This study was performed to obtain information on the sex ratio, spawning period, and size at sexual maturity for fishery management of the largehead hairtail Trichiurus japonicus in Korean waters. The overall sex ratio (female, F; male, M) was 1:0.46 (n = 1274 females:589 males, 68.4% female) and as fish increased in length, the proportion of females increased. The oocyte development pattern was group-synchronous development, for which oocyte groups at different stages can be identified within the same ovary. The average gonadosomatic index (GSI) showed two peaks in June (3.03) and August (3.10) in females and in May (1.81) and September (2.24) in males. The median value of GSI showed two peaks in May (2.65F, 1.78M) and September (2.55F, 1.87M) for both females and males. As a result of analyzing the GSI and the monthly gonadal developmental stages, the main spawning season was estimated to be bi-annual (May–June and September–October). The anal length of fish at 50% sexual maturity was analyzed using a logistic regression model and was determined to be 16.38 cm (female) and 18.31 cm (male).

The climate crisis and growing petroleum demand have put the health of aquatic animals in jeopardy. Fish are sensitive to chemical pollutants in aquatic environments, such as polycyclic aromatic hydrocarbons, dioxins, and dibenzofurans. This study investigated the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and β-naphthoflavone (β-NF) exposure on histopathological and immunohistochemical features and expression patterns of cytochrome P450 1 (CYP1) family genes in black rockfish, Sebastes schlegelii. Histopathological alterations in the liver included congested central vein, sinusoidal dilatation, lymphocyte infiltration, and severe vacuolation within hepatocytes. The most prevalent alterations in TCDD-exposed kidneys were glomerular enlargement, narrowing of tubular lumen, melanomacrophage centers (MMCs), and necrosis. Moreover, CYP1A immunostaining was strong in renal tubules following TCDD exposure. All CYP1 family genes (CYP1A, CYP1B, CYP1C1, and CYP1C2) were significantly increased in the gills, liver, and kidney exposed to TCDD. Similarly, a significant increase of CYP1A mRNA expression in the kidney was observed upon exposure to TCDD (30.9-folds) and β-NF (25.5-folds) compared with that of the control group (p < 0.05). TCDD and β-NF exposure exerted more adverse effects on the kidney than the liver, and TCDD had a greater in vivo toxic effect than β-NF. The combined histopathological, immunohistochemical, and molecular alternations may be helpful for diagnosing chemical contaminant exposure in S. schlegelii.

론 지구 온난화로 인한 태풍 및 기상 이변은 수산 자원 지속 생 산을 통한 식량화의 시급성을 요구하고 있다. 이러한 환경 속에 서 수산물 거대 소비 시장을 겨냥한 외해 양식장의 대형화는 양식장 피해 보상 규모를

This study attempts to propose the possibility of the sex reversal in Sinonovacula constricta and Gomphina veneriformis by confirming the changes in the sex ratio with the shell length in the same population level. For analysis of sex ratio, 100 individuals of S. constricta (SL 26.5-95.0 mm) and 2385 individuals of G. veneriformis (SL 15.1-60.1 mm) were used. Sex was analyzed histologically. Both species displayed the tendency of increase in the female proportion with increase in shell length. In this study, changes in the sex ratio in accordance with the growth of S. constricta and G. veneriformis are determined to be indirect evidence that signifies their sex reversal.