Fluke-Up Feeding in Hawaiian Waters

In the past few weeks our office has received numerous calls from concerned citizens about seeing a whale in distress.  The whale observed is spending long periods of time at the surface with its flukes extended above the water’s surface.  Some have conjectured that it is a whale using its tail flukes to sail; others have suggested it is attempting to cool down using its tail as a thermoregulatory device.

We believe a different hypothesis to be true.  The whale with the extended flukes is most likely a female humpback with a newborn calf. The mother is resting while still allowing her calf access to her mammary glands (located near the posterior portion of her body some 6-8 feet from her flukes).  By extending her tail into the air she is able to keep her body relatively close to the surface, allowing her to rest while minimizing dive depths for her young calf.  The calf is then able to nurse at will and expend less energy.

While it is rare to see a female displaying this resting/nursing posture in Hawaii, it is not without precedent.  PWF researchers have observed this feeding behavior in over three dozen female humpback whales off east Australia since 1984.  It appears to be a socially transmitted behavior: initially just a few whales employed this resting and feeding posture, and over the past 20 years we have seen a steady increase of females displaying this behavior. We refer to it as “fluke-up feeding”, or “tail-up feeding”, and once an animal employs this method, they then tend to repeat the behavior with subsequent calves.

The gestation period for humpback whales is between 10 and 12 months, and they have only one calf at a time. A whale has never been seen with two live young, but there are records from the whaling days of a pregnant whale with two fetuses. Humpback whale calves observed in Hawaii are both conceived and born in the Hawaii region. Surprisingly, there is little firsthand evidence of birthing. Scientists have observed newborn calves with their dorsal fin still folded flat against the back and fetal folds along the body. There have also been reports of a placenta being recovered while floating at the surface of the water.

A recent finding by Murdoch University Cetacean Research Unit in West Australia reveals nursing occurs at an average depth of 16 feet.  Most calves nurse throughout the day, and spend 30% of their time nursing in a 24-hour period.  Although most calves nurse opportunistically throughout the day, some females only nurse their calves during the morning hours, and others nurse only at night. Humpback whales have two nipples which, when nursing, will protrude through the mammary slit. To nurse, the calf curls a specially shaped tongue around the nipple and the thick, fatty milk is reflexively squirted into the calf’s mouth. Humpback whale calves drink many gallons of milk per day, which allows them to grow quickly. Newborn humpback whales average 12-14 feet in length and weigh upward of two tons. Lactation continues for 10-11 months and once the calf has weaned, it has little contact with its mother.

There is no need to be alarmed at the sight of a whale with its tail extended for long periods of time: the animal is neither injured nor in harm’s way.  In this case it is a mother who has figured out a novel way to feed her calf while resting and conserving her energetic resources for the long journey back to the northern feeding grounds.

FACT OF THE WEEK: False Killer Whales Call Hawaii Home

MORE ON THIS: False killer whales, while a globally distributed species, have a special tie to Maui and the four-island region. Recent research has found that a very small group of this odontocete, or toothed whale species,  calls Hawaiian waters home, making them genetically different from offshore groups. This makes this population especially interesting because false killer whales are generally thought to prefer deep ocean environments far from any land.

Genetic tests were completed on samples collected from groups of false killer whales around the main Hawaiian islands and locations throughout the North Pacific. Researchers found samples collected from individual whales close to the Islands were most genetically unique when compared to samples from whales in the Pacific Ocean, Panama and Mexico. The uniqueness of the samples indicates there are two separate populations; an inshore population and an offshore population.

Their acrobatic displays and tendencies to bow ride make false killer whales hard to miss if you are lucky enough to see one. Hawaii insular population numbers are predicted to be as low as 123 individuals, with only 46 capable of breeding. There is good news though. The insular false killer whale population was classified as an Endangered Species in 2012, meaning this population now has extra protection. Keep your eyes open. If you’re lucky you will see one of Hawaii’s very own false killer whales.

FURTHER READING:

  1. Protecting Hawaii’s False Killer Whale. Pacific Whale Foundation. Accessed October 8, 2015
  2. Baird, R. (2009). A review of false killer whales in Hawaiian waters: biology, status, and risk factors. US Marine Mammal Commission: 1-40.
  3. Chivers et al. (2009). Genetic Variation and Evidence for population structure in eastern North Pacific false killer whales. Canadian Journal of Zoology, 85: 783-94.

Written by Chelsea Brown

FACT OF THE WEEK: Hairy Humpback Whales

FACT OF THE WEEK: Humpback whales have hair!

MORE ON THIS: You probably know that whales and dolphins are marine mammals. Marine mammals, like terrestrial or land mammals, must have a certain set of characteristics to be called mammals – these include giving birth to live young and having hairs on their bodies. But where are the hairs on whales?

