The mackerel fishery is currently Taiwan’s coastal fishery with the highest output. It has accounted for more than half of the total output since 2010. Since fishing has already occurred, a strategy for sustainable use of resources should be found. Past reproductive biology studies have shown that the waters of northeastern Taiwan from Pengjiayu to Yilan Bay are within the spawning area of mackerel, and the spawning period is approximately from January to May each year, with Yilan Bay as the main spawning area. Actually conduct marine fish roe survey. The plan is to hire a fishing boat on April 15-17 to conduct fish roe surveys in the waters of Yilan Bay with a zooplankton collection net (500um aperture).
To the east from Jiao to Dong’aokou, 18 stations were counted, and the reproductive parameters of adult mackerel were collected weekly from January. After obtaining the daily spawning volume, spawning area, average female weight, percentage of female fish, number of pregnant eggs and spawning ratio, try to use the Daily Egg Production Method (DEPM) to spawn in Yilan Bay Estimated weight of spawning broodstock of field mackerel. This year's study has obtained a total of 845 adult mackerel parameters, the average wet weight of female fish is 528.0g, the female fish's proportion is 0.472, the average batch of pregnant eggs is 43,733 eggs/female, and the spawning ratio is 0.275.
Dongao Baykou (Station 4-1) and Guishan Island Dongfang (Station 2-4) are the main hotspots. The egg density of mackerel is 1.07 and 0.52/m^3, and most of them belong to the first half of the eighth stage. (Phase 2-4), it is speculated that the mother fish should be born within 24 hours. Only 2 mackerel eggs that developed to the final stage 8 were recovered this voyage. The spawning area is 1.78x10^9 m^2, and it is estimated that the existing stock of the oviposition group is about 6354-24031 tons