Effects of shell abrasion and aerial exposure on the performance of Pacific Oysters Crassostrea gigas (Thunberg, 1793) cultured in Tasmania, Australia.

Two of the major management strategies used by Tasmanian oyster farmers for grow-out of unattached (single-seed) Pacific oysters (Crassostrea gigas) are shell abrasion, occurring either deliberately or inadvertently during mechanised grading, and manipulation of intertidal growing height (degree of aerial exposure). Some farmers assert that these strategies can promote faster meat growth, and hence higher condition indices [meat weight relative either to shell cavity volume (Clvol), or to shell weight (Clshe1l). These reports, however, are anecdotal and have not been substantiated in the literature. The present study was undertaken to evaluate the effects of shell abrasion and aerial exposure on the performance (growth, condition index, shell shape, glycogen content and gonad development) of Pacific oysters cultured in mesh baskets, in two separate experiments, on two commercial leases in Tasmania.