Echinoid landings at Mandapam, south-east coast of India with a note on gonadal maturity of two species of sea urchins

The sea urchins, belonging to phylum Echinodermata, are a good source of “roe”, (gonads) and are being consumed by humans since pre-historic times. In many countries of the world, it is a delicacy among the food items and in retail markets in Japan, it is sold at prices as high as US$ 600 kg-1. Among the 800 species of echinoids, 105 species are found along the east coast of India and 30 species are recorded along the coast of Tamil Nadu. There is a paucity of information on the biology and ecology of sea urchins and lack of studies on its edibility and palatability. The sea urchin aquaculture called as echiniculture is picking up in subtropics and temperate areas. Importantly, the tropical marine ecosystem of India, which supports diverse flora and fauna is a suitable environment for echiniculture, and the future research needs to be focused to find out the potential species and developing techniques for their aquaculture. The present investigation analysed the landings of echinoderms in the Gulf of Mannar and Palk Bay along the south-east coast of India and also studied the gonadal maturity of two species of sea urchins viz., Salmacis virgulata and Temnopleurus toreumaticus in order to assess their suitability for echiniculture. S. virgulata and T. toreumaticus formed 70 and 30% respectively of the sea urchins landings at Vedalai and Pampan landing centres. The overall sex ratio of both the species did not deviate significantly from 1:1. In S. virgulata the mean monthly gonad index was highest (9.62±0.46) during September 2014 and for T. toreumaticus, the peak GSI was observed during December 2013. Further studies on captive maturation and breeding are needed to explore the potential of these species for echiniculture