THE GROWTH-RATES OF 4 POPULATIONS OF ARTEMIA-FRANCISCANA (ANOSTRACA, ARTEMIIDAE)

The growth rates of three populations of Artemia franciscana from Mexi co (one from Yavaros, Sonora and two from San Jose, Baja California) a nd that of the reference strain from San Francisco Bay, California, gr own under the same laboratory conditions, were not statistically diffe rent, either considering total mean increase in length, or increase by stages. However, interpopulational differences were detected in the f inal length of some developmental stages. In addition, regressive chan ges of dimensions were noted in some populations at the time of stage change. These might be the result of inborn characteristics of each st rain, causing each population of Artemia franciscana to respond, in ph ysiological terms, in different ways to the same environmental conditi ons.