Urchin: Red Sea, Green Sea

Red Sea Urchin, Green Sea Urchin

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Red sea urchins are found in the Pacific Ocean from Baja, California to Alaska. Green sea urchins occur in both the Atlantic and Pacific Oceans. Red and green sea urchin are fished primarily for their gonads (reproductive organs) which are referred to by the culinary term “roe”. Urchin roe is a popular sushi item, sold under the Japanese name uni.

Green sea urchins have a low age at maturity (< 5 years), an assumed high growth coefficient, are long lived (>30 years), and have a high reproductive potential (several million eggs per spawning event). This species is considered inherently resilient to fishing pressure.

Biomass estimates for Maine’s green sea urchin fishery have been decreasing since the beginning of the time series. The green sea urchin stock in Maine is overfished and as of 2001, the biomass was estimated to be 10% of the virgin biomass according to the stock assessment published in 2003. Estimates of size distributions are skewed. Overall this stock is ranked as having a “critical” conservation concern.

Sea urchins are captured primarily via hand collection by SCUBA divers and consequently this method is highly selective. A small portion of the green sea urchin fishery in Maine is fished by draggers (27%). This gear type is not selective, resulting in moderate bycatch levels comprising mostly invertebrates that are returned to sea, alive. Overall,drag caught urchins represent a relatively small portion of the fishery and the overall ranking for bycatch from Maine urchin fisheries is considered a low conservation concern.

Dive or hand collection fisheries have very minimal, if any, direct impacts on the habitats. However, within kelp forest ecosystems, phase shifts have been noted as a direct result of commercial urchin fisheries, causing functional changes in recruitment. Draggers, a small component of the Maine fishery, have adopted precautions to minimize impacts associated with this gear type. The effects of hand collection on habitats and ecosystems in the red and green urchin fisheries are moderate.

The sea urchin fishery in Maine has a similar structure to that of the Canadian fishery (regular stock updates, limited entry, quotas, restrictions on: season, gear, area and size). This management system in Maine however, was not sufficient to prevent substantial decline in the stock and thus far, stocks have not recovered. Maine’s green sea urchin management system is considered moderately effective.

Where is this urchin from? (Canada = Green, California = Yellow, or Maine = Red)

Contaminant levels do not warrant a consumption advisory.

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