Monk Seal Monday #91: Vibrissae

Today’s topic: vibrissae. More commonly known as whiskers.

You may have noticed Hawaiian monk seals have prominent vibrissae.

If this were a nursery rhyme, the little girl might say, “My what big whiskers you have.” And the monk seal would respond, “All the better to find food to eat, my dear.”

Basically, a monk seals’ whiskers help it to detect and analyze objects in the water. But they can also help monk seals maneuver through the water.

Hawaiian monk seals belong to the order of carnivorous aquatic mammals known as Pinnipedia or “pinnipeds,” which means flipper-footed. Basically, marine mammals that are characterized by front and rear flippers. There are 33 extant species of pinnipeds, of which Hawaiian monk seals are one.

According to Scholarpedia, “All pinnipeds possess prominent vibrissae (whiskers) in the facial region. Pinnipeds use their whiskers for orientation by directly touching objects and by perceiving and analyzing water movements.”

But not all whiskers are alike. In most true seals, the vibrissae is “waved” or “beaded,” often compared to the outline of a pearl necklace. Basically, the diameter changes throughout the length of the whisker. However, monk seals and bearded seals sport smooth whiskers as do eared seals and the walrus.

Each vibrissae emerges from a relatively large blood-filled follicle chock full of receptor cells and nerve endings. Some pinnipeds possess about ten times as many nerve endings at the base of their vibrissae than terrestrial mammals.

Another thing about monk seal whiskers: Mostly, they’re straight. Sometimes, however, they curl.

There’s some thought that curled whiskers might be an indication of seal health, in particular, dehydration. However, that’s not a hard and fast rule. Some very healthy seals have curled whiskers. Some really long whiskers curl at the end. Some curl the longer the monk seal spends out of the water.

Think of vibrissae this way: They’re another critical sensory modality to help monk seals navigate the sometimes murky waters of deep sea life and survive. Those whiskers? They’re not just about a cute face.

Monk Seal Monday #90: Official Stand Down

Due to the evolving COVID-19 situation, NOAA and DLNR has announced today that they will not be sending volunteers into the field to survey, monitor, ID, take photos, or pup watch. This means all volunteer activities will temporarily cease. Volunteers are asked to heed the advice of federal, state, and local leaders and stay-at-home as much as possible.

For the time-being, volunteers are asked to NOT set-up seal signs on beaches, do not email photos to the Kauai Hawaiian Monk Seal Conservation Hui, and do not call or text with seal haul-out reports.

NOAA and DLNR will respond to strandings (illness, injury, hookings, out-of-habitat, etc) ONLY, but only on a limited basis and only after careful evaluation and approval from leadership on Oahu.

Once this situation changes, volunteers will be alerted.

Be well.

Monk Seal Monday #89: Pup News!

Yesterday afternoon, before a massive storm rolled over the island and during the midst of the craziness that is our world right, a rather large Hawaiian monk seal galumphed up a Kauai beach and provided some hope and joy.

RB00 was born on Kauai in 2007 and has been sighted on every main Hawaiian Island since weaning. In 2016. RB00 gave birth to a stillborn pup. In 2018, she gave birth to a healthy–and large–pup on Lanai. Last year, on February 2019, she returned to her natal beach to give birth. Now, several weeks after her expected delivery date, she returned once again to her natal beach and gave birth to Kauai’s first Hawaiian monk seal pup of the year on March 15, 2020.

Here’s a photo of RB00 looking rather large in the hours before she pupped.

The gestation period for Hawaiian monk seals is 10 to 11 months. At birth, pups weight anywhere from 30 to 35 pounds and measure approximately three feet in length. Their lanugo coat is jet black. RB00’s large size should ensure her pup will be well-nourished in the weeks to come. Typical Hawaiian monk seal mothers nurse their pups for anywhere from four to six weeks. Last year, RB00 nursed her pup for nearly eight weeks–a whopping 54 days–and her pup turned out to be a whopper, too.

