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Volume 38- Number 1 - 2003
Article


Hatching induction, embryonic and larval development of grunt Haemulon bonariense Cuvier, 1830 (Pisces: Haemulidae)

A. Cuartas1, J. Rosas2, A. Velásquez1 & T. Cabrera1

 

(1) Escuela de Ciencias Aplicadas del Mar
(2) Instituto de Investigaciones Científicas. Universidad de Oriente Núcleo de Nueva Esparta, Apartado Postal 788, Porlamar, Venezuela

 

E-mail: rosas@ne.udo.edu.ve

 

During September and October 2001, hatching induction using Human Chorionic Gonadotropin hormone (HCG) was carried out in 61 Haemulon bonariense specimens (56% females and 44% males). The range of their total length was 240 to 320 mm and the range of weight was 217 to 705 g. The hormonal doses used were 3.00; 1.00 and 0.50 UI/g/fish for females and 1.50; 0.50 and 0.25 UI/g/fish for males. Females hatched out with all doses used, but viable oocytes were produced only with 0.50 UI/g/fish. On the other hand, males specimens hatched out only with 0.25 UI/g/fish. In both cases hatching took place ten hours after injection. The fertilized eggs are spherical, floating, transparent, with a smooth envelope, non adherent, telolecite, with an average diameter of 0.80 ± 0.05 mm and a oil drop with an average diameter of 0.20 ± 0.02 mm. The embryonic and larval development was described, observing the first cleavage at 0h: 24 min, the blastula at 1 h: 56 min, the gastrula at 5 h: 7 min. The hatching out started at 15 h: 19 min after fertilization at 27.25 ± 0.50 °C. The larval total length was 1.42 ± 0.05 mm, the vitelline sac total length was 0.94 ± 0.10 mm and the volume was 0.13 mm3. At 48 hours, the larval total length was 2.52 ± 0.10 mm, the vitelline sac was completely reabsorbed and the mouth opened. At 78 hours the larval total length was 2.32 ± 0.14 mm, and pigmented optical lenses were observed. Tetraselmis chuii microalgae (40 X 103 cells mL–1) was offered to the larvae and it was observed in their intestinal tract; a gradual larval mortality occurred from 88 hours. The hatching induction with Human Corionic Gonadotropin hormone (HCG) was effective although it is recommended nutritional studies on Haemulon bonariense larvae to establish the base for its larvae culture.


Key words: Embryonic and larval development, hatching induction, larva

 

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1Laboratorio de Zooplancton, Instituto de Ciencias del Mar y Limnología,Universidad Nacional Autónoma de México. A. P. 70-305, 04510 México, D. F. México
 
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