fisheries

1. fisheries

2. efficient harvests • biology • economic

3. biological dimension • Schaefer model (1957) • abstracting from water temp / quality, age structure, etc. • relationship btw. growth of popn and size of popn

4. growth as a function of stock

5. carrying capacity vs. minimum viable popn • : carrying capacity / natural equilibrium • stable, movements away set forces in motion back towards it • : minimum viable popn • below growth is negative • unstable • to right, growth to natural equilibrium • to left, decline to extinction

6. “sustainable yield” • catch growth rate each period, catch and population can be maintained forever • S*: “maximum sustainable yield” (MSY) • yields maximum growth • largest catch that can be perpetually sustained

7. economics: efficient yield • is MSY synonymous with efficiency? (no) • for efficient solution: maximize net benefits from use of resource • need to include costs and benefits of harvest, not just quantity • examine static efficient sustainable yield (largest annual net benefit)

8. 3 assumptions • price of fish constant • MC fishing effort constant • fish caught per unit effort is proportional to size of population (smaller popn, fewer fish caught per unit effort)

9. efficient sustainable yield

10. efficient fishing effort • TR follows Schaefer model since price constant • TC linear since MC effort constant • Em: further effort reduces sustainable catch and revenue for all years (MSY) • net benefit: vertical distance btw B & C • Ee: efficient effort, where net benefits maximized • MB (slope of TB) = MC (slope of constant TC curve)

12. efficient fishing effort • effort > Ee inefficient, since additional cost exceeds value of fish obtained • MSY not efficient unless MC effort = 0 (why?) • efficient level of effort LESS than MSY • efficiency implies LESS harvesting and LARGER population

13. efficient vs. market allocation • with well-defined property rights, sole owner of fishery would max profit by increasing effort until MR=MC • harvest at Ee (efficient) • but…fisheries typically OPEN ACCESS

14. open access solution • sole owner of fishery chooses to not expend > Ee because to do so reduces profit of fishery (personal loss) • if unrestricted access, decision to expend > Ee reduces total profit, but not to individual fisher • in open access, Ec effort (net benefits zero)

16. fishery prisoner’s dilemma Note: Payoffs in thousands $ (A, B)

17. too much effort! policy responses • increase MC– require fishing farther from shore, use smaller nets, boats, or motors • but artificially increasing cost inefficient • total allowable catch – restrictions on effort or size of catch • monitoring, enforcement difficult, also creates race to catch • individual transferable quotas –quotas allocated, then trade • no race, allows most efficient fishers to buy rights from inefficient fishers

18. Sample problem • Costs fisher $20 to fish salmon • Salmon sells for $10 • Harvest rate given X fishers is S = 30X-2X2 • How many people will go fishing, how many salmon will be caught, and what are total profits under • Open access • Limited entry (how many fishers should be allowed to maximize profit?)