| Hucho bleekeri Kimura, belongs to Salomoniformes, Salmonidae, Hucho, is a large cold-water and endemic fish in China. It mainly distributed in Make River system in Qinghai province, Minjiang River Sichuan province and Hanjiang River in Shaanxi province. In recent years, due to the factors of human activities, such as, the construction of hydropower stations, gold mining, gravel acquisition, the habitat and spawing grounds of H.bleekeri have been seriously damaged, and the population quantity was getting less and less. It became one of the class II national protected animal in China in 1998, and was listed in the International Union for Conservation of Nature(IUCN) as Critically endangered(CR). This study firstly researched artificial breeding of H.bleekeri, observed its early development process, and explored suitable first food for H.bleekeri larvae. This study designed to protect the population of the species, ensured the continuation of the species, protect the species diversity, and provide references for artificial breeding early development reserch. The main results are as follows:1. The oxytocin drug is salmon gonadotropin-releasing hormone analogue(S-GnRH-A), Domperidone(DOM) and vitamin B1(VB1). The first needle: S-GnRH-A 8ug/kg, the second needle VB1 and DOM 12ug/kg, the third needle S-GnRH-A and DOM 8ug/kg in 2013. The first needle: S-GnRH-A 12ug/kg, VB1 2.56mg/kg, the second needle S-GnRH-A 12ug/kg, VB1 2.56mg/kg and DOM, 4ug/kg, the third needle S-GnRH-A, 8ug/kg of the first artificial reproduction in 2014.The first needle S-GnRH-A 10ug/kg and VB1 2mg/L, the second needle S-GnRH-A 11ug/kg of the second artificial reproduction in 2014. The results of three artificial reproduction shown: The fertility rate was 83.00%, hatchability was 41.00%, the number of newly hatched larvae were 3270 in 2013. The fertilization rate of the first artificial reproduction was 79.97%, hatching rate was 33.11%, the number of newly hatched larvae was 2458 in 2014. The fertilization rate of the second artificial reproduction was 75.71%, hatching rate was 25.49%, the number of newly hatched larvae was 800 in 2014.2. The fertilized egg of H.bleekeri was spherical with oil globules, non-adhesive, pale yellow, and oolemma was thick, and it’s density was greater than the water. The perivitelline space increased to the maximum diameter(4.36±0.20 mm) after absorbing water. The first fertilized egg hatched at 494.5 h post fertilization(hpf), peak hatching occurred at 549 hpf, and the hatching period lasted about 168 h at water temperature 9.47-11.30 oC(mean 10.17 oC). Embryo development was categorized into six stages: fertilized egg(0-13 h), cleavage(13-45 h), blastula(45-122 h), gastrula(122-170.5h), neurula(170.5-183.5 h), organogenesis to hatching(183.5-549 h).3 The mean total length of newly hatched larvae was(11.62±1.00) mm, the mean body weight of larvae was(0.0254±0.0016) g, the yolk sac volume of larvae was(53.82±1.03) mm3. Primordia dorsal, anal primordia, pelvic primordia, adipose fin primordia appeared on 2d, 4d, 9d, 11 d respectively. The first chamber air bladder was formed on 17 d. Larvae began into the mixing vegetative stage on 18 d. First scales appeared in the larva of abdomen, entered into juvenile stage on 20 d. The yolk sac was completely absorbed, juvenile completely exogenous nutrition on 26 d. All fins completed development on 52 d. Stripes completed development on the body surface on 64 d. The scales fully distributed the body on 73 d, entered the young period. Growth model equations fish larvae period is: TL = 0.3766 d + 13.318,(R2 = 0.9772, TL: total length, d: is days-old), the specific growth rate was 0.030.4. H. bleekeri larvae were feed with Limnodrilus sp., Artemia salina, eggs of crucian carp and two artificial commercial diets for 20 days to study the effects of different initial feeding diets on the growth and survival of the larvae. The results showed that: larvae fedwith A. salina showed the highest survival rate(91.11±5.09) %, larvae fed with Limnodrilus sp. showed the lowest survival rate(43.33±6.67) %. Larvae feeding with A. salina showed the highest specific growth rate(3.14 ± 0.20) % from 0 to 10 days, but a negative growth(-0.38 %) after 15 days. The growth rate of larvae fed with two artificial commercial diets increased sharply after 10 days. According to the results, the best weaning and rearing plan of H.bleekeri larvae is as follows, feeding with A. salina in the first 10 days, and then adding artificial commercial diet step-by-step to finish diet switch. |
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