This year, the construction of the newly-built Coryphaena hippurus fry breeding pond has been completed. Two circular ponds with a diameter of 9 meters and a depth of 2 meters have been completed. The design of this pool includes functions such as sun protection black net, central sewage, high water overflow, and water flow by water intake and air pumping by the pool.This year, the Coryphaena hippurus was collected live for livestock breeding, and a total of 108 juveniles and 7 adult fish were obtained. And conduct live fish transportation, bait domestication and growth observation experiments.From April 2021 to October, the C oryphaena hippurus was collected at the Xingang Fishing Port Fish Market for preliminary reproductive biology research. A total of 45 female fish and 40 male fish were collected. The results showed that the body length of the collected female fish ranged from 73 to 114.5 cm, and the body length of the male fish was 65 to 120 cm. The lowest and highest monthly GSI values of females were in October and April, ranging from 1.65 to 8.38. There were two peaks in April and July. The lowest and highest monthly GSI values of males were October and June, ranging from 0.22 to 1.04. The peak is in June.
Scomberomorus commerson is an important oceanic migratory economic fish species in Taiwan. The aim of this study is to establish a genetic divergence analysis method and reproductive period for Scomberomorus commerson. On the basis of progressive changes in ovary size, ovary histology, oocyte diameter, and gonadosomatic index, the spawning season was estimated to extend from March through August, peakingbetween March and May that the Taiwan Strait is a spawning ground for Scomberomorus commerson. Based on a logistic model, sizes at 50% of maturity were 68.0 and 68.4 cm in FL for female and male specimens, respectively. After checking tissues and confirming the genome extraction method, we selected 73 sets of RAPD primers and eliminated 6 sets of primers that were unable to produce products. Finally, screened 10 sets of primers with clearly identifiable and highly reproducible products to participate in the analysis in this study. 75 Scomberomorus commerson gill tissues sampled at different times were used as samples for this study. these RAPD PCR products’ ranges are from 100bp to 1500bp, and an average of 51 (at least 4, at most 81) bands can be amplified per sample for analysis. After the cluster analysis tree calculated by UPGMA, Scombero morus commerson can be divided into 2 subgroups when the genetic distance is 0.63. This study established RAPD method can be used as a preliminary grouping and evaluation of the genetic divergence of Scomberomorus commerson. It can be used in the future to track the genetic divergence of Scomberomorus commerson involved in reproduction.
Seriola dumerili from Wude cage culture are captured by set-net from Suogang in Penghu, about 3-4 years of breeding, weight 5-11 kg, stored in a 8×8×5 M sea cage. Since April 1, S. dumerili have been successively moved to the onshore 200 mt HDPE round pool for mating and egg collection, but the spawning condition is poor. By early July, it was observed that the reproductive pore has been closed. One gram fertilized eggs were collected for preliminary bait test. Oyster fertilized eggs were used as open bait, followed by rotifers and copepods, with an average length of about 5mm at the age of 18 days. The Gonado Somatic Index (GSI) of the wild caught S. dumerili was investigated. The GSI of male and female
fish in January was lower than 1, doubled in February, and March to April is about 2, the highest peak. In May, fell to the February level, indicating the end of the breeding season. From October 20, 145 S. dumerili（420-1292 g）in 8 batches were catched from the set-net, and 112 survived, with a survival rate of 77.24 %，will be cultured as new broodstock of S. dumerili.