Harvest Rules When Price Depends On Quantity: The Case of Norwegian Spring Spawning Herring (Clupea harengus L.)

For fish stocks where the unit price of harvest is constant and unit harvest costs are independent of quantity and non-increasing in biomass, regulation based on target escapement (TE) has been shown to optimise the net present value (NPV) of harvest to society. This result has also been shown to hold for fish stocks characterised by stochastic recruitment, whereas a more asymptotic approach has been advocated if price depends on quantity. In this paper, these theoretical results are empirically investigated. Our case is the Norwegian spring spawning herring fishery, a stock with stochastic recruitment and price decreasing in harvest. For this fishery, the theoretical results are verified in that TE can no longer claim optimality. At constant prices, TE is found to outperform a more gradual approach, but this comes at a cost of a lower expected spawning stock at the end of the period investigated.