Recruitment pattern of commercially harvested clam, venerupis aurea (bivalvia: veneridae) at the southern region of Lake Timsah, Suez Canal, Egypt

The recruitment pattern of the venerid Venerupis aurea was monitored from August 2004 to September 2005 to investigate the feasibility of collecting natural spat for management or maricultural purposes. Three sites of varying adult densities were chosen in the southern region of Lake Timsah, Suez Canal, Egypt. Recruitment is used, herein, to refer to juveniles of generally less than 9 mm shell length. The separation between juveniles and adults was based on the size at onset of maturity. Recruitment of V. aurea was continuous throughout most of the year and varied significantly among the three sites. Monthly collections yielded an average of 687.1, 239.5, and 115.3 spat m-2 at sites I, II, and III, respectively. Higher abundance of recruits occurred during the period from November 2004 to March 2005. The average density of juveniles for this period (n = 5) was 1508.0, 293.6, and 262.4 ind. m-2 at the three sites, respectively. The data suggest that the survival of recruits is probably influenced by abiotic factors, particularly sediment composition, rather than by biotic factors such as adult-juvenile interactions. The growth in length for juveniles from site I is accompanied by growth in weight (isometric growth). At site II and III, weight increased relatively slower than length indicating negative allometric growth.

本研究于2004年8月至2005年9月对帘蛤科Venerupis aurea的补充模式开展监测，以探究采集天然幼贝（spat）用于渔业资源管理与海水养殖的可行性。研究团队在埃及苏伊士运河沿岸的提姆萨湖南部区域，选取了3个成体密度各异的采样站点。
本研究中，“补充”特指壳长普遍小于9毫米的幼贝；幼贝与成贝的划分标准为性成熟起始时的个体规格。Venerupis aurea的补充群体全年多数时段均有出现，且3个采样站点的补充量存在显著差异。月度采样结果显示，站点I、II、III的平均幼贝密度分别为687.1、239.5及115.3个/平方米。幼贝丰度的峰值出现在2004年11月至2005年3月期间，该时段（n=5）内3个站点的幼贝平均密度分别为1508.0、293.6及262.4个/平方米。
研究数据表明，幼贝的存活大概率受非生物因子（abiotic factors）影响，尤以沉积物组成为甚，而非成贝与幼贝的种内互作等生物因子。站点I的幼贝壳长增长与体重增长呈等速生长（isometric growth）关系；站点II与III的幼贝体重增长速率相对滞后于壳长增长，表现为负异速生长（negative allometric growth）。