An Age-Structured Backward-Bending Supply of Fish; Implications for Conservation of Bluefin Tuna

摘要

We develop a bioeconomic model to analyze the long-run supply of fish and find that steady-state supply can have multiple bends in an age-structured setting. We parameterize the model using data for the Eastern stock of Atlantic Bluefin tuna during the predominantly open-access period (1950-2006). The numerical Bluefin supply curve bends backward just once and at a price below the current ex-vessel price and far below historic real prices from the 1990s. Reestimating the model using data through 2015 to account for new management and allowing for cost changes finds that the current backward-bending price is far above the current market price. The results suggest that market developments that lower price, including growth in closed-cycle aquaculture, can influence the stock condition. However, strengthening management in the mid-2000s was necessary to keep the fishery from operating on the backward-bending portion of supply in the long run.