- Based on the analysis of the fishery data of the Keelung Fishery Association, the annual production of tiger prawns in the northern waters from 2012 to 2020, that fell from 5,7066.4 kg in 2013 to 31108.6 kg in 2014. It began to decline significantly in 2018 and was the lowest in 2020 to 13877.5kg. By the monthly CPUE (kg/boat*day), the main catch month is September to November. In 2020, the average monthly CPUE is 24.68 kg /boat*day. While it was 57.90 kg/boat*day from September to November. By the number of fishing vessels, the peak is also from September to October, and the least is from July to August.
- The gonad development of female tiger prawns is divided into four stages, including: the first stage gonad development is not obvious, the second stage appears thin white gonads, the third stage gonads begin to swell and become yellow, and the fourth stage gonads The breastplate of the head and the back of the abdomen are filled with dark green, and the maturity ratio by month is analyzed. In May, the first period accounted for 27.3 %, the second period accounted for 63.7 %, the third period accounted for 9.1 %, and the fourth period None, in June the first period was none, the second period accounted for 27.8%, the third period 55.6 %, the fourth period m16.6 %, the July first period was none, the second period 7.7 %, and the third period It can be found that the maturity ratio of female gonads of female shrimps increases as the months pass by 30.8 % and 61.5 % during the fourth stage. Therefore, the main breeding period for the giant tiger prawns in the northern waters should be summer.
- Through the investigation of prawns in Tam-sui river estuaries, the species of prawns include: Metapenaeus ensis, Penaeus penicillatus, Penaeus monodon and Penaeus japonicus. Juvenile prawns can be found in the flow bag nets in December. The average body length of P. japonicus is 48.95mm, and 53.43 mm in February. For P. monodon is 64.85 mm in July, 34.09mm in December, 95.74 mm in February and 128.06 mm in July, showing a significantly larger growth rate.