| 英文摘要 |
Objectives: Larval anchovy is an important resource for coastal artisan fishery in Taiwan, although harvesting fish at early stages may impose crucial impact on fragile resource, and cause conservation concerns. The fisheries that catch larval anchovy are called "Bua fishery" in Taiwan, and they utilize specialized fishing types fit to various coastal geo-morph. The Bua catches are appreciated with high prices, resulted in very complicated cases governmental regulations. From different perspectives , both larval and adult anchovies are important mid-way component in coastal marine ecosystem, where they function as bio-energy converter between plankton and higher trophic levels. The fluctuation of anchovy population influences not only the amount of fisheries catches, but also the stability of coastal ecosystem. Previous studies have shown that the mechanism for the formation of apt fishing sites may relate to global meteorological events, such as ENSO and typhoon. The species richness of Bua catches resembles that of traditional bottom trawls, but with different percentage of species composition in biomass. The Bua catch is primarily composed of engraulia and clupeid fishes, however tens to hundred “non-Bua” species are also caught, among which some are of economic importance. Major Bua fishes, accounted by more than 5% in any single day, are identified to 8 species. And, the top 3 species composed about 90% of total catches; i.e., Encrasicholina heteroloba, Encr. punctifer and Engraulis japonicus. The objectives of this project are getting uptodate information to assist fisheries management, including 1) to estimate the stock size of major species, 2) to explore the fishing effort and catches, and 3) to quantify their spatio-temporal variations. Frameworks: Fish compositions in two major fishing seasons of spring and autumn are comprehensively documented, however population size of major species is dynamic. For effective regulate the fishing activity at a suitable level, county governments set the limits of vessel number, total allowable catches and no-catch period (NCP) for their fishermen. In the meanwhile, the licensing time was set to a period of 5 years. Phasing-out of the Bua fishery is also announced that was effective on January 1, 2006 at first. However, for the sake of mitigating difficult position in local economy, deferring was put forward to extend the licensing period until December 31, 2008. In 2009, effective regulation of the fisheries is established to replace the then phasing-out hoping to reduce socio-economic impact. To facilitate effective regulation, the major tasks of this project are set to assess potential fishing capacity, and realized fishing effort and catches. Expected usefulness: This project works on three major fishing grounds: the northeast, northwest and southwest in sequences. In the end, this project will get following parameters: fishing capacity, fishing effort, catches, catches composition and length frequencies. We will analyze these parameters to conclude the by-catch rate, total allowable catch and optimal size of the fisheries. |