spinner dolphin – NOAA Teacher at Sea Blog

NOAA Teacher at Sea
Suzanne Acord
Aboard NOAA Ship Oscar Elton Sette
March 17 – 28, 2014

Mission: Kona Area Integrated Ecosystems Assessment Project
Geographical area of cruise: Hawaiian Islands
Date: March 21, 2014

Weather Data from the Bridge at 14:00
Wind: 6 knots
Visibility: 10 nautical miles
Weather: Hazy
Depth in fathoms: 2,275
Depth in feet: 13,650
Temperature: 25.1˚ Celsius

Science and Technology Log

The Bridge

Learning how to use the dividers for navigational purposes

The Sette crew frequently encourages me to explore the many operations that take place around the clock on the ship. I continue to meet new people who complete countless tasks that allow the Sette to operate smoothly and safely.

XO Haner explains how the radar functions on the bridge

NOAA Corps officers operate the bridge. The bridge is the central command station for the ship. NOAA Corps officers consistently ensure that everyone and everything on board is safe. Officers alternate shifts to monitor all radios and radar twenty-four hours a day.

They use numerous instruments to determine the ship’s location. A magnetic compass, maps, dividers, triangles, radar, a steering wheel, and visual observation are just a few of the resources used to guarantee we are on course. According to the NOAA Corps officers, the traditional magnetic compass continues to serve as one of the most reliable tools for navigation.

Location and weather data are officially recorded in the deck log on an hourly basis. However, officers are keeping an eye on the radar, compasses, and weather conditions every moment of the day. On top of that, they are monitoring nearby marine life, boats, and potential hazards.

Teamwork: NOAA Corps officers on the bridge

Personal Log

Marine Mammal Observation Off the Kona Coast

Ali Bayless, Our Marine Mammal Observation (MMO) Lead, has thus far organized three MMO trips out on one of the small boats. Dropping a small boat from the Sette is a task that involves excellent and efficient communication among at least a dozen crew members. The small boat is carefully dropped into the water. Boat operators and scientists then climb down a ladder in their hard hats and lifejackets to embark on their day trip. Today, I was fortunate to take part in one of these MMO expeditions. Two scientists, two boat operators, and I ventured away from the Sette for three hours in hopes of spotting and hearing marine mammals. Excitingly, we did indeed spot up to one hundred spotted dolphins and spinner dolphins.

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If you look closely at the photos, you can see round spots on the dolphins. Our MMO lead believes these are cookie cutter shark bite marks. This is an indication that cookie cutter sharks live in this vicinity. Two of our scientists from the Monterey Bay Aquarium are hoping to return to the Monterey Bay Aquarium with live cookie cutter sharks for the aquarium’s educational exhibits. There is a good possibility that we will find these sharks in our trawl lines that will be dropped later this week.

Listening to whales using the hydrophone during small boat operations. — Listening to whales using the hydrophone during small boat operations

Science Party Interview with Jessica Chen

University of Hawaii PhD student, Jessica Chen, is working the night shift in acoustics from 16:00 to 01:00 during this IEA cruise. She displays patience and a high level of knowledge when I stopped by to pester her around 20:00. During our conversation, Jessica stated that she is from Colorado and came to Hawaii for her graduate studies. She will complete her PhD in 2015. She is interested in learning more about marine mammal behavior through acoustic monitoring and analysis.

Jessica points to the line of micronekton during a late night conversation — Jessica points to the line of micronekton during a night shift conversation

This is Jessica’s second IEA cruise. Jessica, Aimee, and Adrienne monitor our acoustic screens 24/7. In the photo above, Jessica points out the slanted line (slanting up) that represents the diel (daily) vertical migration of the micronekton. The micronekton migrate daily from around 400-500 meters up to approximately 100 meters from the surface. Many even migrate all the way to the surface. When the sun goes down, they come up. When the sun comes up, they start their journey back down to their 400-500 meter starting point. Micronekton consist of potentially billions of small organisms including larval fish, crustaceans, and jellyfish. Their behavior is not completely understood at this point, but they may be migrating at these very specific times to avoid predators.

When asked what Jessica’s long term goals are, she shares that she would like to increase personal and public knowledge of the animals in the ocean. This will allow us to better manage the ocean and protect the ocean. It is clear that Jessica truly enjoys her work and studies. She states that she especially appreciates the opportunities to see wildlife such as dolphins and whales.

Did You Know?

Cookie cutter sharks have extremely sharp teeth. Their round bite is quick and leaves a mark that resembles one that could have been made with a cookie cutter. Hence the name, cookie cutter shark.

