AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Sustainable fisheries: Fish stocks in the oceans are declining.
Fish stocks are populations of fish that are harvested for food.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 3
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Fish stocks are populations of fish that are harvested for food. They are declining because humans catch fish faster than the populations can reproduce. Modern fishing fleets use sonar, large nets and factory ships, so they can locate and remove huge numbers of fish in a short time. As the breeding population shrinks, fewer young fish are produced, so the stock falls further. This is unsustainable because the ocean cannot replace the fish as quickly as they are removed. For example, if a cod population is reduced below the level needed for successful spawning, recruitment of young cod falls and the stock may not recover for many years. Understanding this decline is the first step towards managing fisheries sustainably.
What earns the marks
- State that fish stocks are populations of fish that are caught for food and that their numbers are falling.
- Explain that the rate of fishing exceeds the rate at which fish populations can reproduce.
- Describe how improved technology, such as sonar and large factory ships, increases the number of fish caught.
- Explain that a reduced breeding population produces fewer offspring, so the stock continues to decline.
- Recognise that the decline is unsustainable because fish are being removed faster than they can be replaced.
Common mistakes and how to put them right
Thinking that fish stocks decline only because of pollution.
Put it right: The main cause is overfishing, where fish are caught faster than they can breed.
Confusing a fish stock with the total number of all fish species in the ocean.
Put it right: A stock is a particular population that is fished.
Assuming that fish populations can always recover quickly.
Put it right: If the breeding population becomes too small, recovery may take many years or may not happen.
Exam tips
- Use the phrase ‘caught faster than they can reproduce’ to make the cause of decline clear.
- Link the decline to human demand for food and advances in fishing technology.
- When describing a consequence, refer to the breeding population and the number of young fish produced.
Try the lesson
The start of the Sustainable fisheries: Fish stocks in the oceans are declining. lesson, made from checked teaching notes for this specification point.
Have a go first
Which human activity is the main reason why fish stocks in the oceans are declining?
Listen
Fish stocks are populations of fish that are harvested for food. They are declining because humans catch fish faster than the populations can reproduce. Modern fishing fleets use sonar, large nets and factory ships, so they can locate and remove huge numbers of fish in a short time. As the breeding population shrinks, fewer young fish are produced, so the stock falls further. This is unsustainable because the ocean cannot replace the fish as quickly as they are removed. For example, if a cod population is reduced below the level needed for successful spawning, recruitment of young cod falls and the stock may not recover for many years. Understanding this decline is the first step towards managing fisheries sustainably. A strong answer earns marks for these points. State that fish stocks are populations of fish that are caught for food and that their numbers are falling. Explain that the rate of fishing exceeds the rate at which fish populations can reproduce. Describe how improved technology, such as sonar and large factory ships, increases the number of fish caught. Explain that a reduced breeding population produces fewer offspring, so the stock continues to decline. Exam tip: Use the phrase ‘caught faster than they can reproduce’ to make the cause of decline clear.
Key words
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Fish stocks
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Overfishing
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Breeding population
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Unsustainable
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See every definition
- Fish stocks
- Populations of fish that are harvested for food, and whose numbers are declining in the oceans.
- Overfishing
- Catching fish faster than the populations can reproduce, which is the main cause of fish stock decline.
- Breeding population
- The part of a stock that reproduces; as it shrinks, fewer young fish are produced, so the stock falls further.
- Unsustainable
- Describes a situation where the ocean cannot replace the fish as quickly as they are removed.
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