🎣 Control of net size
Nets with a large mesh let small, young fish escape through the holes. These young fish grow up and breed, so the stock can recover. Small mesh nets catch young fish before they can breed.
Food Production » Sustainable Fisheries and Biotechnology
What you'll learn this session
Study time: 30 minutes
AQA spec: 4.7.5.3, 4.7.5.4 (Biology only)
- Why fish stocks are declining and why breeding must be able to continue
- How net size control and fishing quotas protect fish stocks
- How microorganisms can be cultured for food, including Fusarium mycoprotein
- How GM bacteria and GM crops help to meet the demands of a growing population
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Unlock This CourseDeclining fish stocks
Fish are an important food for millions of people. But fish stocks in the oceans are declining. If too many fish are caught, there are not enough left to breed and replace the ones that were taken.
Key terms:
- Fish stock: the population of one type of fish in an area of ocean.
- Conservation: protecting living things and their habitats so they are not lost.
- Quota: a limit on how much of something can be caught.
It is important to maintain fish stocks at a level where breeding continues. If breeding stops, certain species may disappear altogether in some areas.
Keeping fishing sustainable
The specification names two methods that play important roles in conservation of fish stocks at a sustainable level.
⚖ Fishing quotas
A quota sets a limit on the amount of a species that can be caught. Fishing boats must stop when they reach it. This stops too many fish being taken, so enough are left to breed.
Using these fishing techniques properly promotes the recovery of fish stocks. Fish numbers go back up over time, and fishing can carry on for many years.
Common mistakes
Do not say that large mesh nets "let the fish go". Say that they let young fish escape so they can breed. The reason for both methods is to keep a breeding population.
Growing microorganisms for food
The human population is growing, so more food is needed. One solution comes from biotechnology. Modern biotechnology techniques enable large quantities of microorganisms to be cultured for food.
Key terms:
- Biotechnology: using living organisms to make useful products.
- Mycoprotein: a protein-rich food made from a fungus.
Fusarium and mycoprotein
The fungus Fusarium is useful for producing mycoprotein. Mycoprotein is a protein-rich food that is suitable for vegetarians, because it does not come from animals.
The steps are:
- The fungus is grown on glucose syrup, which is its food.
- It is grown in aerobic conditions, which means oxygen is supplied.
- The fungus increases its mass. This mass of living material is called biomass.
- The biomass is harvested and purified, then used as food.
Worked example
Question: Why must oxygen be supplied when Fusarium is grown?
Answer: The fungus is grown in aerobic conditions. Aerobic means with oxygen, so oxygen must be supplied.
Genetically modified bacteria and human insulin
Another biotechnology solution is genetic modification. A genetically modified (GM) bacterium produces human insulin. How the gene is transferred is covered in the lesson on Genetic Engineering.
When the insulin is harvested and purified, it is used to treat people with diabetes.
GM crops
GM crops could provide more food, or food with an improved nutritional value. A good example is golden rice. It has been genetically modified to contain beta-carotene, which the body can use to make vitamin A. It is designed to help people whose diet is short of vitamin A.
🍄 Fusarium
A fungus grown on glucose syrup in aerobic conditions. Gives mycoprotein.
🧪 GM bacteria
Make human insulin, which is harvested and purified to treat diabetes.
🌾 GM crops
More food, or better nutrition, for example golden rice.
Putting it together
Sustainable fishing keeps a food source going. Culturing microorganisms makes a protein-rich food. GM crops can give more food or better food. Each one is a possible solution to the demands of the growing human population.
Common mistakes
Remember that Fusarium is grown on glucose syrup in aerobic conditions (with oxygen). Mycoprotein is made from a fungus, not a plant or an animal.
Exam-style question
(a) Explain how using nets with a large mesh helps to conserve fish stocks. [2 marks]
(b) Describe how mycoprotein is produced from Fusarium. [3 marks]
(c) Give one way GM crops could help to feed a growing population. [1 mark]
Model answer
(a) Young fish can escape through the large holes (1). They grow up and breed, so the fish stock is kept at a level where breeding continues (1).
(b) The fungus is grown on glucose syrup (1) in aerobic conditions (1). The biomass is harvested and purified (1).
(c) They could provide more food, or food with an improved nutritional value such as golden rice (1).
Exam tip
In part (a), the second mark is for linking the escape of young fish to breeding. Always finish the chain: escape, grow, breed, stock recovers.