Abundance, age distributions, and growth of the Texas hard clam, Mercenaria mercenaria texana in Texas bays.

Abstract

The hard clam Mercenaria mercenaria (Linne) has been well studied; however, little information is available on Mercenaria mercenaria texana, the subspecies found in Texas bays. Age and growth of Mercenaria mercenaria texana in Christmas Bay, Texas were determined by sectioning the shell and examining annual growth bands. Christmas Bay harbors a sparse population of older clams with few under five years old. Substrate type plays an important role in distribution and growth of the bivalve. Christmas Bay clams exhibited poorer recruitment and slower first year growth than did clams from Texas bays further south. Mercenaria mercenaria texana shows a pattern of growth similar to that reported in the literature for hybrids of Mercenaria mercenaria (Linne) and Mercenaria campechiensis (Gmelin).