Resumo

ALVAREZ, Fernando  e  RANGEL, Rebeca. Population study of the crayfish Cambarellus montezumae (Crustacea: Decapoda: Cambaridae) in Xochimilco, Mexico. Rev. Mex. Biodiv. [online]. 2007, vol.78, n.2, pp.431-437. ISSN 2007-8706.

A population study of the crayfish Cambarellus montezumae in Xochimilco, Mexico, is presented. The study is based on the analysis of 12 samplings, from October 2001 to May 2002, in which 668 organisms were collected. The size range recorded was 2.1 to 41.5 mm total length. The males had smaller sizes than females, and were classified as juveniles, form I and form II. The constant presence of form I males and ovigerous females, together with the presence of small sized individuals in most of the samples suggest that there is a continuous reproduction during the study period. The growth estimates, based on a modal progression analysis of length-frequency data, resulted in a mean daily growth rate of 0.084 mm, or a mean monthly rate of 2.535 mm. The sizes at first reproduction were 24 mm total length for females and 21 mm for males, attained between 248 and 284 days of age. The mortality estimate, computed as Z (instantaneous mortality rate), shows that there is a high mortality during the first two months of life and that only 4% of the population is reaching reproductive sizes. No relation was found between number of C. montezumae collected and temperature, dissolved oxygen concentration and pH.

Palavras-chave : Crustacea; Cambaridae; Cambarellus montezumae; Xochimilco.

        · resumo em Espanhol     · texto em Espanhol     · Espanhol ( pdf )