Abstract
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. 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. The identified agent responsible for this reduction in C. gigas production was Ostreid Herpesvirus microvar (OsHV-1 μvar), which has been associated with C. gigas spat mortalities in France, and in many other countries. In Spain the episodes of mortality became critical for the regional shellfish production between 2008 until 2014, with mortality percentage up to 100%. In this study, local hatchery C. 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. A production calendar mainly based on water temperature dynamics was designed around an optimal schedule for spat immersion. The immersion calendar included two optimal periods for spat immersion, in summer when temperatures are ≥25°C and at the end of autumn and beginning of winter when they are ≤13°C. Such production planning has reduced mortalities from 80% (in 2014 and previous years) to 2–7.5% in 2015 in cemented oysters. 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. 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. This approach could be used as a management model in areas presenting similar production practices and environmental characteristics.
Highlights
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◦C
Water temperature dynamics was used as a basis to define an optimal production calendar in the Ebro Delta reducing OsHV1 μvar impact on C. gigas cultures
The epidemiological study showed that OsHV-1 μvar seems to be present during all seasons, FIGURE 2 | (A) Epidemiological study
Summary
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◦C. In France recent studies reported temperatures between 16 and 20◦C (up to 24◦C) associated with disease outbreaks (Petton et al, 2013; Pernet et al, 2014), while in Australia the threshold for inducing mortalities was observed between 21 and 27◦C (Paul-Pont et al, 2014). Oyster age and size influences how the animals respond to an infection and effects survival rates (Dégremont, 2013; Green et al, 2014). Both water temperature and oyster size seems to play a relevant role in OsHV-1 μvar epidemiology dynamics. The management approach needs to be production-area specific taking into account the particularities of each site: the local epidemiology, and the environmental and production/commercial characteristics of each particular cultivation area (Pernet et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
