This study focused on the spatial and temporal variation of water qualities and the phytoplankton and zooplankton standing crop of southwestern Taiwan. Data were collected from 30 cruises of research and fishermen vessels between August 1999 and December 2002. The yield of sergestid shrimp in this area was also analyzed for possible relationship with physical environment. Concentrations of phosphate and ammonia in the study area were highest in autumn, while the concentration of dissolved silicon peaked in winter; In spring, the concentration of all three nutrients similarly dropped to their lowest level. Regardless of seasonal variation, the concentration of dissolved silicon positively correlated with the water depth around the year. Positive correlation was found between phosphate and river discharge rates of Kao-Ping River in autumn. Negative correlation was found in spring, summer and autumn for ammonia, negative correlation in spring and autumn for dissolved silicon, respectively. Variations of phytoplankton in seasons and locations were also studied. Chlorophyll a blooms in winter but was at lowest level in summer. Concentration of total-chlorophyll a decreased with distance from the shoreline. Concentration of total-chlorophyll a negatively correlated with the river discharge rate in summer, but was positively correlated in winter. Nanophytoplankton (< 10 £gm) appeared to be the major component of phytoplankton. High standing crop of copepods was found at regions near the Liu-Chiu Yu, the estuary of Kao-Ping River, and near the coast. Significant positive correlation between phytoplankton and Copepoda standing crop indicates possible feeding and grazing relationship between them. Changes of the concentration of chlorophyll a corresponds with relative levels of phosphate and ammonia in some seasons. The period with the highest phytoplanktonic standing crop also coincides with the high yield season of sergestid shrimp (from November to March). Variation of Copepoda standing crop does not follow seasonal changes of phytoplankton. Based on the results from General Linear Model analysis, lunar phases, river discharge rates of Kao-Ping River, and the Fishing Effort (hrs/haul-boat) have significant effects on the yield (kgs/haul-boat) of sergestid shrimp respectively. The yield of sergestid shrimp in the full moon period and the last quarter of a lunar month is higher than other periods. The occurrence of thick thermocline water layer matched with the period of high CPUE of sergestid shrimp.

The catch of Sergestid (Sergia lucens) shrimp is one of notable self-managed fishery in Taiwan. In 1992, Tung-Kang fishery association has assembled ship owners for a sale and marketing sector within the local fishery association which is a organization to regulate and manipulate relevant to the fishing guideline and fund management. Up to now, no adjustment has been made on the catch limit under the fishing guideline. Although there is some improvement on such species catch. The result however shows still problem of fishery management resulting from high density of fishing. To better monitor the Sergestid shrimp fishery, this study aims to collect the Sergestid shrimp sample monthly from November, 2006 to December, 2007, for measuring the body length and weight of shrimp. The monitoring data appears that monthly mature female and Sergestid shrimp ratio are as low as 20% during April-June of 2007 and 36.01% in June of 2007 among the monitoring period. After reviewing a correlation between monthly mature female and Sergestid shrimp, the female is heavier than male shrimp at same length. When applying body length into FiSAT ¢º to calculate female and male coefficients, the VBGF (Von Bertalanffy Growth Function) growth coefficient (K) is 0.67 and 0.92 respectively; Limit body long (L¡Û) is 43.47mm and 40.29mm respectively; Total mortality coefficient (Z) is 2.97 and 3.57 respectively; the Fishing mortality coefficient (F) is 1.96 and 2.3 and rate of exploitation (E) is 0.66 and 0.64 respectively. The estimate resource of female can be deduced from above data, for example, annual catches is 562.4 tons in 2007. The estimates resources of female is 1995.5¡Ñ106 per tail; male is 925.0¡Ñ106 per tail; total female and male is 2,920.5¡Ñ106 per tail. In addition to the earlier result of research, this study concludes that the peak season of spawning around marine water of western Taiwan occurs from December to next February and July, which does not correspond to the forbidden period from June to October under the fishing regulation. Thus, two forbidden periods in December to next February and June to August are necessary to avoid the spawning from over fishing. The study also found that the current size of fishing gear such as outer codend in 28.9mm and cover codend in 21.2mm are smaller than size at the first maturity for female in 26.19mm and the L50 for total female and male in 31.88mm. This implied that the size of outer codend and cover codend may catch immature shrimp, which is not bigger enough for spawning. In order to avoid the catch of immature female shrimp, the size of fishing gear should be reset at bigger size. Further studies is needed for the size of fishing gear correction. Finally, the resulting fishing mortality coefficient calculated from FiSAT is 2.10 that the resources of Sergestid shrimp are approximately 2,920.5¡Ñ106 per tail. This shows down trend of stock over time. This suggests that the fishing guideline should reinforce to limit the number of fishing boat and harvest. Another suggestion is to limit the number of fishing per boat daily or adopt fishing boat rotation without reducing the amount of fishing boat. If the shrimp fishery population remain no significant improvement, the implementation of a long-term fishing boat reduction and the total allowance per catch regulation are the useful policy. These measures shall be employed to raise the value of Sergestid shrimp, in order to increasing the income of fisherman and also to achieving the sustainable development of Sergestid shrimp.

Sergestid Shrimp contains rich nutrition, regards as a high-class aquatic product in Japan. The management of the catch has come into operation, and it¡¦s led the price raising and the output value increasing rapidly when the establishment of TungKung producer organization of the Sergestid Shrimp in 1993 and it also has become the important seasonal fishery in the southwestern coast of Taiwan. This study is based on the fundamental model of fish dynamic- Gordon Schaefer Model, to discuss the equilibrium values for the optimal conduction of open access and dynamic optimization, and to do the comparative statics analysis. By applying the data provided by Fisheries Research Institute, the evaluation of the variation are under both conductions were available, and in additions, the sensitivity analysis had been done by assuming all bio-economics parameters varied within a reasonable range. The study can figure out the fact that the management of TungKang producer organization of the Sergestid Shrimp with the notion of the sustainable administration by the derivation of theoretical model and the simulate analysis of historical data, and the conclusions of analysis are consistency. Furthermore, the study discusses the fishery management policies of TungKung Sergestid Shrimp. I hope the management policies of TungKung producer organization of the Sergestid Shrimp could be popularized in the related industry.