碩士 / 國立臺灣大學 / 海洋研究所 / 90 / Portunus sanguinolentus is one of the most economically productive swimming crabs in the waters off northern and southwestern Taiwan. The fishery consists of pot fishing in the northern Taiwanese waters and trawling in the southwestern Taiwanese waters. Recent catch statistics reports indicated that a trend of declining landings might result in shrinkage of the fishery. Management measures are difficult to undertake because the population parameters and status are not yet known. Therefore, the objective of this study was to estimate fundamental population parameters in growth, mortality, and fecundity by size frequency data collected from pot fishery in the northern Taiwanese waters from October 2000 to January 2002. Bhattacharya’s method, the probability graph paper method, and seasonal von Bertalanffy growth curve were used for age determination and growth parameters were estimated as the form: Lt=L∞{1-exp(-(KD(t-t0)+CKD/2π)sin2π(t-ts))} in which: D = 1, C = 0.4 and ts = 0 for both sexes, L∞ = 204.75 mm, 194.25 mm, and K = 0.87/year, 0.97/year for males and females, respectively. Growth increment of each molt decreases and duration of inter-molt increases as size increases. Size-converted catch curve was used to estimate instantaneous total mortality (Z), and the Pauly’s empirical equation was used to estimate instantaneous natural mortality (M). The results were: Z = 3.18/year and M = 1.59/year for males; and Z = 3.37/year and M = 1.73/year for females. Accordingly, instantaneous fishing mortality (F) was estimated as 1.59/year and 1.64/year; and exploitation rate (E) was 0.5 and 0.49 for males and females, respectively. Fecundity of gravid females was expressed by exponential relationship of the number (Negg) and weight (Wegg) of egg mass extruded vs. the corresponding carapace width (CW) and body weight (BW), respectively. The results were: Negg = 13.051 CW2.3127 ; Wegg = CW2.4013 ; Negg = BW0.8822 ; Wegg = 0.2116 BW0.897 with highly statistical significance (P<0.001). Nonetheless, some population parameters were estimated, however, further advanced studies, such as yield per recruit model and size-structured models are recommended to understand the stock status in future.
| Identifer | oai:union.ndltd.org:TW/090NTU00279019 |
| Date | January 2002 |
| Creators | Hui Hua Lee, 李卉華 |
| Contributors | Chien Chung Hsu, 許建宗 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 90 |
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