Oysters are not uniform in nature.

Oysters are not uniform in nature. Some are very long, others have a depth to them and others can be thin and round. Growth varies based on factors such as growing area salinity, species of oyster, available food and tidal action. Oysters from the same area may be similar but never identical. There are at least three grades by oyster size and possibly more depending upon the markets. Some customers prefer oysters that are round and 2 in. in diameter (Hutt, 2004). Depth and shape are used to determine three categories: choice, standard, and commercial and to establish four oyster grades: perfect, excellent, good, and irregular portion (Little Shemogue Oyster Company). Experts from the west coast oyster farms attempted to establish guidelines to describe desirable (good) and undesirable (bad) shell shapes (Brake et al., 2003). The ratio of the greatest depth to greatest shell length (D/L) was found to be more effective in categorizing good and bad shell shapes. Good shell shape has a mean D/L of 0.316 and bad oysters had a significantly lower D/L mean of 0.219. A D/L threshold of 0.25 was used to achieve 85.6% accuracy in separating good and bad oysters.