CAROTENOIDS IN THE TIGER PRAWN PENAEUS-ESCULENTUS DURING OVARIAN MATURATION

Female Penaeus esculentus Haswell were collected by 15 to 20 min duration trawls during 1990. Carotenoids were analysed in the digestive gland, abdominal muscle, the remainder of the body (hereafter called ''integument'') and ovary of prawns in Stage 2 through Stage 4 (fully mature) of maturation. The only oxycarotenoids (xanthophylls) identified were astaxanthins or astaxanthin esters; occasionally low levels of beta-carotene were detected in the digestive gland. The concentrations of astaxanthin monoesters (AM) and diesters (AD) were highest, with only minor amounts of free astaxanthins (Ast), except in the maturing ovaries, where free astaxanthins predominated (up to 80% of the total carotenoid). Of the total carotenoid, 82 to 94% was in the integument, but at maturity the digestive gland contained 10.7 +/- 3.4% and the ovary 5.6 +/- 0.9% of the total carotenoid. Only the ovary increased in mass during maturation, reaching up to 5.2% of total prawn mass. During this period, digestive gland concentrations of AM, AD and Ast all increased (total 20 to 120 mu g g(-1)), levels in the muscle and integument varied little throughout maturation (total similar to 0.4 and 100 mu g(-1), respectively); ovary AM levels remained low throughout (1.5 to 1.2 mu g g(-1)), AD increased from only 2 to 5 mu g g(-1), but Ast increased from 2 to 34 mu g g(-1). Apart from the ovary, AM concentrations were the most variable. In common with other decapod Crustacea, the maturing ovary of P. esculentus contained high levels of carotenoids, indicating that these may have an important role in early development. The natural diet of P. esculentus includes a variety of carotenoids, but except for a little beta-carotene, the digestive gland, where absorption occurs, contained astaxanthins, with only an occasional trace of beta-carotene. This suggests that the conversion of dietary carotenoids to astaxanthin occurs soon after ingestion.