Junior researchers present studies on mud crab

By Development Communication Section

AQD technical assistants Ms. Joana Joy de la Cruz-Huervana and Mr. Michael Ray Burlas shared the results of their master’s degree theses, “Induction of molting in hatchery-reared mud crab Scylla serrata juveniles” and “Evaluation of commercial shrimp larval diet as replacement of live feeds in mud crab larval rearing,” to AQD research staff on 4 September, respectively.

Ms. de la Cruz-Huervana studied the effects of temperature and autotomy or removal of chelipeds on the growth, survival and molting of mud crab juveniles. She exposed hatchery produced mud crab with internal carapace width of 2-3 cm and body weight of 1.7-2.2 g to various temperatures (ambient, 29, 32 and 35°C) during the intermolt stage. Based on the results, it is suggested that the optimum temperature level for rearing mud crab juveniles is at 29°C. There were three treatments for the experiment on autotomy: (1) the control where the chelipeds are intact, (2) one cheliped was autotomized and (3) two chelipeds were autotomized. The results showed that autotomy of one cheliped promoted molting without adversely affecting the growth and survival of mud crab juveniles.

Mr. Burlas on the other hand evaluated four commercial shrimp larval diet as a replacement to the natural food used in mud crab larval rearing. He tested the effects on growth and survival of these commercial shrimp larval diets on the growth and survival of various larval stages of mud crab compared to feeding with natural food. It was found out that artificial diet can be given beginning Zoea 2 since growth and survival at this stage is comparable in groups fed the artificial diets and those fed with natural food. Moreover, he also tested various natural food-artificial diet ratios to determine how much of the natural food can be replaced with artificial diet. The results showed that 25-50% of the natural food can be replaced with commercial larval shrimp diets.

Both presenters were recent graduates of MS Fisheries (Aquaculture) at the University of the Philippines Visayas.