World Fisheries (Copy)
5.2 World Fisheries – Cheat Sheet
Distribution of Major Ocean Currents
| Type | Characteristics | Impact on Fisheries |
|---|---|---|
| Cold Currents | Flow from polar → equatorial regions, nutrient-rich | Encourage plankton growth → supports large fish populations |
| Warm Currents | Flow from equatorial → polar regions, less nutrient-rich | Support fewer fish compared to cold currents |
Distribution of Major Marine Fish Populations
| Factor | Explanation | Example |
|---|---|---|
| Continental Shelves | Shallow seas, sunlight penetration, nutrient upwelling → rich fishing grounds | North Sea, Grand Banks (Canada) |
| Cold Currents | Carry nutrients to surface → high plankton → fish thrive | Peru Current off South America |
| Mix of Warm + Cold Currents | Where currents meet, nutrients rise and plankton multiply | Off coast of Japan (Kuroshio & Oyashio currents) |
El Niño Southern Oscillation (ENSO)
| Aspect | Description | Impact on Fisheries |
|---|---|---|
| Normal Conditions | Peru Current (cold) brings nutrient-rich water → supports plankton and anchovy fisheries | Peru = one of world’s richest fisheries |
| El Niño Event | Trade winds weaken → warm water flows eastwards → suppresses upwelling | Collapse of anchovy stocks in Peru |
| Consequences | – Reduced fish catches → unemployment & economic loss- Impacts seabirds & marine mammals dependent on fish | Peru anchovy collapse (1972 El Niño) |
Quick Pointers
- Best fisheries = shallow continental shelves + cold nutrient-rich waters.
- Cold currents = high productivity, warm currents = lower productivity.
- ENSO shows how climate variations disrupt fisheries → major economic & ecological effects.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Environmental Management Full Scale Course