Scientia Marina, Vol 68, No 2 (2004)

Morphometry, growth and reproduction of an Atlantic population of the razor clam Ensis macha (Molina, 1782)


https://doi.org/10.3989/scimar.2004.68n2211

Pedro J. Barón
Centro Nacional Patagónico, CONICET - Universidad Nacional de la Patagonia San Juan Bosco, Argentina

Luciano E. Real
Universidad Nacional de la Patagonia San Juan Bosco, Argentina

Néstor F. Ciocco
Centro Nacional Patagónico, CONICET - Universidad Nacional de la Patagonia San Juan Bosco, Argentina

María E. Ré
Centro Nacional Patagónico, CONICET, Argentina

Abstract


Ensis macha is a razor clam distributed throughout the coasts of southern Argentina and Chile. Even though it represents a valuable fishery resource, the exploitation of its Atlantic populations has begun only in recent years. This study provides the first estimates of growth rate, an interpretation of the reproductive cycle on the coast of the northern Argentine Patagonia and an analysis of the species morphometry. Growth was estimated by direct observation of growth rings on the valves by two observers. The reproductive cycle was interpreted by the analysis of temporal change of oocyte size frequency distributions. Parameter estimations for the von Bertalanffy equations respectively obtained by observers 1 and 2 were 154 and 153.7 mm for L?, 0.25 and 0.20 yr-1 for k, and -0.08 and -0.72 yr for t0. Two spawning peaks were detected: September-November 1999 and May-June 2000. However, mature females were found all year round. An abrupt change in the relationship between shell length and height was detected at 11.2 mm length.

Keywords


razor clam; morphometric relationships; growth; reproduction; Ensismacha; allometric growth

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