In fact, you have probably seen the hairs on humpback whales and not known what they were. The bumps on the rostrum, or head, and the pectoral fins of a humpback whale are, in fact, hair follicles. Called “tubercles,” these fist-sized bumps contain one hair follicle each, connected to a set of sensitive nerves. Why do humpback whales have these sensitive whiskers? There are multiple speculative theories in scientific literature, but no consensus.

Some think that tubercles serve as a sensory organ for the whale. It is thought that the single hair in each tubercle is used to detect temperature change in the water, the speed of the whale, and may even help to detect the presence of prey in the whale’s “blind spots.” Along with the idea that these tubercles serve a sensory purpose, comes an idea that tubercles assist with the hydrodynamics of the animal. It has been shown that these bumps increase lift and decrease drag in the water. Humpbacks are assumed to be one of the most acrobatic whales for their size. These tubercles may be a contributing factor for their agility.

Whale tubercles have inspired design ideas behind wind turbines, airplane wings and propellers. An energy company called WhalePower is applying tubercle-inspired bumps to numerous types of wind turbines and fans including industrial ceiling fans and computer fans to improve their efficiency, safety, and cost-effectiveness. These hairy humpback whales have inspired a new type of “greener” energy technology.

FURTHER READING:

  1. Forestell, P. H. and Kaufman, G. D. 2008. Humpbacks of Hawaiʻi: The Long Journey Back. Hawaii, USA. 216 pages.
  2. “Whalepower.” N.D. The Science.
  3. Canter, N. 2008. Humpback whales inspire new wind turbine technology.

Written by Stephanie Stack

FACT OF THE WEEK: Bio-Fluorescent Coral Flaunts Underwater Light Show

MORE ON THIS: It is easy to see the beauty of coral reefs when snorkeling or diving during the day, but have you ever seen the colors of coral at night?

Coral reefs are known to put on a light show known as bio-fluorescence.  A family of proteins provides this fluorescence by absorbing one color and emitting another.  Each protein provides a different color; the most common is the green fluorescent protein known as GFP.  When the wavelengths of color are absorbed then re-emitted, some of the energy is lost.  This changes the wavelength, which determines the color.

Species of coral known to give off this fluorescence are found in Hawai‘i and can be seen on night dives with special dive lights.  If you’re interested in seeing this phenomenon, you can contact your local dive shop to ask about night diving to see fluorescent coral or, if you’d like to stay dry, you can visit the Maui Ocean Center which has some of this coral on exhibit.

It is unknown why fluorescence occurs, but there are speculations from scientists.  Some believe that it acts as a sunscreen for the coral.  Researchers also have proposed that the fluorescence creates light to allow algae to grow in deeper water; algae is the major food source of most corals.

Research is focusing on coral fluorescence for several reasons.  The first reason is due to the fragile state of coral reefs in our climate-changing world.  Some studies suggest that the intensity of the fluorescence can be a sign that the coral is under stress and may indicate that the coral is about to bleach.

Medical research is also greatly benefiting from coral fluorescence research.  The same proteins the corals use to fluoresce are being used to help monitor biological processes within diseases to further understand how they work. This is done by using the fluorescence as a marker so scientists can watch cells divide or viruses spread.

FURTHER READING:

  1. Roach, John. 2005. “Glowing Coral Proteins Aid Medical Research.” National Geographic. http://news.nationalgeographic.com/news/2005/01/0112_050112_coralproteins.html
  2. Roth,  Melissa S., Fran, Tung-Yung, Deheyen, Dimitri D. 2013. “Life History Changes in Coral Fluorescence and the Effects of Light Intensity on Larval Physiology and Settelement in Seriatopora hystrix.” Plos One. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0059476
  3. University of California – San Diego. 2013. “Fluorescent light revealed as gauge of coral health: Mysterious glow of light found to correlate with coral stress prior to bleaching.” Science Daily. www.sciencedaily.com/releases/2013/03/130312092918.htm.

Written by Sarah Mousel

FACT OF THE WEEK: Hawaii’s State Mammal is Critically Endangered

MORE ON THIS: To native Hawaiians, this furry creature may be referred to as ‘llioholoikauaua, but you personally know them as Hawaiian monk seals. These monk seals are endemic, meaning they are only found in Hawai‘i. They are one of the most endangered animals in the world, with their population of about 1,100 still declining.

These marine mammals are semiaquatic, spending most of their time at sea and some of their time on land.  “Hauling out” is a process where the seal goes onto the beaches to sleep, nurse, molt and rest. Here, a mother will nurse her pup for about 6 weeks and then the roughly 200-pound pup will have to fend for itself. An adult will grow from 6 to 7.5 feet in length and will weight between 375 to 600 pounds. They are generalist feeders, feeding on what is readily available, such as squid, eel, octopi, fish, and crustaceans.

There are many dangers that threaten the life of a monk seal. Food limitations, marine debris entanglement, falling victim to bycatch, mother-pup disturbances and illegal sealing (killing) are some of the anthropogenic, or human-caused, threats to these mammals. Disease outbreaks, predators and low genetic diversity are some of the natural threats that can harm them.  However, overfishing, littering, utilizing harmful fishery equipment, and harassing or killing seals are all very crucial things that humans can cease doing to promote population growth. Natural disturbances may not be able to be avoided, but humans can learn to live in harmony with these animals.

