Growth model of the reared sea urchin Paracentrotus ... - SciViews

General introduction
this study. Second, a brief review of selected aspects of its biology
provides essential background for this work. The third section reviews the
historical development of growth models. Finally, use of these growth
curves with sea urchins is summarized and discussed.
Economical interest of sea urchins
a. Sea urchin markets and fisheries
The most important market in the world is Japan. Sea urchin roe (both
male and female gonads, uni in Japanese) are marketed under different
forms: fresh (65%), but also dried, salted, frozen or cooked (35%) (Saito,
1992; Hagen, 1996a). According to various authors, the main species
exploited in Japan are Strongylocentrotus intermedius (A. Agassiz), S.
nudus (A. Agassiz), Heterocentrotus pulcherrimus (A. Agassiz),
Pseudocentrotus depressus (A. Agassiz), Anthocidaris crassispina (A.
Agassiz) and Tripneustes gratilla (L.) (Fuji, 1967; Fuji & Kamura, 1970;
Fernandez, 1996; Hagen, 1996a). Both Strongylocentrotus droebachiensis
(Müller) and S. franciscanus (A. Agassiz) are imported from North
America (Kato, 1972; Sloan, 1985), while Loxechinus albus Molina is
imported from Chile (Gonzalez et al, 1993; Lawrence et al, 1997). The
Japanese market is quite stable, around 60,000 tons of fresh echinoids per
annum (Hagen, 1996a), since several years and accounts for more than
95% of the whole world sea urchin market. Current landings in Japan
average 14,000 tons per year. Japanese imports total approximately 5,000
tons of roe under different forms, corresponding to 40 to 50,000 tons of
live sea urchins.
The average price of roe on the Japanese market ranges from 18.6 €/kg
(750 BEF/kg) for the local production (fresh animals considered as top
quality), to 7.9 €/kg (320 BEF/kg) of fresh imported echinoids (Hagen,
1996a). These figures equate to a total market of approximately 657
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