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Posts Tagged ‘science’

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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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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PC: B. Becker

In September, two Hawaiian monk seals were outfitted with dive recording tags that not only capture the seals’ location but time spent hauled out, time at the surface of the sea, and time spent (and depth of ) diving. Data from the tags is transmitted whenever the seals come within range of a cell phone tower. The instruments tags were affixed to the middle of the seals’ backs using an epoxy. When the seals next molt, the tags will fall off.

This first graphic shows the movement of the two tagged seals. The yellowish-green dots represent R1KT, a male. The red dots represent R7AA, a female. The graphs give us a look into three week’s worth of these two seals’ lives.Slide1In the graph on the right, we see the depths of R7AA’s dives. She records several dives in excess of 150 meters, but the vast majority of her dives log at under 100 meters of depth.Slide2

On the other hand, the majority of R1KT’s dives record upwards of 150 meters. There are numerous factors that could explain the differences. One, age. R7AA is a juvenile; whereas, R1KT is older. Too, underwater topography may affect their dive depths. Generally, according to science, monk seals like to forage on or near the ocean floor. They are generalist feeders and their diet includes a variety of fishes (eels, wrasses, squirrelfish, soldierfish, triggerfish, parrotfish), cephalopods (octopus and squid), and crustaceans (crab, shrimp, and lobster). Diet studies indicate they prefer prey that hides in the sand or under rocks, unlike most of the locally popular game fish (e.g. ulua, papio and ʻoʻio) and the proportion and type of prey consumed varies significantly by island, year, age and sex. Slide3

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Last week, on a sunny day, our second pup of the year graduated to “weaner” status and was tagged RJ36. After about six weeks of dedicated nursing, RJ36’s mother, RK30, weaned him and headed back to the nourishing depths of the ocean to replenish the approximate one-third body weight she lost during the nearly six weeks she nursed RJ36 to a healthy weaner weight in the neighborhood of 175 pounds.

While the procedure to tag monk seal weaners only takes about five minutes, the effort to tag this pup took much longer–all due to the remote location of where RK30 chose to birth.

For years now, the Kauai Hawaiian Monk Seal Hui has been aided when accessing remote beaches by marine biologist Captain Tara Leota, sole owner-operator of Kauai Sea Rider Adventures. Captain Tara leads small groups of ecologically-minded guests on snorkeling adventures around Kauai. Captain Tara, her crew, and her guests welcomed our tagging team aboard her 25-foot rigid inflatable boat for the adventurous journey to find RJ36.

Currently, the way we track matriarchal lineage of monk seals is by visual observations of mothers and pups. As such, our goal is always to tag pups within days of their weaning. Once weaners start exploring other parts of the island and mixing with other monk seals, we cannot be sure of their lineage. Thus, Captain Tara has likely helped us know with surety the matriarchal lines of six or eight monk seals over the years. That’s a great effort.

Mahalo Kauai Sea Rider Adventures!

RJ36 (5) 7.19.17-2

Photo credit: V. Bloy

RJ36 (3) 7.9.17-2

Photo credit: V. Bloy

RJ36 tags 7.19.17-2

Photo credit: V. Bloy

Kauai Sea Riders Crew-2

Photo credit: V. Bloy

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Happy Summer from the Kauai Hawaiian Monk Seal Conservation Hui!

Hawaiian monk seal and marine debris

Photo credit: Mary Werthwine

On June 13, juvenile male seal RA36 was reported with a decaying water bottle stuck to his face!  Luckily, the bottle was open at both ends, so RA36 could breathe, but he could not eat or use his whiskers.  Our team mobilized immediately to try to remove the bottle, and RA36 ended up dislodging it himself by knocking his head on our rescue equipment and causing the bottle to pop off!

June brought the PIFSC Monk Seal Research team to Kauai!  Their goals were to apply flipper tags to our newly weaned pups, to apply cell phone tags to more seals, and to conduct health assessments on a couple seals of concern.  They succeeded on all fronts!

Hawaiian monk seal on the beach

Photo credit: Lloyd Miyashiro

Our first 2011 Kauai pup’s new permanent ID number is RK54.  His brand-new tags read K54 and K55.  The second pup is female RK52, with tags reading K52 and K53.  RK52 is plumper than RK54, and is seen here exploring her own Seal Protection Zone!  When the weaned pups received their tags, they were also measured and given pit tags (like your pets’ microchips.)

Adult male RK36, with flipper tags 4DI/4DJ, was fitted with a cell phone tag.   We use the cell phone tags to monitor habitat use, dives and foraging behavior!

The PIFSC team got to take a good look at our aging male seal TT40.  While his advanced age seems to be causing his body’s normal processes (like molting) to slow down, our vets and scientists agree that he looks great for his age.

We also assessed the health of subadult female RB24, who has been observed to be losing body condition (i.e., getting thinner).  The cause of her weight loss has not yet been determined, but results of her blood samples, tissue samples and de-worming medication should help us learn more.

At the end of June, we rode out to Miloli’i to flipper-tag our third Kauai pup of the year.  This little male’s permanent number is RK56, and his tags say K56 and K57.  Special thanks to PIFSC and DLNR’s Department of Boating and Ocean Recreation for making this tagging trip possible!

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