Detailed methods are presented in Sasaki & Dam 2019 (DOI: 10.1111/gcb.14811). Copepods were collected from ten locations across the Northwest Atlantic (recorded in the Population column). Populations were maintained at the UConn Avery Point campus for three generations at 18oC, with a 12:12 light:dark cycle and a diet of Tetrasemis sp., Thalassiosira weissflogii, and Rhodomonas salina. F3 generation eggs were collected and split into two groups, which developed at either 18oC or 22oC. Egg production assays were performed at the temperature individuals developed at (recorded in the Temp column).