The effects of wave and feeding disturbance on roe enhancement of the sea urchin Evechinus chloroticus held in sea-cages

An experiment was conducted over a 10-week period to test the effects of wave and feeding disturbance on the gonad index (GI) and gonad color of sea urchins fed an artificial diet. The sea urchins were held in sea-cages at a depth of 6 m. Eight cages were suspended from a surface line (wave disturbed) and eight were subsurface buoyed from a bottom line (not wave disturbed). These two treatments were further divided into four replicates that were fed and cleaned in situ underwater (no feed disturbance) and four replicates that were removed from the water three times per week for feeding and cleaning (feed disturbance). Increased water movement, probably caused by the vertical motion in the wave disturbed cages resulted in a higher GI in these urchins compared to urchins in cages that were subsurface buoyed and did not experience any vertical movement. Feeding disturbance had no effect on the GI values or color quality of the urchin gonads, regardless of whether the urchins were held in sea-cages that were wave disturbed or not wave disturbed.