For more information about RB00, read this report.

Lucky for us, some stalwart Hawaiian monk seal volunteers witnessed the birth and provided some video footage post-birth, showing an active pup and an attentive mother.

Field Report: February 2020

Update: The Kauai team logged 264 seal sightings this month. This included 39 individually identified seals.

February: 264
January: 319
December: 180
November: 223
October: 258
September: 203
August: 324
July: 239
June: 179
May: 262
April: 348
March: 350

New:

• Adult female RK13 hauled out on the road shoulder at Fuji Beach, Kapaa, requiring one lane to be closed. She was displaced back into water by NOAA and DLNR staff, and the lane was re-opened.
• Adult female RK13 hauled out with a small amount of gillnet wrapped around her muzzle and top teeth. A blunt hook attached to a pole was used to pull most of the net off. A small amount remained attached to the top left canine but did not pose a hazard and was gone by the next day.
• Juvenile male R1NI was displaced from under a hazardous undercut bank at Kiahuna Beach, Poipu. The overhanging bank collapsed two days later.
• Juvenile female NL04 sighted on Kauai. This seal was born on Niihau and flipper tagged during a Niihau survey. She hauled out on the north shore and was the first sighting her on Kauai. 

Updates on previously reported issues:

• Five of the six pups born in 2019 have been sighted recently and continue to thrive, the sixth is likely on the remote Na Pali Coast.
• Displacements: Adult male R4DW was displaced from Glass Beach at sunset due to the unsafe night time haul-out location.
• Molting: 
  • RN44 completed his molt on the north shore.
  • RJ36 molted on the south shore.
  • RK58 molted on the south shore.
• Bleach marking: 1 applied this month.

Research/Support of Pacific Islands Fisheries Science Center

• Sub-sampled scat, molt, and tissue plug samples accordingly.
• Logged all seal sightings for PIFSC database. Organized photos and reported sightings, molt tallies, survival factors to send to PIFSC.

Monk Seal Monday #88: Netted.

Hawaiian monk seals are curious creatures, sticking their noses in places to find food. Unfortunately, some of those places can be dangerous for them. It seems those causing the most harm are a result of humans. Over the years, the Kauai Hawaiian Monk Seal Conservation Hui has removed all kinds of things from the muzzles of monk seals, including plastic rings and, even, a plastic water bottle. Thankfully, our team has gotten pretty creative at responding to these situations.

At 3:30 on the afternoon of February 10, a volunteer called the hotline to report that adult female RK13 was entangled with a small amount of lay gillnet (fishing net) around her mouth. Importantly, she was able to open her mouth and did not appear in distress.  

When NOAA officials arrived at 4:15, RK13 was resting comfortably. A small amount of light-weight gillnet was wrapped around her muzzle, nose, and upper teeth. What was unclear, however, was how much gillnet was in her mouth.  Or, even, if she’d ingested any of it.

After receiving authorization, the team approached the sleeping seal with a blunt hook attached to a pole. The object was to snag the gillnet in order to pull it off. When the hook made contact with her face, RK13 flinched and made an open mouth threat which revealed a small amount of net attached to her top left canine. Another small piece of similar size was removed with the pole hook. No further net was observed inside the seal’s mouth. The small piece remained attached to the top left canine but did not pose a hazard to the seal. The seal entered the water and swam away.

RK13 was sighted the next day free of the final small piece of the gillnet. 

(FYI: The gillnet size was 3 inches (8 cm) stretched mesh size, which is legal in Hawaii. Legal stretched mesh size is 2 inches or larger.)

As these photos illustrate, this gillnet could have easily gone unnoticed. (This is why a good pair of binoculars come in super handy.) Thankfully, a very alert volunteer didn’t miss it.

Monk Seal Monday #87: Metabolizing at Sea.

Have you ever wondered how Hawaiian monk seals stay hydrated? Because unlike fish, they don’t purposefully drink salty seawater, right? Nor can they absorb water through their skin and gills, known as osmosis. But what about seawater? How do monk seals cope with all that salt?

