Comparison of gonad quality factors:: color, hardness and resilience, of Strongylocentrotus franciscanus between sea urchins fed prepared feed or algal diets and sea urchins harvested from the Northern California fishery

Quality factors important in sea urchin roe marketing are color and texture. In two laboratory experiments, spring and fall, Strongylocentrotus franciscanus, were starved or fed a low carotenoid pigment diet (13.86 mug/g), a high carotenoid pigment diet (146.83 mug/g) or kelp, Nereocystis luetkeana (73.60 mug/g). Gonads from laboratory groups and three grades of commercially processed roe (Fort Bragg A, B, and C) were examined for color and texture. Grade A roe is the most commercially valuable. S. franciscanus weighed 329.1 +/- 43.0 g and had a test diameter of 91.4 +/- 5.3 mm. Feed consumption was greater in fall than spring for prepared diets and lower in fall for N. luetkeana. The lightness (L*) of S. franciscanus gonads was significantly greater in spring than fall. Gonads from laboratory treatments showed lower values for red and yellow resulting in overall lighter color than commercially processed roe. Red color (a*) remained similar in both season while yellow color (b*) decreased significantly in fall. Hardness and resilience were greater in fall than spring, reflecting greater dry matter content and gonad reproductive condition. Spring gonads were large, soft and mature. Fall gonads were large, firm and in the recovering and growing stages of the reproductive cycle. Seasonal differences in color, hardness, and resilience indicate reproductive state and must be considered in aquaculture strategies of sea urchins. (C) 2004 Elsevier B.V. All rights reserved.