Impact of exploitation of the oceans Revision Notes

Overfishing occurs when fish are caught at a rate faster than they can reproduce, leading to a decline in the population of the target species. For example, cod populations in the North Atlantic have dramatically decreased due to overfishing, disrupting the marine food web.

Removing large numbers of a single species can unbalance marine ecosystems. Predators that rely on the overfished species for food may decline, while prey species may increase unchecked, causing further ecological shifts.

Overfishing can also lead to the collapse of fisheries, threatening food security and livelihoods dependent on fishing. This demonstrates the importance of managing fish stocks sustainably to maintain ecosystem health and economic stability.

• Overfishing reduces target species populations below sustainable levels.
• Ecosystem balance is disrupted, affecting predator-prey relationships.
• Fisheries collapse risks food supply and economic impacts.

Bycatch refers to the unintended capture of non-target species during fishing activities. This includes juvenile fish, other marine animals such as turtles, dolphins, and seabirds, many of which may be endangered or vulnerable.

Bycatch mortality can significantly reduce populations of these species, threatening biodiversity and ecosystem function. For instance, sea turtles caught as bycatch in shrimp trawling nets often die, contributing to their population decline.

Reducing bycatch is crucial for conservation. Techniques such as using turtle excluder devices (TEDs) in nets or modifying fishing gear can help minimise bycatch and protect non-target species.

• Bycatch includes unintended capture of non-target and endangered species.
• Bycatch mortality harms marine biodiversity and ecosystem stability.
• Gear modifications can reduce bycatch and protect vulnerable species.

Aquaculture involves breeding and raising marine species such as fish, shellfish, and seaweed in controlled environments. This method produces seafood without removing wild populations directly from the ocean.

By supplying seafood through farming, aquaculture reduces the demand on wild fish stocks, helping to prevent overfishing and allowing wild populations to recover.

For example, farmed salmon provides a significant portion of global salmon consumption, reducing pressure on wild salmon populations. However, aquaculture must be managed carefully to avoid environmental problems like pollution or disease spread.

• Aquaculture produces seafood in controlled environments, reducing wild catch.
• It helps alleviate fishing pressure on wild marine populations.
• Sustainable aquaculture management is essential to avoid environmental harm.

Sustainable management of ocean resources requires balancing wild fishing with aquaculture to maintain healthy marine ecosystems and meet human demand.

Overreliance on either method can cause problems: excessive fishing depletes wild stocks, while poorly managed aquaculture can pollute habitats and spread disease.

Effective policies include setting fishing quotas, protecting breeding grounds, and regulating aquaculture practices to ensure long-term productivity and biodiversity conservation.

• Sustainable ocean use balances fishing and aquaculture.
• Overfishing and poor aquaculture management both pose risks.
• Regulations and conservation measures support ecosystem health and resource availability.