EarthLabs > Fisheries > Lab 8: Hot Topic: Effects of Climate Variability on Fisheries > 8B: Intermediate Variability: Anchovy Collapse

Hot Topic: Effects of Climate Variability on Fisheries

Part B: Intermediate Variability: Anchovy Collapse

Most of the world's largest ocean fisheries are based on small fish such as anchovies and sardines. These species dominate in the highly productive upwelling regions along the coasts of California, Peru, the Canary Islands, and South Africa. These species are also common in other nutrient enriched areas such as those near Japan and Argentina. Populations of anchovies and sardines tend to expand rapidly when feeding and spawning conditions are favorable, but are susceptible to rapid collapse when ocean conditions change.

  1. Examine the graph below of Peruvian anchovy catches from 1950-2000.

    Data for image from FAO 2001.

    Checking In

    Answer the following questions to check your understanding of the information presented in the graph above.

    • What major trends do you see in Peruvian anchovy catches between 1950 and 2000?
      There was a steady increase in anchovy landings from 1950-1970, followed by a sharp decline in the early 1970s. Catches remained low through the mid-1980s, but grew steadily from the mid-1980s through the mid-1990s. From the mid-1990s through 2000, anchovy catches experienced a sharp decline followed by a quick recovery.
    • What are some possible reasons for the low anchovy catches during the 1970s and 1980s?
      Possible reasons for low catches include overfishing, implementation of fishery closures or restrictions, or changes in ocean climate.

    Stop and Think

    1: Given that anchovies rely on upwelling for food, how do you think El Niño events might affect the anchovy fishing industry?

    2: Based on your observations in Part A of how quickly California squid have typically rebounded after El Niño events, which (if any) of the trends in Peruvian anchovy catches do you think might be due to El Niño, and which (if any) do you think are due to other influences? Explain your reasoning.

  2. Read this passage about The Peruvian anchovy industry and El Niño.

    Checking In

    Answer the following questions to check your understanding of the information presented in the passage about El Niño and the Peruvian anchovy industry.

    • What caused the 1972 anchovy collapse?
      Although the failure of the anchovy harvest in 1972 was originally blamed on El Niño, it was discovered that overfishing also played a part. Harvests prior to 1972 had been over the estimated sustainable limit.
    • What were some of the consequences of the anchovy collapse?
      During the growth years of the Peruvian fishing industry, fishmeal made from anchovies had become a major source of feed for livestock and poultry around the world. When the anchovy catch collapsed, nations that had become dependent on the fishmeal had to find other, more expensive, sources of feed, causing meat prices to rise. Another result of the collapse was the death of many birds, which had depended on the anchovies for food. The death of the birds caused a decrease in the harvest of bird droppings used as fertilizer by Peruvian farmers.
    • What other effects has El Niño had on biospheric events worldwide?
      In both the southwest United States and South Africa, rodent infestations occur after El Niño rains because of an increased abundance of food. In southern Asia, El Niño events have been recognized since the 1960s to be correlated with algal blooms and cholera outbreaks. Across the globe, wherever weather changes brought about by El Niño give rise to warmer and wetter conditions, mosquito populations mushroom, leading to an increase in mosquito-borne diseases such as malaria, yellow fever, dengue fever, and encephalitis. [end hidden']