Pm. Anastacio et al., CRISP (crayfish and rice integrated system of production): 2. Modelling crayfish (Procambarus clarkii) population dynamics, ECOL MODEL, 123(1), 1999, pp. 5-16
An ecological sub-model of crayfish (Procambarus clarkii) population dynami
cs is presented for integration into the CRISP (crayfish and rice integrate
d system of production) series of models. The present structure is directed
towards simulation of crayfish population responses under different human
interventions, namely different capture rates. The crayfish population was
subdivided into seven age classes of 80 days, each one constituting a state
variable. The increase in weight for each 80-day period was considered dep
endent on the temperature, the oxygen level and the water level. Mortality
was assumed to be dependent on the dry weight of the crayfish and regulated
by the total crayfish biomass. Food, water and oxygen content of the water
were considered to be non limiting. Total crayfish biomass and total wet w
eight of crayfish captures were very sensitive to both the temperature for
maximum growth and the mortality rates. Our most optimistic simulation, wit
h a 50% decrease in the mortality rates, resulted in a fourfold increase in
captures, from 230 to 917 kg ha(-1) per year. Without capture, a value of
121 kg ha(-1) was simulated for the average crayfish biomass, which is clos
e to the 124 kg ha(-1) obtained with crayfish capture. Our simulated averag
e crayfish biomass was approximately 120 kg ha(-1) in a natural situation,
which lies inside the reported ranges from areas at approximately the same
latitude. (C) 1999 Elsevier Science B.V. All rights reserved.