Monk Seal Monday #13: RA20

In June 2009, an extra large R5AY gave birth to a chunky female pup on a shallow stretch of sand along a rocky shoreline on Kauai’s north shore. It was mid-day and almost high tide. As tide ebbed and flowed, the placenta, still attached to the pup, kept getting pulled from between the rocks and offshore. Luckily, the assembly of rocks prevented the hours-old pup from getting dragged into open water. Once the tide turned, the little pup was able to stay on dry sand, and eventually her umbilicus released and her placenta fell off. Some weeks later, once the pup weaned, she was tagged RA20–and hardly ever seen again. Because of her healthy size, she was nicknamed “Momona,” which translates from Hawaiian to something like, “very large.”

One year to the day of her birth, a sighting of RA20 was reported to the Kauai HMS Hui hotline. In 2011, she was reported on the east side and south shore on several occasions. Then, she all but disappeared from Kauai. Over the years, periodic sightings placed her on Maui and Hawaii Island.

In 2017, word traveled down the Hawaiian Island chain that RA20 had given birth on Hawaii Island. Unfortunately, three days later, the pup was found dead and floating in a tide pool. A necropsy was performed and a histopathology report supported drowning as the ultimate cause of death. However, other tests showed some abnormalities that may have led to a weakness in the pup and predisposed it to death from drowning and/or trauma. Even with milk found in the stomach, there was evidence of poor nutrition (declining blubber cells, fatty liver) as well as a possible infection in the liver (necrotic cells) and belly button, all consistent in a poorly thriving pup.

But that brings us to 2018.

On February 8, RA20 gave birth to her second pup, boosting the Hawaii Island monk seal population to five resident seals. Reports are that mom and pup are doing well. DOCARE and state park officials have been super supportive and helping that island’s monk seal response coordinator, a member of Ke Kai Ola/The Marine Mammal Center.

And, so, kicks off the 2018 pupping season. We’ve got more news on that front to come. Meanwhile, enjoy this unusual video submitted by one of our many loyal volunteers. It shows visible stomach movement of Kauai’s resident RK13. Could she be pregnant?

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Monachus Monday #12

In 1891, during the height of what’s now known as the golden age of scientific exploration, the first specimen of a Hawaiian monk seal was collected for science. But it wasn’t until 1905, when Dr. H. Schauinsland recovered a skull from Laysan Island in what’s now the marine protected area known as Papahanaumokuakea Marine National Monument that the species’ taxonomy was determined. Given the scientific name–Monachus schauinslandi, the Hawaiian monk seal joined the Monachus tropicalis (Carribbean monk seal) and Monachus monachus (Mediterranean monk seal) in the genus Monachus.

As you may have read a few years back, the Caribbean monk seal was declared extinct. Over in the Mediterranean, their monk seal is staving off extinction with a population of individuals numbering six to seven hundred, about half that of the Hawaiian monk seal.

The cool thing about science is that as technology improves, we can effectively go back in time and re-evaluate things–like that 1905 taxonomic classification of Monachus.

Recently, DNA and skull morphology (shape, size, and structure) was compared across all three monk seal species–using museum study skins in the case of the Caribbean monk seal. The result of this study  determined that both the Hawaiian monk seal and the extinct Caribbean monk seal were quite distinct from the Mediterranean monk seal.

Too, the speciation was estimated to occur with the formation of the Panamanian Isthmus. In fact, the molecular, morphological, and temporal differences between the Caribbean and Hawaiian monk seals compared to the Mediterranean monk seal were so great that a new genus was established–Neomonachus for “New world.”

In a way, this new classification for Hawaiian monk seals as Neomonachus schauinslandi makes Hawaiian monk seals even more rare, because they are the sole surviving species in the Neomonachus genus.

On the subject of genetics, you may have heard Hawaiian monk seals referred to as “living fossils.” An exhaustive genetics study running from 1994 through 2007 revealed the Hawaiian monk seal has lower genetic diversity than any other mammal tested to date, including the cheetah, the northern elephant seal and the North Atlantic right whale. That means there is no genetic difference between Hawaiian monk seals born at Kure Atoll in the northernmost range of the population and those born at Hawaii Island in the southernmost end of the range.

