Fish Feature

The Hooded Seal – Battling Foes with a Bladder Nose

Image via NOAA/NMFS

Welcome to another installation of Fish Friday! For the past six weeks, we’ve stayed true to our name and featured nothing but fish. But this week, we couldn’t resist sharing this super adorable, territorial, and insanely weird Gulf of Maine marine mammal visitor – the hooded seal (Cystophora cristata).

Bladder Noses

Hooded seal pups are born cute and fluffy with blue-black pelts. They’re about 3 feet long and weigh 55 pounds at birth. They quickly shoot up to 90 pounds before they are weaned at around 4 days old (the shortest weaning period for any mammal)! At five days old, pups begin to eat crustaceans while honing their swimming and diving skills. What a busy first week of life!

Once males reach sexual maturity, the days of cute, fuzzy little noses are gone. Between 5 and 7 years old, male hooded seals develop an elastic, bi-lobed nasal cavity and nasal septum that can inflate from the front of the face to the top of the head. When inflated, a seal’s “hood” resembles a pink balloon — smack dab in the middle of its face! Hence the nickname “bladder nose.”

Males use this “bladder nose” to get females’ attention during mating season and to scare off competition for mates. It may not sound like the most frightening tactic, but think about it – if your adversary could blow up his nasal cavity to twice the size of your own nose balloon, you’d probably realize your infinitesimal chances at winning that fight and scamper off to pursue another potential mate.

Sizing each other up via nose balloon size saves these big guys a lot of energy — but if it looks like an evenly-matched fight, they will resort to physical blows.

And when adult male hooded seals battle, there’s a lot of weight thrown around. At around 8 feet long and some 660 pounds, it takes a lot of effort to just move, let alone fling their bodies at competitors. (Females are noticeably smaller than males, weighing in at around 440 pounds and measuring about 7 feet long.)

These seals are less social, more territorial, and more aggressive than other seal species. They gather together at their historic breeding grounds in the spring to produce young and molt. The main breeding grounds include the Gulf of St. Lawrence, off the coast of Newfoundland and Labrador, Davis Strait, and the Norwegian Sea near Jan Mayen Island.

After breeding and molting, hooded seals spend a majority of the year migrating. Many pass through the Gulf of Maine during their travels. While some are spotted as far south as Florida and the Caribbean, most stay in the Arctic Ocean and Northern Atlantic, where they thrive on pack ice in colder waters.

Hooded seals spend their days diving to depths of about 325-1,950 feet, searching for crustaceans, squid, starfish, mussels, and fish such as cod, halibut, and herring. Their only known natural predators are polar bears and orcas — but human hunting has had a huge impact on hooded seal populations.

Historically Hunted

In the 19th and 20th centuries, hooded seals were hunted commercially, mainly by Norway, the Soviet Union, Canada, and Greenland. Adults were harvested for oil and leather products, while pups were taken for their prized blue-black pelts.

In the 1970s, the Northwest Atlantic Fisheries Organization (NAFO) was created and began managing seal harvesting in international waters. NAFO controls sealer licenses, sets quotas for allowable take, prohibits harvesting in specific regions, and has banned all pup harvests. In the early 1980s, the European Economic Community outlawed hooded seal commercial harvests, as well as the import of hooded seal products. In the United States, hooded seals are protected by the Marine Mammal Protection Act. 

On Thin Ice

Unfortunately, many hooded seal populations are still vulnerable to a number of threats. Illegal harvests still occur, even though populations are carefully managed. Fisheries catch and discard hooded seals as bycatch and may force seals into competition for food.

Finally, as a pack ice- and cold water-dependent species, the future of hooded seals on a warming planet remains uncertain. Will their breeding grounds still exist in 50 years? Will prey species such as Arctic cod be available? Will polar development further expose Arctic marine mammals to contaminants and pollutants?

For now, we must focus on limiting the indirect impacts to hooded seal populations. Let’s work hard to reduce our emissions and to ensure that our fisheries are sustainable. In doing so, we’ll be protecting the hooded seals and the ecosystems within which they exist.



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