Maggie Prevenas, April 20, 2007


NOAA Teacher at Sea
Maggie Prevenas
Onboard US Coast Guard Ship Healy
April 20 – May 15, 2007

Mission: Bering Sea Ecosystem Survey
Geographic Region: Alaska
Date: April 20, 2007

Species Profiles

Bearded Seal: Scientific name: Erignathus barbatus

For the past few days, we have been seeing bearded seals. Bearded seals are extremely important to the Alaskan Native population that live along the Bering Sea. They use their skins for watertight boats, and their meat for food. They are solitary, love to hang out by themselves and are bottom feeders. Many times their heads appear reddish brown, stained from the benthic muck.

Alaskan Natives carve beautiful animals from walrus ivory. This carving is located on the  second floor of the Anchorage Airport.

Alaskan Natives carve beautiful animals from walrus ivory. This carving is located on the second floor of the Anchorage Airport.

Where do bearded seals live?
Bearded seals live in areas of the Atlantic, Pacific, and Arctic Oceans that freeze and form ice during the winter.

How many bearded seals are there?
There is no accurate population count at this time, but it is estimated that there are probably over 500,000 bearded seals worldwide.

Bearded seals often have reddish heads from grubbing for  their food in the bottom sediment. Photo by Gavin Brady.

Bearded seals often have reddish heads from grubbing for their food in the bottom sediment.

How can I identify bearded seals?
A bearded seals most distinguishing feature is the beard of white whiskers they use to find food on the sea floor. Adult bearded seals are gray to brown, pups silver-gray, and do not have spots or other identifying markings. They do have small heads and flippers for the size of their bodies. The average length of adult bearded seals is 6.5 to 7 feet. They can weigh as much as 700 pounds, but the average weight is 400 to 500 pounds.

What do bearded seals eat?
Bearded seals are mainly bottom feeders that eat shrimps, crabs, clams and whelks. They will prey on fish such as cod and sculpin when they get a chance.

How do bearded seals have their young?
The bearded seal pups are born on the ice from the middle of March to the early May. Pups are weaned in approximately 3 weeks, and during those three weeks they gain a lot of weight. Their mothers then leave them to fend for themselves. The bearded seal pups learn to swim and dive within the first week of life. The pups then live a solitary life-like the rest of the bearded seals.

How long do bearded seals live? How do they die?
The life span of bearded seals is believed to be up to 31 years. The main predator of the bearded seal are the polar bear. Sharks, and walrus have been known to feed on pups, and humans also hunt bearded seals for subsistence.

Bearded seal pups usually stay on the ice. The mother seal will dive into the water but hangs around the pup.

Bearded seal pups usually stay on the ice. The mother seal will dive into the water but hangs around the pup.

Do you know what is really cool about bearded seals?
Bearded seals will ram their heads through thin ice to produce breathing holes!

Bearded seals lay on the edge of the ice looking downward into the water. They can then get away if a predator approaches!

The bearded seal gets its name from the white whiskers on its face! The whiskers are very sensitive and are used to find food on the ocean bottom!

Within a week of birth pups are capable of diving to a depth of 200 feet!

The bearded seals can be easily recognized because the body looks too big for the size of its head and front flippers!

Orca: The Killer Whale

The pilot from the helicopter gave us a heads up. Two killer whales headed our way. The announcement resounded through the ship via the pipes (announcement system). For some people on board ship, this was their first glimpse of the orca. Keep on reading if you are interested in learning more about the whale called Killer.

We saw a pod of killer whales all eating heartily. What was on their menu for dinner? Take a guess.

We saw a pod of killer whales all eating heartily. What was on their menu for dinner? Take a guess.

Killer whales are social animals that live in stable family-related groups.  Killer whales display a high level of care for their offspring.  In addition to the mothers, various pod members (mainly adolescent females) perform most of the care for the calves.  As with most mammals, killer whales are very protective of their young.

Different killer whale pods “sound” different.  Each pod has their own dialect of sounds.  They can easily recognize their own pod from several miles away based on the differences in calls.

Killer whales are often compared to wolves because both species are top predators, maintain complex social relationships, and hunt cooperatively.

To some, killer whales look exactly alike however they can be distinguished from one another by the shape and size of their dorsal fins, the distinctive grayish-white saddle patches behind their dorsal fins, as well as distinctive scars, nicks and marks on their dorsal fins.

What are killer whales like?
Though killer whales, also called orcas, are considered whales by most people, they are actually members of the Delphinidae (dolphin) family. Killer whales are excellent hunters that a wide range of prey, including fish, seals, and big whales such as blue whales. Despite their hunting of other animals, free-ranging killer whales have never been reported killing a human being.

Where do killer whales live?
Killer whales can be found in all oceans but they seem to prefer coastal waters and cooler regions.  Killer whales occur in family groups called pods.  Three types of pods have been described:

* Resident pods: remain stable over time     * Transient pods:  dynamic in structure (are constantly changing)     * Offshore pods:  Are seen only in outer coast waters and not much else is known of them.

