Preliminary Design of an Electrical Inhibition Gate for Application in an Automated Soft-Shell Crawfish Separation System

Abstract

Two types of electrical inhibition gates were evaluated for their effectiveness in separating soft-shell crawfish from an intermolt population within a culture tray. A normally open circuit gate (A) effectuated a significant decrease in the intermoly escape rate over both a normally closed circuit gate (B) and a no gate situation. The effects of voltage, gate gap, and equivalent resistance of the electrical circuit were investigated to determine the critical design values for the normally open gate A. The operative voltage was above three V, with no difference in escape rate between three and 12 V. For an average carapace height of 18.9 mm, the threshold gate gap was 17 mm. The equivalent resistance of the circuit when a crawfish is contacting the gate varied with the conductivity of the water and the contact positions of the crawfish. The lowest equivalent resistance corresponded with the highest conductivity with contact between the base of the crawfish antenna and the gate.