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

摘要

Reservoir fisheries management must be based on an understanding that they arecomplex and dynamic ecosystem. This study describes fisheries activities status in theTri An reservoir. The main objective is to determine an efficient exploitation level offisheries resources affected by the stocking program. The Verhulst-Schaefer model(logistic growth) was applied and the classic model modified to also include the caseof stocking. The modified surplus production model (MSPM) that considers fishstocking as a major factor influencing population growth has been employed toestimate static reference points. Adding economic components to the MSPM, abioeconomic model was established and applied in analyzing the interaction betweenhuman harvesting pressures, stocking and biological resources regeneration. Data oncatch/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 bothpopulation growth and the harvest regime in the reservoir. Fish stocking waspositively correlated to change in population growth, and led to a considerableenhancement in fish production. The fisheries resources cannot sustain currentexploitation levels which have led to both biological and economic overfishing as aresult of ineffective management. The current centralized top-down management hasproven ineffective and inappropriate. Therefore, rational management is required torescue the fisheries resources from depletion, to maintain the fisheries productivitycapacity and to prevent further resource degradation. However, reservoir fisheries arecurrently dependent on harvesting and stocking regimes, so a change of managementplan should be achieved by simultaneously changing the level of effort and stocking rate