Turns out, over millennia, Hawaiian monk seals, like other marine mammals, have adapted some unique metabolic systems that allow them to live in the ocean.

To start, monk seals “drink” whenever they eat in two ways. First, their favorite foods, fish and invertebrates, consist of 60 to 80 percent water. Monk seals also produce water as a byproduct when they metabolize carbohydrate and fat. But not all food sources are equal in their hydration benefits. Interestingly, the fattier the fish, the more water and energy available to seals.

While fish possess a similar salt content to that found in the blood of marine mammals, another food source of monk seals—invertebrates—possess a much higher salt content. Too, seals may ingest seawater as they feed. This presents a challenge: what to do about the excess salt? Turns out, the kidneys of marine mammals are uniquely adapted to handle saltwater that’s upwards of two-thirds saltier than their own blood. Their kidneys are multi-lobed like cows, in which each lobe has all the components of a metanephric (single) kidney the likes of humans. This multi-lobed kidney employs a two-step filtering process that allows seals to maximize water retention while excreting salt-rich urine that’s seven or eight times saltier than their blood.

Another metabolic process that monk seals employ is something called catabolism. This is when large molecules are broken own into smaller ones, as in when fat and protein reserves are broken down to provide energy and water. This comes in handy when monk seals fast. Fasting is a normal part of the lifecycle of Hawaiian monk seals. Healthy seals fast annually when they molt; females fast for five or six weeks while they nurse young, and pups, after weaning, generally fast, too, while they figure out where to find nourishment. Amazingly, monk seals are able to fast for extended periods without critical organ failure.

Hawaiian monk seals have been called “living fossils,” likely because they figured out long ago how to survive at sea and haven’t needed to make many adaptations since then.

Monk Seal Monday #86: When A Nap Turns Into A (Potential) Nightmare

In October 2018, a hurricane swept north of Kauai and, for a time, sunk an 11-acre sliver of sand at French Frigate Shoals, an atoll that’s part of Papahānaumokuākea National Marine Monument. On this 150-foot stretch of sand, Hawaiian green sea turtles nest and Hawaiian monk seals haul out, molt, and pup. Luckily, the storm hit late in the breeding season, and the wildlife escaped potential catastrophe.

An increase in storms such as Hurricane Walaka is one characteristic of climate change. So, too, is sea level rise. Both can result in the loss of suitable habitat necessary for Hawaiian monk seals to rest, molt, and birth pups.

Another result of increased storms and, subsequent, big wave events is a changing coastline.

Recently, a juvenile male monk seal known as R1N1 hauled out at Kiahuna Beach in Poipu. His choice of napping location was beneath a severely undercut and actively eroding stretch of ground, resulting in a seemingly perfect cave in which to sleep. (In fact, this might mimic underwater ledges where monk seals are known to rest.) Unfortunately, this spot presented the very real possibility of ground collapsing on top of the seal. What’s more, he was partially entangled in a root system that was still intact with the ground above him. As R1N1 settled in for sleep, putting pressure on the roots, he could easily have buried himself by pulling down the ground above him.

This situation was reported by one of our volunteers at 10:50 a.m. By noon, with authorization from NOAA, a trained team of DLNR and NOAA representatives and volunteers assessed the situation and crafted a creative solution that included a pair of pruning loppers, a pair of windsurfing masts, and a crowding board. The roots were cut, the seal nudged with the windsurfing masts, and the crowding board used to direct R1N1 to the water. Once there, he slowly swam away, hauling out 500 yards down the beach where he rested for the remainder of the day.

There was an additional challenge facing the efforts—the numerous bystanders always present at busy Poipu. So before any actions—filed as “haze/displace” on the subsequent “take form” that was filed with NOAA—outreach was conducted.

All this to say: there are few ordinary days in the lives of those trying to recover the species of tropical seals known as Hawaiian monk seals.