1. Fishery Economics The role of economics in fishery regulation

2. Renewable Resources Examples Fisheries Forests Characteristics Natural growth Carrying Capacity

3. Motivation Group Project: Otters eating lots of shellfish, south of Pt. Conception. Marine Fisheries Service considering removing otters. What is the damage the otters are causing and thus the value of restricting them to the north of Pt. Conception? See http://www.bren.ucsb.edu/research/2001Gro up_Projects/Final_Docs/otters_final.pdf

4. Some terms we will use Stock – total population or biomass Natural growth rate – biologic term Harvest – how many are extracted (flow) Effort – how hard fisherman try to harvest (economic term)

5. Simple Model of Fish Biology Exponential growth With constant growth rate, r: = rx  x=ae rt Crowding/congestion/food limits Carrying capacity: point, k, where stock cannot grow anymore: x ≤ k Resource limitations, spawning location limitations Stock, x t t x k

6. Put growth and drag together time Biomass (x) x “Carrying Capacity” x MSY Stock that gives “maximum sustainable yield”

7. Interpreting the growth-stock curve Curve AKA: “stock –recruitment”; “yield-biomass” x Growth rate of population depends on stock size low stock  slow growth high stock  slow growth

8. Introduce harvesting x H1H1 H2H2 H3H3 H 1 : nonsustainable  extinction H 2 : MSY – consistent with stock size X b H 3 : consistent with two stock sizes, x a and x c x a is stable equilibrium; x c is unstable. Why?? xcxc xbxb xaxa (# new fish per Year)

9. Introduce humans Harvest depends on How hard you try (“effort”); stock size; technology H = E*x*q x qE H x qE L x H q = technology “catchability” E = effort (e.g. fishing days) x = biomass or stock Harvest for low effort Harvest for high effort

10. Will stock grow or shrink? If more fish are harvested than recruit to population, population shrinks. If more fish recruit than are harvested, population grows. For any given E and q, what harvest level is just sustainable? This is a differential equation that needs solving for x – solution yields H(E) Where q*E*x = = H

11. “Yield-effort curve” H(E) E Gives sustainable harvest as a function of effort level Notice that this looks like recruitment-stock graph. This is different though it comes from recruitment-stock relation.

12. Introduce economics Costs of harvesting effort TC = w*E w is the cost per unit effort Revenues from harvesting TR = p*H(E) p is the price per unit harvest Draw the picture

13. $ TR=p*H(E) TC=w*E E MC=AC MR $/E E w Rents to the fishery E OA E* Value of fishery maximized at E*. Profits attract entry to E OA (open access) Open Access vs. Efficient Fishery AR

14. Open access resource Economic profit: when revenues exceed costs (not accounting profit) Open access creates externality of entry. I’m making profit, that attracts you, you harvest fish, stock declines, profits decline. Entrants pay AC, get AR (should get MR<AR) So fishers enter until AR = AC (  TR = TC) But even open access is sustainable Though not socially desirable What is social value of fish caught in open access fishery? Zero: total value of fish = total cost of catching them

15. Illustration of equilibria X Sustainable Catch Maximum Sustainable Yield Efficient Catch ○ ○ Open Access Catch (Either side of MSY) ○ Note: efficient catch lets biology (stock) do some of the work!

16. Mechanics of solving fishery problems (with solutions for specific functions) Start with biological mechanics: G(X) = aX – bX 2 [G, growth; X stock] Harvest depends on effort: H=qEX Sustainable harvest when G(X) = H First compute X as a function of E Then substitute for X in harvest equation to yield H(E) which will depend on E only Costs: TC = c E Total Revenue TR=p*H(E) where p is price of fish Open access: find E where TC=TR Efficient access: find E where Marginal revenue from effort (dTR/dE) equals Marginal cost (cost per unit of effort)

17. Example: NE Lobster Fishery Bell (1972) used data to determine catch (lb. lobsters) per unit of effort (# traps), using 1966 data H(E) = 49.4 E - 0.000024E 2 Price is perfectly elastic at $0.762/lb. Average cost of effort: $21.43 per trap Open access equilibrium: TC = TR E=891,000 traps; H=25 million lbs. Compare to actual data: E=947,000;H=25.6 million lbs. Maximum Sustainable Yield E=1,000,000 traps; H=25.5 million lbs. Efficient equilibrium E=443,000 traps; H=17.2 million lbs.