The scientific research fishing was conducted by the Greenstar (KOR) and Marigolds (UKR) in in Subarea 88.3 following the survey design (WG-FSA-2022/26). The total catch of Dissostichus mawsoni was 97217.8 kg comprising 3816 individuals. The CPUE for D. mawsoni varied among the research blocks; CPUE demonstrated high variability in research blocks 88.3_1, 88.3_3 and 88.3_4 with the mean range of 54.6 – 279.6 kg/1000 hooks. This season in research blokes 883_6, 883_7 was obtained CPUE with the mean range 67.1 – 111.1 kg/1000 hooks. The vessel calibration study was completed in research block 88.3_3, 88.3_4 planned number of stations was set. The tagging rate and tag overlap in Subarea 88.3 were 5.22 fish per ton and 88.5 % overlap for Greenstar, and 5.25 fish and 84.7% for Marigolds.
In block 88.3_3 observed single pick size distribution (with median 138 cm for females and 128cm for males) with high number of mature fishes with small presence of juveniles. In block 88.3_1 and 88.3_4 was observed bimodal distribution with higher presence of juvenile toothfish. Medians 133 cm for females and 124 cm for males in 88.3_1; 127 cm and 113 cm for Block 88.3_4 were observed. Block 88.3_6 has demonstrated high presence of juvenile fishes, 88.3_7 in opposite has dominating presence of adult fish (>100 cm). Regional and time differences in female and male maturities were observed with stage 2 and 3. Otolith, stomach contents, gonad, fin and muscle samples were collected to obtain biological information of D. mawsoni. Also, plankton samples were collected through the research.
The main bycatch species and main prey of toothfish for the area of research were macrourids with highest mean CPUE up to 33 kg/1000 hooks in Block 88.1_1. 95% of macrourids were identified on board as Macrourus caml. Whole specimens of bycatch species and otoliths of macrourids were collected for off water taxonomic identification and age determination.