Improving Size Selectivity of Captured Coonstripe Shrimp (Pandalus hypsinotus) in Hokkaido by Altering the Slope Length and Angle of Pots

Abstract

The purpose of the current study was to optimize shrimp-pot design to allow greater control over the size of captured individuals for the purposes of shrimp resource management. Tank experiments were conducted to determine the optimal slope length and slope angle by analyzing the sizes of shrimp that entered 25 model pots with combinations of five different slope lengths and five different angles. Shrimp size was measured using carapace length. The results showed that as the slope angle of the pot increased, the size of individuals that entered the pot increased. Furthermore, as the slope length increased, each of the five different slope angles of the pot increased, and the size of individuals entering also increased. The data indicated that the optimum pot design for reducing the capture of immature individuals had a <TEX>$75^{\circ}$</TEX> slope angle and a 35.4 cm slope length.