Predator/Prey Relationships
Harbor Seal vs Herring
The harbor seals seen in Glacier Bay National Park have been described as “hairy sausages lounging on floating ice”. These predators are perfectly adapted to their chilled environment and dine on many of the aquatic delicacies housed in the bay. These mammals are frequently seen pursuing fish and their other prey along the surface. They use their back flippers to propel through the water to catch their prey such as herring, salmon, and octopus. Their slowed heart rate and reduced peripheral circulation allow them to thrive in the environment. Harbor seals have the ability to dive down to depths over 1500 feet and can hold their breath for around twenty minutes.
Humpback Whale vs Krill
Humpback whales are seen returning to Glacier Bay each summer for only one reason and one reason only. Food. These whales weigh 40 tons and can grow from 40-50 feet in length. These enormous mammals gorge themselves on krill, euphausiids, and varying other small schooling fish. These whales eat one and half tons of food every day. Theses whales have many mechanisms for catching their prey. One is by using “bubble nets” they create to concentrate their prey. They release air bubbles while swimming in circles and then lunge to the surface through the center of their concentrated prey. Humpback whales feed for about 23 hours a day during the summer.