Scientists don’t really known why, but there are theories. It could be a genetic bottleneck occurred due to sealing during the 19th century. It could be possible that the Hawaiian monk seal has never existed in large numbers, and thus has always had low genetic diversity. It could also be that the species was exploited prior to historical record-keeping.

Knowing this helps when it comes to recovery and management practices. It’s one reason for the recent effort to vaccinate Hawaiian monk seals against morbillivirus–to prevent an outbreak of disease.

As science continues to evolve, we can expect the Hawaiian Monk Seal Genetics Research Initiative to continue using molecular science to help in the recovery of the endangered Hawaiian monk seal.

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Field Report: January 2018

Sightings:

The Kauai team logged 336 seal sightings this month. This included 34 individually identified seals.

Jan:336
Dec: 270
Nov: 239
Oct: 225
Sep: 354

New Issues:

• R376, adult female, hooked with small j-hook in lip. Hook came out without intervention several days later.
• One new juvenile male, untagged and unknown, sighted on West Side.

Updates on previously reported issues:

• R7AA, juvenile female, was observed with a moderate injury to right cheek, possibly a hook pull-out or moray eel bite. Antibiotics were given. Close monitoring continued, wound currently healing.
• NG00, sub-adult male, was observed with a circle hook in lower right lip. Sighted on Niihau in January. Photos match pictures sent in by fisherman along Kaumakani in September of a hooked seal. Seal in good condition. Hook not life threatening. Will attempt to de-hook next time hauled out on sand.
• Poipu Keiki Pool: 3 seals displaced from Keiki Pool.
• Morbillivirus vaccinations: All vaccines on Kauai have expired. No further vaccinations will occur for the time being.
• Bleach markings: 1 seal bleach marked this month.
• Molting activity: no seals molted this month.

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Monk Seal Monday #11: Dive Reflex

Last fall, the Hawaiian Monk Seal Research Program placed dive recording tags on two monk seals that make their home in Kauai waters. We briefly wrote about it here. During one recording period, the two seals (R1KT and R7AA) both made numerous dives deeper than 150 meters (492 feet). One bottomed out at 170 meters (557 feet) and the other at close to 200 meters (656 feet).

These are mammals diving to 500 feet on a single breath of air. But that’s not unusual for monk seals. In fact, the deepest known dive for a monk seal occurred in 2003 when scientists in a Pisces submersible descended to a depth of 543 meters (1,781 feet). They were studying deep sea corals, submarine canyons, and seamounts when a Hawaiian monk seal swam into their field of view. The on-board microphone captured their reaction. It went like this:

“Whoa.”

“What’s that?”

“That’s a monk seal.”

“Oh my god.”

“No way.”

“Look it. Right in front of us.”

“No way.”

“Oh my god.”

So, how do they do it? How do monk seals dive to depths of 1,781 feet?

There are numerous physiological responses involved; collectively the process that allows monk seals to dive deep is known as “mammalian diving reflex.” It involves the respiratory and cardiovascular systems. Typically, before a dive, seals exhale completely. This allows their lungs to completely collapse and avoid gas transfer at depth that could cause nitrogen narcosis. Then, holding their breath, the heartbeat slows from about 125 beats per minute to as low as 10 beats per minute. This is known as bradycardia. A slowing heart rate reduces oxygen consumption. Too, blood is diverted from the limbs and all organs except the heart and brain. This is known as blood shift. It’s accomplished through a process known as peripheral vasoconstriction. Too, diving mammals have high blood volume. That is, elevated hemoglobin and myoglobin levels, which provides greater oxygen storage. The whole idea is to conserve oxygen consumption, so the seal can dive deeper and longer.

Simply, they can hold their breath, slow their heart rate, and direct blood to just the heart and brain. This also helps explain their torpedo-like shape and abbreviated pectoral fins.

Here’s a video of that astonishing 1,781-foot-diving monk seal.

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