Enhancement of gonad production in the sea urchin Loxechinus albus in Chile fed extruded feeds

Loxechinus albus were fed algae (Macrocystis pyrifera and Ulva sp.) and two feeds prepared by extrusion (one containing kelp). Results were the same for individuals maintained in suspended cages in the sea and in aquaria on land. Gonads increased in size in individuals fed extruded feeds and decreased in individuals fed algae during the spawning season. Gonads increased ca. four-fold in size in individuals fed the extruded feeds during the post-spawning season, much greater than those fed algae. Individuals fed extruded feeds had a lower feeding rate than individuals fed algae on a wet-weight but not on a dry-weight basis. The extruded feed supports gonadal growth more than natural food and has potential for use for aquaculture of sea urchins.