| Hyriopsis cumingii is endemic to China, where it is the dominant speciesused in pearl culture. This paper focuses on differences in growth traits andpearl production between male and female mussels under traditional cultureconditions. We also explored such differences in artificially separated femalesfrom males to elucidate factors that determine differences in pearl formationbetween male and female mussels, and to collect basic information to assistthe improvement of yields and quality of pearl culture.1). Growth and pearl production were compared between male and femaleabout different age groups.Hyriopsis cumingii from the full-sib family were cultured undertraditional condition (in the mussel ponds with carps). The results indicatedthat there was no significant difference (p>0.05) on individual weightbetween male and female mussels of one or two years old, while significantdifference (p<0.01) lay among three or four-year-old mussels with malegreater than female. The average shell width of the male mussels was lessthan that of the female individual (p<0.05). One-and2-year-old males andfemales did not differ significantly with respect to the total weights, grainweights, or grain sizes of the pearls they produced but these three parameterswere all significantly greater in3-and4-year-old males (p<0.05). The roundpearl percent were similar between male and females at ages1,2,3and4years.2). Effect of separate culture of male and female mussels on growth andpearl productionMale and female mussels were cultured in separate enclosures and inmixed enclosures. The rates of growth in shell width and body weight offemales separated from males were3.42%and4.16%, respectively, higherthan in females mixed with males (p<0.05). The total pearl weight per mussel, the average weight per pearl, and the average pearl size of females separatedfrom males were6.61%,7.10%, and3.59%, respectively, greater than infemales mixed with males (p<0.05). There was no significant difference in thegrowth rate or pearl yield of males cultured with or without females (p>0.05).Under traditional culture methods, male mussels have a better pearlperformance, and artificial separation of females from males can improve thegrowth and pearl production of female mussels.3). Morphological comparison and correlation analysis of gender betweenmale and female musselsA total of300male and female Hyriopsis cumingii of3-year-old from thefull-sib family were randomly selected under traditional condition.8morphometric characters of male and female pearl mussels, standardized toshell length. The results indicated that shell width/shell length and OE/shelllength were significantly greater in females than in males, whereas OB/shelllength and OD/shell length were significantly lower in females (p<0.05). Inthe principal component analysis, two principal components were constructed,the contributory ratio of the first principal component was28.44%, the secondprincipal component was25.18%, the cumulative contributory ratio was low(53.62%). The discriminant functions of the male and female were established,and the discriminant accuracy was45.7%-59.3%(P1) and40.7%-54.3%(P2).The total discriminant accuracy was low (54.3%) with no significantdifference between male and female in the morphological variations. Thecorrelation coefficient between weight and growth traits of female was asfollows: shell length>OE>OB> shell width>OD>OA; The correlationcoefficient between weight and growth traits of male was as follows: OE>shell length> OD> shell width> OB> shell height. Visual inspectionrevealed that the posterior margin of3-year-old female mussels was stronglycurved and relatively thick and short whereas, in males, the margin was bluntand flat and the mussel was thinner and longer in overall appearance. |
