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Fisheries Management and Externalities: A Generalized Model

This study explores a generalized model for fisheries management, incorporating the Shaeffer model, generalization of the Vernon Smith model, and analysis of various externalities. The model considers factors such as profit, stock of fish, abundance externality, and crowding externality.

marilynweaver
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Fisheries Management and Externalities: A Generalized Model

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  1. Fisheries II 2014

  2. Vernon Smith Model • Generalization of Shaeffer • Biology as usual • Entry proportional to profit (number of boats) • Output per boat function of price, stock of fish. (Schaefer, output per boat not function of price.) • Standard IO model of firm and industry

  3. e.g. • C(Q,x) = Qk/x • MC = kQk-1/x • Q= (px/k)1/(k-1) • Hence h = EQ = EX1/(k-1)(p/k)1/(k-1) • dx/dt = f(x) - EX1/(k-1)(p/k)1/(k-1) • (here little k is a cost function parameter)

  4. PB’s version of Smith

  5. Externality • We model the abundance externality as c/x. • Could be cxa(t) • a < 0 • Guess: If you could estimate this abs(a) would become smaller over time • Lack of fish no longer makes it hard to catch the ones that still exist • As a becomes small all the fish will be caught.

  6. Other externality • Could have the boats crowding each other, so more boats increases costs. • E.g. C(Q,x,E) = Ebc/x with b>0.

  7. Homans-Wilen • How fisheries management should work and how IPHC does work. • At least close enough!

  8. Homans-Wilen • Regulator has a biologic rule for TAC • Desire is to keep above some safe minimum or hit a target stock • Assumes that TAC is enforced • TAC = c + d x ; this is the RULE for setting TAC • X(t+1)=x(t) +F(x) – c – d x ; biology • Equilib: F(x) – c – d x = 0 • gx(1-x/K)- d x = c • gx2/K-(g-d)x +c= 0 • obviously two roots– only one should be stable

  9. H-W • Economics • season length T is adjusted so that the TAC is just caught.

  10. TAC Season Length Effort Last equality comes from substituting the TAC for Q from line above

  11. Temporary Equilibrium • Given an x0 equilibrium is found by solving And PQ – variable costs – fixed costs = 0; Assumes instant entry/exit of boats

  12. dynamics • Are just that x approaches its steady state and the season length and effort adjust as it goes. • Larger stocks have more potential rents which results in more boats fishing an ever smaller amount of time. • not sure that this is actually proved

  13. Estimation • Error terms are added and the system is estimated. • Assumes that the right number of boats (zero profit level) are present at all times • A little strong for my tastes. • Uses Pacific Halibut • Doesn’t generalize to Magnuson Act fisheries • Halibut has maintained its stock, others haven’t

  14. How Fishery Management Doesn’t Work • This is the paper where the referee wanted to use a gun. • Don’t quite know what made him so mad…perhaps it is that we called him an evil earth destroying troll, but maybe it was something else..

  15. Berck and Costello • Councils max PV of profits for incumbent • choose catchability constant—could just as easily choose season, if it were discrete time. • s.t. usual entrance requirement. • conclude that f’=r • no account is taken of the more fish easier to catch externality. • get there by following open access rules and then going down a convergent to the equilibrium

  16. Exceptional Control • Grad of H vanishes, as does it first and second derivatives. Substitute for time derivative of costate variables from costate equations. Get

  17. conclusion • BerckCostello is a setup where you get an intermediate answer. First open access and then f’=r, with NO offset for costs. • f’(x)= r might well call for extinction. Interest rate might = 19% and fish growth rate is less than that for most species.

  18. Patchy Distributions • Sanchirico and Wilen • Suppose that the sea is broken into “patches” each with its own population. • The populations migrate. • Approx in an ODE • Let x be vector of stocks • Growth is dx/dt = Ax • A is a matrix and gives the growths and migrations.

  19. A little care is needed in formulating A so that the fish that move don’t get counted twice. • Max’s producer surplus s.t. usual boat entry equation—same as my previous. • Considers steady states.

  20. Reserves • Interesting finding is • If there is an area with great growth and good outmigration then it can be right to set it aside as a preserve • The same model could be used to show that setting up a preserve for an endangered species wouldn’t be as deleterious (from a fisherman’s view) as first expected for a species one wanted to exploit.

  21. Thomas Sterner’s Cod • Story: cod live in sub-populations, further and further from port. Each year a sub-population a little further out is hunted to extinction. • Fishers say to themselves-plenty of cod, they just moved more offshore this year. • Until the last cod is caught.

  22. Halibut—IVQ’s • IPHC went from short seasons to Individual Vessel Quotas in 1991 • Fishers liked IVQ because of increased saftey • IVQ spread out the season—this alone increased value by almost ¼.

  23. Fisher’s were afraid that transferable quotas would lead to processors owning the fishery. • Regulations prohibit a boat from having more than a double share of quota. • Regulations and regulations in related fisheries (salmon) limit what boats in the fishery look like—how large • Fishery shed many employees as the season spread out.

  24. Grafton-Squires-Kirkley • Estimate cobb-douglas frontier production functions • Use them to ask how much more efficiency could be had in fishery if there was real transferability=answer 5 times greater

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