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Blackspot seabream, Pagellus bogaraveo (Brunnich), has been identi¢ed as a potential species to diversify European aquaculture production. Although rearing aspects have been widely investigated, little information exists on the nutritional requirements for this species. The aim of this study was to build up information on the activity of digestive enzymes at certain developmental stages of blackspot seabream in order to understand the nutritional needs of larvae and post larvae. Fish larvae were reared from hatching to 55 days after hatching (dah), and the feeding plan consisted in rotifers (5^35 dah), Artemia naupli (303 5 dah) metanaupli (35^45) and Gemma microdiet (45^55 dah). At 7, 11, 21, 45 and 55 days after hatching (dah), pooled samples of ¢sh larvae were collected for analysis of trypsin, amylase, lipase, alkaline phosphatase and leucine^alanine peptidase activity. Up to 21dah, the whole larvae body was used for enzymatic analysis, whereas in older larvae only the dissected abdominal cavity was used. Blackspot seabream body dry weight growth was exponential, increasing from 60 mg at 5 dah to 30 AE 9.7 mg at 55 dah. Amylase speci¢c activity decreased signi¢cantly during development, exhibiting at 11dah (0.6 U mg À1 protein) an average value 2.7 times lower than at 7 dah, and remaining stable between 45 and 55 dah (0.7 U mg protein À1 ). Trypsin speci¢c activity remained constant until 21dah (between 38 and 44 mU mg protein À1 ), which could be related to the larvae feeding regime. At later stages of development, lipase-speci¢c activity exhibited a signi¢cant increase (Po0.05), being three times higher at 55 dah (8 U mg protein À1 ) than at 45 dah. The total activity of the studied digestive enzymes increased signi¢cantly during larval development (until 21dah), whereas afterwards only lipase and leucine^alanine peptidase increased signi¢cantly between 45 and 55 dah. The pattern of digestive enzymes activity was related to organogenesis and the type of food used at di¡erent developmental stages. Digestive enzyme activity during P. bogaraveo development L Ribeiro et al.

The survival, growth, gonadal development and sex ratios of gynogenetic diploid turbot Scophthalmus maximus between 9 and 36 months of age were investigated. Gynogenesis was induced by activation of freshly collected eggs with diluted (1 : 10 with Ringer) and UVirradiated (30000 erg mm À2 ) sperm, followed by a cold shock at À1 to 0 C for 25 min, starting at 6Á5 min after fertilization. The exclusive maternal inheritance of the resulting gynogenetic diploids was confirmed in all individuals used in the experiment by microsatellite markers. Mean total length and mass throughout the experiment was higher in the controls than in the gynogenetics. The gonadal development in gynogenetic males proceeded normally, and in gynogenetic females it was delayed during the first sexual maturation but was normal during the second one. The sex ratio was 1 male (M) : 1 female (F) in the controls, as expected, but 1 M : 3 F in the gynogenetics. In a second, independent experiment, carried out with fish originating from different broodstock, however, the sex ratio was 1 M : 1 F in the controls and 0 M : 1 F (i.e. 100% females) in the gynogenetics. Together, these results suggested that the main sex-determining genetic component in turbot fits well to female homogamety, in accordance with data from other flatfishes. These results indicate that it will be possible to obtain near or all-female turbot stocks through induced gynogenesis or by crosses involving hormonally sex-reversed fish.