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Monk Seal Monday #149: Sense of Smell

Let’s talk smell.

Hawaiian monk seals have two vertical slits for nostrils that are adapted to close when they dive, begging the question how much do Hawaiian monk seals rely on a sense of smell when flipping over rocks on the ocean floor in search of, say, flat fish like flounder? Or when they stick their nose in a puka in rock, hopeful to snag a lobster or eel for a good meal? For that matter, what about when Hawaiian monk seals are hauled out on the beach, and their nostrils are open?

Turns out there are probably more questions at this point in time than there are published scientific papers on Hawaiian monk seals and their sniffing prowess.

Let’s tackle the use of smell on land (air) by taking a look at other seal species. 

Take Antarctic fur seals. According to The Wire, when this species gives birth, mothers nurse their young for some four months. During that time, mothers leave their pups on the beach and head to the sea to search for food. They may be gone for up to 10 days. When they return, researchers suggest mothers rely on smell to sniff out their own pup from the many others on the beach. 

Researchers believe the same is true of Harbor seals.

More closely related to Hawaiian monk seals, the Mediterranean monk seal is also thought to use smell in mother-pup bonding. According to the Eastern Adriatic Monk Seal Project, “…sense of smell plays an important role in the life of a Mediterranean monk seal as scent and sniffing is used intensively in the first weeks of a newborn pup’s life in order to communicate and find its mother in the dark caves where they live.”

Compared to Antarctic fur seals, Hawaiian monk seals nurse their young for a fraction of time—four to six weeks instead of four months. While nursing, Hawaiian monk seals don’t leave their pups alone on the beach to forage. And Hawaiian monk seals birth their pups on beaches, not in caves like Mediterranean monk seals. Interestingly, especially at islands and atolls in Papahānaumokuākea Marine National Monument, it’s not uncommon for pup-switches to occur among Hawaiian monk seals. That is, moms and pups get mixed up. It happened on Kauai in 2018 when there were three moms and pups on the same beach.

Researchers propose there are more uses of smell among Antarctic fur seals. They may rely on “signature scents” to mate with unrelated seals, according to the same article in The Wire. Because fur seals tend to colonize, they may use smell as a way to form stable social groups.

But what about when foraging? How might smell be involved? Steller sea lions possess a large number of olfactory receptor genes, possibly because they are more terrestrial, that might help them hunt for food. 

This unique research paper posits that “aquatic carnivores” forage “noseblind,” that is without airborne chemical cues and, thus, have reduced olfactory anatomy, especially among deep-divers, relative to closely related land-based carnivores. That is, if sense of smell isn’t a critical component to their way of life, the anatomy that supports it diminishes over time in an adaptive response. Why build it if it’s not needed?

Over millennia, Hawaiian monk seals have adapted to their tropical ecosystem in unique ways. They don’t “colonize” in the same ways as some seals. They don’t birth their pups in caves. They spend the vast majority of their lives at sea. They can dive as deep as 1,800 feet; however, average foraging dives of several hundred feet. So, just how great—or not—is Hawaiian monk seals’ sense of smell? Good question.

This will be updated as more information come to light.

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After canceling last summer’s field season in the Northwestern Hawaiian Islands of Papahānaumokuākea Marine National Monument, NOAA’s field crew returned this spring, staying through the summer, making every day and minute count.

They collected population data, identified individual seals, tagged weaners and yearlings, disentangled seals and turtles, surveyed basking and nesting turtles, surveyed Laysan ducks, staged marine debris for pickup, and assisted in numerous additional conservation and research activities on behalf of conservation partners.

The field crew left civilization behind for tents, canned food, and starry starry nights, and you can read about their efforts and their experiences here in a very thorough report of their tremendous effort. 

https://www.fisheries.noaa.gov/feature-story/challenges-satisfaction-and-lots-monk-seal-pups-during-2021-field-season

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Long-time volunteers with the Kauai Hawaiian Monk Seal Conservation Hui will remember working with David Schofield. David served as the point person with NOAA for marine mammal strandings. In his early days, he was also more heavily involved in monk seal response. Now, after 16 years, David has announced his retirement from NOAA, and he’s planning to move to the East Coast and start a Christian outrigger canoe ministry through New Hope Church.

Last week, Hawaii News Now interviewed David about his work at NOAA and his plans for the future. Click on this link to watch the video interview; it provides a good history of NOAA’s work in this field, as well as, a history of David’s hair styles!

David Schofield

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Turtle Tuesday #9: Questions

With the ongoing recovery of Green sea turtles in Hawaii, some common questions come up:

  1. Is it now legal to harvest turtles for human consumption; and
  2. Is it now legal to harvest turtle eggs?

The answer to both questions is: No. 

Hawaiian green sea turtles—honu—are still protected federally under the Endangered Species Act, and, as well, by state laws. 

Yes, their numbers have improved, but they still face threats, primary among them is sea level rise, due to climate change, and the subsequent loss of nesting habitat, especially on low-lying nesting beaches in the Northwestern Hawaiian Islands in Papahānaumokuākea Marine National Monument. 

