Management of Harvesting of Marine Species (Cambridge International IGCSE Environmental Management)

Management of harvesting of marine species

• Management strategies aim to protect fish populations and ensure marine species are harvested sustainably

  • These strategies prevent overfishing, protect breeding adults and reduce bycatch

• Successful management requires cooperation between fishers, governments and international organisations

Limits on size of boat and overall net size

• Smaller boats have lower fishing capacity

  • This reduces the number of fish taken at once

• Limiting net size restricts how much marine life can be captured

  • Helps prevent overharvesting of large areas in a single trip

Increased mesh size of nets

• Larger mesh sizes allow juvenile fish to escape

  • Gives young fish time to grow and reproduce
  • Protects breeding populations
  • Helps maintain long-term fish stocks

Sustainable methods: pole and line

• Pole and line fishing targets individual fish, using individual fishing poles

  • This reduces bycatch because unwanted species can be released

• A more selective and sustainable method than large trawling nets

  • Helps protect non-target species such as dolphins or turtles

Quotas

• Quotas limit how much of each species can be caught

  • Prevents fishers from exceeding sustainable levels

• Governments use scientific data to set quotas

  • This helps species recover when numbers fall too low

Closed seasons

• Closed seasons stop fishing during breeding periods

  • Allows populations to reproduce and grow
  • Protects eggs, larvae and young fish
  • Increases long-term sustainability

Limited number of fishing days

• Restricting fishing days reduces the total amount caught

  • Helps prevent overfishing throughout the year
  • Allows fish populations time to recover between fishing periods

Protected areas

• Marine protected areas (MPAs) restrict or ban fishing in certain zones

  • These areas act as safe breeding grounds
  • Populations inside MPAs can grow larger
  • Fish may then move into surrounding areas, increasing catches sustainably

Conservation laws

• Laws regulate how, when and where fishing can occur

• These laws help enforce sustainable practices

• Penalties for breaking rules discourage illegal fishing

  • Includes fines, boat seizures, or bans on fishing licences

International agreements: implementation and monitoring

• Many marine species migrate across international waters
• This means countries must work together to manage shared stocks
• Agreements set rules on quotas, protected species and fishing methods
• Monitoring ensures countries follow the rules
• Satellite tracking, inspections and reporting systems help detect illegal fishing

Benefits & limitations of marine harvesting management strategies

Limitations of marine harvesting management strategies

• Marine harvesting management strategies vary in effectiveness, cost and difficulty of enforcement

Limitations of boat and net size limits

• Smaller boats and nets may reduce short-term catches

  • This can cause financial difficulties for small-scale fishers

• Hard to enforce (e.g. in areas with many small, unregistered or mobile vessels)

• Fishers may oppose restrictions if they feel their livelihoods are threatened

Limitations of increased mesh size

• Larger mesh reduces immediate catch numbers

  • Some fishers may resist the change due to lower income

• Illegal use of small-mesh nets can continue without strong monitoring

• Less effective if fish populations are already severely depleted

Limitations of pole and line fishing

• Much slower and more labour-intensive than net fishing
• May not meet high commercial demand for seafood
• Requires trained workers and a constant bait supply

Limitations of quotas

• Political pressure may lead to quotas being set too high

  • This reduces the conservation benefit

• Requires strong monitoring to prevent illegal fishing

• Can encourage fishers to discard unwanted catch to stay within limits

  • This increases waste and harms ecosystems

Limitations of closed seasons

• Causes loss of income during the closed period

• Compliance depends on effective enforcement

  • Illegal fishing during breeding seasons can undo benefits

• Short-term economic impacts may make fishers resist the strategy

Limitations of fishing day limits

• Fishers may increase effort on allowed days

  • This reduces the strategy’s overall effectiveness

• Hard to monitor fishing effort in remote coastal areas

• Does not directly protect breeding adults unless paired with closed seasons

Limitations of protected areas

• Restrict fishing grounds, creating conflict with local communities
• Require funding for patrols, monitoring and enforcement
• Illegal fishing inside MPAs can continue if enforcement is weak
• Benefits may take years to appear, so fishers may lose patience or support

Limitations of conservation laws

• Enforcement can be costly and difficult
• Laws may exist but not be properly implemented
• Strict regulations may reduce short-term income, leading to resistance

Limitations of international agreements

• Countries may disagree on quotas, enforcement or shared responsibilities
• Some nations may ignore regulations or fish illegally in protected zones
• Monitoring migratory species across huge ocean areas is challenging and expensive

Exam Hint Pair management strategies with their benefits and limitations in your answers. Examiners reward structured evaluation like this because it shows you have a balanced understanding.

Most of these strategies are beneficial in theory, but they all come with enforcement challenges—this is a very real limitation students sometimes overlook.