AQA GCSE Biology Foundation (8461), Foundation tier · Ecology › Food production
Practise Sustainable fisheries. 5 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Fish stocks in the oceans are declining. You need to explain why stocks must be kept at a level where fish can still breed, and how controlling net size and fishing quotas help. This subtopic is in GCSE Biology only, not Combined Science.
Key facts
Fish stocks in the oceans are declining (overfishing)
Stocks must be kept at a level where breeding continues
Net size control: larger mesh lets young fish escape to grow and breed
Fishing quotas: limit the amount of each species caught in an area
Aim: conserve fish stocks at a sustainable level
Notes
Why fish stocks matter
Fish stocks in the oceans are declining because fish are being caught faster than they can reproduce (overfishing).
Stocks must be kept high enough for the fish to keep breeding; otherwise some species could vanish completely from some areas.
Fish are an important source of protein, so falling stocks threaten food security and fishing jobs.
Losing a fish species also affects food webs: its predators lose food and its prey may increase.
Controlling net size
diagram
Nets with a larger mesh size (bigger holes) let young, small fish escape.
These fish survive, grow and reach breeding age, so they can reproduce and replace the fish that are caught.
A bigger mesh lets young fish escape, grow and breed.
Fewer young fish are caught and thrown back dead.
Fishing quotas
Fishing quotas limit the amount of each species of fish that can be caught in an area.
This leaves enough adult fish in the sea to breed, so the population can stay stable or recover.
Quotas can be lowered when scientists' surveys show that a stock is falling.
Problems
Fishers may catch less and earn less money in the short term, and some may break the rules, so quotas have to be enforced.
Fish caught above the quota, or of the wrong species, may be thrown back already dead.
In the long term, sustainable fishing means there will still be fish to catch.
How to answer each type of question
Name methods of conserving fish stocks
2 marksGrade 4
The two methods in the specification are control of net size and fishing quotas.
Be precise: 'nets with a larger mesh size', not just 'bigger nets'.
Example. Give two methods used to conserve fish stocks at a sustainable level.
Show the model answerHide the model answer
Controlling net size, e.g. using nets with a larger mesh (1); fishing quotas, which limit the amount of fish caught (1)
Don’t lose marks
Saying 'bigger nets' help. It is a larger mesh size (bigger holes) that lets young fish escape.
Saying quotas stop fishing. They limit the amount of each species caught.
Leaving out the key idea: fish must survive to breed.
More tips
Memory tricks
Two tools: nets and numbers (net size and quotas).
Big holes: baby fish swim free, grow up and breed.
Sustainable = breeding keeps up with catching.
Exam technique
Finish with breeding: 'so more fish reach breeding age and reproduce'.
In data questions, give values from before and after the control was introduced.
If asked for disadvantages, think about fishers' income and whether the rules are followed.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
State that fish stocks are decliningFish are being caught faster than they can reproduce (overfishing), so numbers in the oceans are falling.
Grade 4
Name two methods to conserve fish stocksControlling net (mesh) size and introducing fishing quotas.
Grade 5
Explain why fish stocks must be maintainedIf too few fish are left to breed, the species may disappear altogether in some areas.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Fish stocks in the oceans are declining.
(a) Which two measures help to conserve fish stocks at a sustainable level? Tick (✓) two boxes.[2]
Controlling the mesh size of fishing nets
Introducing fishing quotas
Using larger fishing boats
Fishing in areas where fish breed
(b) What is a fishing quota?[1]
(c) Why is it important to keep fish stocks at a level where breeding continues?[1]
Show the answer and mark scheme
(a)Answer: Controlling the mesh size of fishing nets; Introducing fishing quotas
(b)
a limit on the number / mass of fish (of each species) that can be caught
(c)
otherwise the population declines and some species may disappear from some areas
Question 2Medium6 marks
Fishing boats catch fish using large nets.
(a) Explain how increasing the mesh size of fishing nets helps to conserve fish stocks.[3]
(b) Explain how fishing quotas help to conserve fish stocks.[2]
(c) Suggest one reason why some people who work in the fishing industry oppose quotas.[1]
Show the answer and mark scheme
(a)
larger holes let smaller / younger fish escape
so these fish survive to reach breeding age and breed
so the population is replaced / maintained
(b)
they limit the number / mass of fish caught
so enough fish survive to breed / fish are not removed faster than they are replaced
(c)
they catch fewer fish, so earn less money
jobs may be lost
fish caught over the quota may be thrown back dead (wasted)