Nonlinear regression modeling was used to study the nursery production of the oyster Crassostrea virginica in the Celest & uacute;n (CL) and Rio Lagartos (RL) lagoons in Yucat & aacute;n, Mexico. Relationships between production parameters and environmental variables were also established. Spat (2.40 +/- 0.20 mm) was obtained from a hatchery and reared in Nestier-type trays using an off-bottom system. Oyster cultivation took place from May 2021 to September 2021 and ended after 122-126 days when oysters reached 30.00 mm. There were no significant differences in final height (CL: 30.80 +/- 0.42 mm; RL: 31.80 +/- 0.65 mm; P = 0.18) and growth rate (CL: 0.23 +/- 0.02 mm<middle dot>d(-1); RL: 0.23 +/- 0.01 mm<middle dot>d(-1); P = 0.98). Final survival was 71.45% in CL and 99.40% in RL. Nonlinear regression curves were statistically satisfactory for analyzing growth and survival. Except for dissolved oxygen, mean salinity (CL: 15.23 ppt; RL: 35.02 ppt), temperature (CL: 29.64 degrees C; RL: 31.02 degrees C), dissolved oxygen (CL: 4.50 mg<middle dot>L-1; RL: 5.04 mg<middle dot>L-1), pH (CL: 8.10; RL: 8.34), chlorophyll a (Chl a) (CL: 3.23 mg<middle dot>m(-3); RL: 6.85 mg<middle dot>m(-3)), and total dissolved solids (CL: 16,101 mg<middle dot>L-1; RL: 34,838 mg<middle dot>L-1) were significantly higher in RL (P < 0.05). Except for Chl a, the environmental variables were more stable in RL than in CL (P < 0.05). In RL, the growth rate was positively related to salinity and pH. In CL, the growth rate slowed when salinity decreased, and the mortality rate diminished when salinity, dissolved oxygen, and total dissolved solids increased and pH decreased. Salinity was mainly responsible for the observed differences in production between lagoons. Even when temperature and salinity were high in RL, acceptable growth rate and survival were observed, possibly due to stable rearing conditions.
