France and New Zealand have approached this problem mainly with the development of selective breeding programs aimed toward virus-resistance oyster stocks in order to obtain better spat performance with higher survival when facing critical viral episodes ( Dégremont et al., 2015a, 2016b Pernet et al., 2016). Since then, the problem of oyster herpesvirus has become a relevant issue in most of the European countries where Pacific oyster production occurs, as well as in other countries outside Europe, such as Australia and New Zealand ( Jenkins et al., 2013 Keeling et al., 2014). The ostreid herpesvirus microvar (OsHV-1 μvar) was described in 2010 as a virulent OsHV-1 variant associated with high mortality in spat and juvenile Pacific oyster Crassostrea gigas in France, at least since 2008 ( Segarra et al., 2010), when temperatures reached 16☌. This approach could be used as a management model in areas presenting similar production practices and environmental characteristics. This work presents a successfully tested management strategy reducing OsHV-1 μvar impact by designing new field management practices mainly focused on the handling and timing of spat immersion. Furthermore, other recommendations related to spat immersion size, culture density and methodology, and cementing calendar, which helped to achieve the results presented, were also recorded and transferred to local producers. Such production planning has reduced mortalities from 80% (in 2014 and previous years) to 2–7.5% in 2015 in cemented oysters. The immersion calendar included two optimal periods for spat immersion, in summer when temperatures are ≥25☌ and at the end of autumn and beginning of winter when they are ≤13☌. A production calendar mainly based on water temperature dynamics was designed around an optimal schedule for spat immersion. gigas spat was used as sentinel animals for epidemiological studies and management tests carried out with the aim of reducing oyster mortality in the Ebro Delta area. In Spain the episodes of mortality became critical for the regional shellfish production between 2008 until 2014, with mortality percentage up to 100%. gigas spat mortalities in France, and in many other countries. gigas production was Ostreid Herpesvirus microvar (OsHV-1 μvar), which has been associated with C. The identified agent responsible for this reduction in C. This decline in production has had a significant socio-economic impact in a region where the shellfish sector is a traditional economic activity for many families.
Since 2006, the production of Pacific oyster Crassostrea gigas in the Ebro Delta area has dramatically declined from around 800 metric tons (MT) per year to 138 MT in 2011. Institute for Research and Technology in Food and Agriculture, Sant Carles de la Ràpita, Spain.Andree, Ana Roque, Margarita Fernández-Tejedor, Chris J. Noèlia Carrasco *, Ignasi Gairin, Josu Pérez, Karl B.
0 kommentar(er)
