'A travel cost analysis of the value of Carnarvon Gorge National Park for recreational use': comment

Resource /Energy Economics and Policy,

A Computable Game Theoretic Approach to Modelling Competitive Fishing

A fishery is considered in which the young are harvested by one nation, and the adults by another. The harvests are sold on separate markets. Finding the optimal strategies of the two nations is treated as a problem in dynamic non-cooperative game theory. While in most other models players make decisions simultaneously at each stage, in this model each player makes his decision separately in time, knowing the action of the previous player. The model is applied to the southern bluefin tuna fishery which is jointly exploited by Australia and Japan. The results of non-cooperative and cooperative strategies are compared.Environmental Economics and Policy, International Development, International Relations/Trade, Resource /Energy Economics and Policy,

Within-Season Rents: Maximised or Dissipated in an Open-Access Fishery?

Abstract It is pervasively argued that the equilibrium outcome for an open-access fishery in which harvesting cost is inversely related to fish stock is inefficient, with complete dissipation of within-season rents. However, some argue instead that within-season rents are maximised. Conditions under which either outcome can be justified are considered. Competitive open-access outcomes are presented for different versions of continuous-time and discrete-time models of within-season fishing. The general conclusion is that in many cases rent maximisation is the more plausible outcome. The issue is important for determining the benefits of different types of regulation under uncertainty, the optimal settings of instruments such as quotas and landing fees, and the way in which open-access outcomes should be modelled in applied work.Open-access fishery, within-season rent, non-cooperative game., Resource /Energy Economics and Policy, D62, Q22,

Rent-Maximization versus Competition in the Western and Central Pacific Tuna Fishery

Where a fish stock straddles or migrates between country A's exclusive economic zone (EEZ) and country B's EEZ, or the high seas, vesting ownership rights in the stock with A does not ensure efficient harvesting of the stock. This problem arises in the case of migratory tuna stocks in the Western and Central Pacific Ocean (WCPO). Four species of tuna reside for only part of the year in the EEZs of coastal states, many of which are Pacific Island Countries (PICs). Most of the harvesting of the stocks is carried out by distant water fishing nations such as the USA, Japan, Taiwan, China and Korea. Problems arise for achieving efficiency and equity in the harvesting of the stocks by disparate countries. The problems are made more difficult by changes in the harvesting levels of one fleet affecting the rents of another fleet through changes in the age distribution of stock. These types of problem are under review by the Western and Central Pacific Fisheries Commission, formed in 2005. Results from an age-structured steady-state bioeconomic model are used to show: the changes in fleet rents and catches of tuna if all fleets form a cooperative grand coalition to deploy fishing effort to maximize rents over the WCPO; the likely non-stability of the grand coalition; and the inferior Nash Equilibrium outcomes if all fleets fish non-cooperatively to maximize their own rents.Bioeconomic modelling, Game theory, Optimisation, Migratory tuna, Resource /Energy Economics and Policy,

Time-Dependent Quotas for the Southern Bluefin Tuna Fishery

It is now officially recognized by the governments of Australia and Japan that the southern bluefin tuna fishery has been overexploited and that harvests must be controlled. A dynamic programming model applicable to multicohort fisheries is developed for finding approximately optimal time-dependent quotas. Results from applying the model to the southern bluefin tuna fishery indicate that restricting or eliminating the Australian catch of under 4-year-olds would benefit both countries.Environmental Economics and Policy, International Relations/Trade, Resource /Energy Economics and Policy,

Optimal management of a flammable forest providing timber and carbon sequestration benefits: an Australian case study

In deciding to keep or fell a forest stand given its age, the risk of loss of timber through wildfire is an important consideration. If trees also have value from sequestration of carbon, another effect of fire is the unplanned loss of stored carbon. Factors affecting the decision to keep or fell trees, and how much to spend on fire protection, are investigated using stochastic dynamic programming, using carbon sequestration in stands of mountain ash in Victoria as a case study. The effect of treating sawlogs as a permanent carbon sink after harvesting is explored.Forest management, timber, carbon, dynamic, programming, Resource /Energy Economics and Policy,

Optimal Batch Lengths for Barramundi Farming Under Seasonal Variations: A Dynamic Programming Approach

Key decision variables in aquaculture management are stocking level, feeding schedule, temperature control and batch length. In many management problems with an infinite planning horizon, the aim is to find the batch length which results in maximum return if the same batch length applies to all future batches. This may be an optimal strategy if all environmental and economic parameters are the same for all time periods, but not necessarily otherwise. The optimal sequence of possibly variable batch lengths for an infinite sequence of batches is determined for a barramundi farm in Port Stephens in New South Wales, Australia. This serves as a case study, in which there is seasonal variation in fish price and outside temperature. The problem is formulated and solved using dynamic programming. The extent to which the net present value of returns is increased by allowing batch length to be variable instead of fixed over an infinite planning horizon is evaluated

Rules For Optimal Fertilizer Carryover: An Alternative Explanation

A method of deriving rules for optimal fertilizer application when there is carryover is presented. The carryover situations considered are: carryover a deterministic function of fertilizer available in the previous period; carryover a deterministic function of fertilizer applied in more than one previous period; and carryover a stochastic function of fertilizer available in the previous period. The method of derivation is more direct than an inductive one previously presented. The rules are given an economic interpretation, and the gains from using them in practice are considered