NOAA Teacher at Sea
Patricia Greene
Onboard NOAA Ship Hi’ialakai
June 26 – July 30, 2006

Mission: Ecosystem Survey
Geographical Area: Central Pacific Ocean, Hawaii
Date: July 17, 2006

Science and Technology Log

The first creatures we experienced at Kure Atoll were the spinner dolphins. These creatures delight in playing in the wake of our bow; doing somersaults, spins, and jumps; crisscrossing fearlessly in front of our boat, then losing interest when we slow down. Scientists are not sure what make spinner dolphins exhibit this type of behavior. Interestingly, scientists have observed that spinners in the Northwestern Hawaiian Islands have a different social structure than those around the main Hawaiian Islands. In the Northwestern Hawaiian Islands, dolphins demonstrate group cohesion and typically stay together in the same group socializing in the lagoons or when they feed offshore. In the main islands a spinner dolphin may join a different feeding group every night; scientists have dubbed this behavior “fission-fusion,” since groups form and split repeatedly.We observed mothers with calves at their side; the babies easily keeping up and enjoying the sport as much as the adults. During the day the dolphins are relatively inactive and take group naps but at night they leave the atoll to forage and feed.

Cynthia Vanderlip and her team conduct spinner dolphin surveys in the lagoon around Green Island at Kure Atoll.

We observed a large group of spinner dolphins at Kure; approximately 70, although they swam so rapidly they were difficult to count. Other pods or groups have been identified at Pearl and Hermes and Midway. Typically, crossover between these groups in the Northwestern Hawaiian Islands is rare. Recently we visited Southeast Island at Pearl and Hermes and interviewed NOAA Fisheries monk seal researchers; Hugh Finn, Jessie Lopez, and Kennedy Renland regarding their spinner dolphin research. Basically, the dolphin research is done at the same time as they do the atoll counts for the monk seals; approximately every third day if the weather cooperates. If winds exceed 15 knots, safety becomes a concern and researchers will not go out in the small boats. During an atoll count day the researchers leave camp at 9:00 am and return at approximately 4:00 pm. For safety reasons, only two researchers go out in the boat at a time; one person remains on shore and monitors the radio in case assistance is needed. During an atoll count they will visit North Island, Seal Kittery, Grass Island, and various sand spits to assess the population.

Majestic Hawaiian spinner dolphins in the clear lagoon waters of Kure Atoll, State Wildlife Refuge.

Dolphins at Pearl and Hermes Atoll usually travel in groups or pods of 50 to 60. Mothers with calves are often seen at this time of year. Researchers explained that the age of the calf can often be estimated by the existence of “fetal folds.” The female dolphin has a 12-month gestation period and while inside the mother the calf develops creases in its body. These “fetal folds” will exist until the calf is two or three months of age.Dolphin surveys involve taking digital photographs of as many dolphins as possible. This year the Pearl and Hermes Atoll researchers have taken approximately 2,000 photographs to date. These digital images will be forwarded to Dr. Lezek Karczmarski at Texas A&M and fed into a database for his research. Individual dolphins usually have distinctive cuts, scars or marks that help identify them. Researchers also take small biopsy samples from the dolphins. This is accomplished by using a crossbow type instrument with a dart that removes a tiny piece tissue from the skin.

During a dolphin survey, researchers record the start and end times, initial and final GPS coordinates, swell, water depth, water temperature and bottom type. They assess the numbers and ages of any calves observed and record the numbers of juveniles and adults. Total number of digital images taken and any ID ratio is also recorded. The Northwestern Hawaiian Islands spinner dolphin pods have a habitat relatively free from typical human interference. Threats to dolphins in more populated areas include collisions with vessels, entanglement in fishing nets and other marine debris, and acoustic disturbances. In the Northwestern Hawaiian Islands few of these threats exist. Spinner dolphins are protected under the Marine Mammal Protection Act. Exact population numbers worldwide are unknown.Spinner dolphins have a wide range; found in tropical waters, subtropical, the Pacific, Atlantic and Indian Oceans. They feed on mesopelagic fish, squid, and shrimp. The females reach sexual maturity at 7 to 10 years, and give birth to a single calf every other year. Calves are weaned at seven months. Spinner dolphins may have a life span exceeding 20 years.

Special thanks to the Hawaiian Islands National Wildlife Refuge, United States Fish and Wildlife Service, Department of Interior for access to Southeast Island and an opportunity to spend a day with the NOAA Fisheries biologists to learn more about the spinner dolphin research they conduct during their field season.

Tag: spinner dolphin

Patricia Greene, July 17, 2006