Background:

Macrobrachium tenellum from the San Pedro Mezquital River in Nayarit, Mexico, started being used in 1995 as a seasonal crustacean that satisfied local demand. Fishing of this species later intensified as an alternative economic activity, with a regional impact based on food production and job creation.

Goals:

To estimate the growth and mortality parameters of M. tenellum from the San Pedro Mezquital River, Nayarit.

Methods:

Sampling took place from February to October 2010. Drop nets (atarrayas) with mesh sizes of 1 and 1.5 inches were used to collect samples of 100 individuals. Age groups were defined following the Cassie method, growth parameters with the Walford method, total annual mortality with the Beverton and Holt method, and natural mortality with the Rikhter and Effanov equation.

Results:

Data obtained were for females L∞= 19 cm, P∞ = 55 g, k = 0.369 month-1 and t0= -0.035 month-1, and for males L∞= 26.6 cm, P∞ = 239 g, k = 0.221 month-1 and t0 = -0.042 month-1. Based on the length-weight relationship, the females had negative allometric growth (b<3) and the males positive allometric growth (b>3). The mortality parameters were for females Z = 3.84 year-1, M = 0.72 year-1, and E = 0.79 year-1, and for males Z = 2.75 year-1, M = 0.69 year-1, and E = 0.70 year-1.

Conclusions:

The prawn Macrobrachium tenellum has a short life cycle of less than two years, a moderate growth rate, and high rates of total mortality and exploitation, which result in an over-exploitation of the resource in the study area.