APES Video Notes for 5.8 - Overfishing

Introduction to Overfishing

Focus on the impacts of overfishing relating to:
- Environmental problems (e.g., biodiversity decline)
- Economic problems (e.g., income loss, tourism loss)
Objective:
- Describe the causes and problems related to overfishing, including biodiversity decline and economic losses.
Skill practiced:
- Describing approaches or responses to environmental problems.

Fisheries:
- Defined as populations of fish utilized for commercial fishing.
- Areas designated for collection of fish in large quantities for livelihood.
Fishery Collapse:
- Occurs when overfishing reduces fish population or fishery by over 90%.
- Consequence: Fish populations may fail to recover.
  - Leads to issues like low genetic diversity, skewed sex ratios, and inbreeding depression.
  - Affects resilience to disturbances and may lead to complete species loss.
  - Major effects on the trophic pyramid.

Genetic Diversity:
- Low genetic diversity leads to vulnerability against ecosystem disturbances.
- Lack of mutations for beneficial adaptations.
Biodiversity Decline:
- Loss of certain species leads to decreased marine biodiversity.
- Significant implications for ecological balance within the trohic pyramid.

When fisheries collapse:
- Loss of income source for fishermen.
- Negative impact on communities reliant on tourism (e.g., hotels, restaurants).
- Economic data indicates a sharp decline in profitability from peak years (e.g., $325 million in 1985 to below $100 million by 2008).

Tragedy of the Commons:
- Lack of laws, regulations, or penalties leads to unchecked overfishing.
- Assumption that if one does not fish, others will, incentivizing overfishing.

Bottom Trawling:
- A fishing technique that involves dragging nets along the ocean floor.
- Effectively catches targeted species but results in significant bycatch (e.g., dolphins, whales, turtles).
- Increases turbidity which hinders photosynthesis in algae and visibility for predators.
- Damages coral reefs, affecting diverse marine habitats.

Trophic Cascade Concept:
- As larger predatory fish (e.g., tuna, salmon) are depleted, fishing shifts to smaller forage fish (e.g., herring, sardines).
- Depletion of prey fish impacts marine mammals and seabirds relying on them for food.
Population Dynamics:
- Overfishing reduces prey, leading to increased zooplankton populations and decreased phytoplankton populations.
- This chain reaction is termed a trophic cascade, resulting in broad ecological consequences.

Discussed extensive problems resulting from overfishing.
Practice FRQ 5.8:
- Focus on proposing solutions to address fishery depletion.