Differences Between Male And Female Hypomesus Olidus Individuals And Its Early Biology Characters Research

Hypomesus olidus naturally development sexually mature individuals were taken back from the Tagang reservoir, comparing the differences between male and female individuals. Fertilized eggs were get from Artificial insemination. Research the embryonic development and larval growth under different temperature .At the same time, research the larval growth and feeding characteristics. The results are as follows:1. Differences between Hypomesus olidus male and female individuals1.1 Hypomesus olidus is one kind of small fish. The fish is in the range of 6-9 cm long. The body takes the shape of spindle; every fins without spines, two dorsal fins,8-10 pieces of the first dorsal fin rays, second dorsal is adipose fin; pectoral fin is at ventral position; number of buttock fin rays is15-17;body wrap silver microlepis; lateral line incomplete. There were no significant difference at the body color, size, number and scalability between male and female individuals.1.2 Frame structure(1) Pectoral to pelvic section: body length Female: 3.530±0.085 Male: 3.766±0.145 The difference is significant(P <0.05).(2) length of buttock fin: body length Female: 6.408±0.243 Male: 5.129±0.473 The difference is significant(P <0.05).(3) Dorsal fin to caudal fin section: body length Female:2.549±0.049 Male:2.437±0.082The difference is significant(P <0.05).Females are larger than males in the proportion from the pectoral fin to the pelvic of total body, the difference was significant (P <0.05); while males are larger than females in the proportion of anal fin length and dorsal fin to the caudal segment of total body, significant difference (P < 0.05). 1.3 Fullness coefficient Female: 0.744; Male: 0.778.1.4 Length-weight relationship Female: y=-8.618+1.567x(r=0.878) Male: y=-10.727+1.845x(r=0.766) y representative body weight(unit:g), x length.(unit:cm)1.5 Mature coefficient Female: 39.63, its absolute fecundity was 4831, and the relative fecundity was 1934 / g body weight; Male: 5.02.2. Hypomesus olidus embryo development under different temperatures2.1 Incubation timeAt 8℃, 12℃, 16℃, 20℃and 24℃conditions, Hypomesus olidus fertilized eggs incubate at different time: 8℃,311.50h;12℃,272.67h;16℃,177.07h;20℃,142.00h;24℃,118.03h, shorter with increasing temperature.2.2 hatchabilityAt 8℃, 12℃, 16℃, 20℃and 24℃conditions, the hatchability of Hypomesus olidus fertilized eggs was: 8℃,68%;12℃, 72%;16℃,40%;20℃,29%;24℃,25%.The highest at 12℃, the lowest at 24℃.2.3 Incubation accumulatedAt 8℃, 12℃, 16℃, 20℃and 24℃conditions, the Incubation accumulated of Hypomesus olidus fertilized eggs was 2492.00℃·h-3272.04℃·h.3. Hypomesus olidus larvae feeding and growth3.1 The initially feeding rateUnder normal temperature of laboratory conditions (water temperature 11.5±0.5℃),Hypomesus olidus larvae began to feed in 4 days after hatching. The initially feeding rate was 20%. Reached the peak initially feeding rate (100%) in 7 days,the peak initially feeding rate last two days.The initially feeding rate began to decline in 9 days.3.2 Hunger irreversible points In 11 days, Hypomesus olidus hungry larvae initially feeding rate dropped to the half of the maximum initial feeding rate (50%). So the hunger irreversible points of Hypomesus olidus was determined at 11 days old.3.3 Hypomesus olidus larvae growth modelRegressing the full-length TL (mm) and age is D (d) from hatched larvae to 13 days age, establish larval growth model of full-length and age, the relation is: TL=0.0002D3-0.0075 D2+0.1955 D+6.2699 (R2=0.9891,n=300)4. Hypomesus olidus larvae grow and develop under different temperatures:4.1 Length changingAt 12℃,16,20℃, with the temperature increased, the length of Hypomesus olidus larvae growed acceleratly,different temperature changed significantly differently (p <0.05). When the water temperature reached 24℃, the length growed no longer.4.2 yolk sac and oil globule absorptionAt 12℃,16,20℃, with the temperature increasing, the larvae of Hypomesus olidus absorbed the yolk sac and oil globules faster, different temperatures changed differently(p <0.05). When the temperature reaches 24℃, the larvae can not normally absorb yolk and oil globule.