As part of feasibility studies on the farming of Pinctada imbricata along the central coast of New South Wales, pearl oysters were introduced at a series of sites ranging from the state of Victoria to New South Wales.

This three-year series of trials aimed to measure the influence of site on growth, survival, and nacre quality. Groups of sibling oysters were placed at sites stretching from Port Phillip Bay, in the far south of Victoria, to the central coast of New South Wales. The results revealed significant differences depending on location.

Latitude and Growth: An Observed Correlation

Observations show that oyster growth generally decreases as latitude increases. This trend may be linked to lower average water temperatures. However, significant growth variations were also recorded at sites where temperature did not appear to be a determining factor.

Shell analysis revealed a close correlation between nacre thickness and oyster growth.

Color and Luster: Variability Across Sites

Nacre quality — in terms of color and luster — was assessed by a panel of independent experts, who rated it according to commercial value. The results show that color and luster vary significantly from one site to another, without showing a correlation with growth.

Moreover, the quality of color and luster are not necessarily related to each other at a given site.

Changes Over Time

At sites monitored over multiple consecutive years, the relative quality of nacre color and luster changed over time, confirming the importance of long-term monitoring to better understand the effect of the environment on pearl production.