Breeding Focus 2018 – Reducing Heat Stress

Summer mortality is a phenomenon that causes mass die offs of molluscs during the summer months. Summer mortality affected molluscs include many economical important animals including; oysters, mussels, clams, scallops and abalone. The condition occurs in both natural and aquaculture environments and represents a considerable threat towards aquaculture and fi sheries industries world-wide. Although sudden increases in water temperature are known contributors to summer mortality events, intrinsic factors (i.e. animal age and gametogenesis) and extrinsic factors (i.e. food availability and quality, increased salinity, decreased dissolved oxygen and the presence of pathogenic viruses and bacteria) can also play a role. Genetically driven factors are also considered to play a crucial role in susceptibility and resilience to summer mortality and these have been investigated recently using transcriptomics (i.e. broad scale patterns of gene expression). Immune, metabolic and stress response processes have commonly been found to differ between resilient and susceptible families, lines and/or populations. In addition, more complex genetic interactions such as regulatory transcription and epigenetic