AQA GCSE Biology

Revision Notes

7.5.3 Sustainable Fisheries

Fish Stocks

  • Fish stocks (the populations of fish that we catch for food) in the oceans are declining
  • This is mainly due to overfishing
  • This could potentially result in:
    • Some species of fish completely disappearing in certain areas or even going extinct (eg. we are at risk of losing cod completely in the north-west Atlantic)
    • Ocean food chains being disrupted, affecting many other aquatic species
    • Fewer fish for human consumption – this would be especially problematic for populations that rely on fish as a main source of food
  • For these reasons, it is important to maintain fish stocks at a level where breeding continues
  • Sustainable fisheries are required to achieve this – these are fisheries in which the overall population size of fish species does not decrease, because the number of fish caught does not exceed the number of new fish born

Control of Nets

  • Control of net size and the introduction of fishing quotas play important roles in the conservation of fish stocks at a sustainable level
  • Increasing the size of gaps in fishing nets can help in two main ways:
    • Fewer unwanted species (that are often simply discarded) will be caught and killed, as they can escape through larger net gaps (as long as they are smaller than the species being caught – the accidental capture and killing of larger species is still a problem that is reducing the populations of these species)
    • Juvenile fish of the fish species being caught can escape through larger net gaps, meaning they can reach breeding age and have offspring before they are caught and killed. This ensures the population of the fish species being caught can be replenished
  • In addition to tighter controls on net size, fishing quotas that limit the number and size of particular fish species that can be caught in a given area have been introduced by many countries to stop species becoming overfished

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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