Impact of an Invasive Species Partner

7/23/2019 Impact of an Invasive Species | National Geographic Society

R E S O U R C E L I B R A R Y | V I D E O Impact of an Invasive Species

Nile perch were introduced to Lake Victoria in the 1950s to boost the fishing industry. Thought the introduction of Nile perch resulted in an economic boom, it almost caused cichlids, a native fish, to go extinct.

G R A D E S 6 - 12

S U B J E C T S Biology, Ecology, Geography

C O N T E N T S 1 Video

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Nile perch were introduced to Lake Victoria in the 1950s to boost the fishing industry. The introduction caused an economic boom, but also drove hundreds of species of native cichlids to near-extinction.

Watch this video, from the Nat Geo WILD series “Destination Wild,” to discover the role an invasive species can play in an ecosystem and social system.

Instructional Ideas

https://www.nationalgeographic.org/media/impact-invasive-species/print/ 1/5 7/W23a/2t0c1h9 the video and use our glossaImrpya ctt oof eanx Inpvlaosivre S ptehciees d| Nisactiounsasl iGoeong rqapuhiec sSotcioietny s in the Questions tab. Learn more about Nile perch with our Fast Facts, and dig deeper with links to related resources. This media spotlight aligns to Next Generation Science Standards in middle school and high school life science: MS-LS 2-4: “Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.” HS-LS 2-7: “Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.” Questions

Why do you think Lake Victoria’s cichlids are vulnerable to predation from the Nile perch?

The Nile perch is an invasive species. This means that the fish is not a natural part of the ecology of Lake Victoria. The lake’s cichlids have no defense against the unfamiliar predator.

Why were Nile perch introduced to Lake Victoria?

The huge fish were intentionally introduced to the lake in the 1950s to boost the fishing industry.

Was the introduction of the Nile perch economically successful?

Yes. According to the video, “the shores of Lake Victoria are lined with fish-processing plants that sell the perch to the world.” The industry provides jobs for thousands of Tanzanians, Ugandans, and Kenyans.

According to the video, the population of Nile perch has declined. Why do you think this has happened?

Overfishing and a lack of sustainable food resources (cichlids and other fish) have contributed to the decline of the Nile perch population in Lake Victoria.

Lake Victoria’s Nile perch fishery is an “environmental catastrophe” and shrinking support for the local economy. How can local and global partners address the environmental and economic issues created by the invasive species? https://www.nationalgeographic.org/media/impact-invasive-species/print/ 2/5 7/L2o3/c2a01l 9communities can invest in othImepra citn odf auns Itnvraiesivse, Sipnecileus d| Ninatgion ianl Gdeioggreapnhoic uSosc ifetiysheries in Lake Victoria.

Governments of surrounding countries (Tanzania, Uganda, and Kenya) could also impose taxes and tariffs on Nile perch products, making the fish more costly to buy.

The international community could invest in alternate businesses in the Lake Victoria area, allowing companies and individuals associated with the Nile perch fishery to transition to other industries.

As most sales of Nile perch products are exports, global consumers could also reduce demand for the fish or establish new fisheries and aquaculture farms in areas where the Nile perch is native. Fast Facts

The wild fishery for Nile perch as been steadily decreasing since 2005. However, fishermen and women still catch more Nile perch than are harvested through aquaculture. In 2012, fishers harvested 278,675 tons of Nile perch, while 15,996 tons were harvested through “fish farms.”

Nile perch are carnivores. As fry (juvenile fish) they consume zooplankton, shrimp, clams, snails, and insects. As adults, they prey mostly on other fish. Nile perch can sometimes be cannibals— eating members of their own species.

Female Nile perch are generally larger than males.

Nile perch are some of the biggest freshwater fish in the world. Only these fish are consistently larger: • taimen (indigenous to rivers of Mongolia and Russia) • bull sharks (indigenous to coastlines throughout the tropics and subtropics) • arapaima (indigenous to the Amazon River) • alligator gar (indigenous to the southeastern United States) • Mekong giant catfish (indigenous to the Mekong River in Southeast Asia) • giant freshwater stingray (indigenous to Southeast Asia) • white sturgeon (indigenous to North America) • beluga sturgeon (indigenous to the Caspian, Black, and Adriatic Seas) The Nile perch is known by many names (language in parentheses): • dzo (Adangme) • am’kal (Arabic) https://www.nationalgeographic.org/media/impact-invasive-species/print/ 3/5 7/23/20•1 9cal (Dinka) Impact of an Invasive Species | National Geographic Society • leshie (Ewe) • giwan ruwa (Hausa) • saalen (Jula) • mputa (Luo) • sangala (Swahili) • igbo (Yoruba) • iji (Turkana)

Although Nile perch are not indigenous to Lake Victoria, they are native to other African lakes, including Lake Albert and Lake Turkana. Vocabulary

Part of Term Definition Speech the art and science of cultivating marine or freshwater life for food and aquaculture noun industry. cannibal noun organism that eats the meat of members of its own species. carnivore noun organism that eats meat. economic adjectivehaving to do with money. ecosystem noun community and interactions of living and nonliving things in an area. extinction noun process of complete disappearance of a species from Earth. fish verb to catch or harvest fish. industry or occupation of harvesting fish, either in the wild or through fishery noun aquaculture. freshwater adjectivehaving to do with a habitat or ecosystem of a lake, river, or spring. plural recently hatched fish that has reached the stage where its yolk-sac has fry noun almost disappeared and it can largely feed for itself. the gathering and collection of crops, including both plants and harvest noun animals. indigenous adjectivecharacteristic to or of a specific place. industry noun activity that produces goods and services. introduced a species that does not naturally occur in an area. Also called alien, noun species exotic, or non-native species. invasive type of plant or animal that is not indigenous to a particular area and noun species causes economic or environmental harm. https://www.nationalgeographic.org/media/impact-invasive-species/print/ 4/5 7/23/2019 Part of Impact of an Invasive Species | National Geographic Society Term Definition Speech plural zooplankton microscopic, heterotrophic organism that lives in the ocean. noun Articles & Profiles National Geographic News: On Africa's Largest Lake, Fishers Suffer Falling Stocks, Rising Demand

Images National Geographic Education: Nile Perch

Video National Geographic Channel: Nile Giants National Geographic Channel: Monster Fish—100-Pound Fish

Websites FAO Fisheries and Aquaculture Department: Species Fact Sheets—Lates niloticus

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