Trends of Abundance of Salton Sea Fish: A Reversible Collapse or a Permanent Condition?

Abstract

The Salton Sea is a closed-basin, 980 km 2 salt lake in the Sonoran Desert of southern California. Three marine species, bairdiella ( Bairdiella icistia ), orangemouth corvina ( Cynoscion xanthulus ), and sargo ( Anisotremus davidsoni ), established from introductions of over 34 species beginning in 1929. During the late 1960s and early 1970s, a hybrid tilapia ( Oreochromis mossambicus × O. urolepis hornorum ) invaded the Salton Sea and became dominant by number and weight. Recent surveys show a precipitous decline of all four species above starting sometime between 2001 and 2002. Declines were more evident in nearshore than in estuarine habitats. Corvina has probably declined the soonest, followed by Gulf croaker. Tilapia declines were followed by more recent increases in population numbers. The tilapia rebound observed are probably only sustainable if a curb in Salton Sea salinity levels is realized. The marine species will likely need restocking to reach historic levels, if the salinity of the lake is managed at 40 g • L – 1 or below. Restoration alternatives for the Salton Sea must take into consideration estuarine areas as essential fish habitats and fish refuge against high salinities.