FISHING FOR PROFIT, NOT FISH: AN ECONOMIC ASSESSMENT OF MARINE RESERVE EFFECTS ON FISHERIES Crow White, Bruce Kendall, Dave Siegel, and Chris Costello University of California – Santa Barbara

Compared to traditional (open access) management… …reserves maintain yields: ▪ Hastings and Botsford 1999 …reserves enhance yield: ▪ Gerber et al (a review) ▪ Neubert 2003 ▪ Gaylord et al. 2005

θ = 5 θ = 0 Cost of catching one fish = Density of fish at that location θ

θ = 5 θ = 0 Bottom line for fishermen: Profit = Revenue - cost Cost of catching one fish = Density of fish at that location θ

θ = 20 θ = 0 Bottom line for fishermen: Profit = Revenue - cost Cost of catching one fish = Density of fish at that location θ

No Fishing

For coastal fish species: Myers & Cadigan 1993 Botsford & Hobbs 1995 Carr et al Caley et al Fokvord 1997 Hixon & Webster 2002 Webster 2003 Skajaa et al. In Prep.

An integro-difference model describing coastal fish population dynamics: Adult abundance at location x during time-step t+1 Number of adults harvested Natural mortality of adults that escaped being harvested Fecundity Larval survival Larval dispersal (Gaussian) (Siegel et al. 2003) Larval recruitment at x Number of larvae that successfully recruit to location x

Incorporating Density Dependence Post-dispersal: Larva settlement and/or recruitment success increases with decreasing adult population density at that location.

To maximize maximize profits, should reserves be… …few and large, What is the optimal reserve design? …or many and small? SLOSS debate

PROFIT = Revenue - Cost Initial fish density Final fish density This year’s harvest at location x

integrate PROFIT = Revenue - Cost Final fish density Initial fish density This year’s harvest at location x

FEW LARGE RESERVES SEVERAL SMALL RESERVES

Scale bar = 100 km

Max yield without reserves

Max profit without reserves

Spectrum of high-profit scenarios

Max profit without reserves Spectrum of high-profit scenarios Cost = θ/density (Stop fishing when cost = $1)

Max profit without reserves Spectrum of high-profit scenarios Cost = θ/density (Stop fishing when cost = $1) Escapement = % of virgin K (K = 100)

Max profit without reserves Spectrum of high-profit scenarios Cost = θ/density (Stop fishing when cost = $1) Escapement = % of virgin K (K = 100) Zero-profit escapement level = θ/K = 20%

Max profit without reserves Spectrum of high-profit scenarios Cost = θ/density (Stop fishing when cost = $1) Escapement = % of virgin K (K = 100) Zero-profit escapement level = θ/K = 20%

Max profit without reserves Spectrum of high-profit scenarios θ/K = 15/100 = 15%

Max profit without reserves Spectrum of high-profit scenarios θ/K = 15/100 = 15%

Max profit without reserves Spectrum of high-profit scenarios θ/K = 10/100 = 10% 10%

Max profit without reserves Spectrum of high-profit scenarios θ/K = 5/100 = 5% 10%

Summary 1.Profit is bottom line for fishermen and fisheries. 2.Fishery yield and profit maximized via…  Less than ~15% coastline in reserves …Any reserve spacing option.  More than ~15% coastline in reserves …Several small or few medium-sized reserves.

Summary 4.Reserves effects on fishery profit: ▪ Cost of fishing low/moderate: Increase profit ▪ Cost of fishing exorbitant: At best maintain profit

Summary 4.Reserves effects on fishery profit: ▪ Cost of fishing low/moderate: Increase profit ▪ Cost of fishing exorbitant: At best maintain profit 5.Near-maximum profits are maintained across a spectrum of reserve and harvest scenarios: ReservesNone Many EscapementHighLow

Summary 4.Reserves effects on fishery profit: ▪ Cost of fishing low/moderate: Increase profit ▪ Cost of fishing exorbitant: At best maintain profit 5.Near-maximum profits are maintained across a spectrum of reserve and harvest scenarios: ReservesNone Many EscapementHighLow 6. A single management strategy, based on fishermen’s self-regulated escapement levels, promotes high profits for multiple independent fisheries.

University of California – Santa Barbara National Science Foundation Coastal Environmental Quality Initiative The Canon National Parks Science Scholars Program THANK YOU!!

Older, bigger fish produce many more young