-10 years (females). Longevity is unknown.
Spinners congregate in groups that vary from just a few dolphins to great schools numbering in the thousands. They are consistly acrobatic and keen bow-riders. The reason for the creature’s spinning is not known. One suggestion is that the great cauldron of bubbles created on exit and re-entry make act as a target for echolocation by other individuals in the school. It may also be
simply play-acting. Individuals have been spotted completing at least 14 spinning jumps in quick succession.
In the Atlantic the Spinner may be mistaken for the Clymene Dolphin which also spins, but not to such a regular and dramatic extent. The species also shares common characteristics with the Pantropical Spotted Dolphin.
:: POPULATION AND DISTRIBUTION
Spinner Dolphins occur in pelagic tropical waters in all the world’s major oceans. Although they mainly live in the open ocean, they are sometimes found near the shores of tropical island chains such as in the waters off Hawaii. Their greatest population density occurs between the Tropics of Cancer and Capricorn. Although described as pantropical the species roughly divides up into
geographical areas corresponding to subspecies. The total population is unknown and was certainly dramatically reduced by fishing activity in the eastern Pacific, but is still regarded as endangered.
:: HUMAN INTERACTION
Spinner Dolphins have been studied both in the wild and in captivity in Hawaii. Up to two million Spinner Dolphins, mostly eastern and white-bellied varieties, were killed in the thirty years after purse seine fishing for tuna was introduced in the 1950s. The process killed probably half of all Eastern Spinner Dolphins. See Pantropical Spotted Dolphin for a discussion.
Although not caught in purse seine nets, spinner dolphins in Hawaii can be subjected to multiple daily visits to their nearshore resting grounds. If continued without strong regulations, the magnitude of people desiring wild dolphin encounters and some not-so-ethical tour operators exploiting the proximity of nearshore dolphin habitats while guaranteeing up-close interactions
may result in the ‘loving nature to death’ syndrome as found in similar areas, e.g. the Orcas of the Pacific Northwest.
