Question

Humans have been shaping the traits of organisms for thousands of years. The methods for changing desirable traits have evolved as new technologies have become available.

In the aquaculture industry (fish farming), fish are selectively bred to have desirable traits in order to be more profitable. Desirable traits such as quick growth, resistance to disease, efficient feed-to-growth ratio, ability to tolerate a range of environmental conditions, and high meat yield are all characteristics that are selected and bred for. Sometimes, fish are genetically modified through gene editing to have specific traits. Selective breeding and genetic modification have evolved the genes of many fish species over time and caused a decrease in the genetic diversity of many fish species.



One of the ways fish are farmed is by creating enclosures in the open ocean where fish are grown and collected. These fish are often non-native to the areas in which they are farmed. Various drugs, herbicides, and foods containing non-native fish meal, fish oil, and fish eggs, are often added to the water in the fish enclosures. The diagram shows many of the environmental risks associated with this type of aquaculture.







When farmed fish escape from aquaculture settings, they can impact the surrounding native species and ecosystems. This can cause increased competition of resources for the native species, causing organisms with the most beneficial traits to survive and reproduce. This process is known as natural selection.



An aquaculture farm moves from enclosures in the open ocean to tanks inside a building in a controlled environment. Which statement BEST describes how the desired characteristics of the fish might change?


Fish with quick growth and high meat yield would be bred more often.


Fish with smaller sizes to fit into indoor tanks would be bred more often.


Fish that can survive a wide range of water salinity would be bred more often.


Fish that are more tolerant to temperature changes would be bred more often.

Answer 1

Fish with quick growth and high meat yield would be bred more often.

Explanation: Indoor tanks provide a stable, controlled environment (consistent salinity and temperature), so tolerance to wide environmental fluctuations becomes less important. Producers instead select traits that maximize production and profit—faster growth and higher meat yield reduce time to market and increase return.