Overfishing Krill (Secondary) - Lesson Two
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Lesson duration is: 45 minIntroduction
This lesson covers the role of krill in the ocean ecosystem.
Instructions
Time: 45 minutes
Contact: education@seashepherdglobal.org
© Sea Shepherd 2025
Instructions
Items in this lesson
Slide 1 - Slide
This lesson is provided by Sea Shepherd. Sea Shepherd was founded in 1977 and is a marine conservation organisation working to protect the oceans and marine wildlife. Sea Shepherd works globally on a range of issues impacting the oceans, running numerous direct action campaigns each year.
Slide 2 - Slide
During the lesson we will use these icons to identify the learning actions.
How does krill fit into the ocean ecosystem?
Slide 3 - Open question
Today we are going to discuss the role of krill in the ocean ecosystem.
Ask students what they think is the role of krill?
Slide 4 - Slide
Focusing on Antarctica, let’s look at species that are connected to krill.
Krill are the primary food source for Antarctic birds and marine mammals, including whales, penguins, seals, squid, and fish. To put it simply: without krill, the Antarctic delicate ecosystem would collapse.
Krill provides 96% of calories for seabirds and mammals in the Antarctic Peninsula:
Looking at baleen whale species found in this region, it includes blue whales, fin whales, sei whales, minke whales, and humpback whales. These can consume between 34 million and 43 million tons of krill per year.
Krill are the primary food source for Antarctic birds and marine mammals, including whales, penguins, seals, squid, and fish. To put it simply: without krill, the Antarctic delicate ecosystem would collapse.
Krill provides 96% of calories for seabirds and mammals in the Antarctic Peninsula:
Looking at baleen whale species found in this region, it includes blue whales, fin whales, sei whales, minke whales, and humpback whales. These can consume between 34 million and 43 million tons of krill per year.
Slide 5 - Slide
The Southern Ocean is home to seven of the world’s 17 penguin species (emperor, gentoo, bridled, chinstrap, Adélie, macaroni, and rockhopper)
All penguin species feed on krill. It’s an important part of the diet of emperor, gentoo, bridled, chinstrap, Adélie, macaroni, and rockhopper penguins, each consuming an average of one kilo per day. The chinstrap penguins in the South Sandwich Islands eat 4000 tons of krill per day, and while raising their chicks, the Adélie penguins in the South Orkney Islands eat 9000 tons of krill and fish larvae each season.
All penguin species feed on krill. It’s an important part of the diet of emperor, gentoo, bridled, chinstrap, Adélie, macaroni, and rockhopper penguins, each consuming an average of one kilo per day. The chinstrap penguins in the South Sandwich Islands eat 4000 tons of krill per day, and while raising their chicks, the Adélie penguins in the South Orkney Islands eat 9000 tons of krill and fish larvae each season.
Slide 6 - Slide
The Southern Ocean is home to six different species of seal (Ross, Weddell, crabeater, leopard, Antarctic fur, and elephant).
Antarctic fur seals, Ross seals, leopard seals, and especially crabeater seals, who consume 50 to 150 million tons of krill per year.
Antarctic fur seals, Ross seals, leopard seals, and especially crabeater seals, who consume 50 to 150 million tons of krill per year.
Slide 7 - Slide
Several species of Albatross, petrels, prions and other marine birds consume krill, along with some species of squid and fish, including icefish (toothfish).
The krill ecosystem in the Antarctic is a delicate and intricate web of life, where numerous species rely on these small, shrimp-like crustaceans for their survival. At the very foundation of this complex system, Antarctic krill, play a pivotal role as a keystone species.
The krill ecosystem in the Antarctic is a delicate and intricate web of life, where numerous species rely on these small, shrimp-like crustaceans for their survival. At the very foundation of this complex system, Antarctic krill, play a pivotal role as a keystone species.
Slide 8 - Slide
When we start to remove a species, like krill, in large numbers it will have implications for other species in the food web.
Ask students: “What do you think the impacts would be if we remove krill in large numbers?”
Discuss the potential impact on species that feed on krill.
Health
Migration
Breeding
Teachers note:
Researchers monitored whales in the west of Antarctica Peninsula over 8 years;
In 2017, when krill was abundant, 86% of humpback whales were pregnant.
In 2020, after a year of less krill, only 29% were pregnant.
In 2021 scientists from Stanford already concluded that even in the absence of krill fishing there is no longer enough krill in the Southern Ocean to support recovery of whale populations to pre-whaling numbers. Combined with temperature rising and acidification, continuing to commercially exploit marine wildlife would be disastrous for the entire Antarctic ecosystem. Yet krill fishing is a booming industry.
Ask students: “What do you think the impacts would be if we remove krill in large numbers?”
Discuss the potential impact on species that feed on krill.
Health
Migration
Breeding
Teachers note:
Researchers monitored whales in the west of Antarctica Peninsula over 8 years;
In 2017, when krill was abundant, 86% of humpback whales were pregnant.
In 2020, after a year of less krill, only 29% were pregnant.
In 2021 scientists from Stanford already concluded that even in the absence of krill fishing there is no longer enough krill in the Southern Ocean to support recovery of whale populations to pre-whaling numbers. Combined with temperature rising and acidification, continuing to commercially exploit marine wildlife would be disastrous for the entire Antarctic ecosystem. Yet krill fishing is a booming industry.
Slide 9 - Video
Show this video “Blue Planet - Krill” (3.52 min)
https://www.youtube.com/watch?v=WRkxyROtjn4
https://www.youtube.com/watch?v=WRkxyROtjn4
Slide 10 - Slide
Close
Slide 11 - Slide
Refer Lesson Guide for activity suggestions.
