Cost–Benefit Analysis of Alternative Techniques for Rehabilitating Abalone Reefs Depleted by Abalone Viral Ganglioneuritis

Abstract

The relative cost–benefit of alternative methods for rehabilitating blacklip abalone (Haliotis rubra) reefs depleted by viral ganglioneuritis was evaluated using quantitative population and bio-economic modeling. Fishery assessment models were adapted to describe population dynamics and economics of reseeding, translocation, and natural rebuilding. Past and current literature on reseeding, translocation, and mortality rates informed a stakeholders’ workshop that agreed on the parameters for the analysis. Comparative economic performance was quantified as the impaired value of the individual transferable quota from the area until the stock recovered to the level of maximum sustainable yield, as it was prior to the abalone viral ganglioneuritis impact. When the cost of capital is considered, none of the intervention scenarios produced any cost–benefit above that estimated to accrue from an unfished natural recovery. The translocation of adults and reseeding of juveniles were found to be similarly effective largely due to the productivity of the assumed stock–recruitment relationship at low stock densities. Across the scenarios, translocation was estimated to always at least pay for direct costs but rarely covered capital costs while reseeding only covered direct costs if the price of abalone was >$25/kg and seed was <$0.50 per individual. When a depensatory form of stock–recruitment relationship, related to adult biomass, was assumed, translocation was estimated to be an order of magnitude more effective due to the time required to augment the breeding biomass with reseeded juveniles.