Question

What Happened to the Anchovy? - Part 2

Natural events and human activity can threaten the health of the anchovy population off
the coast of Peru. El Niño events are natural events that occur about every two to seven
years. During these events, lower air pressure over South America results in changes to
wind patterns. Normally winds blow from east to west, pushing surface water away from
the coast of Peru. During El Niño events, winds blow from west to east. This pushes
warm surface water toward Peru's coast. The warm surface water contains less oxygen
than cold water and blocks upwelling from bringing nutrients to the surface
Commercial fishing is a human activity that harvests millions of tons of anchovies each
year. In the 1970s, the fishing Industry recognized the need to protect both the
anchovies and the ocean ecosystem. As a result, the government set limits on the
amount of anchovies a fishing boat could catch each year,
The list shows the years in which El Niño events were the strongest. The graph shows
the amount of anchovies caught off the coast of Peru each year,
Strong El Niño Events Annual Catch of
1950 - 2000
Peruvian Anchovy
10
1957 - 1958
1965 - 1966
1972 - 1973
1982 - 1983
1987 - 1988
1991 - 1992
1997 - 1998
Annual Catch
(million metric tons)
1950 1960 1970 1980 1990 2000
Year
Based on the evidence provided, which factors most influenced the
number of anchovies caught in 1984?
A overfishing in previous years and warm waters with few nutrients
B. movement of anchovies to other waters and fishing of large fish
C. conservation of anchovies and habitat management
D. warm winds and low-pressure areas

Answer 1

Note about the question:

You will find the graph in the attached files.

Answer:

A) overfishing in previous years and warm waters with few nutrients

Step-by-step explanation:

Under El Niño conditions, there is a tropical stream, which is usually weak, that acquires strength while the opposite streams debilitate. This event impedes warm water to go eastward, remaining in South America´s coasts, which produces unusual precipitations in Chile followed by floral bloom in Atacama desert and fewer precipitations events in Eastsouth Asia and North Australia. During and after the El Niño, occurs a fishery crisis because there is no upwelling on the coasts of South America, nutrients from the bottom do no ascend, and fish populations remain equal or decrease.

Around 1970, there was excessive overexploitation of fishes. This overfishing probably led to a significant decrease in the anchovy population size, reducing the number of individuals in the reproductive stage, especially the females. The graph reflects that during the following years, there were also peaks in anchovy catch. The population did not have enough time to recover from the highest peak in 1970.

From 1982-1983 El Niño event was severe. No upwelling meant no nutrients to survive, and that the remaining anchovy population, previously affected by fishery, hardly made it that year. There was probably a fishery crisis, and hence, no animals were caught in 1984.