Quality aspects of Crassostrea gigas (Thunberg, 1793) reared in the Varano Lagoon (southern Italy) in relation to marketability

Abstract

Shellfish culture, based on ecological and market assessment, is considered a driving force for socio-economic change in ecologically complex coastal systems such as lagoons throughout the Mediterranean area. To diversify fish production, the Pacific oyster Crassostrea gigas was cultured at commercial farms in the Varano Lagoon (SE Italy). The aims of this study were to evaluate through four condition indices (CI, CICG, CIE and AFNOR index), the Polydora index (PI), lipid content, quality and market aspects of oysters reared at two different sites (FO and LA) of the Varano Lagoon, which are characterized by different hydrodynamic conditions. The results of this study highlighted the potential economic benefits associated with sustainable aquaculture development in the Varano Lagoon, proving that the area surrounding the LA site was more suitable for oyster culture, reaching commercial size (60 mm) in a shorter time (6–8 months). Higher growth performance of oysters was observed in the spring, when the nutrient availability positively affected the feeding response of suspension feeders. The opposite was found in winter and in summer, when the decrease in growth could be due to the reduction of nutrient and to the increase of salinity, TSM and ISM. The presence of the mud blister worm (Polydora sp.) during rearing could be a real problem, as it damages oyster market value and threatens serious financial loss to the local farmers.

Rearing equipment on the quality aspects and growth performance of Crassostrea gigas (Thunberg, 1793): Implications for marketability

“…In our study, we obtained a fast growth of C. gigas during the first two months (12 weeks) of experiment: 70 mm of average shell length and 32.3 ± 0.4 g (floating bag) and 26.8 ± 0.5 g (Ortac) of average total wet weight. The growth rate here obtained is similar to those reported in Cilenti et al (2017) and Graham, Brundu, et al (2019), according to which the total length of the oysters increased from ~40 to ~70 mm in 8 and 10 weeks, respectively, but it is important to consider the different referring period for this comparison. In both Cilenti et al (2017) and Graham, Brundu, et al (2019), the shell length increasing from 40 to 70 mm was obtained during a more suitable growing period for oysters in Mediterranean lagoons, May to October (Alessandro Gorla, Compagnia Ostricola Mediterranea, personal communication), than in this study was obtained later, from September to December.…”

“…The growth rate here obtained is similar to those reported in Cilenti et al (2017) and Graham, Brundu, et al (2019), according to which the total length of the oysters increased from ~40 to ~70 mm in 8 and 10 weeks, respectively, but it is important to consider the different referring period for this comparison. In both Cilenti et al (2017) and Graham, Brundu, et al (2019), the shell length increasing from 40 to 70 mm was obtained during a more suitable growing period for oysters in Mediterranean lagoons, May to October (Alessandro Gorla, Compagnia Ostricola Mediterranea, personal communication), than in this study was obtained later, from September to December. For this reason, we hypothesize the growth rate of C. gigas in S’Ena Arrubia lagoon could be improved by anticipating the seeding of spat in spring.…”

“…In the Mediterranean context, Cilenti et al (2017, Varano lagoon, Southern Italy) reported growth rates lower than those previously obtained in Atlantic coasts for C. gigas , from 50 to 70 mm in shell length and from 10 to 40 g of total wet weight in 7 months of grow‐out period. Recently, in a 6‐month rearing experiment conducted at San Teodoro lagoon (Sardinia Island, Italy), Graham, Brundu, et al (2019) recorded a significantly higher wet weight of triploids C. gigas grown in floating bags (55.8 ± 0.9 g) than in Ortac units (50.1 ± 1.3 g).…”

Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia

“…On the other hand, the lack of reports of R. dubia on farmed M. gigas might also be derived from the lack of research on fauna associated with Pacific oysters, particularly in the Mediterranean Sea. There are only three papers reporting species associated with farmed M. gigas in the Mediterranean Sea [43][44][45], while no papers refer to the fauna associated with natural populations of Pacific oysters (Mikac et al, in prep.). Moreover, comprehensive investigation of the literature dealing with fauna associated with farmed Pacific oysters outside the Mediterranean (Mikac et al, in prep.…”

Testing a Model of Pacific Oysters’ (Crassostrea gigas) Growth in the Adriatic Sea: Implications for Aquaculture Spatial Planning

“…Three growth-performance indicators used by the producers, namely shell length (L), total weight (W) and the number of days required to reach the marketable size of 6 cm (TTM-time to market), were selected [38,39].…”