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.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0625110-025933 |
| Date | 25 June 2010 |
| Creators | Jiang, Yu-ning |
| Contributors | Mao-sen Su, Chiu-lung Chou, Shou-ren Chen, Wann-duen Chiou |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0625110-025933 |
| Rights | not_available, Copyright information available at source archive |
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