In this study, the population genetic variation, GSI Index, growth rate and aquaculture experiment of Chocolate hind Cephalopholis boenak and Coral trout Plectropomus leopardus were surveyed during 2012 to 2014. A total of 406 individual of C. boenak and 59 individual of P. leopardus were collected, which average length were 15.43±3.05 cm TL and 21.78±6.12 cm FL, average weight were 71.7±45.85 g. and 192±128.54 g, respectively. Additionally, the SST of 15 sites around Penghu was also recorded by in situ SST logger. The detail results of each experiment were as following:
1. Genetic variation of C. boenak
The whole genome sequence of C. boenak was determined by NGS method and 15 microsatellite loci were isolated and characterized. After Hardy-Weinberg equilibrium and Linkage Disequilibrium tests, only 11 loci primers were labeled with fluorescent and used to analysis the genetic variation. The result revealed that all C. boenak among sample sites almost had no genetic differentiation exist (Fst < 0.05) and could have high level gene flow. It suggest that C. boenak could have an abundant population and should be viewed as one metapopulation.
2. GSI Index and gonad development
A total of 369 specimens of C. boenak were used to histological processing and GSI Index calculation. The numbers of transitional, female and male were 73, 50 and 246, respectively. Female to male ratio was about 4.92:1. The GSI Index of both sex revealed fluctuation monthly, but male had peak value of 0.32 in July and female had peak value of 2.14 in June.
3. Aquaculture experiment and growth rate
The C. boenak individual collected different area in Penghu performed different growth rate. The individual from southern area had higher growth rate (4.51％ length; 18.84％ weight) than northern area (1.99％ length; 9.32％ weight). It could result from: (1) different genetic clades, even cryptic species exist; (2) different life stage and some social behavior related to reproduction.
4. Observation of reproduction behavior and probability of aquaculture
The mortality of C. boenak reared in artificial environment was low and they could easy to accept different artificial or fresh meal and had good anti-disease physique. However, it needed to prevent damage by water pressure changed immediately when fishing.
5. Genetic variation of P. leopardus
According to the results of mtDNA control region sequence, it revealed that there were 2 distinctly genetic clades existed in Penghu, Philippine (Cebu and Palawan) and aquaculture individual in PH research center. It could result from different spawning population or some hydrographic isolation mechanism. Further studies are needed to confirm these finding and be applied to management of fishery resource and broodstock population in PH research center.
6. SST record and analysis in Penghu
SST loggers were set up in 15 sites at depth of 6 m from Mudo islet to Chimei islet in Penghu and SST was recorded with an interval with one hour. Amount to 8,760 records in each site, and a total of 131,400 records of SST were collected during July 2013 to Aug 2014. The result showed that south sector had the higher SST than north and inner sectors, regardless of either the highest SST or the lowest SST. Donggi islet had the highest annual SST with value of 24.76℃, while Chungkwang had the lowest annual SST with value of 23.05℃.