AACL Bioflux, vol: 10,2 (2017)
The mud crab (Scylla serrata) behavior in different inclination angles of funnel and escape vent for trap net
Fitri A.D.P., Boesono H., Sabdono A., Supadminingsih F.N., Nadiaadlina N.
Abstract
Mud crab (Scylla serrata) is one of the most valuable commodities among the Portunidae group that is caught by collapsible trap in Semarang, Indonesia. The trap entrance (funnel) is designed to allow adult crabs to pass in and prevent them from passing out, with the help of inclination angles. The other design uses escape vents that allow smaller crabs to escape. The trap used in this experiment was constructed of PE 210D/6 ¾ inch iron rode frame with 20o, 30o, 40o, 45o and 60o inclination angles, and 2, 3, 4 cm high escape vents. The objective of this experiment is to analyze mud crab behavior in different inclination angles of funnel and escape vent for trap net. The method used in this research is laboratory experiment of 2 life stages; sub-adult carapace width (CW < 10 cm) and adult carapace width (CW > 11 cm) crabs, by counting the crawling time and escape rate. Results show that the 40o inclination makes it easier for adult crabs to pass than the sub-adult crab and the 4 cm high escape vent enables 92.30% of sub-adult crabs to escape and keeps 69% of adult crab stuck in the trap. The conclusion found that the slope angle of 40° and a gap for passage of 4 cm providing opportunities mature crabs trapped in trap. © 2017, BIOFLUX SRL. All rights reserved.
Keyword: Crawling; Escape vent; Inclination; Life stage; Mud crab