Growth and gametogenic cycle of the blood ark, Anadara ovalis (Bruguiere, 1789) in coastal Georgia

We collected two cohorts (1994, 1995) of blood arks, Anadara ovalis from sets that had occurred on surf clam cages in Wassaw Sound, Georgia. Subsequent to transferal into pearl nets, the arks were suspended from the main dock at the Skidaway Institute of Oceanography on the Skidaway River, Georgia, between January 1995 and April 1997. To determine the reproductive cycle and growth rate, we collected arks monthly, measured each individual for shell length, and took a gonadal sample for histological analysis. Arks from the 1994 cohort grew from a mean shell length of 17.8 mm to 39.9 mm in 15 months, a rate of 1.47 mm per month. Arks from the 1995 cohort grew from a mean shell length of 9.9 mm to 42.6 mm in 16 months, a rate of 2.04 mm per month. Growth was most rapid during the spring and summer months. Of the 747 arks sectioned for histological examination, males dominated the population (66%) and 7.2% were sexually indeterminate. A minor spawning event occurred in the winter months of the first year for each cohort [0+ years) followed by a major spawning commencing in April and continuing through the summer months. In Georgia, it appears that blood arks recruit in summer-early fall, and that juveniles grow rapidly to reach sexual maturity at an early size (10-12 mm) and age (-8 months).