On the Spinicaudata (Branchiopoda) from Lake Cuitzeo, Michoacán, México: First report of a clam shrimp fishery.

Cuitzeo is the second largest lake in México (ca. 425 km²). Indigenous people collect clam shrimp (locally known as ‘conchilla’) and sell them dry as pets' food; the income is important for the local economy. To our knowledge, this is the first report of a clam shrimp fishery. Two conchilla species co-occur: Eocyzicus digueti (Richard) and Leptestheria compleximanus (Packard). They were restricted to the saline, soda-alkaline, and temporally astatic W and NW portions of the lake. E. digueti constituted 70% of the total clam shrimp abundance, and L. compleximanus the remainder. Populations were dominated by juveniles, followed by females and males, with sex ratios (male:female) of 1:1.2 to 1:1.4. E. digueti was larger (3–11 mm) than L. compleximanus (3–8.5 mm), and males were larger than females in both species. There were highly significant correlations between carapace size and the number of growth lines and carapace size and the number of eggs. Although previously reported from México, both species are new records for Lake Cuitzeo and for Michoacán state. [ABSTRACT FROM AUTHOR]