1. Over Fishing
Oceans 11

2. What is “fishing”?
Exploitation of marine organisms for sustenance, profit, or fun.
Examples:
Fish- cod, halibut, salmon, redfish, stripped bass…
Shellfish
Mollusks- clams, scallops, oysters, abalone…
Crustaceans- crabs, shrimp, lobster…
Reptiles- turtles
Mammals- whales

3. Why do we fish?
Survival- many costal communities, particularly in developing countries, fish as a primary food source.
Recreation- fishing for fun.
Profit- commercial exploitation as a means of earning a livelihood.

4. What are some of the effects of fishing on humans?
Sociology- in some places people need to fish to survive, in many others they simply want to fish as a mode of recreation.
Economics- individuals and regions can be dependent on fishing as a source of income.
Ecology- natural systems are easily disrupted by fishing.

5. What is “over fishing”?
Removal of organisms from the marine environment by humans at a rate which cannot be sustained by the local ecosystem and therefore significantly alters natural ecosystem. or
Fishing a population faster than it can replace itself; the population decreases in size as a result.

6. How big is the problem?
The world marine catch is nearly 100 million tonnes per year.
27 millon tonnes of by-catch (almost 1/3 of total catch) is thrown back dead into the ocean
Larger shrimps fetch a higher price, there is an incentive for discarding smaller fish as shown left.

7. What are some consequences of over fishing?
Much more complicated than reduction of one species
Trophic interactions
Examples: Salmon, killer whale, sea otter
Change in ecosystem structure
Loss of biodiversity

8. Consequences…By - Catch!
By-catch is all non-target species caught with target species whether retained then sold or discarded
One example of by-catch is dolphins caught in tuna nets.
Often a problem with widespread use of unselective fishing gear
Bottom trawling disturbs everything on the ocean floor

10. Collapse of the North Atlantic Cod Fishery
Canadian cod stock severely depleted by local and distant water fleets
Canada declared Extended Fisheries Jurisdiction in 1979 to control and rebuild the fishery
Expected a rise in Total Allowable Catch (TAC) by 1985
Instead the fishery continued to decline and effectively closed in 1992

11. What Happen? Mismanagement?
Fishing mortality exceeded sustainable level estimates
Stocks never achieved 50% of predicted total allowable catch
Canadian fleet over harvested cod

12. How? Upper limit was used to calculate harvest quota every year
When upper limit became insufficient to economically support fishery quota was increased
Short term economic gain won out over biology

13. The Irony
Biologists could see the catastrophe happening and were powerless to stop it
Long term economic loss (closure of fishery) far outweighs short term benefit
Economy loses more

14. Facts on file science online

15. Now what?
How can we fish only to an extent which does not significantly alter it and the natural system in which it occurs?
Widely varying degrees of opinion.

16. Problems Estimating populations Estimating catch Predicting population
change based on…
catch.
environmental statistics
limited knowledge of life history.
Tends to err on the side of over harvest
Doesn’t always consider ecology

17. Some Solutions: Marine Protected Areas Effective if: Large enough
Protect source populations
Effectively enforced
Currently well below 1% of marine systems are protected by MPA’s

18. Legislation
Through regulation and laws control the total allowable catch
Effective regulation should be consistent with biology
International Compliance

19. Responsible Recreation
Increasing evidence suggests impacts of recreational fishing

20. Conclusions
Conservation of marine fisheries impacts peoples livelihoods, survival, and recreation.
It influences the marine and terrestrial environments.
It is everyone's responsibility.

21. Case Study: The Impact of Overfishing
Case Study: The Impact of Overfishing ***Please put all answers on looseleaf!
Vocab: list the definition of the following
fishstock, net growth rate,
MSY, TAC, OSY
Do case study but omit “l” and “m”
Do only question #2 from Questions for Application and Further Research