What’s more there are dangers associated with the consumption and handling of honu. 

One concern is fibropapillomatosis. Or “FP,” a tumor-causing disease that affects some sea turtles, forming cauliflower-like tumors on the body, often around the eyes and mouth but also internally around organs. FP is closely associated with a herpesvirus. Some sea turtles develop non-threatening tumors; others develop tumors that interfere with vital functions. While some viruses can move from animals to humans and there are similar diseases in humans, there are currently no known cases of sea turtle FP transmitting to humans, according to NOAA.

But consumption of sea turtles—specifically meat, adipose tissue, organs, blood, eggs—can pose a health risk to humans.

According to a scientific study published in EcoHealth reports, “…there may be hazards associated with this consumption due to the presence of bacteria, parasites, biotoxins, and environmental contaminants. Reported health effects of consuming sea turtles infected with zoonotic pathogens include diarrhea, vomiting, and extreme dehydration, which occasionally have resulted in hospitalization and death.” (Update: This study has more to do with the consumption of Hawksbill turtles than Green sea turtles.)

Little can be done to treat Chelonitoxism, considered a type of food poisoning, with only supportive care offered. Symptoms can present within hours to a week following ingestion and recovery can take weeks. Children are particularly susceptible. 

In terms of the effect of turtle tumors on people who might eat them, there hasn’t been too much direct research on that since people haven’t been eating them. 

Remember the recommended viewing distance of sea turtles is a minimum of 10 feet—on land and in water. Because honu are still protected in Hawaii, it’s illegal to harm, harass, or even touch a sea turtle.

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Monk Seal Monday #144: Meet Temp607

There’s a new girl on island. Nope, not a pup. A juvenile. She made her first appearance in early September, and because she was reported in the same place as another similarly-sized juvenile seal, a male, had been recently seen, it was thought she was he. He had first been identified in July.

Neither are flipper-tagged and, for now, the male is known as Temp606 and the female as Temp607. So, not only are they similar in size and age and frequently sighted in the same area, they have similar identification numbers!

But there are differences (if sex is not readily identifiable), mainly in scars and natural bleach marks, so a close look (preferably through binoculars), can result in correct identifications.

Here are some notable identifiers for Temp606:

  • Two parallel line scars below his right fore flipper;
  • a V scar on his upper chest; and
  • Three white nails (a natural bleach identifiers) on his right fore flipper.

Temp607 is a very wary seal and spooks easily into the water. She also has her own unique set of scars:

  • Two pits scars on her back–one lower and one mid; and
  • Puncture-type wounds on the top of her head.

Photo credit: M. Olry and V. Poelzl.

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Monk Seal Monday #142: Travel Pono

Recently, Hawaiian Airlines released this video. Please feel free to share it via your social media accounts.

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Monk Seal Monday #140: RP20 Update

Six weeks ago, the newly-weaned RP20 was translocated from her natal beach at Polihale to a more appropriate location for a young monk seal learning how to be a monk seal–learning to forage, that is. During the translocation, she was flipper-tagged and given the first dose of a vaccine to prevent morbillivirus.

Now, six weeks later, P20 continues to do quite well. She’s been spotted nibbling on sea cucumbers, a meal she will soon eschew in favor of eel, lobster, and flat fish like flounder–once she gets a taste of the good stuff. In the first few days after her release, P20 was sighted approaching other monk seals, trying to nurse. However, that failed. Now, she’s resorted to just socializing with a variety of other monk seals, even holding her own against adult males.

She also received her booster vaccination, so she’s all set on that front, too. She’s off to a good start in life.

Here are some recent photos of her.

PC: Poelzl
PC: Poelzl
PC: Olry
PC: Megonnell

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A news report broadcast earlier today confirmed a novel strain of morbillivirus killed a Fraser’s dolphin that stranded on Maui in 2018. Elsewhere in the world morbillivirus has killed hundreds of dolphins and/or whales. While only one dolphin has been confirmed to die of the highly infectious morbillivirus, it’s for the potential to spread to monk seals that NOAA vaccinates Hawaiian monk seals against morbillivirus.

Good news: KP1 has thrown his hook. Last week, on the heels of the news of a hooked Temp 606, KP1 turned up with a fish hook in his mouth. In both cases, the hookings were determined to be non-life-threatening. Rather than risk handling–and injuring–a wild animal, the seals were left untouched. And in both cases, the animals managed to help themselves by throwing their own hooks without the aid of human intervention.

WARNING: But not all monk seals seem to be helping themselves and their own species’ survival. The video below illustrates the phenomenon known as “male mobbing” in Hawaiian monk seals. It’s a disturbing turn of events, and you may not wish to watch it.

This interaction generally but not always takes place between a group of males, generally competing sub-adult males, and a single female and is called male mobbing.

In 2016, RK28 was observed with large wounds and abscesses on her back. It was determined these wounds were caused by male monk seals who had attempted to mount her and while doing so, biting her repeatedly on the back. The wounds can be severe and certainly disturbing-looking to our eyes. For good reason, it turns out.

