These hawaiian monk seals are threatened

Let’s give a big Aloha to our new “whale” of the month, the Hawaiian Monk Seal!  In this post, we will dive into their subtropical home and explore these endangered creatures.

What in the Monk?

The monk seal gets its common name from the thick fold of skin around its neck, which resembles a monk’s hood. In addition, the seal lives a solitary lifestyle! This differs significantly from other seals that live in colonies. However, the Hawaiian name for the monk seal is “ilio-holo-i-ka-uaua,” which means “dog running in the rough water,” living up to the name of sea dogs!

Welcome to Paradise!

Endemic to the Hawaiian archipelago, the Hawaiian Monk seal can only be found in the main and Northwestern Hawaiian Islands. Rarely, however, can they be found 1,000 miles southwest of Hawai’i at Johnston Atoll.

They spend only 1/3 of their time on land where they like to haul out. Typically they rest, molt, nurse, or give birth on the diverse shore of the Hawaiian archipelago. The monk seals can be found on sand, coral rubble, and volcanic rock! The other 2/3rds of their time, they forage offshore on reefs and submerged banks. Their diet essentially consists of fish, spiny lobster, octopus, and eel.

A threatened species…

At one point, there were three species of monk seal: Hawaiian, Caribbean, and Mediterranean. The Caribbean monk seal went extinct in the 1950s due to anthropogenic presence and hunting. The other two species follow close behind. Only 500 Mediterranean monk seals remain. Though they are fairing better, with 1,400 individuals, the Hawaiian Monk seal still faces significant threats.

Climate Change

Due to sea-level rise, low-lying islands are losing shoreline. Examples of significant pupping site habitat disappearance are Whale-Skate and Trig Islands at French Frigate Shoals. Erosion from storms puts pups at risk as well. A lack of resting space puts the seals under tremendous stress! Furthermore, juvenile monk seals already struggle to compete with apex predators for food. With climate change inducing ecosystem disruptions, researchers worry about the future success of the pups.

Troublesome Humans

Humans pose a major threat via fishing gear because monk seals can get hooked or tangled in nets. Intentional killing of seals is an extreme example of negative human impacts. As of 2018, at least four seals have died from apparent gunshots!  

Disturbance of sleeping or resting seals (including dog attacks) are also significant concerns because it puts a lot of stress on the animals and can decrease their ability to reproduce healthily. Hawaiian beaches are famous for human recreation and accidents like boat or vehicle strikes can kill monk seals. Mother monk seals can get protective during these pupping events, which can be a problem when tourists invade the beaches.

Natural threats

First, scientists have witnessed adult males killing pups in a variety of animal species. This is typically called “mobbing,” as this is a group attack. It usually happens during mating when males want better access to the females. This can be an issue as it can prevent many pups from reaching adulthood and reproduce to keep the population healthy.

Sharks are natural predators of Hawaiian monk seals! Indeed, sharks were responsible for the death of a quarter of all pups born between 1997 and 2010 in the French Frigate Shoals. This kind of predation continues to be a concern. You can read more about it on the Marine Mammal Commission site.

Lastly, diseases can affect the population’s survival. The primary disease that has killed off a lot of Hawaiian monk seals is toxoplasmosis. Most infected seals die before humans can respond, making it hard for rescuers to help the population. Other infections sometimes detected in Hawaiian monk seals include Brucella, herpesvirus, and Leptospira

Thanks for Reading!

Here are a few links you can click if you want to learn more!

Naomi Mathew is a PhD student at University of Louisiana at Lafayette. She works on bioacoustics in marine mammals from the Gulf of Mexico. She is the co-founder of Whale Scientists. You can read more about her here

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