Effect of feeding frequency and various shelter of blue swimming crab larvae, Portunus pelagicus (Linnaeus, 1758)

Abstract

The objectives of this experiment were to improve blue swimming crab, Portunus pelagicus, rearing techniques by investigating (1) the applied frequency of feeding and (2) the effect of shelter on crab larvae survival. The results showed that the feeding frequency at 2 times (0900 hrs and 1500 hrs), 4 times (0700 hrs, 1300 hrs, 1900 hrs and 2300 hrs) and 6 times (0700 hrs, 1100 hrs, 1500 hrs, 1900 hrs, 2300 hrs and 0300 hrs) per day did not affect the survival rate of crab larvae from the zoea I (Z1) to first crab (C1) stages. The survival rate of crab larvae from the megalopa (M) to C1 stages with shelter was higher than without shelter, and the type of shelter affected the survival rate of the crab larvae. The survival rate of the C1 stage with artificial seaweed made of plastic shield membrane (36.61±3.64%) and artificial seaweed made of polyvinyl rope (35.79±6.04%) as shelters were not significantly different and higher than for artificial plastic grass as shelter (22.18±4.00%). In addition, the survival rates of the C1 stage with vertical shelter, horizontal shelter and a combination of vertical and horizontal shelter on the bottom of the tank were not significantly different. This study recommends that crab larvae rearing with shelters is important for increasing the survival rate and that the type of shelter affected the survival rate of crab larvae.

Keywords

• Portunus pelagicus
• survival rate of crab larvae
• feeding frequency
• shelter