Poaching and the Success of Marine Reserves Suresh A. Sethi School of Aquatic and Fisheries Sciences 7/06

Background Marine reserves are proposed as tools to augment fisheries: -habitat protection -spillover -age structure protection These are best case scenarios…poaching within reserves may significantly affect the biological and economic outcomes of reserves. Photo from NMFS

Questions 1. What are the biological effects of poaching inside and out of reserves? -Abundances, age structure, yield 2. What are the economic effects? -Closely linked to the biological effects through CPUE. 3. What are the drivers of poaching? -Wealth status, expected profits, opportunity cost of time 4. What are effective enforcement measures? -Monitoring, fines, rewards, education

Biological Effects: Age structure analysis with maternal effects on larval survival Some Assumptions: -B-H recruitment relationship -Sedentary adults, common pool larvae mixture (abalone, scallop, rockfish) -Lingcod life history characteristics -Asymptotic knifedge selectivity, maturity -Maternal effects on larval survival: RLS = (1-e^(-.247*age)) Age Structure

Effort Readjusts Outside

Effort Constant Outside

B40% Rule for Outside Only

Conclusions: -Yield is lower with a reserve in place -Poaching can quickly reduce the age structure benefits from marine reserves by reducing SSB in reserves and resulting ELO. -If age structure protection is a primary goal of reserves, enforcement of reserve will be a key determinant in the success of the reserve. -Raises question about whether or not populations inside the reserve should be considered in the B40% rule. Age Structure Photo from Fisheries and Oceans Canada

Biological Effects: 2Box model with logistic growth, adult movement, and poaching as a function of profit 2Box Model

Future Work Age Structure Model: -incorporate movement and space 2Box Logistic Model: -expand into spatial model -alternative ways of modelling poaching behavior -poaching in open areas -heterogeneous costs based on location (space)

Thank You! Funding: SAFS ARCS Thanks to R. Hilborn and his lab, and A. Haynie.

Age Structure Biological Effects: Age structure analysis with maternal effects on larval survival

Age Structure Biological Effects: Age structure analysis with maternal effects on larval survival

Previous Work Majority of prior modeling work considers reserves to be 100% effective, i.e. no poaching. Of 800+ papers on marine reserves, only 3 consider noncompliance within reserve boundaries.

Previous Work Little et al. (2005), Kritzer (2004): -2D spatial models to examine the effects of poaching on different shaped reserves. -Found if poaching is a function of distance from an edge, single large reserves are more robust than several small reserves. -Poaching negated benefits of reserves even at high F. Hallwood (2005): -Analytical model of sustainable rents in a reserve-fishery complex when there is costly enforcement of reserve areas. -Optimization finds that m. benefit of policing = m. cost of policing, optimal stock size may be smaller than size without poaching

No S-R Relationship