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Marine Biodiversity and Fisheries Management
November 29th, 2006
For section this week: look at last year’s final exam and Valuation homework (both are on course website). Come to section with questions.
Valuing Biodiversity: Key Points Externalities Cost/Benefit analysis
Valuation methods (substitutes, revealed pref’s, contingent valuation) Calculating C/B under uncertainty: Expected Value
Discounting the Future: Net Present Value Calculations Sustainable management: tends to have costs now, benefits later
Discounting makes Benefit:Cost ratio look worse Example: organic, crop rotation based agriculture
Unsustainable management: tends to have benefits now, costs later Discounting makes Benefit:Cost ratio look better Example: Continue to use fossil fuels instead of renewable energy
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Importance of Marine Resources: PROTIEN
Especially in LDC’s
EMPLOYMENTEspecially in LDC’s
Recreation, tourism, intrinsic values…
What happens when marine resources become scarce?
Marine harvestseems to have leveled off…
Human population growth has not!!!
Humans as Optimal Foragers: prey switching
Fisheries: Classic Example of T.O.C.
Before 1982, fisheries were an “open access” resourceT.O.C: profit-seeking individuals will over-exploit a
resource that is unrestricted (open-access)
Fisheries: Classic Example of T.O.C.
Before 1982, fisheries were an “open access” resource T.O.C: profit-seeking individuals will over-exploit a resource
that is unrestricted (open-access)
1982: UN passes the “Law of the Sea” Countries bordering oceans can claim exclusive economic rights
of ocean harvest out to 200 nautical mi.out to 200 nautical mi. Did this “privatization” work?
The Problem:
Source: United Nations Food and Agriculture Organization: The Status of World Fisheries and Aquaculture, 2002
Key Terms
Stock – total population or biomass Recruitment - influx of new members into a
population by reproduction or immigration Harvest – how many are extracted Effort – how hard fisherman try to harvest (could be
measured by # of boats, # of hours spent fishing…ect) Bycatch- the unintentional harvest of species
Set limit on fishing using MSY model
Remember the logistic growth model???
Set limit on fishing using MSY model
Population growth rate isn’t always density dependent!
Set limit on fishing using MSY model
Theory: If harvest = growth rate, population size will stay the sameTheory: If harvest = growth rate, population size will stay the same
MSY model with Stochasticity
What happens if you Over-harvest?
Point
A Sustainable, below MSYB Sustainable (risky)C Unsustainable (above MSY)D Sustainable (safe)E Sustainable, below MSY
Why are fish getting smaller?
Fig. 14.11 Declines in the average size of the five mostimportant fish species landed by sport-fishing boats in the southeastern U.S. from 1972-1988.
“Fishing down” the food web
Shift to lower trophic levels (sardines, herring, ect) Anomoly from Peruvian anchovy
fishery Did we learn from its collapse?
Dynamics of harvesting large predatory fish
Fisheries take much longer to rebuild than to deplete
How do countries over-exploit their own resources?
Discounting & Subsidies: China Ineffective Management
Trouble assessing population levels Environmental fluctuation Over-reporting catches (competition + globalization) Fish dynamics (movement + growth dynamics)
Trouble enforcing limits
Technological Advances to catch fish Bycatch
Dynamics of Orange Roughy: yummy, mild fish
Orange Roughy Population Decline
Atlantic Cod Fishery Collapse
How do countries over-exploit their own resources?
Discounting and Subsidies Ineffective Management
Trouble assessing population levels Environmental fluctuation Over-reporting catches (competition + globalization) Fish dynamics (movement + growth dynamics)
Trouble enforcing limits
Technological AdvancesTechnological Advances to catch fish Bycatch
The Role of Technology
How does a ‘cheap’ fishery compare with an ‘expensive’ fishery?
Cos
t or
Ben
efit
($/ti
me)
Expensive Fishery
CheapFishery
How can you get the same yearly fish yield, with less boats?
Bycatch: Externalities
Management Options
TechnologyLimit technologyUse technology to decrease bycatch
The Role of Human Values and Perceptions
•Scarcity price increases: Expected Value of fishing?•Establishing and shifting baselines
Management Options Fix problems identified with privatization
Better population assessments Technology Fines/Permits Inform Consumers-change perceptions
--- Shift focus from individual stocks to ecosystems ---
Marine Reserves Aquaculture
Next time!