Global Change Exam #2 Terms and Concepts

Shifting Baselines

How we perceive what’s natural and whether those perceptions are representative of their value

Why are marine fisheries important?

• They are a significant source of protein

• Could have a trophic cascade

• Loss of ecosystem function

• Resistance

• Resilience

• Important source of food and economic growth for people in other developing countries

Where do we catch most fish?

Most fish are caught from coastal waters

• Coral

• Tropical shelves

• Only 4% of fish are from from the open ocean!!!

Why are capture fisheries going flat?

• over-exploitation

• No more fish to catch

• We are putting in more effort to catch the same amount of fish

  • Catch per unit effort is going down

• Fishermen spend longer to meet the quota

  • More money spent at sea

These are global indicators that marine fish are over-exploited

Cod Fish In Atlantic Case Study

Previously cod was caught in small family boats 

• Late 1950s, new technology brought deep trawlers and were successful in deep waters 

• Populations of cod were over-exploited

• NO place of refuge       

What has happened with the cod since the 1950s?

The cod have NOT recovered since

• They are not playing the same role ecologically

• They are functionally extinct

What are some issues contributing to the overexploitation of marine fisheries?

• We are really good at catching fish

  • Huge nets made of monofilament lines and durable plastic 

• Sonar

  • Made it easier to find fish

• GPS

  • Allows you to come back to the same place you found fish

• Refrigeration and freezing

  • Boats can go longer

  • Can go beyond the inland shores to fish

• Diesel engines

  • Winches

Tragedy of the Commons

From philosopher Garrett Hardin

• We expect individual players to over-use and over-exploit a resource

  • Getting as much as possible from one source for a short amount of time

• Goes against preserving or managing a fisheries source

By catch 

• Incidental catch of marine organisms caught accidentally with the target species 

• One average a quarter of the catch is discarded as bycatch 

  • In shrimp fisheries bycatch may me 8x larger  

Other issues contributing to the overexploitation of marine fisheries

• We are really good at catching fish

• Economics of fishing are complex and intertwined with cultural perceptions

• Biological factors

• Fish don’t abide by national boundaries

• Tragedy of the commons

• Bycatch

Solutions towards sustainable fisheries

• Ecosystem-based fishery management

  • Thinking more holistically about the system

  • Think about the food for those fish

  • The fact that fish can move and don’t stay in one bay, lake, or harbor