Killer whale pods are based on the lineage of the mother (mothers, daughters, and sons form groups); the whales live and travel with their mothers even after they are full-grown, forming strongly matriarchal whale societies.

How many killer whales are there?
There are no official killer whale worldwide population estimates.  There are minimum counts in local areas.  For example, approximately 1000 whales have been individually identified in Alaskan waters through photographs. Killer whales are at the top of the food chain and are not considered endangered.

How can I identify a killer whale?
Killer whales are extremely distinctive with jet-black bodies and white patches usually over the eyes, under the jaw, on the belly, and extending onto their sides.   Female killer whales can grow up to 26 feet (7.9 meters) with a 3 foot dorsal fin while males are larger than the females growing up to 28 feet (8.5 meters) with a 6 foot (1.3 meters) dorsal fin. Killer whales have 48 to 52 teeth that are large and conical shaped as well as slightly curved back and inward.

How well do killer whales see or hear?
Killer whales have well-developed, acute senses.  They can hear a vast range of sounds and possess skin that is sensitive to touch.  Killer whales have excellent vision in and out of water.  It is not known whether or not they may have some sort of sense of taste.

What do killer whales eat?
The killer whale diet consists of fish, squid, seals, sea lions, penguins, dolphins, porpoises and large whales like the blue whale.  Some killer whales have been known to slide on to beaches in order to capture a good meal.   Resident pods (pods that primarily reside in one area) prefer fish whereas transient pods (pods that travel over a relatively wide area) appear to target other marine mammals as prey.

Killer whales are very successful hunters due to their cooperative hunting, where all animals within the pod  participate.  This coordination is apparently developed and learned within pods.

How do killer whales have their young?
Killer whale males reach breeding age when they are around 22 feet (6.7 meters) long while females can breed when they are about 16 feet (4.9 meters) long. Killer whales breed all year around and calves are born about 8 feet (2.4 meters) long after a 17 month gestation period. Female killer whales usually give birth every 3 to 10 years.

How long do killer whales live? How do they die?
Killer whales have no natural predators (they are the top predators of the oceans) and can live to about 50-80 years old. Killer whales have been hunted by humans but not with enthusiasm as it takes 21 killer whales to produce the same amount of oil as 1 sperm whale.

Ribbon Seals: Phoca fasciata

I saw my first ribbon seal today! These beautiful creature are the most highly vulnerable critter that live up in the Arctic. Why? They never touch land. They spend their entire lives on ice flows, even give birth there. What will happen to them if there is less and less ice? Think about it.

Where do ribbon seals live?

Ribbon seals range northward from Bristol Bay in the Bering Sea into the Chukchi, Okhotsk and western Beaufort Seas.

This walrus tusk caving is a perfect minature of the beautiful animals know as ribbon seals.

This walrus tusk caving is a perfect miniature of the beautiful animals know as ribbon seals.

How many ribbon seals are there? In the mid-70s, the estimate of the world’s population of ribbon seals was thought to be 240,000, but there is no accurate estimate at this time.

How can I identify a ribbon seal? Ribbon seals are very distinctive. Males are dark brown to black with four ribbons of white. Females are lighter with less distinctive stripes. The stripes are located around the front shoulders, the neck and the rear section. Young seals are gray and will acquire the distinctive ribbons by the age of four. Ribbon seals have large eyes and small teeth.

Ribbon seals are generally easy to catch because they do not fear humans.

Ribbon seals are generally easy to catch because they do not fear humans.

What do ribbon seals eat? Ribbon seals feed mainly on groundfish and shrimp, along with some crustaceans.

How do ribbon seals have their young? Ribbon seal pups are born on the ice in the spring. They are white at birth and become silver gray in 3 to 6 weeks. They are weaned in about at month and then spend time learning to move on ice and to dive.

How long do ribbon seals live? How do they die? The life span of ribbon seals is believed to be up to 25 years.

The main predators of the ribbon seal are the killer whale, sharks and humans. There seems to be little interaction between commercial fishing and the ribbon seal.

Do you know what is really cool about ribbon seals? Ribbon seals have an internal air sack, over their ribs on the right side of their body. They are the only seals with this air sack! We do not know what it is used for!!

Ribbon seals move on the ice differently than other Arctic seals, they move one fore flipper at a time at a time, while other seals pull with both their front flippers to move forward! For short distances, they can move on the ice as fast as a man can run!!

Ribbon seals hang out where humans are not. They love to spend time out in the Bering Sea. The ice flow is their home.

Ribbon seals hang out where humans are not. They love to spend time out in the Bering Sea. The ice flow is their home.

Why do we know so little about ribbon seals? Ribbon seals are hard to study because of the amount of time they spend floating on pack ice and in open water, away from land. Luckily, this also makes it harder for predators to prey on them. At birth the pups are pure white. We know that ribbon seals stay close to the pack ice, but after most of the pack ice has melted, the ribbon seals are believed to be in the open sea.