Trond Bjørndal

The East Atlantic Bluefin Tuna Fisheries: Stock Collapse or Recovery?

A discrete time, multi-gear, and age structured bio-economic model is developed for the East Atlantic bluefin tuna fisheries, a paradigmatic example of the difficulties faced in managing highly migratory fish stocks. The model is used to analyse alternative management strategies for the Regional Fisheries Management Organisation (RFMO) managing this fishery, and to investigate some of the policy implications. For the various scenarios, the optimal stock level varies between 500-800,000 tonnes, which compares with a stock level of 150,000 tonnes in 1995. In other words, there is a very strong case for rebuilding the stock. Moreover, the sustainability of the stock is threatened unless a recovery programme is implemented; indeed, the alternative may be stock collapse. Second, to rebuild the stock, Draconian measures are called for: either outright moratoria over fairly lengthy periods, or possibly a more gradual approach to steady state given by a Total Allowable Catch (TAC) at a low level for an extended period of time. Third, the cost of inefficient gear structure is very high indeed.

Essays on the Economics of Migratory Fish Stocks

A. Theoretical Papers.- The Management of Transboundary Fishery Resources: A Theoretical Overview.- On the Optimal Harvesting of Migratory Species.- Maximizing Yield in Some Fluctuating Fisheries.- Optimal Exploitation of Migratory Fish Stocks: The Multiple Species Case.- A Stochastic Fisheries Problem with Seasonal Migrations.- B. Empirical Papers.- The Management of Migratory Fishery Resources in the Pacific: Tropical Tuna and Pacific Salmon.- MIGFISH: A Computer Programme for Studying the Harvesting Economics of Migratory Species.- The Optimal Management of a Transboundary Fish Resource: The Arcto-Norwegian Cod Stock.- Competition in Salmon Fisheries.- On Optimal Harvesting of Fluctuating Fish Stocks: The Case of the Arcto-Norwegian Cod.

The Northern Atlantic Bluefin Tuna Fisheries: Management and Policy Implications

In this paper, a discrete time, multi-gear and age structured bio-economic model is developed for the Northern Atlantic Bluefin Tuna, which is a paradigmatic example of the difficulties faced in managing highly migratory fish stocks. The 1995 U.N. Fish Stocks Agreement provides guidance as to the sustainable management of straddling and highly migratory fish stocks, maintaining that coastal states and distant water fishing nations should cooperate in the management of these stocks through Regional Fisheries Management Organisations (RFMO). The objective of this paper is to propose alternative management strategies that could be taken into account by the RFMO managing this fishery, and to investigate some of the policy implications.