Growth and mortality of oysters (Crassostrea gigas, Thunberg 1793) in Sacca degli Scardovari (Italy)

• Published in: Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science
• Main Authors: Trocino A., Zomeño C., Gratta F., Birolo M., PASCUAL GUZMÁN, ANTÓN, Bordignon F., Rossetti E., Xiccato G.
• Other Authors: Trocino, A., Zomeño, C., Gratta, F., Birolo, M., PASCUAL GUZMÁN, Antón, Bordignon, F., Rossetti, E., Xiccato, G.
• Format: Conference Object
• Language: English
• Published: Wageningen Academic Publishers, The Netherlands 2018
• Subjects: Crassostrea gigas
• Online Access: http://hdl.handle.net/11577/3276733; https://doi.org/10.3920/978-90-8686-871-1

This study assessed growth and mortality of oysters reared in suspended ropes, and tested the effect of rope emersion time throughout fattening (8 months; October 2016-June 2017). A total of 4,320 triploid oysters were stuck to 36 ropes (320 oysters/rope) and subjected to three emersion systems (12 ropes/system): standard of the farm (F), i.e. variable emersion duration changing according to daily atmospheric conditions; long (L), i.e. 14 emersion hours per day; short (S), i.e. 7 emersion hours per day. Biometric traits were collected at sticking, and after 2, 4, and 8 months. Biometric data were analysed with PROC MIXED (SAS), with emersion system, sampling time and their interactions as fixed effects, and rope as random effect; mortality was analysed with PROC CATMOD. At sticking, oysters exhibited an average weight of 6.04±2.63 g, a length of 39.8±8.38 mm and a width of 23.9±4.39 mm. Oyster length and width were similar from 2 to 4 months (46.1 mm and 33.3 mm on average, respectively), and increased after 8 months (76.0 mm length and 59.6 mm width) (P<0.001). After 8 months, oysters subjected to F and L emersion programs were heavier (68.3 g and 66.3 g vs 56.8 g; P<0.01), longer (78.1 mm and 77.2 mm vs 71.6 mm; P<0.01) and wider (55.6 mm and 55.0 vs 50.8 mm; P<0.10) than those subjected to S emersion. Total mortality reached 44.3% in F, 63.3% in L, and 66.8% in S system (P<0.001). To conclude, under the tested conditions, oysters fattening appeared feasible and promising, but the short fixed emersion system was the least favourable due to higher mortality and lower growth. Acknowledgements: La Perla del Delta; Veneto Region, Reg. (UE) 508 15/05/2014, DGR 213 28/02/2017.