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!