2.2.5 Growth

Only general statements can be made about growth in juveniles and adults since it varies greatly between species, geographic distribution, i.e. climate, location in the subtidal or intertidal zones, as well as differences in individuals and in their genetic make up. Growth can also vary greatly from year to year and in temperate areas there are seasonal patterns in growth.

Growth can be measured in bivalves by different methods including increments in shell length or height, increases in total or soft body weight, or a combination of all of these factors. In tropical areas growth can vary with season, being faster during or after rainy periods when nutrients are washed into the ocean leading to increased production of phytoplankton. In temperate areas, growth is generally rapid during spring and summer when food is abundant and water temperatures are warmer. It virtually ceases in winter, resulting in annual checks in the shell. These winter checks can be used to age some bivalves. Some species are short lived but others may live to over 150 years.
In culture operations the important considerations in bivalve growth are length of time taken to grow to sexual maturity and to market size. The goal of bivalve culture is to grow bivalves to commercial size as quickly as possible to make the operation as economically attractive as possible.