ABSTRACT
The population biology of Micropterus salmoides were examined in Goe-san Lake from March 2010 to February 2011. The development of ovary and testis was separated into 5 stages by the criteria. The ratio of females to males increased with total length. Females were sampled in slightly larger size and greater number. Mean size and age was greater for females (255 mm total length and 2.03 years, respectively) than males (227 mm and 2.44 years, respectively). Growth was described by 3 parameter von Bertalanffy model by otoliths as Lt = 459.01(1-exp [-0.126(t+0.416)]). The spawning season of M. salmoides was from April to June, with a peak in May by the gonadosomatic indices and the monthly proportions of female and male gonad stages. Ripe females were collected during the spawning period. Mean fecundity was 27656±1424 oocytes every female. Fecundity was positively correlated with total length, and it was described by mean fecundity 202.4 Total length – 38188. Higher fecundity well indicated that the largemouth bass has a flexible spawning strategy and has acclimatized well to Goe-san Lake.
ABSTRACT
This study analyzed the reproduction and growth of freshwater prawn, Palaemon paucidens De Haan 1844 from Suk-dang lake(Korea). The analysis of the sex ratio showed a higher proportion of males than that of females. The average size of the eggs was 6.12 (+/-0.55) mm3 in the non-eyed stage (stageA) and 7.20 (+/-0.86)mm3 in the eyed stage (stage B). The reproductive output (RO) calculated with the dried-body weight of an incubating female and the weight of the eggs in dried condition was 26.97% (n = 17) of the average females weight. Incubating prawn appeared in April, and the gonadosomatic indices(GSI) showed the highest value during three months from January to March. Based on the month when there was a high proportion of incubating females with a high GSI, the estimated spawning season of P. paucidens was April. The maturity of the female was evaluated by the development of the ovaries and the existence of eggs. The average body length when 50% of the females in the group reached maturity was 8.55 (+/-2.74) mm. The analysis of the length-frequency distribution showed that the life span of P. paucidens ranged from 12 to 13 months. Females mature faster than males.