How Can Fisheries Be Managed Sustainably?

Fisheries can be managed sustainably by controlling fishing net sizes and introducing fishing quotas. These measures allow enough fish to survive and reproduce, so fish stocks can recover and remain available in the future.

Controlling net size

Fishing nets can be designed with a minimum mesh size, meaning the gaps in the net must be large enough for smaller fish to escape.

This helps because:

• young fish are less likely to be caught;
• they have time to grow to reproductive age;
• they can breed before being caught;
• the population is more likely to replace the fish removed.

Using fishing quotas

A fishing quota is a limit on how many fish, or what mass of fish, may be caught in a particular period.

Quotas reduce overfishing by preventing too many fish from being removed at once. If enough breeding adults remain, they can reproduce and help maintain the population.

Why sustainable management matters

A fishery is sustainable when fish are removed at a rate that allows the population to continue breeding and replacing those caught. Without controls, fish stocks may fall so low that breeding cannot maintain the population. The species could then disappear from that area, and fishing communities could lose an important food source and income.

Worked example

Suppose many young fish are being caught before they can reproduce. Increasing the net's mesh size allows these smaller fish to escape. They can then mature and breed, increasing the chance that the fish stock will recover.

Common exam mistake

Do not simply write that quotas or larger net sizes mean “fewer fish are caught.” Explain the biological consequence: more fish survive to reproductive age, breeding continues, and the population is maintained.

This is AQA GCSE Biology separate-science content and applies to both Foundation and Higher tiers. Higher tier has been assumed because no tier was specified.