The Use of Mulberry (Morus alba) Extract in the Mass Production of Blue Swimming Crab (Portunus pelagicus L.) Larvae to Overcome the Mortality Rate Due to Molting Syndrome

Portunus pelagicus L. is one of the commercial crabs traded widely around the world. In Indonesia, the crab species is under intensive development to meet the increasing overseas market demand. The export volume reaches 23 to 25 million tons per year. The increasing amount of crab fishing caused decrease in natural populations, in both quantity and quality. FAO (2011) in World Bank (2012) mentioned that in 2008, Indonesia contributed 20 % of the world blue swimming crab production and ranked second of the biggest producer after China. Unfortunately, along with the increase of human needs and pressure on the marine biological resources environment, the live stock of crabs in Indonesia is continually decreasing by 20 – 30% each year (Mahesa, 2010). Therefore, other methods to increase crab the supply of crab raw material is highly needed, for example through culture.

The blue swimming crab can be cultured in ponds but the seeds still rely on the catch from natural habitat so this action is still potential to press the natural population. Attempts to culture them using seeds from hatchery is still being studied, and have not yet carried out in mass production. One of the causes is that blue swimming crab seedling in hatchery has not given any consistent result yet. The survival rate of seeds usually fluctuates and is generally low. Maheswarudu (2008) reported that the highest survival rate (10.3±5.76%) from zoea-1 to Crab-1 is achieved in low density stocking (50 larvae/liter). Moreover, Juwana et al., (2010) was successful in increasing the survival rate from 2.2% to 8.7% through probiotic administration. Zmora et al., in 2005 then reported that cannibalism is one the factors causing high mortality, so it is suggested to use the shelter and size grading, and decrease stock density.

The main problem in the blue swimming crab seedling is mortality (Soundarapandian et al., 2008). Mortality is caused by various factors, such as disease attack (Govindasamy & Srinivasan, 2012; Talpur et al., 2011a; Talpur et al., 2011b), molting syndrome (Hamasaki et al., 2002 and cannibalism (Soundarapandian et al., 2008). Many ways have been done to overcome those problems, such as nutrition enrichment of natural food using HUFA to increase EPA and DHA in order to increase larval resistance (Hamasaki et al., 2002; Samuel et al., 2011) by using probiotic to control the pathogenic bacterial attack, Vibrio (Juwana et al., 2010), adjusting the amount and feeding time of natural food (Ikhwanuddin et al., 2012; Redzuari et al., 2012), using shelter and size grading, and reducing stock to reduce cannibalism (Zmora et al., 2005). Nevertheless, litte investigation has focused on the control on molting syndrome through hormonal regulation controlling molting syndrome in crab larvae.

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(Author: Yushinta Fujaya, Dody Dharmawan Trijuno, Andi Nikhlani, Indra Cahyono, Hasnidar Hasnidar

 Published by Macrothink Institute)