Quantitative Assessment of Gamete Production in Two Commercially Harvested Clams, Venerupis aurea and Tapes decussata (Bivalvia:Veneridae) in Lake Timsah, Suez Canal, Egypt

Document Type : Original Article

Author

Zoology Department, Faculty of Science, Fayoum University, 63514 Fayoum, Egypt

Abstract

Monthly relationships between shell length and gonad weight for two clams of commercial value;
Venerupis aurea and Tapes decussata from El-Taawen area in Lake Timsah, Suez Canal, were
determined between August 2004 and September 2005. Spawning frequency and individual gamete
production (fecundity) under natural conditions were assessed by monitoring fluctuations in the gonad
weight of standard-sized individuals. The results showed that the gonadal development and spawning
continue throughout the year. There is no evidence of clearly defined reproductive cycles. The two
species showed no “reproductive senility” and spawned several times per year. Gamete production,
expressed as weight loss at spawning, occurred at different rates throughout the consecutive spawning
periods and was positively correlated with body size. Spawning efficiency increased or decreased linearly
with size. The relative amounts of reproductive material released by examined clams of different sizes
reached 45.34 and 53.62% of the gonad weight during December 2004 for V. aurea and T. decussata,
respectively. Both species exhibited remarkable reproductive effort in Lake Timash.

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