Status of capture fisheries activities and management in Tri An reservoir, Vietnam

Abstract

Reservoir fisheries management must be based on an understanding that they are complex and dynamic ecosystem. This study describes fisheries activities status in the Tri An reservoir. The main objective is to determine an efficient exploitation level of fisheries resources affected by the stocking program. The Verhulst-Schaefer model (logistic growth) was applied and the classic model modified to also include the case of stocking. The modified surplus production model (MSPM) that considers fish stocking as a major factor influencing population growth has been employed to estimate static reference points. Adding economic components to the MSPM, a bioeconomic model was established and applied in analyzing the interaction between human harvesting pressures, stocking and biological resources regeneration. Data on catch/effort and stocking from 1993 to 2005 were used to analyze the fishery. Empirical results reveal that the stocking program was a major factor influencing both population growth and the harvest regime in the reservoir. Fish stocking was positively correlated to change in population growth, and led to a considerable enhancement in fish production. The fisheries resources cannot sustain current exploitation levels which have led to both biological and economic overfishing as a result of ineffective management. The current centralized top-down management has proven ineffective and inappropriate. Therefore, rational management is required to rescue the fisheries resources from depletion, to maintain the fisheries productivity capacity and to prevent further resource degradation. However, reservoir fisheries are currently dependent on harvesting and stocking regimes, so a change of management plan should be achieved by simultaneously changing the level of effort and stocking rate