5.8 Impacts of Overfishing

Overfishing depletes fish stocks

Overfishing occurs when fish are harvested faster than populations can reproduce and replenish, causing stock collapse. This reduces biodiversity, disrupts food webs, and threatens the livelihoods of fishing communities. Iconic examples include the collapse of the Atlantic cod fishery off Newfoundland, which devastated local economies for decades.

Bycatch and destructive methods

Bycatch is the unintentional capture of non-target species (sea turtles, dolphins, sharks) in fishing gear, killing organisms not meant to be harvested. Methods like bottom trawling drag heavy nets across the seafloor, destroying habitats such as coral reefs and seagrass beds, while longlining and driftnets increase bycatch and harm marine biodiversity.

Managing fisheries sustainably

Solutions include quotas (catch limits), marine protected areas (MPAs), aquaculture (fish farming), and enforcing sustainable yield practices that allow populations to regenerate. International agreements and consumer choices (like sustainable seafood labeling) also help reduce pressure on wild fish stocks and promote long-term ocean health.

Key terms

Overfishing

Harvesting fish faster than populations can reproduce, leading to stock depletion and collapse.

Bycatch

Unintentional capture of non-target species (e.g., turtles, dolphins, sharks) during fishing.

Bottom trawling

A fishing method that drags heavy nets across the seafloor, destroying habitats like coral reefs.

Marine Protected Area (MPA)

A designated ocean region where fishing and other activities are restricted to protect ecosystems and allow recovery.

Aquaculture

The farming of fish and other aquatic organisms, used to reduce pressure on wild fish stocks.

Try an AP-style question

What is bycatch?

1. Fish released back to breed in the wild
2. Unintended species caught in fishing gear
3. The target fish species the boat seeks
4. Fish raised in ponds on fish farms