Question

What Happened to the Anchovy? - Part 2

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

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.