Abstract
The Greenshell™ mussel, Perna canaliculus , is the most lucrative aquaculture species in New Zealand; however, losses of commercial juvenile mussels (spat) are common and can drastically reduce the yield of adults. Modification of seeding density is a potential method to manage loss of spat (~ 1–20-mm shell length), by reducing biofouling and intraspecific competition. Understanding the stress responses of spat in production systems during the early stages of aquaculture is a high priority for mussel farmers who aim to manage and optimise mussel production. Here, the effects of seeding density (low: 257, mid: 515, and high: 1030 mussels 10 cm −1 of culture rope), space (depth, site), and time (December 2019 and February 2020) on oxidative stress responses (total antioxidant capacity [TAC] and lipid peroxidation [LP] biomarkers) in spat and their viability (freshwater immersion test) were assessed in the Marlborough Sounds, New Zealand. The effect of seeding density on TAC was variable among depths, sites, and times, whereas seeding density had no impact on LP. In late summer (February 2020), oxidative stress appeared to be higher compared to early summer (December 2019). This indicates that mussels were exposed to more stressful conditions later in summer, although this did not reduce their short-term viability. This research found that seeding density had no major impact on oxidative stress biomarkers and suggests that stress responses and viability of Greenshell™ mussel spat during the summer months are not affected by the seeding density levels measured in this study.