Harvest method does not affect survival and condition during gonad enhancement of an overabundant sea urchin

Abstract

Interest in sea urchin roe enhancement aquaculture is growing due to an increased global demand for high-quality roe that is suitable for export to international markets. Yet, fine-tuning of efficient collection methods and improved growing techniques are still key bottlenecks to industry success. Urchins suitable for roe enhancement are generally collected from rocky barrens where they occur in high densities. Few studies have investigated the efficiency of methods used to collect urchins from barrens or the associated short- and long-term handling effects due to collection methods. Here, we tested 2 methods to collect the purple sea urchin Heliocidaris erythrogramma, a species that is highly abundant in barrens in temperate waters and which is a viable candidate for roe enhancement aquaculture. We assessed short- and long-term survival, external urchin condition and final gonad indices after 12 wk of roe enhancement. Divers using a 3-pronged hook and catch bag collected urchins 1.9 times faster (392 urchins h-1) than careful hand collection (207 urchins h-1). Collection method did not significantly influence mortality rate, external health or gonad indices after 12 wk of roe enhancement. Our results show that H. erythrogramma in barrens is robust to rapid mechanical collection by divers, which increases its suitability as a candidate capture-based aquaculture species.