Aquaculture: sea Urchins- The spiny hedgehog of the sea Marlee Hayes

Species Green Sea Urchin Purple Sea Urchin Strongylocentrotus droebachiensis Purple Sea Urchin Strongylocentrotus purpuratu Red Sea Urchin Mesocentrotus franciscanus The variegated sea urchin Lytechinus variegatus Over fishing has negatively impacted sea urchin populations. Aquaculture, especially inland, is just beginning. Sea Urchins have great potential for sustainable aquaculture. High fecundity Quick growth rate Hardiness The consumable part of the Sea Urchin is the Roe or Uni.

Sea Urchin Anatomy

Economical/Ecological Importance Valuable food item in Japan, France, United States, China and other areas. California exports a large amount of sea urchin to Japan. Sea Urchins are grazers. Possible keystone species. Urchins can decimate kelp beds. Kelp provides a natural product, algin. Sea otters, sea stars, wolf eels and triggerfish are predators of urchins Model organism for scientific research Market Prices Catalina Offshore Products, California, AL 1 pound live wild whole red or black sea urchin $13.99 California Gold Uni 80 grams $19.99 California Premium Uni 80 grams $11.99 Santa Barbra Fish Market $9.95 each Fresh caught by divers Japan Approximately $ 8.20-$40.98 per tray (imported from California) Seasonality the price of Chilean fresh roe almost triples off-season: from around $12 per kilo roe to around $36 per kilo of roe. 

Life Cycle Diecous Broadcast Spawners External Fertilization Seasonal Conditions Photoperiod, Temperature Salinity Echinopluteus Larvae(months) → Metamorphosis (~30 min) → Adult (max size ~5years)

Reproduction in Captivity Spawning can be induced by acetylcholine/potassium chloride injection Eggs or sperm can be collected by placing urchin upside down over beak and gametes will be released from the gonodapore Sperm needs to be diluted with saltwater to be activated and prevent multiple fertilizations Temperature changes can also induce spawning https://www.youtube.com/watch?v =Qf22WvlDUeI

Production Methods Offshore sea farming Stock enhancement Cages where urchins are raised in open ocean Stock enhancement Hatching larvae and growing until small juveniles, then release into wild until harvest

Production Methods Land based raceways/Tanks Small Scale Successes UAB Texas A&M Gonad enhancement Seasonality issue remedied

Sea Urchin Platter System Ireland UCC Stackable, layered

Feeding Macroalage (Larvae need single celled algae) Juveniles (phytoplankton/diatoms) Seaweed (Kelp) High-protein, sinking, pelleted food No commercially-available feed for large scale Standardized optimal feed is needed

Feeding Research to produce ideal feed to meet nutrition requirements and produce the best marketable product Enhancement of Gonad Size Color Texture Taste

Feeding http://www.travelchannel.com/video/tasty-test-tube-sea-urchins

Water chemistry and Environmental Conditions Temperature 20 -26° Celsius Synthetic Sea Water Salinity 35 mg/L Recirculating System with mechanical, chemical, and biological filters, UV sterilization and aeration Feces must be manually siphoned pH of 7.5 Partial water change 1-3 times weekly Oxygen Levels and Light Cycles can affect growth and development

Advantages High Fecundity Hardy Can be cultured densely Rapid growth rate Gonad development can be enhanced Year round production Potential for poly culture Protection from predation

Disadvantages Standardized feed Can’t see the product Land based Tanks/Raceways Mass spawning event Larval care/stages Intensive Manually siphon system (dense feces) Eat anything including equipment Sea based Cages/Ranches Environmental Impacts Unpredictable Pollution Nutrification Physical Damage Burying/ Crushing

Sea Urchins are Cool! Certain species of sea urchins (such as flower urchin) have spikes filled with venom. The flower urchin is extremely venomous and has caused rare fatalities. Toxopneustes pileolus Sea urchin has special type of mouth, called "Aristotle's lantern". Mouth is equipped with five sharp teeth that are able to drill a hole in the rock. Using its Aristotle’s lantern, the purple sea urchin is capable of biting pieces out of the rock, and the spines slowly erode away at the surface, creating a small pit in which the urchin may remain for long periods of time. Red sea urchin may have the longest lifespan on Earth. It can potential survive up to 200 years in the wild. In other words, an individual red sea urchin that hatched on the day in 1805 that Lewis and Clark arrived in Oregon may still be thriving – and even breeding. https://www.youtube.com/watch?v=hD4zfopXAHY

Acknowledgements Dr. Stephen Watts Dr. Hugh Hammer Dr. Mickie Powell Laura Heflin Watt’s Lab SRAC FAO Sea Urchins: Biology and Ecology by John M Lawrence