Background: The biological information of fish, which include reproduction, is the prerequisite and the basis for the assessment of fisheries. Methods: The aim of this work was to know the reproductive biology with the first sexual maturity (TL50) and the spawning period for 58 mainly fish species in the waters around La Réunion Island (Western Indian Ocean). Twenty families belonging to the Actinopterygii were represented (acanthuridae, berycidae, bramidae, carangidae, cirrhitidae, gempylidae, holocentridae, kyphosidae, labridae, lethrinidae, lutjanidae, malacanthidae, monacanthidae, mullidae, polymixiidae, pomacentridae, scaridae, scorpaenidae, serranidae, sparidae; 56 species; n = 9,751) and two families belonging to the Elasmobranchii (squalidae, centrophoridae; 2 species; n = 781) were sampled. Between 2014 and 2022, 10,532 individuals were sampled covering the maximum months number to follow the reproduction periods of these species. Results: TL50 for the males and the females, respectively, ranged from 103.9 cm (Acanthurus triostegus ) to 1,119.3 cm (Thyrsitoides marleyi ) and from 111.7 cm (A. triostegus ) to 613.1 cm (Centrophorus moluccensis ). The reproduction period could be very different between the species from the very tight peak to a large peak covered all months. Conclusions: Most species breed between October and March but it was not the trend for all species around La Réunion Island.

The bitterling (Cyprinidae, Acheilongnathinae) is a temperate freshwater fish with a unique spawning symbiosis with host mussels. Female bitterlings use their extended ovipositors to lay eggs on the gills of mussels through the mussel's exhalant siphon. In the present study, in April of 2020, we investigated spawning frequencies and patterns of three bitterling fish species in host mussel species in the Nakdong River basin (Hoecheon). During field surveys, a total of four bitterling and three mussel species were found. We observed bitterling's spawning eggs/larvae in the three mussel species: Anodonta arcaeformis (proportion spawned: 45.5%), Corbicula fluminea (12.1%), and Nodularia douglasiae (45.2%). The number of bitterlings’ eggs/larvae per mussel ranged from 1 to 58. Using our developed genetic markers, we identified the eggs/ larvae of each bitterling species in each mussel species (except for A. macropterus): A. arcaeformis (spawned by Acheilognathus yamatsutae), C. fluminea (A. yamatsutae and Tanakia latimarginata), and N. douglasiae (A. yamatsutae, Rhodeus uyekii, and T. latimarginata). Approximately 57.6% of N. douglasiae mussel individuals had eggs/ larvae of more than one bitterling species, suggesting that interspecific competition for occupying spawning grounds is intense. This is the first report on bitterling’s spawning events in the Asian clam C. fluminea from Korea; however, it should be ascertained whether bitterling’s embryo undergoes successful development inside the small mussel and leaves as a free-swimming juvenile. In addition, the importance of its conservation as a new host mussel species for bitterling fishes needs to be studied further.

자연 생물자원 관리를 위해, 광양만내 인공적으로 폐쇄된 슬라그 적재장내에 서식하는 암컷 피뿔고둥 Rapana venose(Valenciennes)를 대상으로 조직학적, 육안적 관찰에 의해 군성숙도, 성비, 산란빈도, 난낭 산출 및 포란수를 조사하였다. 암컷 개체들의 군성숙도(%)는 각고 7.1~8.0 cm의 경우 51.6%이었고, 9.1 cm 이상인 개체들의 경우는 100%이었다. 개체당 총난낭수 및 난낭내의 평균 난수는 각각 192~382개와 500개