Large pelagic fish (LPF hereafter) is an important group of fishes targeted by local fishermen in the Indonesian Fisheries Management Area-713 (IFMA-713). This IFMA includes the Makassar Strait, Flores Sea, Bali Sea, and Gulf of Bone. The objective of this study was to identify the preferred oceanographic conditions based on LPF fishing grounds in the study area. The experimental fishing was conducted from April to September 2018 by using local commercial fisheries (pole and line and purse seine). The fishing base of pole and line vessels operating in the Gulf of Bone was at Murante fish landing site, Luwu Regency, South Sulawesi. On the other hand, the fishing base of purse seine vessels operating in the Makassar Strait was at Siddo fish landing site, Barru Regency, also in South Sulawesi. Oceanographic factors such as sea surface temperature (SST), sea surface chlorophyll-a (SSC) concentration, and depth were derived from satellite data. The LPF fishing grounds were analysed and visualize using Geographic Information System (GIS) techniques. Based on the results, LPF distributions tended to be the highest in specific oceanographic conditions, including SST of 30.0 - 31.0 °C and SSC of 0.20 - 0.30 mg.m−3. They were mostly found in nearshore and offshore areas (maximum depth of about 2,000 m). The selected oceanographic factors played an important role in explaining the LPF fishing grounds. This information could be used for spatial prediction of potential LPF fishing zones in relation to the fish distribution and abundance during the Southeast monsoon in the IFMA-713.

The Asian seabass, Lates calcarifer (Perciformes, Latidae), known as barramundi in Australia, as salamata and bale kanja in South Sulawesi, was first described by Bloch in 1790 under the name Holocentrus calcarifer. The euryhaline L. calcarifer is a high-value marine and freshwater fish, on a par with salmon and tuna. This species has a widespread distribution, but there has been a lack of research on the distribution and identification of the genus Lates in Indonesia, including in South Sulawesi. This research aimed to track the distribution of Asia seabass in South Sulawesi (Makassar Strait, Gulf of Bone and Flores Sea) with identification based on DNA barcoding and characterization based on morphological parameters. The results show that Asian seabass can be found from Takalar to Pinrang Regency in the Makassar Strait, along the coast of Bone Bay from Bone to Luwu Regency, and from Bantaeng Regency to Selayar Island. Nucleotide sequences of COI mtDNA representing four Asian seabass populations in the Makassar Strait and Gulf of Bone had 99.12-99.41% identity with Lates calcarifer sequences from Singapore, Malaysia and Australia (query cover 99-100%). L. calcarifer captured at Cenrana in Bone District had a distinctive silvery-yellowish-white colouring, unlike the silvery-greenish-white observed at the other sites. Body depth (BD) of L. calcarifer was 30.10-32.20% SL and on average caudal peduncle depth was 45.65 % BD. There were several morphological differences between L. calcarifer in this study and L. calcarifer from Thailand: dorsal spine and ray counts, anal ray count, and number of vertebrae.

Matano Ricefish (Oryzias matanensis Aurich, 1935) is an endemic freshwater fish with economic value. This study aims at determining the sex ratio and first maturity size of Matano ricefish. The study was conducted from November 2017 to October 2018 in Lake Towuti, South Sulawesi. Sample was held analysis the Fisheries Biology Laboratory, Department of Fisheries, Hasanuddin University. Total number of fish obtained during the study was 880 individu, consist of 410 male fish and 470 female fish. Sex ratio was analyzed with the chi-square test, while the average size at first gonad maturity was estimated using the Spearman-Karber method. The results showed that the sex ratio of male and female medaka ricefish was 1.00: 1.15, while size at first maturity of male gonad was 36.46 mm, and the female was 34.37 mm.

This research was conducted to investigate the sex ratio and the first gonadal maturity size of mackerel fish(Decapterus macrosomas Bleeker 1841). Samples were taken from June to October 2013 in the sub-district ofPanyula, District of East Riattang, in Bone region. Sample analysis was conducted at the Fisheries biologylaboratory, Department of Fisheries, Hasanuddin University, Makassar. Sex ratio was analyzed by using chiquadrat-testwhereas the first gonadal maturity size was obtained from the first size of the third-gonadal-maturitystage. There were 782 fish collected with male to female ratio 1,02:1,00. Statistically, the sex ratio from Bone waterswas 1:1, in other words, it is still in a balance condition. The male fish reached gonadal maturity stage at the size of195 mm, whereas the female at 210 mm. Keywords: sex ratio, gonadal maturity size, Mackarel fish, Bone strait.

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