- According to the crab catch sampling, the ratio of female to male (male /female*100) of the is 21.67. The proportion Ovalipes punctatus of female crabs is larger than that of male crabs. The average body length is 84.65 ±31.89 mm, and the average weight is 179.82±188.35 g, the size of female crabs is slightly larger than that of male crabs, and the relationship between body length and weight is Y=7.2e^0.348X. Egg-carrying female crabs have been found in October.
- In 2020, the catch of crab fishing boats in Wanli District is estimated to be about 1627.5t. The main production season of crab cage fishing boats is from September to December, and both the catch and catch value reach the peak. In October, the average catch per boat was 2,497.2 kg, which is equivalent to approximately 1.178 million NTD. In 2021, the month with the highest catch and value in September and August. The average catch per boat mcan reach 2,622.9 kg, and approximately equal to 946,000 NTD. During the survey period, the highest proportion of crab cage fishery catches in the northwestern waters was Charybdis feriatus, accounting for 53.38 %, and the second highest was Portunus sanguinolentus, accounting for 36.49 %, followed by Charybdis natator (4.38 %), octopus (3.58 %), and sea snails (0.37 %), other crabs (1.29 %), sharks (0.44 %), eels (0.06 %), etc., the main target species accounted for 94.25 % of the total catch.
- In September and October of 2021, observers assisted in sampling from crab fishing boats, taking all the crab catches from the last cage and bringing them back to the laboratory for analysis. A total of 132 P. sanguinolentus, 106 C. feriatus and 9 C. natator were captured. The female crabs bearing eggs of P. sanguinolentus had 19.3 %, and another 57.8 % reached gonad maturity; C. feriatus had 8.5 % of egg-bearing female crabs. 90.5 % are in the post-ovulation state in September, and 77.5 % are in the early stage of ovarian development in October.