What is marine aquaculture?

farming marine species in captivity. It is farming in the sea.

Which group is farmed in marine aquaculture?

crustaceans. Fish, crustaceans and seaweeds.

Why does disease spread quickly on a fish farm?

the fish are crowded together. Close contact passes disease from fish to fish.

What problem does waste from fish cages cause?

nutrient enrichment of the water. Extra nutrients can lead to eutrophication.

Why can escaped farmed fish harm wild populations?

they compete with wild fish and breed with them. Competition and interbreeding weaken the wild stock.

Why does feeding farmed fish on wild-caught fish limit the benefit of aquaculture?

wild fish are still being taken from the sea. The pressure is shifted to other species.

Marine aquaculture · Cambridge IGCSE Environmental Management

In plain words

If the wild fish are running out, why not farm them, as people farm chickens? About half of the fish people eat is now farmed, not caught. Farming takes pressure off the sea, and it brings problems of its own.

10 things to know

Marine aquaculture is the farming of marine species in captivity. The species farmed are fish, crustaceans such as prawns, and seaweeds.
Fish are usually kept in large cages or pens in sheltered coastal water, fed, and harvested when fully grown.
Benefit: reduced exploitation of natural fisheries. Farmed fish take the place of wild-caught fish, so wild stocks can recover.
Benefit: an increased food supply for humans. It is a reliable source of protein, and it provides jobs.
Risk of escape: farmed animals that escape compete with wild ones, and can breed with them, which weakens the wild population.
Risk of disease: animals crowded together pass disease and parasites easily, and these spread to wild fish nearby. The chemicals used to treat them pollute the water.
Local food webs are changed, by escapes, by disease, and by predators drawn to the cages.
Nutrient enrichment from waste: uneaten food and faeces fall through the cages and can cause eutrophication in the water below.
Energy usage: pumps, boats, feed production and refrigeration all use energy.
Source of food for farmed species: many farmed fish are fed on pellets made from wild-caught fish, so the pressure on the sea is moved to other species, not removed.

Worked example

A salmon farm is planned for a sheltered bay. Give one benefit and two environmental risks.

Benefit: it supplies fish without taking them from wild stocks, and brings jobs to the area.
Risk: waste food and faeces add nutrients to the bay, which can cause eutrophication.
Risk: disease and parasites spread among the crowded fish and can pass to wild fish.

Tips and tricks

Seaweed farming needs no feed at all, since seaweed photosynthesises. The problems of feed and waste apply to fish and crustaceans.
"Reduces overfishing" is only partly true if the farmed fish are fed on wild fish. Saying so shows evaluation.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Marine aquaculture: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

What is marine aquaculture?
- catching wild fish with nets
- farming marine species in captivity (the answer)
- protecting an area of sea from fishing
- cleaning up oil spills
It is farming in the sea.
Which group is farmed in marine aquaculture?
- reptiles
- birds
- crustaceans (the answer)
- insects
Fish, crustaceans and seaweeds.
Why does disease spread quickly on a fish farm?
- the water is too cold
- the fish are too old
- the fish are fed too little
- the fish are crowded together (the answer)
Close contact passes disease from fish to fish.
What problem does waste from fish cages cause?
- nutrient enrichment of the water (the answer)
- acid rain
- salinisation
- ozone depletion
Extra nutrients can lead to eutrophication.
Why can escaped farmed fish harm wild populations?
- they clean the water
- they compete with wild fish and breed with them (the answer)
- they are eaten at once
- they cannot survive
Competition and interbreeding weaken the wild stock.
Why does feeding farmed fish on wild-caught fish limit the benefit of aquaculture?Stretch
- wild fish are still being taken from the sea (the answer)
- the food is too expensive to buy
- the farmed fish grow more slowly
- the farmed fish cannot digest it
The pressure is shifted to other species.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 7 marks. Write your answers on paper, then check them.

Marine aquaculture

Cambridge IGCSE Environmental Management 0680 · 7 marks · papermunch.org

Name ______________________________ Date ______________

Define the term marine aquaculture.[2]
Show answerHide answer
The farming of marine species, such as fish, crustaceans and seaweeds, in captivity.
I got this one
Explain how marine aquaculture can help wild fish populations.[2]
Show answerHide answer
Farmed fish meet some of the demand for food. Fewer wild fish are caught, so wild populations can recover.
I got this one
Explain how a fish farm can damage the water around it.[3]
Show answerHide answer
Uneaten food and faeces add nutrients to the water. This nutrient enrichment causes algae to grow rapidly (eutrophication), and decomposition uses up oxygen. Chemicals used to treat disease also pollute the water.
I got this one

Answers: Marine aquaculture

1. The farming of marine species, such as fish, crustaceans and seaweeds, in captivity.
2. Farmed fish meet some of the demand for food. Fewer wild fish are caught, so wild populations can recover.
3. Uneaten food and faeces add nutrients to the water. This nutrient enrichment causes algae to grow rapidly (eutrophication), and decomposition uses up oxygen. Chemicals used to treat disease also pollute the water.