What we can do to help is:

  • give the seals lots of space when hauled out or in the water
  • follow fishing guidelines and restrictions
  • pick up litter
  • report stranded or entangled seals to the NOAA Fisheries Marine Mammal Hotline at 1-888-256-9840
  • report harassment to NOAA Fisheries Office of Law Enforcement at 1-888-853-1964
  • report ALL sightings of monk seals on Maui to (808) 292-2372

Many foundations around the island may also have volunteer opportunities for the public. Educating the public around hauled out seals and helping with population counts can benefit them immensely.  Even you can help the monk seal!

FURTHER READING:

  1. Hawai‘i Wildlife Watching Guide: Hawaiian Monk Seal. Pacific Whale Foundation. 2010. http://www.pacificwhale.org/sites/pacificwhale.org/files/Monk-Seal-Guide.pdf
  2. Protected Resources Division. NOAA. 2010. http://www.fpir.noaa.gov/PRD/prd_hms_population_threats.html
  3. Hawaiian Monk Seal. National Geographic. n.d. http://animals.nationalgeographic.com/animals/mammals/hawaiian-monk-seal
  4. Who’s Killing Hawaii’s Monk Seals? Huffington Post. 2013. Nathan Eagle & Sophie Cook. http://www.huffingtonpost.com/2013/12/06/killing-monk-seals_n_4399723.html

Written by Melissa Freese

Hawksbill turtle hatchling. Photo courtesy of Cheryl King, Hawaii Wildlife Fund.

FACT OF THE WEEK: Hawksbill turtles are nesting on Maui

MORE ON THIS: In Hawai‘i, Hawksbill turtles mostly nest on Hawai‘i Island, but Maui is home to some of the nesting beaches for ten of these turtles.  Beginning around age 20, a female will return to the area where she was born between May and October every 3 to 9 years to lay her eggs.  Hawksbills will nest at night and will lay 2-5 sets of eggs, or clutches, in the same season. Each clutch will be laid approximately 16-23 days apart.  To lay eggs, the turtle will haul out onto a beach to find a suitable area, dig a deep pit using her flippers, and then fill the pit with her eggs.  A single clutch averages 180 eggs.  Once she is done laying her eggs, she will use her flippers to fill the hole in with sand before returning to the sea.

After approximately 60 days, the eggs will hatch and tiny turtles will begin racing towards the sea.  This is one of the most dangerous times in their life and many don’t make it, except for on Maui where Hawai‘i Wildlife Fund closely monitors each nest to ensure each hatchling crawls to the ocean safely.  A variety of larger animals such as crabs or birds will prey on the small turtles as they make their way to the water.  Hawksbill turtles are listed as endangered throughout the world, including in Hawai‘i, largely in part because of humans.  They have been exploited for many years for tortoise shell, which is thought to make beautiful décor.  Other threats include habitat loss from coastal development, marine debris, being caught as fishing by-catch and light pollution.

Adult Hawksbill Turtle. Photo courtesy of Cheryl King, Hawaii Wildlife Fund.

Adult Hawksbill Turtle. Photo courtesy of Cheryl King, Hawaii Wildlife Fund.

What is being done to help these turtles?  Organizations such as Hawai‘i Wildlife Fund, NOAA, and US Fish and Wildlife Service have built turtle fences to prevent turtles from crossing roads, and created annual nesting and hatching patrols.  They are also working with local home owners, businesses and resorts to reduce coastal lighting that may prevent turtles from nesting on beaches and/or confuse hatching turtles and cause them to head inland instead of out towards the sea.  With these efforts, hawksbill turtle populations will hopefully be on the rise.

Sea turtles are protected under state law and the US endangered species act. It is illegal to harass, kill or capture a sea turtle. If you ever spot a hawksbill on the beach, take a photo of one while swimming, or would like to be a volunteer to help with nesting and hatching patrols, please contact Hawai‘i Wildlife Fund at (808)280-8124 or wild@aloha.net

FURTHER READING:

  1. Hawai‘i Wildlife Watching Guide: Sea turtles. 2010. Pacific Whale Foundation. Available online: http://www.pacificwhale.org/sites/pacificwhale.org/files/Sea-Turtles-Guide.pdf
  2. Hawksbill Sea Turtle. 2014. Florida: US Fish and Wildlife Service. Available online: http://www.fws.gov/northflorida/seaturtles/turtle%20factsheets/hawksbill-sea-turtle.htm
  3. Hawaiian Hawksbill Sea Turtles. N.D. NOAA-NMFS and Hawai‘i Wildlife Fund. Available online: http://wildhawaii.org/documents/hawaiian_hawksbill_brochure.pdf

Written by Sarah Mousel