Agar properties of two potentially commercial important seaweeds from the Gulf of California were studied. Maximum yield in Gracilaria vermiculophylla (45.7%) occurred during the summer months, coinciding with high water temperatures (31°C) whereas minimum yields (11.6%) were obtained during the coldest months of the year when populations of this species diminish in the bay. Gracilariopsis longissima showed two yield peaks, one in spring and another in fall, before the maximum and minimum seawater temperatures. Gel strength in native agar from the two species was low (<22.5 g cm −2 ) for most of the year.