According to the NOAA Pacific Islands Fisheries Science Center’s website, “Events involving multiple and single adult male Hawaiian monk seals exhibiting aggression towards adult females and immature seals has led to a significant number of severe injuries and deaths. Unfortunately, the loss of even a single female, and the loss of her lifetime reproductive potential, represents a significant setback to population recovery of this endangered species.”

Also from the NOAA PIFSC website:

Over an 11 year period from 1984-1994, 37 male seals were selectively removed from Laysan Island to restore a balanced sex ratio. These seals were translocated to Johnston Atoll (n=9) or the main Hawaiian Islands (n=21), placed into captivity (n=5), or died (n=2). Following removal, instances of injury or death from multiple male aggression events drastically declined. The removal of these males from the Laysan Island population has contributed to the restoration of a balanced sex ratio and has proven a valuable mitigation strategy.

Single male aggression events have most notably occurred at French Frigate Shoals and more recently at Kure Atoll. Intervention efforts include hazing of identified aggressors, translocating pups from areas where aggressive males frequent, treating injured seals when appropriate and removal of the adult male. The 3 adult males at French Frigate Shoals observed to repeatedly target pups, were translocated to Johnston Atoll (n=2 in 1998) or euthanized (n=1 in 1991). One adult male was brought into permanent captivity in 2013 after he had been observed injuring pups at Kure Atoll. This mitigation strategy effectively reduced pup deaths as a result of adult male aggression at this site.

To read more about adult male aggression, click here. And if you see a female with fresh wounds on her back, please report it to the Kauai Hawaiian Monk Seal hotline at 808-651-7668. This will allow the animal’s health to be assessed. If the injuries are severe, she may be treated with antibiotics to prevent the wounds from becoming infected. Keep in mind, Hawaiian monk seals have an amazing natural ability to heal. We’ve seen it time and again.

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In the past couple weeks, two Hawaiian monk seals have rolled out of the sea trailing fishing line behind them. Thankfully, observant bystanders and dedicated volunteers provided reports and photographs and numerous text messages for NOAA and DLNR to craft an appropriate response plan.

It started with this untagged juvenile male. Some beachgoers witnessed him fighting a hook along a beach shoreline and called the hotline. Volunteers in the area were alerted. A couple days later, one volunteers found him hauled out high on a beach, tucked under some bushes. Photographs showed fishing gear extending from his mouth, but it was unclear whether the hook was stuck in his mouth or whether he had swallowed it.

This image has been highly cropped.

The next day, more photographs revealed, thankfully, the eye of the hook extending from his mouth. This was good news; it meant the situation wasn’t life threatening. Too, four feet of line was trimmed to reduce the chance of entanglements. But he wasn’t out of the woods yet. There was still a chance the hook was embedded in his jaw, leading to possible infection. But, as seals do, he took off for the water and disappeared for a couple days. When he was next sighted, the hook was gone–he’d somehow dislodged the hook. This was the best result of all.

But with the discovery of this seal–given the identification of Temp 606–having thrown his hook, another seal was reported to be hooked. This one our first weaner of the year–KP1.

PC: D.Megonnell

KP1 was born on April 23rd of this year. This is his first known hooking. Photographs clearly reveal the hook, lodged in his lip, is not life threatening. If he hasn’t already, he will eventually throw this hook, as well.

Now is a good time to remind volunteers–and interested beach-goers–to take a visual health assessment of any and all monk seals encountered on the beach. Binoculars and cameras with super-telephotos lenses are super helpful to see any possible fishing gear extruding from the mouth area. Another indication of possible hooking is the appearance of fishing line trailing and/or wrapping around a seal’s body.

Also, please remember: If you happen to hook a monk seal–or witness one–please report the hooking (and fishing gear) to the Kauai Hawaiian Monk Seal Conservation Hui, so an appropriate response can be implemented. Anonymous reports are fine. Call the Kauai hotline at 808-651-7668.

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As Tuesday, July 20, 2021 rolled around, Kauai’s second pup of the year was found on the beach alone. After 37 days of growing round from nursing, it appeared the pup had been weaned. Hawaiian monk seal mothers spend the entirety of their young pup’s life right by their side, not venturing out to replenish their lost fat stores from birth and weeks of nursing. Eventually, quite thin and hungry, they finally wean their pups to perpetuate their own lives.

But MK2 wasn’t quite gone. Later that afternoon, she returned to her pup. She left again during the night, this time, for good.

Unfortunately, the waters off Polihale can be rough with an on-shore break and strong current. Not a great place for a young “weaner” to learn how to be a monk seal.

So, on Thursday, July 22, 2021, a very plump KP2 was moved to another location with an off-shore reef and the kind of coastline that allows for a Hawaiian monk seal weaner to learn how for forage on her own. Yes, her. In moving her, it was clear that KP2 is female. Upon release in her new location, KP2 was also flipper-tagged and vaccinated. She is now officially RP20. Her left flipper has the tag P20 and her right P21.

Here’s a video of RP20 headed to the water a few minutes after being tagged.

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