Unilateral ablation of Penaeus stylirostris (Stimpson)

Wild females of Penaeus stylirostris, captured in August 1990 in the northern region of the Gulf of California, were induced to maturation by unilateral ablation under standard maturation laboratory conditions. Two experimental groups (A, B) and one control without ablation (C) were structured. Unilateral ablation was applied to A at 24 f 2 h and to B at 38 ± 2 h, once the intenmolt stage had begun. The experimental groups registered similar values in number of spawnings per female per month, signifícantly different from the control (p 0.05). Maximum reproductive response was obtained by group A females; 73.3% of ablated females matured and produced one spawn. The number of ablated females that produced subsequent spawns decreased by 20% in the second and approximately 33% in the third. Among the experimental groups, higher survival (86%) and maximum accumulated production of eggs (4.8 million nauplii) was registered by A

The use of bacterial counts in two mexican shrimp hatcheries

En dos laboratorios situados en la República Mexicana. Se realizaron conteos de bacterias heterótrofas viables, bacterias tipo Vibrio y coliformes totales en muestras de agua del sistema de aprovicionamiento. en alimentos marinos y en estanques de reproductores. Las altas concentraciones de estos grupos bacterianos indican la existencia de puntos de riesgo, los cuales deben ser vigilados sistemáticamente para poder controlar patógenos potenciales, tales como Vibrio spp. En este trabajo, se encontró que los sistemas de filtración y el alimento utilizado, tal como Artemia spp. y organismos marinos Frescos o congelados, son las principales fuentes de patógenos potenciales en los laboratorios de acuicultura estudiados. Counts of viable heterotrophic bacteria, Vibrio-like bacteria and total coliforms were performed in seawater supply, food stocks and broodstock pools at two aquacultural facilities located in Mexico. |00E2|??The high abundance of these bacterial groups indicates risk areas that must be monitored to control potential pathogens, such as Vibrio spp. Filtering systems and food supplies, such as Artemia spp. and fresh or frozen sea food. were found to be the most important sources of potential pathogens

Larval survival of Litopenaeus vannamei (boone) fed Chaetoceros muelleri produced with agricultural fertilizers

Larval survival of Litopenaeus vannamei fed Chaetoceros muelleri produced with agricultural fertilizers and f/2 medium (control) was compared. The microalgae were cultivated in natural sea water fertilized with 36.8 mg L–1 N-NH4NO3 and 3.5 mg L–1 P-P2O5 as a substitute for nitrogen and phosphorus in the f/2 medium. Microalgal concentration during feeding of nauplius5 stages to protozoeaIII was maintained at a density of 100–150 x 103 cells mL–1. From mysisI to postlarvae1 stages, Artemia franciscana nauplii were the only source of food. Average growth of C. muelleri with agricultural fertilizers was greater and significant (P < 0.05) with respect to the control on days 2, 3 and 4 of the culture; however, on day 5, there was no significant difference in the cellular density. Survival of the larvae of the mysisI stage fed C. muelleri produced with agricultural fertilizers and f/2 medium was 69% and 77.5%, respectively, and showed significant differences (P < 0.05). However, survival at the postlarvae1 stage in both treatments (60.1% and 65.6%) was not significantly different. We conclude that the use of nutrients from agricultural fertilizer as a substitute for nitrogen and phosphorus in the f/2 medium constitutes a viable alternative for the culture of C. muelleri as food for larvae of L. vannamei